United States
          Environmental Protection
          Agency
Office of Air Quality
Ranning and Standards
Research Triangle Park, NC
EPA 340/1-92-01 5b
September 1992
Revised March 1993
          Stationary Source Compliance Training Series
fVEPA  COURSE #345
          EMISSION CAPTURE AND
          GAS HANDLING SYSTEM
          INSPECTION
          Instructor Manual

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                                    EPA 340/1-92-01 5b
                                    Revised March 1993
        Course Module #345



       Emission  Capture And

Gas Handling System Inspection



            Instructor Manual



                  Prepared by:

        Crowder Environmental Associates, Inc.
               2905 Province Place
                Piano, TX 75075
                     and
           Entrophy Environmentalist, Inc.
                 PO Box 12291
          Research Triangle Park, NC 27709
             Contract No. 68-02-4462
             Work Assignment No. 174
       EPA Work Assignment Manager: Kirk Foster
          EPA Project Officer: Aaron Martin
    US. ENVIRONMENTAL PROTECTION AGENCY
       Stationary Source Compliance Division
     Office of Air Quality Planning and Standards
             Washington, DC 20460
                September 1992
               Revised March 1993

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                          DISCLAIMER


     This manual was prepared by Crowder Environmental Associates,
Inc. and Entropy Environmentalists, Inc. for the Stationary Source
Compliance Division  of the  U.S.  Environmental  Protection Agency.
It has been completed in accordance with EPA Contract Number 68-02-
4462, Work Assignment No.  174.   The contents of this  report are
reproduced herein  as received from the  authors.   The opinions,
findings, and conclusions expressed are those  of the authors and
not necessarily those of the U.S. Environmental Protection Agency.
Any mention of product names does not constitute endorsement by the
U.S. Environmental Protection Agency.

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                     ACKNOWLEDGEMENTS
          This manual is a revised version of a manual originally
prepared by  Crowder  Environmental Associates,  Inc. for  the  U.S.
EPA,  Stationary  Source  Compliance  Division   (SSCD).    It  was
originally prepared  under a subcontract to  PEI  Associates,  Inc.
Entropy Environmentalists,  Inc.  has  converted the manual  into  a
standardized format developed by the EPA Work Assignment Manager,
Mr. Kirk  Foster.   The  majority  of the drawings  and  photographs
included in the original manual have been redrawn and modified by
Ms. Sherry Peeler, Pendragon Inc.  with  the  assistance of Entropy
Environmentalists, Inc.
                                   nr   Pf  ENRV  Library
                                   U.S. EPA Region VII
                                11

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                     TABLE OF CONTENTS
          Topic                                       Page

Introductory Material
     Course Description                               0-1
     Course Goals                                     0-2
     Responsibilities of Course  Director               0-3
     Instructors                                      0-5
     Physical Settings and Equipment                   0-5
     Lesson Plans                                     0-6
     Testing Information                              0-6
     Grading Philosophy                               0-7
     Sample Agenda                                    0-8
     Pre-test                                         0-10
     Pre-test key                                     0-15
     Post-test                                        0-16
     Post-test key                                    0-21
Lesson l. General Principles of Ventilation

     Goal                                             1-1
     Objectives                                       1-1
     List of Slides                                   1-2
     Lesson Outline                                   1-3
     Problem Set 1                                    1-10

Lesson 2. Hood Systems

     Goal                                             2-1
     Objectives                                       2-1
     List of Slides                                   2-2
     Lesson Outline                                   2-3
     Problem Set 2                                    2-11

Lesson 3. Duct Systems

     Goal                                             3-1
     Objectives                                       3-1
     List of Slides                                   3-2
     Lesson Outline                                   3-3
     Problem Set 3                                    3-12
                                IV

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Lesson 4. Gas Cooling Systems

     Goal                                              4-1
     Objectives                                        4-1
     List of Slides                                    4~2
     Lesson Outline                                    4-3
     Problem Set 4                                     4-11

Lesson 5. Fan Systems

     Goal                                              5-1
     Objectives                                        5-1
     List of Slides                                    5-2
     Lesson Outline                                    5-3
     Problem Set 5                                     5-18

Lesson 6. Measurement of Ventilation System Parameters

     Goal                                              6-1
     Objectives                                        6-1
     List of Slides                                    6-2
     Lesson Outline                                    6-3
     Problem Set 6                                     6-18

Lesson 7. Ventilation System Inspection

     Goal                                              7-1
     Objectives                                        7-1
     List of Slides                                    7-2
     Lesson Outline                                    7-3
     Problem Set 7                                     7-7

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                   INTRODUCTORY MATERIAL
     This  guide  will  provide  you,   as  Course  Director,  with
 assistance  in the  preparation and  presentation  of  the  course,
 "Inspection  of Industrial  Ventilation  Systems."   It will  provide
 you  with guidelines,  instructions  and general information  that
 should make  it easier to conduct this course.
 COURSE  DESCRIPTION

      This training course is a four-day lecture course dealing with
 the  inspection of industrial ventilation  systems.   In is  not  a
 course  in the design of ventilation systems.  Although much of the
 information presented comes from the design literature, many of the
 topics  needed to design systems  have not  been included.   That
 information  that  is  utilized is oriented to  focus  on inspection
 applications,  rather than on design applications.

      The course is organized into several lessons, with each lesson
 having  a problem  set  that allows  the  student  to apply the skills
 taught.  The  lesson topics are as follows:

      1.  General Principles of Ventilation

      2.  Hood  Systems

      3.  Duct  Systems

      4.  Gas cooling Systems

      5.  Fan Systems

      6.  Measurement of  Ventilation System Parameters

      7.  Ventilation System Inspection

      This  course should  be  taught  at  an  instructional  level
equivalent to  that  of undergraduate university  study.   Students
should have a college education at the associated or bachelor level
in science  or engineering and should  have  completed APTI Course
445,   "Baseline Source  Inspection  Techniques",  and  Course 446,
"Inspection Procedures and Safety."
Course 345                     0-1          Introductory Material

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 COURSE GOALS

      The overall goal of this course is to provide  students with
 the training and information necessary  to  conduct effective Level
 2 and Level 3 inspections of industrial ventilation  systems.  The
 specific goals are:

      1.  To develop an understanding of the basic information that
          affects the character and behavior of air streams.

      2.  To develop an understanding of the different hood types,
          their design and performance characteristics,  and
          techniques for their evaluation.

      3.  To develop an understanding of duct  systems,  their
          design and performance characteristics,  and
          techniques for their evaluation.

      4.  To develop an understanding of gas cooling  systems,
          their design and performance characteristics,  and
          techniques for their evaluation.

      5.  To develop an understanding of fan systems,  their
          design and performance characteristics,  and
          techniques for their evaluation.

      6.  To develop an understanding of the equipment and
          procedures for the measurement of ventilation system
          parameters and the limitations of the techniques.

 RESPONSIBILITIES OF THE COURSE DIRECTOR

      This course requires four days for a complete  presentation.
 In addition, the  Course Director can  expect  to spend 10  and 20
 hours preparing  for course.   Pre-course  preparation  and course
 continuity   are   the principal  responsibilities  of  the  Course
 Director,  and  the  Course  Director will  coordinate all  on-site
 activities  both before  and  during the  course presentation.   The
 actual  tasks that are considered the direct responsibility of the
 Course  Director  are as  follows:

      1.   Scheduling the  course presentation.

      2.   Recruiting,  hiring,  and briefing  the instructors

      3.   Preparing the  classroom and other teaching  facilities

      4.  Preparing and distributing course materials to instructors
          and students.

      5.   Presenting the  introductory lecture  and other  lectures,
          as  appropriate
Course 345                      0-2          Introductory Material

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      6.  Maintaining  the  continuity  and  coordination  throughout
         the  course.

      The following checklist is provided  as an organization aid for
 the  Course  Directors.

                   Pre-Course  Responsibilities

 	  Reserve  and confirm  classroom.  Consider  size,  set-up
        arrangement, and costs.

 	  Contact  and confirm  all faculty for the course and
        determine  their A/V  requirements.  Send instructional
        materials  to them.   One or more pre-course meetings  are
        advisable  to order to ensure  coordination and  continuity
        of presentations.

 	  Reserve  hotel  accommodations  for  faculty  (if necessary).

 	  Make and confirm arrangements  for coffee  breaks

 	  If any eating  facilities are  likely to be heavily used by
        students,  inform them of anticipated patronage and
        anticipated lunch  break times.

 	  Make and confirm arrangements  for transportation of
        students (if necessary).

 	  Assemble and send  to students  information on exact
        location and times of course  and  information on
        available  lodging, eating, and transportation
        facilities.  Reserve a  block  of rooms for students
        if appropriate.

 	  Prepare  and reproduce final copies of the course agenda.

 	  Reproduce  class roster,  if available

 	  Identify,  order, and confirm  all  audiovisual equipment.

 	  Prepare  course identification signs for posting at meeting
        area.

 	  Arrange  for and confirm any special on-site administrative
        assistance needs.

 	  Obtain copies  of manuals and  hand-outs.

 	  Pack and ship  course materials one week before course
        begins.
Course 345                      0-3           Introductory Material

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                  On-Site Course Responsibilities


        Check on final room arrangements (i.e., tables, chairs,
        lectern, water, cups)

        Each day, set up audiovisual equipment and brief the
        operator.

         Post signs where needed.

         Give receptionist,  phone  operator,  and guards the names,
         location,  and agenda  of the course  and names of the
         attendees.

        Conduct a briefing session for each  new instructor.

        Verify and make final  coffee arrangements.

        Identify and arrange for other physical needs as
        required.

        Make a final check on  arrival of instructors for the day.


                   Post-Course Responsibilities

        Return the  following to EPA (if an EPA course):
           Unused course materials
           Student  registration forms
           Pre-test  answer sheets  - graded
           Post-test answer  sheets - graded
           Student  course critiques
           Instructor course critiques

        Prepare  Course Director's  Report

        Request  honorarium and expense statements from faculty;
        order  and process checks.

        Write  thank-you letters to non-paid  speakers- and to
        others who may have  contributed to the success of the
        course.

        Make sure audiovisual  equipment is returned.
Course 345                      0-4          introductory Material

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INSTRUCTORS

     The  five most  important criteria in the selection of  faculty
for this  course  are:

     1.   A knowledge of the current methods, procedures, and
          industrial situations  involved in the inspection  of
          ventilation systems.

     2.   Recent  relevant practice al experience.

     3.   Knowledge  of  the kinds of jobs for which the training
          is  designed.

     4.   Ability to instruct adults using appropriate methods,
          materials, and techniques.

     5.   A positive attitude toward air quality management.

     Before  instructors are actually involved with instruction in
the classroom, the Course Director should conduct thorough briefing
and  preparation  sessions.   During  these  sessions  the  Director
should provide an overview of the  course, discuss course goals and
lesson  objectives,  and ensure that  the  instructors  are  well
prepared  and   familiar with  the  materials,   procedures,   and
techniques that  they will be using.

     All  instructors should understand the function of the course
goals  and lesson objectives, and  understand  the  relationship of
each goal and objective to the  instructional materials and to the
pre-test  and  post-test.    Attention   to   lesson  objectives  is
essential for successful presentation of course materials  and for
successful student performance  in this course.

     The  Course  Director  should  emphasize  the  importance  of
preparation  by the instructors.  Thorough familiarization with all
the prepared materials is essential for  each "expert" instructors.
Problem sessions  will  require additional preparation, including a
complete  run-through to become  familiar with the methods used.

PHYSICAL  SETTING  AND EQUIPMENT

     Classroom      1200 to 1500 square feet to accommodate 38
                    40 people

     Furnishings    All students should have desks or tables.

     Equipment      35mm slide; projector screen, at least 6  feet
                    square; Chalkboard, erasers and chalk,  (or
                    overhead projector and pens)

     Lighting       Adequate control to facilitate viewing slides
Course 345                     0-5           Introductory  Material

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 LESSON PLANS

      Each lesson plan contains  the  following  information:

      1.   Lesson goal  and objectives

      2.   Content guide for  the  instructor

      3.   Lecture outline

      4.   Guide for the use  of visual  aids

      5.   Solution key for the problem set

      In general,  each lesson plan  is organized  as an  expended
 outline,  with keys to the visual aids given in  the columns on the
 right side of each page.  Following  each lesson outline is a solved
 version of  the problem set  for  that lesson.   The  instructor must
 be familiar  with the  visual aids  and student materials  before
 attempting  to present any lesson.

      Instructors may wish to deviate from the format or content for
 given lesson, but should maintain  the schedule and be  sure that
 lesson objectives are met. Variations should be in the direction of
 greater student participation.   Instructors should  remember that
 the exams reflect the lesson objectives as presented  through the
 lesson outlines.  To stray too far from the prescribed lesson plan
 will  require  changes  in the post-test or  in  the test  grading
 process.

 TESTING INFORMATION

      Every student is  required to take two tests - a pre-test and
 a  post-tests.   The  pre-test  is to  be  given  during the  first
 scheduled class session.   It  is designed  to test  the  student's
 knowledge of the subject matter  on entering the course.  The score
 on this test will not  affect the student's grade  in the course.  It
 is  used only  to estimate  learning  gains and  to  inform  course
 designs about the effectiveness of  the instruction.   The pre-test
 is an open-book test;  in  other works,  the  students may use notes,
 books, or other reference materials.

     The post-test is to be given at the end of the course.  It is
 essentially a final exam.  The test  is designed to measure how well
 the student has  mastered the course goals and  lesson  objectives.
 The student's course  grade  depends  heavily on  the  performance  on
 this test.  The post-test is also an  open-book  test.
Course 345                     0-6          introductory Material

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 GRADING PHILOSOPHY

      The guidelines  for  evaluating student  performance and  for
 granting Continuing Education Units (CEUs)  are as  follows:


      1.   The student must:

           a.   Attend a minimum of  95%  of  all  scheduled sessions.

           b.   Achieve a grade of at least 70% on the  post-test.

      2.   In its current format, satisfactory  completion of  this
          course will entitle  a student to Continuing  Education
          Units (CEUs),  provided that the  organization presenting
          the course has met other  criteria for award  of CEUs.
Course 345                      0-7           Introductory Material

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                            AGENDA

       INSPECTION OF INDUSTRIAL VENTILATION SYSTEMS
                   U.S. EPA, APTI COURSE 345
 Location:
   Room Number
   Street Address
   City
   Phone Number
                  Moderator:
                    Name
                    Street Address
                    Organization
                    City,  State
 Day and Time

 Day 1

  9:00
  9:15
  9:45
 10:00
 10:15

 12:00

  1:00
  2:30
  2:45
  4:30

Day 2

 9:00
10:15
10:30

12:00

 1:00
 2:15
 2:30
 3:30
 4:30
                           Subject
                    Welcome and Registration
                    Pre-Test
                    Break
                    Course Overview
                    General Principles of Ventilation

                    Lunch Break

                    General Principles, Problem Set
                    Break
                    Hood Systems
                    Adjourn
                    Hood Systems, Problem Set
                    Break
                    Duct Systems

                    Lunch

                    Duct Systems, Problem Set
                    Break
                    Gas  Cooling Systems
                    Gas  Cooling Systems, Problem Set
                    Adjourn
                        Instructor
Course 345
0-8
             Introductory Material

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                      AGENDA (Continued)
Day 3

 9 00               Fan Systems
10 15               Break
11 30               Fan Systems, Problem Set

12 00               Lunch

 1 00               Fan Systems, Problem Set (Continued)
 2 00               Measurement of Ventilation System
                      Parameters
 2 45               Break
 3 00               Measurement of Ventilation System
                      Parameters (Continued)

 4:30               Adjourn

Day 4

 9:00               Measurement of Ventilation System
                      Parameters, Problem Set
10:15               Break
10:30               Ventilation System Inspection

11:30               Lunch

12:30               Ventilation System Inspection,  Problem Set
 2:15               Break
 2:30               Post-test
 3:30               Course Critique
 4:30               Adjourn
Course 345                     0-9          Introductory Material

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            Inspection of Industrial  Ventilation Systems

                              Pre-Test
 1. A fan with a 22 inch diameter sheave is driven by a 1725 rpm
    motor with a 10 inch diameter sheave.  What is the estimated
    fan speed?
    a.
    b.
    c.
    d.
       356 rpm
       784 rpm
      1,163 rpm
      2,559 rpm
   e.  3,795 rpm

2.  One pound molecular weight  of  a  gas  at  32°F and 29.92 in.  Hg
   occupies a volume of:

   a.   22.4 liters
   b.  359 cubic feet
   c.  379 cubic feet
   d.  387 cubic feet
   e.  depends on the gas
 3. A pitot tube measures:
    a.  velocity pressure
    b.  total pressure and velocity pressure
    c.  velocity pressure and static pressure
    d.  total pressure and static pressure
    e.  total pressure

 4.  One inch of mercury  is equal to how many inches of water?

    a.  13.6
    b.  14.7
    c.  29.92
    d.  407
    e.  760

 5.  At what distance  from a  hood should its static pressure be
    measured?
   a.  1 duct diameter
   b.  2 duct diameters
   c.  3 duct diameters
   d.  8 duct diameters
   e. 10 duct diameters
Course 345
                              0-10
                                           Introductory Material

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6. Pressure exerted by air  in motion is called:

   a.   static pressure
   b.   total pressure
   c.   absolute pressure
   d.   velocity pressure
   e.   turbulent pressure

7. An  inspector finds that  a hood static pressure is now  50
   percent of its  previous  value.  Approximately how much should
   the capture velocity have changed?

   a.  50  percent less
   b.  71  percent less
   c.  50  percent more
   d.  71  percent more
   e.  29  percent less

8. The coefficient of entry measures the efficiency of a  hood to
   convert:

   a.  kinetic energy to potential energy
   b.  velocity pressure to  static pressure
   c.  static pressure to velocity pressure
   d.  total pressure to static and velocity pressure
   e.  hood entry loss to static pressure

9. Canopy hoods are best suited where:

   a.  thermal currents can  be utilized
   b.  general air  flow is low
   c.  make-up air  is to costly
   d.  room cross-currents are a problem
   e.  none of the  above

10. The air velocity at any point in front of a hood that is
    necessary to overcome air currents and cause the air  to flow
    into  the hood  is called:

    a.  face velocity
    b.  slot velocity
    c. plenum velocity
    d. capture velocity
    e. duct velocity
Course 345                     0-11          Introductory Material

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 11. A flat plate that is inserted perpendicular to the centerline
     of a duct for the purpose of restricting air flow is called
     a:

     a. damper
     b. check valve
     c. solenoid
     d. blast gate
     e. bellows

 12. How much enthalpy change occurs when 2 pounds of air are
    cooled from 1000 F to 10°F?

     a. 323.6 Btu
     b. 224.5 Btu
     c. 449.0 Btu
     d. 567.9 Btu
     e. 748.1 Btu

 13. Which of the following is not a centrifugal fan?

     a. backward curved
     b. forward curved
     c. axial flow
     d. radial
     e. backward curved airfoil

 14. At a point just upstream of a fan,  measurements give a
    velocity pressure of 1.0 in.  H2O and a static pressure of 3.5
   in.  H20.  What  is  the total pressure?

     a. +2.5 in.  H2O
     b. -2.5 in.  H2O
     c. -4.5 in.  H20
     d. +4.5 in.  H2O
     e. +3.5 in.  H2O

 15.  A  freely  suspended flanged hood 2 inches wide and 72 inches
     long  exhausts 600  cfm.   What is the velocity  at a point 12
     inches  in front  of the  opening?

     a.  3.2  fpm
    b.  38.5 fpm
    c.  600  fpm
    d.  100  fpm
    e.  54.5 fpm
Course 345                     0-12          introductory Material

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16.
A 12 inch diameter hood has a flowrate of 1,444 acfm at
70°F.  If the hood entry coefficient is 0.69, what is the
hood static pressure?
     a.
     b.
     c.
     d.
     e.
    0.21 in. H20
    0.11 in.
    0.69 in,
    0.44 in,
H20
H20
H20
    0.30 in. H20
 17. An  air  stream  is  found to have  a dry-bulb temperature  of
    170°F  and  a wet-bulb temperature of  100°F.  What  is the
    relative humidity?

    a.  10  percent
    b.  15  percent
    c.  20  percent
    d.  25  percent
    e.  30  percent

  18. What is  the static pressure  loss when a 700 acfm air  stream
    at  100°F  flows through a 6  inch diameter elbow with  a  radius
    of  12 inches?
a.
b.
c.
d.
e.
0.
0.
0.
0.
0.
13
20
21
25
27
in.
in.
in.
in.
in.
H
H
H
H
H
2°
2°
2°
2°
,0
19. How many  gallons  of water  initially  at  60"F must  be
    evaporated  each minute  to  cool  a  50,000 acfm  gas  stream from
    1000 F to  400°F?
    a. 20.6
    b. 28.4
    c. 50.0
    d. 67.7
    e. 93.2
20. Static pressure measurements  at  the  inlet  and  outlet of a fan
    give -7.3  in. H20 and 0.7 in.  H20,  respectively.   Inlet
    velocity is estimated at  3,500 fpm and  the gas stream
   temperature is 250°F.  What  fan static pressure would
   normally be used to enter  a  fan ratings  table?
a.
b.
c .
d.
e.
6
7
7
8
9
.6
.3
.4
. 0
.9
in.
in.
in.
in.
in.
H
H
H
H
H
2
2
2
2
2
O
0
0
0
O
Course 345
                           0-13
                           Introductory Material

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           Inspection of Industrial Ventilation Systems
                       Pre-Test  Answer  Sheet
 Name:
1. a
2. a
3. a
4. a
5. a
6 . a
7. a
8. a
9. a
10. a
b c
b c
b c
b c
b c
b c
b c
b c
b c
b c
d
d
d
d
d
d
d
d
d
d
e
e
e
e
e
e
e
e
e
e
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                                         12.  a   b    c    d   e
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                                        17   a   b    c    d   e
                                        18.  a   b    c    d   e
                                        19.  a   b    c    d   e
                                        20.  abode
Course 345
                               0-14
Introductory Material

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Name:
           Inspection of Industrial  Ventilation Systems
                    Pre-Test Answer Sheet Key
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          2 .   a  f b)  c   d   e
          3.   a   b   c  ( d   e
          8.   a
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          6.   a   b   c  ( d )  e
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18.   a
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                      19. ( a )  b   c   d   e
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Course 345
             0-15
                                  Introductory Material

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                                    NOTE

The Post-Test and Post-Test Answer Sheet for Course #345 - Emission Capture and
Gas Handling System Inspection - are available to course instructors by contacting the
Air Pollution Training Branch, MD-17, Environmental Protection Agency, Research
Triangle Park, NC 27711, telephone: 919-541-2401.
            (Pages 0-16 through 0-21 are omitted from this manual copy)

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                             LESSON 1

                 GENERAL  PRINCIPLES  OF  VENTILATION
Goal:
To develop  a  basic  understanding  of  the  character and behavior of
air  streams.

Objectives:
At the  end  of this  lesson  the  student  should  be  able to:

      1.  Define standard  air  conditions

      2.  Calculate the  apparent molecular weight  of a mixture

      3.  Use the ideal  gas law to relate  the  pressure,  volume  and
         temperature properties of an air stream

      4.  Define density,  specific  volume  and specific gravity

      5.  Define relative  and  absolute humidity

      6.  Define dry-bulb,  wet-bulb and  dew-point  temperatures

      7.  Calculate the  enthalpy change  of a substance

      8.  Use a psychrometric chart to  determine the properties of an
         air-water vapor  mixture

      9.  Apply the continuity relationship to  an  air stream

     10.  Define and manipulate total pressure,  velocity pressure and
         static pressure

     11.  Calculate   velocity   pressure   from   the   velocity  and
         temperature of an  air  stream

     12.  Calculate   velocity   from   the   velocity   pressure  and
         temperature of an  air  stream
Section 1                                            General Principles
                                1-1

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 List of Slides
 1-1     Ventilation fundamentals
 1-2     Two sections of lecture
 1-3      Properties of air and air-water vapor mixtures
 1-4     Standard air
 1-5     Molecular weight
 1-6     Ideal gas law
 1-7     Volume conversion for temperature and pressure
 1-8     Density and specific volume
 1-9     Specific gravity
 1-10    Gibbs-Dalton rule of partial pressures
 1-11    Relative saturation, relative humidity and absolute
         humidity
 1-12    Dry-bulb,  wet-bulb and dew-point temperatures
 1-13    Enthalpy
 1-14    Defining equation for enthalpy
 1-15    Enthalpy of water vapor
 1-16    Enthalpy of air-water vapor mixture
 1-17    Determination of enthalpy difference
 1-18    Psychrometric chart
 1-19    Principles of fluid flow
 1-20    Continuity
 1-21    Mass balance on flow system
 1-22    Bernoulli's equation
 1-23    Bernoulli's equation in units of head
 1-24    Bernoulli's equation applied to flowing system
 1-25    Bernoulli's equation applied to flowing system
 1-26    Illustration of VP,  SP and TP
 1-27    Determination of velocity from velocity pressure
Section 1                                            General Principles
                                1-2

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 I.  Introduction                                        SLIDES AND
                                                          NOTES
     A. To  conduct  effective inspections,  it is
        important to have a firm understanding  of the       1-1
        basic information that affects the character-
        istics and behavior of air streams.

     B. Lesson is divided into two sections

        1. Properties of  air  and air-water  vapor       1-2
           mixtures  -  definition  of parameter is
           important in ventilation system evaluation
           and in techniques for determining them.

        2. Fundamentals of fluid flow  - discussion of
           continuity and momentum relationships with
           emphasis  on  Bernoulli's equation and its
           implications.

 II.  Properties of air and air-water vapor mixtures

     A. Standard  air:   air with  a density  of 0.075
        Ib /ft3  and  an absolute viscosity of 1.225 x       1-3
        10*  lbm/ft-sec.

        1. The  standard  air  density and  absolute       1-4
           viscosity apply to dry air  at  the  standard
           temperature  of  70°F  and  the  standard
           pressure  of  29.92  in.  of mercury.  These
           values  are used  throughout  this course
           whenever standard conditions are required.

        2. The U.S. EPA uses 25°C (77°F)  as a definition
           of "standard temperature.   This is used in
           many  calculations  involving  regulatory
           compliance.

        3. Other organizations  and  engineering
           disciplines have adopted slightly  different
           definitions of "standard" temperature and
           pressure.

     B. Molecular weight:   air is a mixture  so  it has
        no true molecular  weight -  does  have an
        apparent molecular weight  that is calculated       1-5
        from its composition.
Section 1                                           General Principles
                               1-3

-------
     = S  (Cent) (^component)   trefer to
                                                          SLIDES AND
                                                             NOTES
            Student Manual,  pp.  1-1 and 1-2]

         2 . Molecular weight of  dry air often approxi-
            mated as 28.95 Ib/lb-mole [explain concept
            of Ib-mole]

         3 . For moist air

            MWuetair = < * ~ Cwater) (^dry air) + (Cweter) (^ater)
                                                              1-6

      C. Ideal gas  law:   relates pressure,  volume and
         temperature properties  of  a pure substance or
         mixture.

         1. PV = nRT

               P = absolute  pressure  (lbf/ft2)
               V = gas volume (ft3)
               n = number  of moles  (Ib-moles)
               R = constant (1545 ft-lbf/lb-mole-°R)
               T = absolute  temperature (°R)

         2. Other values of  R [write on board]
               1545 Lbf-ft/lb-moles °R
               10.73 psia-ft3/lb-mole-°R                     1~7
               82.06 cm3-atm/g-mole-°K
               8.31 x 103 kPa-m3/kg-mole-°K
               0.73 atm-ft3/lb-mole-°R
               21.83  (in Hg.) (ft3)/(lb mole-°R)

         3.  If moles don't change:

               PV/T = nR = constant

            or

               PIVI/T! = P2V2/T2
            or
V1  =
                            (T,/T2)
            May also be used to calculate molar volume
            [write on board]

               V/n = RT/P
Section 1                                             General Principles
                                 1-4

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     D. Density  and  specific  volume:

        1. Density = weight/unit  volume                 SLIDES AND
                                                           NOTES
        2. Specific  volume  =
                  volume/unit  weight  =  I/density             1-8

        3. For an ideal  gas -
            Density  (p)  =
               MW,lbm   530
                387  ft3.
T, °R
 (P, in. Her)
29.92  in.  HgJ
         4.  Refer students  to Table  1-1 in  Student
            Manual,  p.  1-4.

      E.  Specific gravity:   ratio of the density of a
         material to  the density  of some  reference
         substance.                                          1-9

         1.  For  a gas,  specific gravity  = rgas/rdl7air

         2.  For  an ideal  gas,  specific gravity  =
      F.  Relative  and  absolute  humidity:

         1.  Gibbs-Dalton  rule  of  partial  pressure  -
            Components exert  a  pressure the same as if
            it  were  alone in  the same total volume at
            the same temperature.

         2.  Relative saturation =     /                      1~10
        3. Relative humidity  =                              1-11
               Relative  saturation  x  100

        4. Absolute humidity  =  Weightwltcr/Weightdiy ^

     G. Dry-bulb, wet-bulb and  dew point temperatures

        1. Temperature measured  with  a standard       1-12
           thermometer is termed dry-bulb temperature.

        2 . A  standard thermometer with a wet porous
           wick  over  the sensing bulb  is a wet-bulb
           thermometer.

           a. Water from the wick will evaporate  into
              a  moving air stream.
Section 1                                            General Principles
                                1-5

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            b. Wick  cools until  the rate  of  energy  SLIDES  AND
               transferred to the wick equals the rate     NOTES
               of energy loss by the evaporating water
               - temperature at equilibrium  is  termed
               wet-bulb temperature.

            c. Rate  of evaporation  depends  on the
               moisture content of  the air - provides
               an indication of the humidity.

         3. Dew-point temperature  is the temperature at
            which condensation  begins when moist air is
            gradually  cooled  - it  is the saturation
            temperature corresponding to the absolute
            humidity.

      H. Enthalpy:  the measure of  the thermal  energy      1-13
         of a substance in Btu/lb - Btu is the  amount
         of heat necessary to raise  one pound of water
         from 59°F  to 60°F at  a  pressure  of one
         atmosphere .

         1. Enthalpy  of  a  substance  at  a  given      1-14
            temperature has no practical value  except
            in relation to  the  enthalpy  at another
            temperature:
                  h = enthalpy (Btu/lb)
                  Cp = heat capacity at constant
                       pressure (Btu/lb-°F)  [refer
                       students to Table 1-1 in
                       Student Manual,  p.  1-4 J
               t = temperature of substance (°F)
                  tpef  =  reference temperature (°F)

                  tref  for  dry  air usually  equals
                       0°F [highly variable]
                  tref  for  water usually  equals  32 °F

            Enthalpy  of water  vapor is equal  to  the      1-15
            enthalpy  of  the water plus the latent heat
            of  vaporization.

            For an air-water vapor mixture:                  1-16

            h  (Btu/lbdryajr) =  hdryajr + f(hwatervapor)

            0 = absolute humidity (lbwater/lbdry air)
Section 1                                            General Principles
                                1-6

-------
         4.  Usually interested in enthalpy difference:   SLIDES AND
                                                            NOTES
            AH = h2  -
                      -  tref)  -  (CpMt,  -  tpef)
         5.  Can also determine enthalpy difference from
            tabulated values [refer students  to Table
            1-2 in Student Manual, p.  1-7].    Before
            subtracting two enthalpy values,  you must
            confirm that they were determined for the
            same reference temperature.

      I.  Psychrometric chart:  graphical representation       1-18
         of  properties of air-water vapor mixtures.

         1.  Demonstrate location/determination  of

            a.  dry-bulb temperature

            b.  wet-bulb temperature

            c.  absolute humidity

            d.  specific volume

            e.  enthalpy at saturated  and non-saturated
               conditions

            f.  dew-point temperature

            g.  relative humidity

         2.  Density of an air-water vapor mixture:

            fixture = (1 + *)/"

            

) II. Principles of fluid flow 1-19 A. Consider flow through the tube shown: 1. Mass flow rate into the tube, G1 , is 1-20 p1V1Al ; mass flow rate out of the tube, G2, is /02V2A2 Section 1 General Principles 1-7


-------
        2. If no accumulation or removal:              SLIDES AND
                                                           IOTES

                                                            1-21
G,  =  G2                                         NOTES
           or

           P1V1A1 = P2V2A2

           or,  if p, = P2

           V1A1  = V2A2

      B. As fluid  flows through a tube, its  momentum
        and pressure may change.

        1. Applying the relationship,  force  equals
           rate of  change  of  momentum to  a  fluid
           element and  then  integrating  over  the
           cross-section  of the  duct,  neglecting
           frictional  forces  and  assuming
           incompressibility ,  gives  Bernoulli's
           equation:

           V2/2 + P/p + gz  = constant                       1-22

              V = fluid velocity
              P = fluid pressure
              p = fluid density
              g = acceleration of gravity
              z = elevation of fluid

        2. Rearranging the terms  to have  units  of      1-23
           length gives:

           V2/2g + P/pg +  z  =  constant

              V2/2g = velocity head  (ft)
              P/P9  = pressure head (ft)
              z     = potential head  (ft)

     C. Consider the situation shown,  in which an open      1-24
        tube has been inserted into a flowing  fluid:

        1. Since the terms in Bernoulli's equation sum
           to a constant,  we may write:
        (V1)/2g + P^pg + z, =  (V2)2/2g + P2/pg
Section 1                                           General Principles
                                1-8

-------
         2.  But z1 = z2  and V2 = 0.   Substituting gives:   SLIDES AND
                                                           NOTES
            V,2/2g + P,/pq = P2/pg                            1-25

            V12/2g = velocity pressure
            P.,/pg  = static pressure
            P2/pg  = total pressure

         3 .  Another  way of writing  this is  [write  on
            board] :

            VP + SP  =  TP

               VP =  velocity  pressure
               SP =  static pressure
               TP =  total pressure

         4.  Discuss  relationship between VP,  SP and  TP      1-26
            using diagram.

         Velocity can  be determined  from  velocity      1-27
         pressure:

         1.  Converting the  units  of  the  velocity
            pressure term  so that it has unit of inches
            of water gives [write on board] :

            VP = [(V/60)2/2g] (pa/PH)12
                              aH
               VP = velocity pressure (in. of H20)
               V = velocity (ft/min)
               pa = air density  (lb/ft3)
               pu = water density  (lb/ft3)

         2.  Substituting  a  water  density  at 70°F  of
            62.302  lb/ft3 and a gravity acceleration at
            sea level of 32.174 ft/sec2 gives [write on
            board] :

            VP  = pfl(V/1096.7)2
        3. Rearranging gives:

           V =  1096.7 (VP/p)°-5

        4 . For  standard air
           (p =  0.075  lb/ft3) :

           V -  4005(VP)°-5
Section 1                                            General Principles
                                1-9

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                          PROBLEM  SET  1

             GENERAL PRINCIPLES OF VENTILATION
 1-1.  How much volume  in  ft3 does 1 Ib-mole of air at 70°F and
      29.92  in.  Hg.  occupy?  What is the volume  if  the air is at
      32°F and 29.92 in. Hg?
       Solution

       a.    70°F  =  70 + 460

            29.92  in.  Hg
     V  =
     n
                  RT
     530 °R

      14.7  psia

no. 73  psia-ft3/lb.-mole
             14.7 psia
                           r530°R1
      b.
    32°F  = 32  + 460
           V
           n
            RT
             P
                               387  ft3/lb-mole
  =  492 °R

[10.73  psia-ft3/lb-mole °Rir492
             14.7 psia
                          =   359  ft3/lb-mole
1-2.  A duct has a  1,500  acfm air  flow  at  110°F and -18.0  inches
      of water.  Atmospheric pressure is 30.12  in.  Hg.   What is
      the flow rate at standard  conditions?
Solution

T,     =    110°F     =   110  +  460

P.     =    30.12  in.  Hg.  - 18/13.6

T^  =   530°R

Patd  =   29.92 in. Hg.

      V,    =  V2  (P2/P,) (T,/T2)

      V,    =  1500 .(28.80/29.92)(530/570)

      V,    =  1342.5 scfm
                                                  570°R

                                                  28.80  in Hg.
Section 1
                               1-10
                                             General Principles

-------
1-3.  Temperature measurements  in  an  air duct indicate  a  dry-bulb
      temperature of 83°F  and  a  wet-bulb temperature of  60°F.
      Determine enthalpy,  humidity ratio  (moisture  content),
      dewpoint temperature and relative humidity/

      Solution

      From psychrometric chart:

         Enthalpy   =    26.5   - 0.15
                         26.35  Btu/lb of dry air

         Absolute Humidity  =  40 grains/lb of dry  air
                            =  0.0057 Ib/lb of dry  air

         Dew Point  =    42.5 °F

         Relative Humidity  = 25%


1-4.  What is the flowrate in a 6 in.  diameter duct  if the  average
      velocity pressure was measured and found to be 0.76  in.  of
      water and the gas temperature is 100°F?   If the duct decreases
to  4  inches in diameter downstream, what will be
      the new velocity and velocity pressure?

      Solution

      a.   Ad    =   (7T/4) (6/12)2   =   0.1963 ft2

          P100 f  =  0.0708  lb/ft3

          Q    =  1096.7 Ad (VP/p)°-5

                  (096.7/0.1963 f t2) ( 0 . 76/0 . 07 08 ) °'5

               =  705.3 acfm

      b.   Ad    =   (7T/4) (4/12)2   =   0.0872 ft2

           V   =  705.3 acfm/0.0872 ft2   =    8079 . 0--ft/min.

           VP   =  p  (V/1096.7)2

               =  0.0708 lb/ft3  (8079.0 ft/min / 1096.7  ft/min.)2

               =  3.84 inches of water
Section 1                                            General  Principles
                                1-11

-------
 1-5.  How much  enthalpy change occurs  when a gas stream is cooled
       from  2000 °F to  250  °F?

       Solution

       h200Q       =     509.5   Btu/lb

       h25Q        =       45.7   BtU/lb
       Ah           =      463.3 Btu/lb
Section 1                                             General Principles
                                 1-12

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                           LESSON 2

                     HOOD SYSTEMS
Goal:
To  develop  an understanding of  the  different hood types, their
design  and  performance  characteristics, and techniques for their
evaluation.
Objectives:
At the end of this lesson the student should be  able  to:

      1. State the importance of hood efficiency  in  the total
        efficiency of a ventilation system

      2. Recognize the different types of hoods and  how each of
        them functions

      3. State the three principles of good hood  design

      4. List the factors that affect hood performance

      5. Determine appropriate capture velocities for  given
        situations

      6. Determine the capture velocity of an existing hood from
        flowrate and configuration information

      7. List the parameters that affect the capture of hot plumes
        with overhead canopy hoods

      8. Determine hood static pressure from flowrate  and
        configuration information

      9. Use measured hood static pressure and configuration
        information to estimate flowrate

    10. Conduct effective inspections of hood systems
Lesson 2                       2-1                   Hood Systems

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                          List of Slides
 2-1      Hood  systems
 2-2      Goal  of  good  hood  design
 2-3      Total penetration  relationship
 2-4      Types of hoods
 2-5      Hood  design principles
 2-6      Bucket elevator  hood
 2-7      Ladle hood
 2-8      Bag filling station hood
 2-9      Grinder  hood
 2-10     Exterior hoods
 2-11     Electric arc  furnace hood
 2-12     Push-pull hood
 2-13     Push-pull hood
 2-14     Factors  affecting  hood performance
 2-15     Capture  velocity
 2-16     Range of capture velocities
 2-17     Cold  flow
 2-18     Flow  into unflanged hood
 2-19     Flow  into flanged  hood
 2-20a    Assorted hood flow relationships
 2-20b    Assorted hood flow relationships
 2-21     Hot flow
 2-22     Application of Bernoulli to hood  flow
 2-23     Simplification of  Bernoulli relationship
 2-24     Vena  Contracta
 2-25     Hood  Entry Coefficient
 2-26     Relationship  between hood  loss  factor  and entry
         coefficient
 2-16     Simplification of  Bernoulli relationship
 2-27     Estimating hood  volume
Lesson 2                       2-2                    Hood Systems

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 I.  Introduction                                       SLIDES AND
                                                          NOTES
    A. To  conduct  effective  inspections,  it  is
       important  to understand  the concepts  behind       2-1
       good  hood  design and to know how to  evaluate
       hood  performance.

    B. The  goal  of good hood design in high  capture
       efficiency.   The  importance  of this  is       2-2
       illustrated  by the following relationship:
                                                           2-3
          Penetration = 1 - Fractional Efficiency

          Pt   =  Pt    +  (i  -  Pt   1 Pt
             total      hood    *•       hood'  collector


 II. Types of hoods
                                                           2-4
    A. Enclosure hoods  - envelope the process  to the
       maximum extent possible.
                                                           2-5
       1. Designer  envisions a  total  enclosure and
          then removes portions as needed for material
          and worker access.

       2. Contains  and removes  contaminants from
          within the enclosure, rather than  capturing.

       3 . Air volume requirement usually the lowest  of
          the three hood types.

       4. Examples  of enclosure hoods:

          a. The bucket elevator is an example of  an       2-6
             enclosure-type hood.  Buckets  mounted  on
             a rotating vertical  belt are  used  to
             transfer material from one elevation  to
             another.   To reduce emissions from this
             process,   a housing  is  provided that
             completely encloses  the  operation, and
             suction is  provided to contain and remove
             the contaminants.   The only  openings are
             those  necessary for receiving and
             transferring the material.

          b. The ladle hood  is an enclosure-type hood.       2-7
             Molten  metal   is  transferred to a hot
             metal ladle from a rotating-dump  torpedo
             car.  The ladle hood contains and removes
             the  emissions  as they evolve from the
             transfer operation.
Lesson 2                       2-3                   Hood Systems

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             Once  the  emissions have  subsided, the   SLIDES AND
             ladle hood  is  tilted  out  of the way  so     NOTES
             that  the  ladle may  be moved  to  other
             operations.


    B. Receiver hoods - located adjacent to  the  point
       of contaminant release.

       1. Hood oriented to receive emissions as they
          are ejected from the process.

       2. Capture capability that must  be provided  by
          air stream is reduced.

       3. Examples of receiver hoods:

          a. The  bag  filling  process utilizes a       2-8
             receiving-type hood.   To  avoid
             interferences with the  weighing scale,
             the hood is mounted above the bag opening
             to take advantage  of the normal vertical
             travel of emissions and somewhat reduce
             the capture flow that might be required
             with another orientation.

          b. The grinding wheel hood is primarily a       2-9
             receiving-type hood.  Material removed by
             the wheel has a normal  travel  direction
             down and to the rear.  The hood is mounted
             in this  location  to  take advantage  of
             this  and  reduce the  necessary capture
             flow.   The hood also extends around the
             top and sides of the wheel to provide for
             enclosure of any contaminants that follow
             the wheel motion.

          c. The  EOF  hood system utilizes two
             receiving-type  hoods.   Buoyant forces
             carry the emissions into the primary hood
             during the  melting phase  and  into the
             secondary hood during charging.


    C. Exterior hoods - located an extended distance
       away from source.

       1. Principal example  is the  overhead canopy       2-10
          employed with hot sources.
Lesson 2                       2-4                   Hood Systems

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       2. Relies  on normal movement  of the buoyant   SLIDES AND
          plume to  carry contaminants into the hood.      NOTES

       3. Subject to losses due to plume meander and
          cross-drafts.

       4 . Requires the largest air volume of the three
          hood types.

       5. Control  of  emissions  from  electric-arc       2-11
          furnaces  typically  uses a  canopy hood in
          combination with an  enclosure-type hood at
          the  furnace.    During the  melting cycle,
          emissions are  controlled  from  the  hood
          mounted on the  furnace,  with only a small
          amount  of flow  drawn from  the  canopy to
          remove  any  contaminants that might escape
          the  furnace.   During charging operations,
          the  roof  swings  off  the furnace  to provide
          access, and all air flow is directed to the
          canopy to collect the significant plume that
          usually results.  In the tapping  cycle, the
          furnace tilts to pour the molten  steel into
          a ladle, disconnecting the furnace hood from
          the duct through  a break-flange arrangement.
          In  the system  shown,  air  flow  is  then
          directed  to an enclosure hood at  the ladle.
          In  other  systems,   the  air  flow is again
          directed  to the canopy hood for contaminant
          capture and removal.

    D. Push-pull hoods.

       1. A controlled jet of  air is  directed across       2-12
          the contaminant source and  in the direction
          of  the  exterior hood.   The exterior hood
          primarily serves to receive the  air jet and
          the contaminants carried with it.

       2. Higher velocities with distance from the jet
          source  result  in  reduced air vol u-m e
          requirements.

       3. System  must  be carefully designed  and
          controlled to avoid dispersing contaminants
          into the workspace.

       4. Disturbance of the jet can  occur if
          obstructions are placed  in  its  path,
          reducing the system's effectiveness.
Lesson 2                       2-5                   Hood Systems

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       5. A variation of the push-pull system is the   SLIDES  AND
          air curtain hood.   Jets  of air are directed     NOTES
          downward to form a barrier that contains the
          emissions while they  are  drawn  off by the      2-13
          exhaust system.


 III.  Hood design principles                               2-5

    A. Whenever possible, an enclosure hood should be
       employed.

    B. If an enclosure hood cannot be used,  the hood
       should  be  placed as  close to the source  as
       possible and  aligned  with  normal  contaminant
       flow.

    C. To  improve  hood  performance,  duct take-offs
       should  also  be  placed  in-line  with  normal
       contaminant flow.
 IV.  Factor affecting hood performance                      2-14

     A. Room air currents associated with the workspace
       ventilation system - currents of  as little as
       50  feet/min  may  be enough to  affect  the
       performance of some hoods.

     B. Thermal  air  currents from  heat  generating
       equipment  and processes  - even low heat
       releases, such as those from an electric motor,
       may be enough to disturb  hood performance.

     C. Machinery motion -  rotating or  reciprocating
       machinery can  be a  source  of significant  air
       currents.

     D. Material motion - downward motion of material
       will create a  downward air current that will
       make the  upward motion  of  contaminants more
       difficult to achieve.

     E. Operator  movements - rapid movements  of an
       operator  can  create  air currents  of  50-100
       feet/min.
V. Capture velocity

    A.  Capture  velocity  is  defined as  that  air       2-15
       velocity  at a point in  front of a  hood  or  at
Lesson 2                       2-6                   Hood  Systems

-------
       the  hood face that  is necessary to  overcome   SLIDES AND
       existing  air currents  and  cause the  contain-     NOTES
       inated air to move into the hood.

    B. Required  capture velocity will depend  on  both
       the direction and velocity of the contaminants
       at the desired point  of capture, as well as the
       level of  disturbing  air currents  that  must be
       overcome.

    C. A  general   guide  for appropriate  capture
       velocities is shown  in  the table.                   2-16

       1. Values at the low end of the range would he
          appropriate when disturbing air currents are
          low,  the  toxicity  of  the contaminants  is
          low,  or the  hood  is large, resulting  in a
          large  air mass in motion.

       2. Values at the high  end of the range would eb
          appropriate when air currents  are high,  the
          toxicity  of the  contaminants is high, or the
          hood  is small.
VI. Cold  flow  into hoods                                   2-17

    A. Relies  totally or in  part  on the ability  to
       provide enough energy to capture a contaminant
       and draw it into the hood, i.e., to develop the
       necessary capture velocity-

    B. Capture velocity decreases  with  distance  from
       the hood  face.   In general,  capture  velocity       2-18
       one hood  diameter  away from the hood face  is
       less  that  10 percent  of  the velocity at the
       hood  face.

    C. Although  the situation is  improved  with the       2-19
       addition of a  flange,  the  improvement is  only
       about 25 percent.

    D. In contrast,  10 percent of the face velocity  of
       a  blowing jet  would  be  found  about thirty
       diameters away.

    E. Expecting a  hood to  provide high  capture
       velocity several diameters  away  from  the  hood
       face may be expecting too much.

    F. Discuss the relationships  for determining air
       volume requirements to  provide a desired
Lesson 2                       2-7                   Hood Systems

-------
       capture velocity a given distance from the hood  SLIDES AND
       face  for  the different  hood  configurations.    NOTES
       Point  our  that,  for an  existing  hood,  these
       same equations can be used to estimate capture     2-20a
       velocity once the  hood  flowrate  is known.           and
                                                         2-10b

 VII. Hot flow into hoods                                  2-21

    A. Relies more on the buoyancy of the hot plume to
       carry  the  contaminants into the  hood  than on
       the ability to generate a capture velocity.

    B. The  velocity  at the hood  face  need  only  be
       about the velocity of the plume at that point.

    C. As a  hot plume  rises it  expands  and  cools by
       entraining  outside  air and  its  velocity
       decreases.

    D. As the distance between the source and the hood
       increases,  the air volume required to capture
       and remove the plume increases.

    E. The slower  moving upper portion of the plume is
       susceptible to being disturbed by air currents,
       causing it to move out  from under the hood


 VIII. Hood pressure losses                                2-22

    A. To  cause  air to move  into a hood it  is
       necessary  to provide  the energy  needed  to
       accelerate the  air from essentially  zero
       velocity up  to the  velocity  in  the  duct
       connected to the hood and to overcome the entry
       resistance  of the hood  itself.

    B. Consider the hood  system shown.   Applying the
       Bernoulli  equation  to  this  situation  would
       indicate that the total  pressure at  point'- 1
       would equal the  total pressure at point 2, or:

          SP,  + VP, = SP2 +  VP2

    C. But  there is  no  air motion  at  point  1;     2-23
       therefore:

          0  = SP2 + VP2

          or

          SP2  = -VP2
Lesson 2                       2-8                   Hood Systems

-------
     D.  In reality,  entering  air  forms a  "vena  SLIDES AND
        contracta",  causing  the  velocity to increase     NOTES
        and then  decrease.   This  is not  a perfect
        process and results in an energy loss as  static      2-24
        pressure is converted to  velocity pressure and
        then  back to  static  pressure.  Therefore,  we
        define the hood  static pressure loss, SPh,  as:

           sph  = -SPZ  = VP2  +  he

           he = hood entry  loss

     E.  Hood  entry loss  is usually expressed as  some
        fraction of the  velocity pressure in the  duct
        attached to the  hood:

           he = FhVP

           Fh = hood loss factor

     F.  Hood  losses may  also be described by the  hood
        entry coefficient,  Cg:

           Ce = (VP/SPJ0-5
                                                            o ^ *2 cr
     G.  The hood entry  coefficient can be related  to
        the hood loss  factor  by recalling that
        SPh =  VP  + he  and he  = FhVP  [Note:   Instructor
        may wish to develop  this relationship  on  the
        board.].   Thus:

           he = {(1 -  Ce2)/Ce2}VP                             2_26

           Therefore

           Fh =  (1 - Ce2)/Ce2

           and

           Ce =  {l/(l+Fh)}°-5

IX.  Evaluation of hood  performance

     A.  Measurements of the hood static pressure can be
        used to estimate the  flowrate at the hood.          2-27

           Q =  VA  = 1096.7A(VP/r)0'5

                  = 1096.7ACe(SPh/r)0'5

             Q =  volumetric  flow rate (ft3/min)
             V =  hood face velocity  (ft/min)
             A =  hood inlet  area (ft2)
             r =  air  density (lb/ft3)
Lesson 2                        2-9                   Hood  Systems

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     B. Performance and condition of a hood should be   SLIDES  AND
        visually evaluated.                                 NOTES

        1. If dusty  material  is  being  handled by  a
           process,  the amount  of  fugitive  losses
           provide  an excellent indication of  the
           effectiveness  of  the  hood system.
           Refraction lines due to the escape of gases
           contaminants may also  be  noticed.

        2. The physical condition of  the hood should be
           assessed.   Particular attention  should  be
           paid  to  any  modifications that  have  been
           made  to the original  hood design or to  any
           damage that it may  have sustained that  may
           affect its performance.

        3. On movable hoods, the  connection between te
           hood  system and  the duct  system  should  be
           assessed  to  determine  the "fit"  of the
           junction.   Break-flanges should  have  a
           maximum gap of 1-1% inches.

        4. Hood  position should be evaluated to assess
           the effects of cross-drafts  or other air
           motion on  hood capture efficiency.
Lesson 2                      2-10                   Hood Systems

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                           PROBLEM SET 2

                       HOOD SYSTEMS


 2-1.    A simple 12  inch  diameter wide-flanged hood has an air fkw
        of 400  acfm.   At  what distance away,  along the centerline,
        does the velocity equal 50% of the hood face velocity?
        10% of  the hood face velocity?


        Solution

        a.  Ah   =   (7T/4)  (12/12)2   =   0.7854 ft2

            V    =  (4000 ft3/min)/  0.785ft2  =  509.3 ft/min

            0.5V =  254.7 ft/min
            Q    =  0.75V (10X2 + A)

            X    =  [ (O/  (0.75)(254.7))  - 0.785
                                10
                           r
                 =  1(4007  (0.75) (254.7) )  - 0.7854
                                10

                 =  0.36  ft   =  4.3 inches
                                                  0.5
        b.   0.1V = 50.9  ft/min
            X
(400/  (0.75) (50.9) )  - 0.78541 °'5
                                10

                 =   0.99  ft   =  11.8 inches
Lesson 2                       2-11                   Hood Systems

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 2-2.  An acid dip tank  is  equipped  with slot vents along both
       long sides.  Slot velocity  is 2,000 fpm and the total
       volume of  1,250 acfm is  exhausted by a 7 inch diameter
       duct.  What is the hood  static pressure, assuming a duct
       entry loss of 0.25 VP?

       Solution

       Assume standard air
           VP
             slot
           V
           VP
(2000/4005)2

 (7T/4) (7/12)2

 1250 ft3/min
   0.2673 ft2
0.25 inches of water

 0.2673 ft2

 4,676.4 ft/min
             duct
                                     2 _
(4676.4/4005)^ =    1.36  inches of water
  1.78
                                        0.25 VP
                                                duct
                          1.78  (0.25)  +  0.25(1.36)

                          0.79  inches of water
           SP,
  VP
                            duct  T  "e

                          1.36    +  0.79

                          2.15 inches of water
Lesson 2
       2-12
            Hood Systems

-------
 2-3.  Measurements in an  18  inch diameter dust  just downstream of
      hood give a hood static pressure  of  2.5 inches of water and
      a temperature of 250 °F.   Assuming a hood  entry  loss of
      1.5 VP,  what is the actual gas  flow  rate?


      Solution

         Ah     =     (TC/4) (18/12)     =    1.7671  ft2

         P250   =    0.0558  lb/ft3

         Fh     =     1.5

         Ce     =    (__1	)°'5    =   [I/  (1 +  l-5)]°-5
                     1 + ^h

                   0.53


         Q     =   1096.7 A Ce (SPh/p)0'5

                   1096.7  (1.7671)  (0.53)  (2 . 5/0 . 0558) °'5

                   3172.3 acfm
Lesson 2                        2-13                   Hood Systems

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 2-4.  A recent  hood  inspection finds a 40% drop in hood  static
       pressure  compared to previous measurements.  What  is the
       percent change in hood face velocity?
       Solution
1
            V    oc   (SPh)°-5

            Therefore
            v1 / v2
            SPM      =   o.4 sph>2

            V,         =   V2  (0.4  SPh(2/SPh(2)°-5
                           0.63 V2
                           The new velocity would be 63% of
                           the previous  velocity.
Lesson 2                        2-14                    Hood Systems

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                            LESSON 3

                         DUCT SYSTEMS
Goal:
To  develop an  understanding  of duct  systems,  their  design  and
performance characteristics, and techniques for their evaluation.

Objectives:
At the end of this lesson the student should be able to:

     1. State the  three  types  of  energy  losses  that occur in duct
       systems.

     2. State three methods for estimating losses in duct systems.

     3. Use  the  velocity pressure  method to estimate  frictional
       losses in  straight ducts.

     4. Use  the  velocity pressure  method  to  estimate losses  in
       elbows.

     5. Calculate  total  static pressure losses in a duct segment.

     6. Estimate hood  flow  rate  from static pressure measurements
       in a duct.

     7. State  appropriate   transport   velocities   for  different
       situations.

     8. Recognize the potential problems from low transport velocity
       in dust containing systems.

     9. Recognize  areas  having high potential for duct erosion.

   10. State the  purpose of balancing duct systems.

   11. State two  techniques for balancing duct systems  and the
       advantages and disadvantages of each.

   12. Conduct effective inspections of duct systems.
Lesson 3                       3-1                   Duct Systems

-------
 List of Slides
 3-1    Duct systems
 3-2    Application of Bernoulli equation to duct segment
 3-3    Effect of friction and non-ideal conversions
           between SP and VP
 3-4    Simplification assuming constant velocity in duct  segment
 3-5    Types of duct losses
 3-6    Techniques for estimating losses
 3-7    Estimating frictional losses in straight duct
 3-8    Estimating fitting losses
 3-9    Velocity pressure calculation method
 3-10   Velocity pressure calculation method
 3-11   Velocity pressure calculation method
 3-12   Result of pressure loss calculations
 3-13    Transport velocity
 3-14   Range of design velocities
 3-15   Build-up concerns
 3-16   Distribution of flow in branched ductwork
 3-17   Branched duct example
 3-18   Techniques to obtain balance
 3-19   Characteristics of balance through design
 3-20   Characteristics of balance with dampers
 3-21   Branched duct example
Lesson 3                       3-2                    Duct Systems

-------
I.  Introduction                                        SLIDES  AND
                                                           NOTES
    A. Once  contaminants  from  a  process have  been
       captured   by   the  hood   system,   it   is  the      3-1
       responsibility  of the duct system to  convey
       these contaminants to the collection device and
       then convey the cleaned air  on to its discharge
       point .

    B. In designing duct systems, much of the concern
       is in selecting proper size ducts and in being
       sure  the  system  is  "balanced"  so  that  the
       proper  quantities of air are drawn from each
       hood.

    C. As inspectors,  the  design  of  a  duct  system is
       of only limited concern.    However, it  may be
       necessary  to use  some of the same tools as the
       designer   in  order   to  accomplish  inspection
       goals .


II. Duct pressure loss

    A. Consider the duct segment shown.                    3-2
       Applying Bernoulli's  equation to  points 1 and
       2, we can  write:

          TP, = TP2

    B. Because of friction between the gas stream and
       the  duct   walls  and because   of  non-ideal
       conversion between static pressure and velocity
       pressure   as  the  gas stream  accelerates  or
       decelerates, pressure losses between  the two
       points  occur.  Thus:                                3-3

          TP1 = TP2 +  hL
             or
                VP1  =  SP2 + VP2 + hL
    C. If we  assume  that  the velocity between points      3-4
       1 and  2  is approximately constant, then VP1 =
       VP2 and:
          SP1 = SP2
    D. Here,  hL  is the  total pressure  loss  due  to
       friction  and non-ideal pressure  conversions.
       For  calculation  purposes,  we  divide  these
       losses into  three categories:                       3-5
Lesson 3                        3-3                    Duct Systems

-------
        1.  Frictional  losses in straight duct-           SLIDES AND
           involves the  loss due  to  friction with the      NOTES
           walls.
                                                            3-5
        2.  Fitting losses  - occur when  the gas stream
           flows  through elbows,  entries,  transitions
           and  other  types of fittings; results  from
           friction with the walls of the  fitting and
           with   increased energy  loss   due  to  an
           increased level of turbulence.

        3.  Acceleration   losses   -  associated   with
           changes in  the  velocity of the gas stream;
           accelerating a gas stream requires the input
           of energy,  while decelerating a gas stream
           may result  in a gain of energy.   The amount
           of  pressure  loss  or   gain depends on  the
           relative abruptness of  the change.

     E.  Because   our   interest  in  duct  losses  will
        usually be over relatively short distances, our
        determination  of  losses  will  be confined  to
        those  associated  with   straight   ducts   and
        fittings.

     F.  There are three  techniques in general use for       3-6
        estimating these  losses:

        1.  Equivalent  length  method  -  fitting  losses
           are  expressed  in  length   of   equivalent
           straight duct;  total losses  are calculated
           by  adding  the  equivalent length for  the
           fittings to the actual length  of straight
           segments and  then  multiplying by  a  factor
           that expresses the pressure loss per length
           of duct.

        2.  Velocity pressure  method  -  both  straight
           duct and fitting losses are  expressed  as a
           factor times  the  velocity pressure  in the
           duct segment.

        3.  Total  pressure  method  - both straight  duct
           and fitting losses are  expressed as a factor
           times  the  total  pressure   in  the  duct
           segment.

        4. The  technique  to  calculate  duct  system
           losses that is used  in this course  is the
          velocity pressure method.

    G. Frictional   losses  in   straight    duct   are       3-7
       expressed as:
Lesson 3                       3-4                   Duct  Systems

-------
           hu = HfL'VP                                   SLIDES AND
                                                           NOTES
              Hf =  velocity  pressure loss per foot  of
                   duct
              L =  length of duct,  feet

        1.  The straight-duct  loss  factor,  Hf,  can  be
           determined  from   the  following  empirical
           equation:

              Hf =  0.0307V°-533/Q°-612 -  0.^937/Q0-079^-066

              V - air velocity in feet/minute
              Q = volumetric flowrate in cubic
                 feet/minute
              D = duct diameter in  inches

        2.  The straight-duct  loss factor can also  be
           determined  from   Figure  3-1  in  Student
           Manual,  pp. 3-4 and 3-5 [refer students  to
           figure].
        3.  Losses  for  rectangular ducts are determined
           using  an  equivalent   diameter   and  the
           calculated  velocity at that diameter.  The
           equivalent  diameter in inches  is determined
           from  [write on board]:

              De = 1.3(AB)°-625/(A +  B)°-25

           where A and B are the lengths of the sides
           of  the  rectangular duct  in inches.

    H.  Fitting  losses are expressed as:                     3-8

           hL2  =  F-VP

              F  =  fitting loss factor

        1.  There are  a  variety  of  fittings  used -in
           ventilation systems and factors  for their
           resistance  can  be  found  in  a  number of
           reference texts.

        2.  The   fitting  of  most  interest  for short
           distance  calculations is  that for  elbows.
           These factors are given for 90° round elbows
           in  Table 3-1  in  Student  Manual,  p.  3-6.
           Resistances for other than 90° elbows are
           determined  as  a percentage of  the 90° elbow
           resistance.
Lesson 3                        3-5                   Duct Systems

-------
 Ill  Velocity pressure calculation method               SLIDES AND
                                                           NOTES
    A.  Calculating  the pressure  loss  from  one  duct
        location  to  another requires determining the      3-9,
        loss  of the  straight  sections and the loss of      3-10,
        all the fittings and then adding them together      and
        to get the total loss.  The specific step-wise      3-11
        procedure for a segment,  beginning at the hood,
        is as follows:

        1. Determine  the  duct velocity  and calculate
          the  velocity pressure.

        2. Determine the hood static pressure.

        3. Multiply  the straight  duct  length by the
          friction  loss factor.

        4. Determine   the   number  and   type   of   all
          fittings.  Multiply the  loss factor for each
          type of fitting  by the  number of that  type
          and sum for all  types.

        5. Add  the  results from  Steps  3  and 4  and
          multiply the result by the velocity pressure
          from Step 1.

        6. Add  the  result  from Step  5  to the  hood
          static pressure  from  Step 2.   If there are
          other losses  (expressed in inches  of water
          column), add them also.

    B. This  calculation procedure  gives  the total       3-13
       energy, expressed as  static pressure,  that is
       needed to move the gas volume through the  duct
       segment.


IV. Estimating hood flowrate

    A. Can measure the static pressure  at  some  safer
       or more  easily reached  location and  use the
       principles of duct resistance presented in this
       lesson to estimate  the air flow  at  a hood.

    B. Recall from Lesson  1  the relationship for the
       hood  entry loss coefficient, C
                                     e
          ce = (vp/sph)°-5

             or
          SPh  = VP/Ce2
Lesson 3                       3-6                   Duct  Systems

-------
    C. The hood static pressure could be determined by   SLIDES AND
       making  a  measurement  anywhere  in  the  duct      NOTES
       leading  to the  hood  and then  correcting the
       measured  value  for  the  losses  between  the
       measurement  location  and the  hood.   Assuming
       losses due to both straight duct and fittings:
           SPh = S^as  ~  HfL'VP ' SF'VP
    D.  Equating the two relationships for hood static
        pressure gives:

          VP/Ce2 = SPmeas -  HfL'VP - SF'VP
                     meas

              or
           VP  =  SPmeas/t1/^2  +  HfL + SF)
     E. To  obtain Hf  a  trial  velocity will have to be
       assumed.   The corresponding velocity pressure
       would  be  compared to  the calculated value and
       the calculations  repeated  until  reasonable
       agreement is  obtained.

     F. Once an  acceptable velocity pressure has been
       determined,  the  flowrate  can be  calculated
       from:


           Q = VA = 1096.7A(VP/ra)°'5

       or, if standard air is  involved:

           Q = 4005A(VP)°-5


V. Balancing  duct systems                                   3-16

    A. Balancing a branched duct system is the role of
       the designer  and  is  done to  insure  that the
       correct  air  volumes are  drawn from all hoods
       that are  connected to  a  common system.   As
       inspectors,   it is  important to  have  some
       understanding of how  this is accomplished and
       the limitations of the  various techniques.

    B. The fundamental rule in  balancing a duct system
       is that all ducts entering a junction must have
       equal  static  pressure requirements.

    C. Consider  the  two-hood duct system shown.             3-17
       At the junction,  the  static pressure  in the
Lesson 3                        3-7                    Duct Systems

-------
        longer duct that  leads  to  Source 1 is 2.0 in.   SLIDES AND
        H20, while  the  static  pressure  in the  duct      NOTES
        leading to Source 2 is 1.5  in.  H2O.  If nothing
        is  done,  the  system  will  adjust itself  by
        reducing  the  flowrate from   Source  1  and
        increasing the flowrate from Source 2 until the
        same static pressure  requirement results.   To
        prevent  this  situation,  the  designer  must
        adjust the resistances  of  each branch so that
        they equal  each  other  at  the  junction,  while
        maintaining design flowrates.

     D.  There are two  techniques for obtaining static
        pressure balance  at a junction:                      3-18

        1.  With dampers  - inserting a  damper  into the
           duct with the  lower static pressure to raise
           its value up to that of  the other duct.

        2.  Through design -  changes are made  in duct
           diameter, duct length,  elbow  radius,  etc.,
           or  in  the air  volume  in order  to  achieve
           matching static pressures.

     E.  Characteristics  of systems balanced  through       3-19
        design include:

        1.  Since the  system  resistance  is  fixed,  air
           volumes cannot be easily changed.

        2.  The  system  has  limited  flexibility  for
           future equipment changes or additions.

        3.  Because  nothing  protrudes  into  the  gas
           stream, there  should be no  unusual erosion
           or accumulation problems.

        4.  Since  balance may  be  achieved by  making
           small,   but  acceptable,  changes  in  hood
           volume, the total volume  from  a  multiple
           source system  may  be quite different than
           the original design.

        5.  The system information must be detailed, so
           that  branch   losses  may  be   determined
           accurately.

        6.  The system must be  installed  exactly as it
           is designed.  Any deviation will change the
           resistance of a branch and the flowrates in
           the system.
Lesson 3                       3-8                   Duct  Systems

-------
    F. Characteristics   of  systems   balanced   with   SLIDES  AND
       dampers  include:                                   NOTES

       1. Over  a limited range,  the  air volumes may be       3-20
          easily changed by changing the positions of
          the dampers.

       2. The system is flexible for future changes or
          additions.

       3. The damper  may  cause  material  accumulation
          in the duct or may be  eroded.

       4. Since no volume  changes  are  required  for
          balancing, the total volume will be the same
          as the original  design.

       5. If    balance   is   to   be   achieved   by
          trial-and-error, detailed  system information
          is not required,  and branches that obviously
          have   lower   resistance   need   not   be
          calculated.  However,  determining the branch
          that   has  the   greatest  resistance   is
          critical.

       6. Moderate  variation  from  the design  during
          system    installation    is    acceptable,
          particularly if the system is to be balanced
          by trial-and-error.


VI. Transport velocity                                    3-13

    A. The velocity maintained  within  a  duct segment
       is referred to as the transport velocity.

       1. For   systems  conveying  vapors,  gases  or
          smoke, the  transport  velocity chosen  is a
          compromise between fan energy cost and duct
          cost  - large diameter ducts result in lower
          pressure losses  and reduced  fan energy but
          cost  more than smaller diameter ducts.

       2. For systems handling particles, a transport
          velocity is chosen to  prevent settling.  The
          value of this velocity increases as the size
          or density of the particles  increases.

       3. Typical  values  for transport  velocity are
          given in the table.                               3-14
Lesson 3                       3-9                    Duct  Systems

-------
    B. There are several problems associated with the  SLIDES  AND
       build-up of material inside ducts:                 NOTES

       1. The resistance of the duct will increase due     3-15
          to the reduction  in effective flow area.

       2. If the material  is sticky or  tends  to form
          solid  cake,  the deposition  may  continue
          until the duct is completely plugged.

       3. Deposition  increases  the  weight of  a duct
          and may  cause the duct system  supports  to
          fail.

       4. Hardened material deposited inside the duct
          may break loose as a result of vibration and
          travel down the duct  to  the  fan or  other
          equipment,  causing damage.

    C. Inspecting  for  material  build-up  in  a  duct
       system  cannot  be  done  effectively  without
       making measurements, since the  accumulation is
       not visible from the outside.

       1. Measured static pressure differences between
          locations along a duct could be compared to
          expected   values   estimated   using   the
          techniques  described above.

       2. Measurements of static  pressure along a duct
          could be plotted as a function of equivalent
          length.  If there are  no  obstructions,  the
          measurements will produce a straight line of
          constant slope,  with the  values decreasing
          (becoming more negative) in the direction of
          gas flow.

    D. Visual inspection points:

       1. Another  concern  of  particle   conveying
          systems is  abrasion of the  duct surf ace,-- a
          potential that  increases  with  increase  in
          transport velocity.   This is  a particular
          problem  wherever  there  is  a  change  in
          direction of  the gas  stream,  such  as  at
          elbows or entries.   When material  strikes
          the duct walls, erosion can produce holes.

          a.  If the duct is under negative pressure,
             air will enter the system  through  the
             holes, reducing the amount  of air that
             enters at the  hood,  possibly causing loss
             of capture efficiency.
Lesson 3                       3-10                   Duct Systems

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           b.  If  the duct is under positive pressure,   SLIDES AND
              fugitive  emissions  may  result  as  air      NOTES
              exits  the  holes.   Also,  segments that
              have  reduced air flow  because  of  holes
              may  become   susceptible   to  build-up
              problems  due  to  the loss  of transport
              velocity.

        2.  The best  technique for locating holes in a
           duct system is a visual inspection.  To make
           more effective use of inspection time,  areas
           on  an  elbow  that are on the outside of the
           turn,  areas  on  a  straight  duct  opposite
           points of entry by  other  ducts,  and  areas
           along  the bottom  of horizontal ducts should
           be  emphasized.

        3.  Somewhat  related to transport  velocity  is
           the problem of duct corrosion.  As the gases
           within a duct cool,  condensation of moisture
           and/or acidic  material can  occur.    This
           cooling may be the result of infiltration of
           outside air or  simply due to  long residence
           times  in  the duct, which can be exacerbated
           by  low transport  velocities.

        4.  Physical  damage to ducts can also increase
           their  resistance.   A  duct  that has  been
           partially collapsed acts  much the  same  as
           a   duct   that   has  accumulated  material.
           Observations  of physical  damage should  be
           included  in the visual inspection of a duct
           system.
Lesson 3                       3-11                   Duct Systems

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                           PROBLEM SET 3

                         DUCT SYSTEMS
 3-1.   In the  system shown  below,  a measurement of hood static
       pressure in the 6  inch diameter duct at position A gives
       1.9 inches  of water.   From  position A back to the hood
       there are 15 feet  of straight duct and one 90°  elbow
       with R  = 2D.  Estimate the  flowrate if the temperature
       of the  air  stream  is 70°F.
       Solution

         Assume  a  velocity  of  3500  fpm

         Fh   =   0.5

         Hf   =   0.43 VP/ft

         IF   =    0.27

         Ce   =   [!/(! + Fh)  ]°'5    =    0.82

         VP   =             S
                                  - —
                   d/Ce2)   +  (HfL)  +  IF


                               1.9
                   I/(0.82)2+(0.0043)(15) +  0.27

             =   0.7909  inches  of water

        V    =   4005  (VP)0-5

                 4005  (0.7909)0'5

             =   3562  fpm  (checks with  assumption

        Q    =   4005  A  (VP)0-5

                 4005  (0.1963)  (0.7909)0'5

                 699 acfm




Lesson 3                       3-12                   Duct Systems

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                            LESSON 4

                    GAS COOLING SYSTEMS
Goal:
    To  develop an  understanding  of gas  cooling systems,  their
    design  and performance  characteristics,  and techniques  for
    their evaluation.
Objectives:
    At the end of this lesson the student should be able to:

    1. State the three commonly used methods for cooling gases in
       industrial ventilation systems.

    2. Recognize  the   fundamental   relationship   governing   the
       performance of a dilution cooling system.

    3. Use enthalpy  and mass  information  to  calculate  air  stream
       volumes in a dilution cooling system.

    4. State three problems associated with dilution cooling.

    5. Recognize  the   fundamental   relationship   governing   the
       performance of an evaporative cooling system.

    6. Use  enthalpy  and  mass   information  to   calculate   the
       theoretical water  requirement  in  an evaporative  cooling
       system.

    7. State three problems associated with evaporative cooling.

    8. Recognize  the   fundamental   relationship   governing   the
       performance of a natural  convection and radiation cooling
       system.

    9 - State four problems associated with natural convection and
       radiation cooling.

    10.  Conduct effective inspections of gas cooling systems.
Lesson 4                                      Gas Cooling Systems
                               4-1

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 List of Slides
 4-1    Gas Cooling
 4-2    Methods for cooling gases
 4-3    Dilution with cooler gases
 4-4    Problems with dilution cooling
 4-5    Sulfuric acid dew-point curve
 4-6    Quenching with water
 4-7    Problems with quenching
 4-8    Natural Convection and Radiation
 4-9    Radiant Cooler
 4-10   Problems with Convection and Radiation Cooling
Lesson 4                                       Gas Cooling Systems
                               4-2

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I. Introduction                                         SLIDES  AND
                                                          NOTES
    A. Many   processes  generate   gas  streams   at
       temperatures  that are too  high for  some  air
       pollution  control devices to accept.   Because
       of this, it is necessary to employ some type of     4-1
       cooling device  to reduce gas temperature.

    B. The  most  commonly  used methods  for  cooling     4-2
       gases  in industrial ventilation systems are:

       1. Dilution with ambient air

       2 . Quenching with water

       3 . Natural convention and radiation

    C. In a limited number of cases, forced convection
       systems using air or water for cooling,  may be
       encountered.

    D. Cooling equipment will add to the resistance of
       the  system  and  may change the  volume  and
       composition  of  the  gases.     If  it  is  not
       functioning   properly,   it  can  affect   the
       performance of  other components in the system.


II. Dilution  with ambient air                             4-3

    A. Cooling gases  by  dilution with  ambient  air is
       the simplest method that can be employed.   Hot
       gases  from  a   process  are  cooled  by  adding
       ambient air  in sufficient quantity  to produce
       a mixture with  the desired temperature.

    B. The    fundamental   relationship    governing
       performance  may be  developed  through  a  heat
       balance on the  dilution system:
          m1 = mass flowrate of hot gases
          h1 = enthalpy of hot gases
          m2 = mass flowrate of dilution air
          h2 = enthalpy of dilution air
          m3 = mass flowrate of gas mixture = m1  + m2
          h3 = enthalpy of gas mixture
Lesson 4                                       Gas  Cooling Systems
                               4-3

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    C. Quantity and temperature of the hot  gases and  SLIDES  AND
       the desired temperature of the mixture are the     NOTES
       parameters  that  control  the  design.     The
       success  of  the design  will  depend  on  the
       quantity of dilution air supplied  in relation
       to these parameters.

    D. There  are  several  potential  problems  with     4-4
       dilution cooling:

       1. Large  air   volumes  may   be  required  to
          accomplish    the    desired    temperature
          reduction.

       2. Problems with temperature  control  may also
          be experienced if the quantity  of dilution
          air is not regulated.

       3. When  the temperature  is  not   controlled,      4-5
          corrosion problems are possible if acid or
          moisture dew points are reached.

    E. The inspection of a dilution cooling  system is
       rather straight-forward.

       1. The system should be visually inspected to
          evaluate the integrity of the system  and to
          determine if there  are any indications of
          corrosion problems.

       2. If the temperature of the  mixed gas  stream
          is being monitored,  this  value should be
          noted and  evaluated in  terms  of  compati-
          bility    with    downstream    equipment,
          particularly  the  control device,   and with
          regard  to moisture  or  acid condensation
          potential.

       3. If controlled introduction  of the dilution
          air  is  employed,  the  condition  of  the
          controller   and   the   damper   should   .-be
          evaluated  and  the   set-point   temperature
          compared with any monitored values.

       4. If    temperature   is    not   monitored,
          measurements in the  mixed gas stream may be
          necessary to complete the evaluation.
Lesson 4                                      Gas Cooling Systems
                               4-4

-------
    F. Measurements on a mixed gas stream that employs  SLIDES AND
       a branch  duct to introduce the  cooling air can     NOTES
       be  used to  estimate  the  volume of air  coming
       from  the  process  and  the  volume  used  for
       dilution.

       1.  Measure   the   volumetric   flowrate   and
           temperature of  the mixed stream  and  the
           temperature of  the hot gas  stream and  the
           dilution  air  (usually  ambient air).

       2.  Convert  the  volumetric  flowrate  of  the
           mixture to a mass flowrate using the density
           corresponding to  the measured temperature.

       3.  Determine  the   enthalpies  of  the   three
           streams based on  their temperatures.

       4.  Substitute values into  the  heat  balance
           shown   previously  to   determine  the  mass
           flowrate  of the  hot  gas  and the  dilution
           air, as follows:

             "hotpot  + Kix ~ "Hiot) Dilution = mmixhmix

           or

             "W  =  mmix(hmix ~ hdi lution) / (hhot ~ ^dilution)

           and

             ^dilution = ^mix ~  "W

       5.  Convert the mass flowrates  to volumetric
           flowrates using the densities  corresponding
           to their  respective temperatures.
III. Quenching with  water                                 4-6

    A. When the  volume of hot gases is large and  the
       amount of air needed to capture them  is  small,
       some cooling  method other  than dilution with
       ambient air is needed.   Since evaporation  of
       water requires  a  large amount  of heat, the  gas
       under  these  circumstances  can be effectively
       cooled by simply  spraying  water  into the  hot
       gas stream.
Lesson 4                                       Gas Cooling  Systems
                                4-5

-------
    B. The    fundamental   relationship    governing   SLIDES AND
       performance  may be developed  through a  heat      NOTES
       balance on the evaporation system:
in
                    ~  ngasout)  = mwater (hwater vapor  ~  hwater)
    C. Again, the quantity and temperature of the hot
       gases  and  the desired outlet temperature are
       the parameters  that  control the design.   The
       success  of  the  design  will  depend  on  the
       quantity of water supplied in relation to these
       parameters   and   the   efficiency   of   its
       evaporation.

    D. There  are  several  potential  problems  with
       evaporative cooling:                                4-7

       1 . Water carry-over - degree of concern depends
          on  downstream equipment .

          a.  With  wet   scrubber   systems,     liquid
              carry-over  is  not  a concern,  and  the
              efficiency  of  the  evaporation  equipment
              need  not  be  particularly  high.    The
              evaporative  cooler may be  little  more
              than a series of spray nozzles mounted in
              the duct leading to the scrubber.

          b.  In systems  where  water carry-over  is  a
              concern, as in a fabric filter system,  a
              separate piece of equipment is likely to
              be used for evaporative cooling.  The gas
              stream  velocity will  be  significantly
              reduced,   and  the   liquid   will   be
              introduced  through   spray   nozzles  at
              pressures  capable  of producing  a  fine
              spray.    In  some  cases,   air-atomized
              nozzles may be used.   These  techniques
              will   likely   be   accompanied   by  an
              elaborate control system.

       2 . Corrosion - since the coolers utilize water
          sprays,   the  potential  for  moisture  and
          condensed  acid corrosion  is  significant,
          particularly  in systems where  all  of the
          water  is  not  evaporated.    The  designer
          usually  seeks to  mitigate these  problems
          through  the  use  of  appropriate  corrosion
          resistant materials and linings.
Lesson 4                                       Gas  Cooling Systems
                               4-6

-------
        3.  Temperature control - this can occur if the   SLIDES AND
           rate  of water addition is not controlled or      NOTES
           if  the  control  system  is unable to respond
           to  the rate  of change  of  the  gas  stream
           temperature.  Temperature control can also
           be  a problem if  the water atomization is not
           efficient.

        Evaluation of an evaporative cooler:

        1.  A   visual  inspection  to  evaluate  system
           integrity  and   indications   of  corrosion
           should be conducted.

        2.  If   the   outlet  temperature    is   being
           monitored, this value should be  noted and
           evaluated  in terms  of  compatibility  with
           downstream equipment.

        3.  If  temperature  is  not  monitored,  it  may be
           necessary  to  measure   it;  however,  this
           measurement  may  be   complicated by  the
           presence  of  water  droplets  in  the  gas
           stream.

        4.  A determination of the quantity of cooling
           water  used  should  be made.   This could be
           compared to calculated requirements.

           a.  Read the value  indicated  by  a flowmeter
              mounted on  the  delivery line  or  in the
              control room.

           b.  Observe the delivery pressure on a gauge
              mounted at the cooler or on the pump.  To
              be certain that any observed changes are
              due only to  a change  in water flowrate,
              the condition of the nozzles must also be
              evaluated.

           c.  Plugged   or   eroded   nozzles  can  --be
              determined by observing the spray pattern
              during operation.

        5.  The  quality of recycled  water  should  be
           evaluated.

           a. Water containing large particles would be
              of concern because  of the potential for
             plugging or  eroding the nozzles.
Lesson 4                                       Gas  Cooling Systems
                               4-7

-------
          b. If  the water contains  small  particles,   SLIDES AND
             there  would be  concerns about  passing      NOTES
             these more difficult to collect particles
             on to the control device after the water
             has been evaporated.

          c. The quality of the water can be evaluated
             by  having  plant  personnel draw a sample
             into a  clear  plastic  container that you
             provide.  The sample should be well mixed
             by  shaking and then allowed  to  settle.
             If the rate of settling is fairly rapid,
             then the water contains large particles.
             If  the settling  rate is very  slow,  the
             water contains fine particles.
 IV. Natural convection and radiation                       4-8

    A. Heat  is transferred  from a  duct surface  by
       natural   convection   and  radiation.     This
       behavior   can   be   exploited   to   produce
       significant amounts of cooling  by providing a
       section of duct that has large  surface area.

    B. The  fundamental  relationship  governing  the
       performance   of   the   cooler   may   again  be
       developed through a heat balance:

          mgas(hgasin ~ hgas out)  = UADTn,

             U   = overall heat transfer coefficient
             A   = heat transfer area
             DTm = log-mean  temperature difference

       1. The overall heat transfer  coefficient is a
          function   of   a   number   of   parameters,
          including  the duct diameter, the  nature of
          the duct surfaces,  the thermal conductivity
          of the metal, the velocity  of the hot gases,
          the   wind   speed,   and  the   temper atuare
          difference between the duct and the ambient
          air.

       2. The  log-mean  temperature  difference  is
          simply  a  means of  calculating an  average
          difference when that difference varies along
          the length of the duct.
Lesson 4                                       Gas  Cooling Systems
                               4-8

-------
    C.  Once again, the quantity and temperature of the   SLIDES  AND
        hot  gases and the desired outlet temperature      NOTES
        are the parameters that control the design. The
        success  of the design will depend  on  all the
        parameters  that   affect  the  heat  transfer
        coefficient  and  on  the total  surface  area
        provided.

    D.  Large  surface area  is typically achieved  by      4-9
        arranging  the duct  in  a  series of  vertical
        columns.    Since  the  velocities through  the
        columns   are  usually   below  the   necessary
        transport  velocity  for particles, the  base of
        alternate  columns are joined across a hopper
        for collection and removal  of any settled dust.

    E.  There are  a number of problems associated with      4-10
        convection and radiation cooling systems.

        1. The  size of  the  cooler  is  usually  quite
          large,  requiring   significant  amounts  of
          plant  area  for its  installation.

        2. Because the velocities in the  cooler  are
          generally below  the transport velocity for
          particles,  the   system  must be  cleaned
          continually to avoid build-up in the hopper
          sections.

        3. Because there  is  essentially  no  control on
          the cooling process,  it is not possible to
          control the outlet temperature.  This could
          result  in outlet temperatures that exceed
          the limitations  of downstream equipment or
          that decrease  into the range of moisture or
          acid condensation.

    F.  Because  of the  nature  of cooler  design  and
        operation, the items  that  can be inspected on
        these systems  is  limited.

        1. The cooler  should  be visually inspected to
          evaluate the integrity of the system and to
          determine  if  there are any  indications of
          corrosion problems.

        2. If the  temperature of the outlet gas stream
          is being  monitored,  this  value  should  be
          noted and evaluated in terms of compatibil-
          ity  with  downstream  equipment  and  with
          regard  to  moisture  or  acid  condensation
          potential.
Lesson 4                                      Gas  Cooling  Systems
                               4-9

-------
        3. If    temperature    is    not   monitored,
           measurements in the outlet gas stream may be
           necessary to complete the evaluation.
Lesson 4                                      Gas Cooling Systems
                               4-10

-------
                          Problem Set 4
                       Gas Cooling Systems
4-1.  Ducts  from  a  hot  process  and  an overhead canopy hood join
      before going  into a  fabric  filter collector.   Measurements
      just downstream of the  junction give an air volume of
      20,188 acfm at 250 °F.  Measurements in the hot duct give a
      temperature of 3,000 °F and the plant air  is estimated  at
      100 °F.  What  are  the actual air volumes being drawn from the
      process  and the canopy  hood?

      Solution
          m3  =   (20,188 ft3/min) (0.0558 lb/ft3)  =   1126.5 Ib/min

          m1(802.3)  +  (1126.5 - m1)(9.6)   =   (1126. 5) (45.7)

          m1   =   51.3 Ib/min


          £3000   =   />2000 (2460/3460)

                 =  0.0161(0.71)    =   0.0114 lb/ft3

          Q1   =   51.3/0.0114   =   4,5000  acfm


          m2   =    1075.2 Ib/min


          Q,   =    1075.2/(0.0708)   =   15,186 acfm
Lesson 4                                       Gas Cooling Systems
                               4-11

-------
 4-2.  A  cupola  furnace  emits  300  Ib/min of gases at 2,250 °F,
      Assuming  100 percent  utilization,  how much water at
      60 °F is required to cool the gas  stream to  350  °F?

      Solution
      Air:
                    Ah
                581.6

                 70.0
                511.6 Btu/lb
     Water:
h350
h60
Ah
A
V
131.
0.
131.
= 1059.

3
0
3
9

                    Ah
                       tot
            =  1191.2 Btu/lb
mw  =
                      [(300)(511.6)] Btu/lb

                         (1191.2) Btu/lb

                       128.8  Ib/min


                      (128.8 Ib/min / 62.4 lb/ft3)  (7.48 gal/ft3)

                       15.4 gal/min
Lesson 4
                               4-12
                                Gas  Cooling Systems

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                            LESSON  5

                         FAN SYSTEMS
Goal:
    To develop an understanding of fan systems, their design and
performance characteristics, and techniques for their evaluation,

Objectives:
    At the end of this lesson the student should be able to:

    1. Discuss the advantages and disadvantages of forced draft
       and induced draft fan systems.

    2. State the two classes of fan types used in industrial
       ventilation systems.

    3. List three types of axial fans and describe their
       performance characteristics.

    4. List five types of centrifugal fans and describe their
       performance characteristics.

    5. Describe three common fan arrangements.

    6. State the fan laws for a homologous series of fans and
       know how to apply them to fan inspection.

    7. Discuss how fan curves and system curves interact to
       determine the air volume delivered.

    8. Discuss how changing system resistance affects fan
       performance.

    9. Discuss how changing fan speed affects fan performance.

   10. Discuss how changing air density affects fan performance.

   11. Define "system effect" as it relates to fan performance.

   12. Estimate losses associated with system effects at the
       inlet and outlet of a fan.

   13. State the procedures involved in fan selection and know
       how to apply them to fan inspections.

   14. Describe how an amperage control system works during fan
       start-up.

   15. Conduct effective inspections of fan systems.
Lesson 5                       5-1                   Fan Systems

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 List of Slides
 5-1    Fan systems
 5-2    Forced-draft induced draft fan arrangements
 5-3    Types of fans
 5-4    Axial fans
 5-5    Centrifugal fan components
 5-6    Types of Centrifugal fans
 5-7    Forward curved fan
 5-8    Forward curved fan performance chart
 5-9    Radial fan
 5-10   Radial fan performance chart
 5-11   Backward inclined fan - standard blade
 5-12   Standard backward inclined fan performance chart
 5-13   Arrangement 1 SWSI
 5-14   Fan laws
 5-15   System curves
 5-16   Interaction of systems curves with fan curve
 5-17   Changes in fan rotation speed
 5-18   Effect of air density on fan performance
 5-19   System effects
 5-20   Fan selection
 5-21   Fan selection
Lesson 5                       5-2                    Fan Systems

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I. Introduction                                        SLIDES AND
                                                          NOTES
    A. The function of a  fan  is  to  cause  the desired
       amount  of air  to move  through a system  by     5-1
       overcoming  resistances in  the hoods,  ducts,
       coolers, collection devices, stacks and any
       other equipment present.

    B. Fan  performance depends  on  the type of  fan
       employed, the parameters of its operation,  the
       characteristics of the system it  is  used  in,
       and  the  properties  of  the  gas  stream  it
       operates on.

    C. A  fan  can be  generally  characterized on  the     5-2
       basis of its location in the ventilation system
       with respect to the control device.

       1. Fans  located before the control device  are
          referred  to as forced draft because they
          force or push the air through the collector

          a. Fan acts on the dirty gas stream and  may
             be subject to increased wear  and require
             a  higher  level  of  maintenance,  thereby
             increasing operating costs.

          b. Control  device  will  only  have  to
             withstand the pressure required to push
             the gas stream through the device and on
             to the stack. As a result, the  collector
             will require less structural  reinforcing
             and will likely  be  somewhat  cheaper.

       2. Fans  located after  the control device  are
          referred  to  as induced draft because they
          induce  or pull the  flow  through  the
          collector.

          a. Fan acts  on the  cleaned gas stream  and
             would  be less subject to wear.  Thds
             would  likely require  a  lower   level  of
             maintenance, reducing operating  costs.

          b. Control device will  have to  be
             structurally reinforced  to withstand
             essentially the entire negative pressure
             of the system and  will probably be more
             expensive.
Lesson 5                       5-3                    Fan  Systems

-------
II. Types of fans                                      SLIDES AND
                                                          NOTES
    A. Fans designs can be classified as either axial
       or centrifugal.  A special  class  of fan that      5-3
       employs a centrifugal wheel mounted in an axial
       arrangement will sometimes  be  encountered in
       industrial ventilation systems.

    B. Axial fans  are  used to  move large volumes of
       air against low resistances.  They may be used
       for general ventilation  or  in  low resistance
       industrial ventilation systems;  however,  they
       are  not  used  very often  in  air  pollution
       control systems.

    C. There are three basic  types  of axial fans:          5-4

       1. Propeller -  used for moving air against very
          low  static  pressures,  such  as  would  be
          encountered  in  general  room  ventilation.
          Their  performance  is very  sensitive  to
          resistance and a small increase will cause
          a significant reduction in flow.

       2. Tubeaxial -  essentially a  propeller-type fan
          mounted in a cylindrical housing and capable
          of moving air against pressures  less  than
          about 2 in. H2O.     Since  the  motor  is
          typically mounted inside  the housing, it is
          not  generally used on particle-containing
          gas streams.

       3. Vaneaxial  -  similar in  construction  to
          tubeaxial, but uses airfoil-style blades and
          straightening vanes on the inlet and outlet
          to improve  efficiency.    It is  capable of
          developing pressures up to about  8  in. H2O
          and  should also  be limited  to clean
          applications.

    D. The principal fan used in air pollution control      5-5
       systems  is  the centrifugal  fan.    The basic
       design  of  the  centrifugal fan employs  a fan
       wheel or impeller mounted inside a scroll-type
       housing.   Air  is draw  into  the  impeller and
       then forced out through  the  housing.

    E. Centrifugal fans  are distinguished  by the      5-6
       design of the  impeller.   There are three basic
       impeller types: (1)  forward  curved,  (2) radial
       and (3)  backward inclined.   The  backward
       inclined impeller may  use a  standard
       single-thickness blade or an airfoil blade.
Lesson 5                       5-4
                                                     Fan Systems

-------
    F. Forward curved impellers have blades that curve   SLIDES AND
       into the direction of rotation.                    NOTES

       1. Commonly referred to  as  "squirrel-cage      5-7
          blowers",  they are  constructed  of
          lightweight materials and usually have 24 to
          64 closely-spaced blades.

       2. For a given duty,  these impellers are the
          smallest of  all  the  centrifugal types and
          operate at the lowest speeds.

       3. They are  quiet in operation  but are  only
          able  to develop low  to moderate  static
          pressures.  Therefore, they are not commonly
          used in air pollution control  systems.

       4. Since  particles  may adhere  to the
          closely-spaced blades  and  cause a balance
          problem,  their use  should be  limited  to
          clean gas streams.

       5. The highest  mechanical  efficiency (ME)  is      5-8
          developed at a point to the right of  peak
          static pressure (SP), at about  50-60 percent
          of the wide open volume,  and the  horsepower
          requirement  (HP)  rises continually toward
          the free delivery volume.

    G. Radial  impellers have  6  to  10  blades  that      5-9
       extend either straight out from the hub (R) or
       in a radial direction (M).

       1. They are the simplest of all the centrifugal
          fans and the least efficient,  but they are
          capable  of  developing  the  highest static
          pressures.

       2. For a given duty, they  operate  at moderate
          speeds.

       3. The  radial blade  shape  is  generally
          resistant to material  build-up and may be
          used in  systems handling  either clean or
          dirty air.   Impeller  designs,  range  from
          "high efficiency, minimum  material"  to
          "heavy impact resistant".

       4. Highest mechanical efficiency is developed      5-10
          just to  the  left of peak static pressure, at
          about 30-40 percent of  the wide open volume
          and the horsepower requirement  again rises
          continually toward the free delivery volume.
Lesson 5                       5-5                   Fan Systems

-------
    H. The  standard backward  inclined  impellers  have  SLIDES AND
       9 to 16 single-thickness blades that incline or     NOTES
       curve  away from the direction of rotation.
                                                          5-11
       1. Peak efficiency and speed are slightly  less
          than the airfoil design.
                                                          5-11
       2. Because  the blades are single  thickness,
          they can be used in gas streams  with light
          dust loadings.  However,they  should not be
          used in heavy loading  situations  that could
          cause build-up on the blade surfaces.

       3. Highest mechanical  efficiency is developed     5-12
          to  the  right of peak  static pressure,  at
          about 50-60 percent  of the wide open volume.
          A  unique characteristic of  the backward
          inclined  impeller   is that  the  horsepower
          requirement reaches  a maximum value near the
          point of peak efficiency and  then declines
          toward the free delivery volume.   For  this
          reason backward inclined fans are sometimes
          referred to as "non-overloading", since any
          variation from the  optimum operating point
          due  to  a  change in system resistance  will
          result  in  a  reduction  in operating
          horsepower.


    I. The airfoil backward inclined impellers have 9
       to 16 hollow airfoil-style  blades that incline
       or curve away from the  direction of  rotation.

       1. They have the highest  efficiency  of all the
       centrifugal fans and,  for  a given  duty,  will
       operate at the highest speed.

       2. Hollow blades can erode  and accumulate
          material inside, causing a balance problem.
          They should, therefore,  be limited to clean
          air applications.

       3. Highest mechanical  efficiency is developed
          to  the  right of peak  static pressure,  at
          about 50-60 percent  of the wide open volume.
          The  horsepower requirement exhibits  a
          non-overloading characteristic.
Lesson 5                       5-6                   Fan Systems

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    J. The tubular centrifugal fan employs a centirif-
       ugal  wheel mounted in  an  axial  arrangement.
       The  impeller design  is  usually backward
       inclined but, although it has the  same general
       performance characteristics and limitations, is
       somewhat  less  efficient.   It  also has lower
       capacity   and  static  pressure capabilities
       because of the  90  degree change  in direction
       that  occurs  as  the  air moves  through  the
       housing.
                        SLIDES AND
                          NOTES
III. Fan arrangements

    A. Fans  are constructed with  different bearing
       locations  and  motor mounting  capabilities,
       generally referred  to as  "arrangements".
       Although these are  not of  any particular
       importance to the inspection task, knowledge of
       the various arrangements is desirable when it
       is useful to  speak the language of fan systems.

    B. There  are  ten  basic  fan arrangements  [refer
       students to  Figure  5-9  in  Student  Manual,  p.
       5-8J.   SW  or  DW  refers  to  single-  or
       double-width  fans,  respectively.   SI  and  DI
       refer to single- or double-inlet, respectively.

    C. The most common fan  arrangements employed are
       Arrangements 1,  3 and 9.

       1.  Arrangement 1 has two shaft bearings mounted
          on the pedestal with  the impeller overhung
          on  the  end  of  the  shaft.   For  a  V-belt
          drive,  the  motor  would be  mounted  on  a
          separate base adjacent to the pedestal and
          at ground level,  with pulleys or sheaves on
          both the motor shaft and the fan  shaft.  For
          direct drive, the motor would be mounted on
          a separate base  and  connected directly to
          the shaft, or on an extended fan base as -in
          Arrangement 8.

       2.  Arrangement 3 also has two shaft bearings,
          but they are located  on either side of the
          impeller and supported by the fan housing.
          The drive arrangement would be the same as
          Arrangement 1.

       3.  Arrangement 9 is the  same as Arrangement 1,
          but has the motor mounted  on the outside of
          the fan base with a V-belt drive system.
                           5-13
Lesson 5
5-7
Fan Systems

-------
    D. Fans driven by V-belts will have  an  effective  SLIDES AND
       horsepower that is less than that provided  by     NOTES
       the motor because of drive losses.

 IV. Fan Laws

    A. The fan  laws relate the performance  variables
       for any homologous series  of  fans.    A     5-14
       homologous  series  is  simply  a range  of fan
       sizes where all of the dimensional parameters
       are proportional.

    B. At the same relative point of operation on any
       two  performance curves in a homologous  series,
       the  mechanical efficiencies  will  be   equal.
       Under  these  conditions, the following
       relationships apply:

          Q2 = Q1(size2/size1)3(rpm2/rpm1)

          P2 = P1(size2/size1)2(rpm2/rpm1)2(r2/r1)

          bhp2 = bhp1(size2/size1)5(rpm2/rpm1)3(r2/r1)

       The  pressure  may  be represented  by total
       pressure, static pressure, velocity  pressure,
       fan total pressure or fan static pressure.

    C. These  expressions  rely  on the  performance
       curves being homologous and apply only at the
       same relative point of rating.   Under  turbulent
       flow, two performance conditions will be at the
       same relative point of rating if the  pressures
       and  flowrates at  these  two  conditions are
       related by:
       This  is  the same  as  saying  that  the two
       performance  points must  lie along  the  same
       system curve.
Lesson 5                       5-8                   Fan  Systems

-------
    D. Fan  laws  are typically used to determine the   SLIDES AND
       effect of changing only one variable at  a time      NOTES
       and  are  most  often  applied to  a  single fan
       size.  The most common variable of  interest  is
       fan  speed.    For  determining  the  effect   of
       changing fan speed while operating  on the same
       gas  stream  (r1 = r2) , the fan laws become:

          Q2 = Q

          P2 = P

          bhp2 = bhp1(rpm2/rpm1)3

    E. Note  that if only changes  in gas density are
       involved,   pressure  capabilities   and  power
       requirements  change  proportionally,  while
       flowrate is  unaffected.   This behavior   is
       sometimes characterized by  stating  that  "a fan
       is a  constant  volume machine", i.e.,  it moves
       volumes of  air not masses of air.
V. Fan performance

    A. Performance  graphs  for centrifugal fans were
       shown earlier.  One of the relationships shown
       on  these figures  was that  between pressure
       developed  and air volume  moved  [draw repre-
       sentation  on board].   This  relationship is
       referred to  as  the  fan  curve or  fan char-
       acteristic.  For a particular fan turning at a
       given rpm,  there is one and only one fan curve.
       It  represents all  of the pressure/air volume
       combinations  that the fan is capable of when
       operating at  that  one rpm.   These range from
       low air  flow delivered against high pressure
       (upper left)  to high air flow delivered  against
       low pressure  (lower  right).   What determines
       which condition  a  fan will operate at is how
       this  curve  interacts with  the  ventilation
       system characteristics, as represented by the
       system curve.

    B. Normalized duct system curves for three  systems       5-15
       are shown in this figure.   Plotted  here is the
       percentage  of  duct  system  resistance  as a
       function  of  the percent  of duct  system
       flowrate.  This is simply a normalized  version
       of a P verses Q plot.   The system curves shown
       follow the  general relationship characteristic
       of turbulent systems:
Lesson 5                       5-9                   Fan Systems

-------
       P  - P (O /O )2                                   SLIDES AND
       p2 - P^QZ/QI)                                       NOTES


       1. In practice, the system curve is developed
          by  first determining the  resistance  or
          static pressure for one flowrate through the
          system, using the  techniques  discussed in
          Lessons 2 and 3.  Other points on the curve
          are then determined  using the above
          relationship.

       2. If the design point for System A were at 100
          percent volume and 100 percent resistance,
          increasing the flowrate to  120  percent of
          the design  flow  would  increase the
          resistance  to 144  percent  of the design
          resistance.

       3. Likewise, decreasing the  flowrate to  50
          percent of the design value would decrease
          the resistance to 25 percent of the design
          resistance.   Note  that,  on  a  percentage
          basis, the same relationships  also hold for
          Systems B and C.

    C. The point of intersection of the system curve      5-16
       with the  fan curve  determines  the  actual fan
       performance.   This  is shown in  this figure,
       where a normalized fan curve has been plotted
       with  the  system curves from the  previous
       figure.   Unless actions are taken  to change
       either the fan curve or the system curve, the
       performance delivered will be that indicated by
       the intersection point.

    D. One way  to  change  the f lowrate would  be  to
       change the  system.   This  could be  done  by
       closing or opening a damper,  producing a system
       with more or less resistance and changing the
       system curve.

       1. Referring to the same figure, the  flowrate
          could   be  decreased to  80  percent  of the
          design volume by  closing  a damper  until the
          more resistant System B curved is  obtained,
          shifting the intersection to Point 2.

       2. Likewise, the flowrate could be increased to
          120 percent of the design value by opening
          the damper and shifting the  intersection to
          Point  3.
Lesson 5                       5-10                   Fan Systems

-------
    E. Changes in flowrate could also be produced  by   SLIDES AND
       changing the fan speed, shifting the fan curve.      NOTES
       This is illustrated in this figure, where a new
       fan curve representing a 10 percent increase  in      5-17
       speed has been  added.  At this new  speed, the
       point of operation shifts to Point 2.

       1. Since flowrate is proportional to fan speed,
          this 10 percent  increase in speed produces
          a  corresponding 10 percent   increase  in
          volume.

       2. However,  following  the fan laws, this  10
          percent increase in speed will  reguire a  33
          percent  increase in operating horsepower,
          which may be beyond the capabilities of the
          existing motor.

    F. According to the fan laws, changing gas  density      5-18
       will shift the  fan  curve.  However,  since gas
       density also affects the system resistance, the
       system  curve  will also be  shifted.   This  is
       illustrated in  this figure  for a doubling  of
       the  density.    The new operating  point  will
       deliver the same  air volume but at  double the
       resistance  and double  the  horsepower
       requirement.

    G. Fan  performance can also be  affected  by the
       manner  in  which the fan  is  installed  in the
       system.  Ratings information is developed in a
       test set-up  that  insures consistency and
       reproducibility of results and permits  the fan
       to develop  its maximum performance.   In any
       installation where uniform flow conditions  do
       not exist, fan performance will be reduced.

       1. Installation conditions that  affect fan      5-19
          performance are  referred  to as "system
          effects".  The three most common causes  of
          deficient performance are:

          a. Non-uniform inlet flow

          b. Swirl at the fan inlet

          c. Improper outlet connections
Lesson 5                       5-11                   Fan Systems

-------
       2. The  influence of  system effects  on  fan  SLIDES AND
          performance is shown  in this figure.            NOTES

          a. The solid fan  curve has been determined
             without consideration  of  system  effects
             and performance corresponding to Point 1
             is anticipated.

          b. Because of system  effects the effective
             fan  curve is  the dashed line and
             performance corresponding to Point 3  is
             obtained.

          c. This  deficient performance  could  be
             prevented by calculating  the  system
             effect  loss,  adding it  to  the system
             resistance and selecting a fan to operate
             at Point 2.

       3. Refer students to Figures 5-15  through 5-17
          in Student Manual,  pp. 5-14 through  5-16,
          for  system effect  loss  factors for  some
          common  installation conditions.    These
          factors are in numbers of velocity pressures
          lost, so the addition to  the system static
          pressure would be egual to the  loss factor
          times the appropriate velocity  pressure.
VI. Fan selection

    A. Selecting a fan is usually the responsibility
       of the ventilation system designer.   However,
       since the inspector may  wish to  apply
       variations of  the selection technique  in
       evaluating the  performance of an existing fan,
       it is important that the methods  used  by the
       designer be understood.

    B. Fan selection is typically done using ratings
       tables published  by  manufacturers for  their
       products.

       1.  The ratings  table  is entered along the row
          corresponding to the design volume and down
          the column  corresponding to  the  design
          static pressure, including  system  effects.
Lesson 5                      5-12                  Fan Systems

-------
       2. The point of intersection indicates the rpm  SLIDES AND
          that the fan would  have  to  turn  to deliver     NOTES
          the required performance and the  horsepower
          that would be needed to  drive it.

       3. Shaded regions  are  usually  included on the
          chart to indicate areas  of  good  mechanical
          efficiency.

       4. Ratings tables  indicate  the performance of
          a fan when operating on standard air.  Since
          a  given  system  may be  handling  air  of  a
          different density,  some adjustments  are
          involved  before  entering  the  table.
          Remember,  density  does not affect  fan
          volume,  but  it does   influence  static
          pressure  conditions and horsepower
          requirements.

    C. The  specific  procedure  involved  in  fan
       selection is as follows:                           5-20

       1. Determine the  design  air volume at actual
          conditions.

       2. Calculate the fan static pressure at actual
          conditions, including system  effects.   Fan
          static pressure  is defined  as:

             FSP = SPout - SPin - VPin

          In calculating fan static pressure, the sign
          of the static pressure is important and must
          be included.

       3. Correct  the  fan  static pressure to  an
          equivalent value for standard air:

             ^equivalent = FSPactual < ° • 075/r8ctual)

       4. Enter the ratings table at the actual volume      5-21
          and  the  equivalent fan static  pressure.
          Determine the  rpm   and  horsepower
          requirements.

       5. Correct the  horsepower   requirement  to the
          conditions of actual operation:

             bhPactual  = ^equivalent
Lesson 5                       5-13                   Fan  Systems

-------
    D. In selecting the appropriate motor for a fan,
       the  designer  must  give consideration  to the
       possible   air densities the fan  may  have to
       handle.  Should the  system be located outdoors
       in an area that has extreme low temperatures,
       the  horsepower  requirement  for  cold start-up
       could be considerable.

    E. An alternate way of  dealing with cold start-up
       would be to install the horsepower  required for
       normal  operation and  then use  an inlet  or
       outlet damper,  together  with  an amperage
       control system, during start-up.

       1. When the  fan is  started on cold air,  the
          amperage control  system would sense a high
          current flow and close the damper to prevent
          or reduce air flow into  the fan.

       2. The fan turning through the restricted air
          flow would heat it up, reducing its density
          and reducing the current draw.   The amperage
          control system would sense this  and open the
          damper a little bit to allow  some air flow
          from the hot process.

       3. This  scenario would continue until  the
          damper was  fully  open  and the  system was
          operating at design conditions.

VII. Evaluation of fan performance

    A. The fan laws and the techniques involved in fan
       selection  may be used by  the  inspector  to
       estimate the air volume  the fan is delivering.
       For example,  if the  air  volume delivered by an
       existing  fan  were  known,  but  a  subsequent
       inspection determined that the  fan speed had
       been  changed, the  new air  volume could  be
       estimated from:
                        the
                        requ ired
                        volume
                        when
                        turned at
                        the

                        SLIDES AND
                           NOTES
          Q2 =
    B. Initial estimates of air volume could be made
       using  measurements  of  the fan  operating
       parameters,  together  with  the appropriate
       ratings table.

       1.  This approach would  apply  only to V-belt or
          variable-speed drive fans,  for which general
          ratings tables are available.  Direct drive
          fans are specially  constructed to  deliver
Lesson 5
5-14
Fan Systems

-------
          speed of the motor and do not have published   SLIDES AND
          performance tables.                              NOTES

       2. Because of  our inability to  make exact
          measurements of some of the  parameters  and
          because of  a  lack  of precision  in  the
          ratings tables, these techniques will yield
          only a rough estimate of flowrate.

       The most satisfactory technique for estimating
       fan performance from the ratings tables would
       be to  use measurements of fan speed and  fan
       static pressure.  The specific procedure  is as
       follows:

       1. Measure or estimate fan rpm.  To  obtain as
          much accuracy  as  possible, measurement of
          the rpm is preferred.  However,  if this is
          not possible, an estimate can be used.

       2. Determine fan static pressure for operation
          on  standard air.    This  would  involve
          measuring inlet and  outlet static pressures
          and estimating  inlet velocity pressure.

          a. To  avoid turbulence problems,  the
             measurements could be made some distance
             away from  the fan, where  acceptable
             readings  can be  obtained.   If measure-
             ments  are  made  at  about the  same
             equivalent length away  from the inlet  and
             outlet,  the error  introduced  by  this
             should be minimal.

          b. If inlet  or  outlet dampers are present,
             the  loss  introduced by these fittings
             would have to be estimated and included
             in the  determination of the  respective
             static pressure.   Likewise,  any losses
             due to system effects should be included.

          c. Air  density  could be  estimated  from  a
             measurement of temperature,  and velocity
             pressure could be estimated based on  the
             expected velocity at the inlet.

             The estimated fan static  pressure would
             then be given by:

                       =  0.075(8?^  - SPin  -
                          VPin)/ractuat
Lesson 5                       5-15                   Fan Systems

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       3. Enter the ratings table for the fan at the  SLIDES AND
          column corresponding to  the  estimated fan     NOTES
          static pressure.  Proceed down this column
          until the row  containing the measured fan
          speed is located.  Read  along this row to
          determine  the  estimated  flowrate.
          Interpolation between values  in the ratings
          table may be necessary.

       4. If  the  air  volume determined from  this
          procedure gives  a  significantly  different
          velocity pressure than that assumed in Step
          2,  the  velocity pressure should  be
          re-estimated and the  procedure repeated
          until a reasonable  agreement  is obtained.

    D. A  less  satisfactory technique  for estimating
       fan performance from the ratings tables would
       be to use measurements of fan static pressure
       and operating horsepower.

       1. Following the same  general  procedures
          outlined  above,  the  fan static pressure
          would be  estimated and  used to  enter  the
          ratings table.

       2. The  row corresponding   to  the  estimated
          operating horsepower  would then be  located
          and  used  to  determine the estimated
          flowrate.

    E. The fan inspection should include an evaluation
       of the condition of the  fan.

       1. A visual determination of the condition of
          the fan housing to assess  any  indications of
          corrosion.

       2. An  evaluation  of  the  condition  of  the
          isolation sleeves used to dampen vibration
          between  the  fan  and  the  inlet  and outlet
          ducts to determine  if  there are any leaks.

       3. An evaluation of  any vibration  or  belt
          squeal.

          a.  Belt  squeal during  operation  indicates
             that  the belts are  slipping  on  the
             pulleys.   This can result  in the loss of
             200-300  rpm,  with  a corresponding
             loss  in air  volume.
Lesson 5                      5-16                  Fan Systems

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          b. A  fan  that  is vibrating  severely
             represents a significant safety hazard.
             If this condition should be
             encountered,  the inspection  should be
             terminated  immediately and plant
             personnel notified of the condition.

       4. Confirmation of the fan  rotation direction.

       5. If the fan is not  operating, an inspection
          of the condition of the fan wheel would also
          be  useful  to  identify any  build-up  or
          corrosion problems.
Lesson 5                      5-17                   Fan Systems

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                         PROBLEM SET 5
                          FAN SYSTEMS
 5-1.   A fan with a 20  inch diameter  inlet  duct  is  exhausting
       8,000 acfm at 150  °F.  The inlet static pressure is
       -4.35 inches of  water and  the  outlet static  pressure
       is 0.55 inches of  water.   What is the actual fan static
       pressure?   What  is the fan static pressure at 70 °F?

       Solution
                  (w/4) (20/12)'
                   2.182 ft2
          V
8000/2.182
3666.4 fpm
          VP  =   0.0651  (3666.4/1096.7)2


          FSP150   =   0.55  -   (-4.35)  -  0.73

                 =  4.17 inches of water

         FSP70    =  4.17  (610/530)

                 =  4.80 inches of water
                              0.73  inches  of
                                   water
Lesson 5
                               5-18
                                   Fan Systems

-------
5-2.  A  fan  is  delivering  10,500  acfm at 3.0 inches of water fan
      static pressure  when running  at 400 rpm and using 16.2
      horsepower.   If  the  fan  speed is increased to 500 rpm,
      determine the new  flowrate, fan static pressure and
      horsepower requirement.


      Solution
           Q2   =   10,500  (500/400)

                    13,125  acfm


           FSP2 =   3.0 (500/400)2

               =    4.69  inches  of  water


           bhp2 =   16.2  (500/400)3


               =    31.64 horsepower
Lesson 5                       5-19                   Fan Systems

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 5-3.  A fan is needed to deliver 5,800 acfm at 200 °F.  The fan
       static pressure at operating conditions is estimated  at
       6.0 inches of water.  For what conditions must  the fan be
       selected from the ratings tables?
       Solution


          FSP7Q     =    6.0 (660/530)

                   =   7.47 inches of water


         Select fan for 5,800  cfm and 7.47 inches of water
Lesson 5                       5-20
Fan Systems

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5-4.  in the  system  shown  below,  actual  gas  temperature is
      150 °F.   Form "A" to the elbow at the fan inlet  is
      20 feet, and from the  fan  outlet to  the discharge elbow
      is 8  feet.  Both inlet and outlet  ducts are 58  inches
      diameter and both elbows have  an R=1.5D.  Using the ratings
      table below, estimate  the  air  volume if the fan speed is
      1,050 rpm.
     Solution

     Assume  a velocity  of  3,500  fpm

         VP   =    (3500/4500)2   =   0.76 inches of water
         IN

         Straight duct =
         Elbow         =
(0.0021) (20) (0.76)  =  0.041 in. water
(0.39)(0.76)   =  0.296 in. water
         System effect  =   (1.1)(0.76)
              =  0.836 in. water

              -11.173 in. water
         OUT

         Straight duct =

         Elbow         =

         System effect =
(0.0027) (8) (0.76)  =  0.016 in. water

(0.39)(0.76)   =  0.296 in. water

(0.33) (0.76)    =  0.251 in. water
                               SP
                                 out
               0.563 in. water
          FSP   =   0.563  -  (-11.173)   -  0.76

                =   10.976 inches  of  water

          Approximate FSP  as  11.0  inches  of water
Lesson 5
     5-21
Fan Systems

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           Interpolation at 1050 rpm gives a volume of  61,813
           acfm.

               V   =   61,813/[(7T/4) (58/12)2]

                       3,369 fpm
           Fairly close to assumption  - could estimate velocity
           as 3400 fpm and repeat.
Lesson 5                       5-22
Fan Systems

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                           LESSON 6

           MEASUREMENT OF VENTILATION SYSTEM
                          PARAMETERS
Goal:
To develop an understanding of the equipment and procedures for the
measurement  of ventilation system performance parameters and the
limitations  of the techniques.

Objectives:
At the end of this lesson the student should  be  able to:

    1. Select  the  proper   size  port  for  ventilation  system
       measurements.

    2. Effectively seal a port while measurements are being made.

    3. Select,  calibrate and  operate equipment  for making static
       pressure measurements.

    4. Select,   calibrate  and  operate  equipment  for  making
       temperature measurements.

    5. Determine the  number and location of traverse points needed
       for a representative measurement of flowrate.

    6. Select,  calibrate and  operate equipment for making  flowrate
       measurements.

    7. State three techniques  for measuring face velocity at hoods.

    8. State three techniques for measuring  fan  speed.

    9. Make an  estimate of fan speed for fans with a V-belt drive.

   10. Describe   a   procedure  for  determining  'the  operating
       horsepower of  a fan.

   11. Describe  two   techniques  for  estimating  fan  operating
       horsepower.

   12. Determine when measurement probes should be grounded and how
       to accomplish  it.
Lesson 6                       6-1                   Measurement

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 List  of  Slides
 6-1    Measurement  of ventilation  system  parameters
 6-2    Measurement  ports  for portable  inspection equipment
 6-3    Large  stack-sampling port
 6-4    Small  measurement  port
 6-5    Differential pressure transmitter  and  port
 6-6    Plugged port
 6-7    Plugged elbow
 6-8    Plugged port
 6-9    Measurement  of pressure
 6-10   Aspiration effect  error  in  static  pressure measurement
 6-11   Slack  tube manometer
 6-12   Static pressure gauges
 6-13   Static pressure gauges
 6-14   Techniques for the measurement  of  temperature
 6-15   Thermocouple calibration recommendations
 6-16   Temperature  measurement  errors
 6-17   Thermocouple support techniques
 6-18   Air  infiltration error in temperature  measurement
 6-19   Effect of water droplets on temperature measurement
 6-20   Measurement  of gas flowrate
 6-21   Gas  flowrate EPA Reference Methods
 6-22   Complete sampling  train  for gas flowrate  measurements
 6-23   Types  of pitot tubes
 6-24   Pitot  tube coefficients
 6-25   Number of sampling points required
 6-26   Locations of sampling points required
 6-27   Locations of sampling points required
 6-28   Checking for cyclonic flow
 6-29   Measurement  of fan speed
 6-30   Checking sheave diameters
 6-31   Checking fan speed using sheave diameters
 6-32   Horsepower measurement
 6-33   Estimating horsepower from amperage measurements
 6-34   Grounding cables
Lesson 6                       6-2                    Measurement

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I. Introduction                                         SLIDES  AND
                                                           NOTES
    A.  In   previous   lessons,   the  use  of  various
        parameters  to  evaluate  the  performance  of
        ventilation   system   components   has   been      6-1
        suggested.

    B.  In  this  lesson,   the methods  available  for      6-1
        making these measurements will be discussed and
        recommendations   on   the  most   appropriate
        techniques and procedures will be made.  Where
        appropriate,    additional    techniques    for
        estimating some parameters  will be given.


II. Measurement ports                                      6-2

    A.  The  most likely port  to  be  found initially on
        a ventilation system  is a 3  or 4 inch diameter
        sampling port located on or near the  stack.
        Although a port in this location may be useful      6-3
        for some inspection measurements, ports of this
        size should,  in general,  be avoided.

        1. Difficult to sealing under  both positive and
          negative conditions

        2. May  be  difficult  to  open because of  the
          large thread area.

    B.  The  most useful  port size  for  inspections is      6-4
        l%-2  inch  diameter,  and  this size  is  needed
        only if measurements  of  velocity pressure are
        anticipated.  For  the  more routine measurements
        of temperature and static  pressure,  ports of
        %-%  inch  will accommodate most  measurement
        probes.

    C.  Permanently  installed  static pressure  lines
        should  be  avoided  by the  inspector.   Plant      6-5
        personnel  will  be needed to  disconnect  thefri,
        only   static   pressure   information   can  be
        obtained from them,  and it  is difficult to
        insure that the lines are clear.

    D.  Measurement   ports   are   subject   to   the      6-6,
        accumulation of material that may cause them to      6-7,
        become plugged, even  if  they are on the clean      and
        side of the control device.   Before using any      6-8
        port,   it   should  be  cleaned  out   with  a
        non-sparking rod to assure unobstructed access
        to the gas stream.
Lesson 6                       6-3                    Measurement

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       Never open a port that was not placed there for  SLIDES AND
       your exclusive use.  Plant monitoring ports may     NOTES
       be  connected  to  controllers  that  initiate
       equipment shut-down if the signal from them is
       lost.

       Because of the potential for fire or explosion
       from  sparks and because of possible damage to
       downstream equipment,  the inspector should not
       request  that  ports  be  installed  while  the
       equipment  is  running.   Rather,  the  locations
       and  sizes  needed should  be marked for  plant
       personnel,  so  that  they may install  them the
       next time the system is shut down.

       The inspector should not make heroic efforts to
       reach existing ports and should not have  ports
       installed in locations that cannot  be reached
       and  used  in  safety.    This  should  include
       consideration   of  hazards  to  walking   and
       climbing, as well as the potential for exposure
       to  inhalation,  vision,  hearing  and  fire  and
       burn hazards.
III. Static pressure measurement
                                                          6-9
    A. There  are  two  widely  used  techniques  for
       sensing static pressures:

       1. U-tube manometer

       2. Magnehelic differential pressure gauge

    B. The U-tube manometer is a reference instrument
       that is available in a  flexible  or slack-tube
       configuration to enhance its portability.  The
       manometer is equipped with magnets at  the  top
       and bottom to facilitate temporary mounting and
       is equipped with threaded connectors that  are
       used to seal the manometer during  transport~
                                                          6-11
       1.  The manometer indicates the static pressure
          by displacing  the fluid  in  the tube.   In
          making static pressure measurements, one leg
          of the manometer  is  connected to the probe
          and  the   other   is   left  open   to  the
          atmosphere.   The  height  difference  between
          the  levels  in  the  two  columns   is  the
          pressure in height of fluid, usually
          expressed in inches of water.
Lesson 6                       6-4                   Measurement

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       2. One  of  the  principal  difficulties with the   SLIDES  AND
          U-tube  manometer  relates  to  the fluid.   If      NOTES
          the   pressure   in  the  duct  exceeds  the
          capacity of the manometer, fluid will either
          be drawn into the duct or  blown  out onto the
          inspector.

       3. The  inspector must remember to  close  the
          seals  when transporting  the manometer  to
          prevent loss  of  fluid  and  to open  them
          before  making  a measurement.

    C. The Magnehelic pressure  gauge  is a product of      6-12
       Dwyer  Instruments,   Inc.    It senses  pressure
       difference by  deflecting a  silicone  rubber
       diaphragm  and then translating that deflection
       to  a  needle  indication through  a  magnetic
       linkage.   Although  not  as accurate  as  the
       U-tube  manometer, it is  much more forgiving,
       making  it  easier  to  use  in field situations.

       1. The  Magnehelic  is accurate to  within  2
          percent of  full  scale  and  has  a  high
          resistance  to  shock and vibration.   It is
          available in over 70 ranges,  from 0-0.25 in.
          H2O to 0-20 psig.  The  most useful ranges for
          ventilation system inspection are 0-5, 0-20
          and  0-50 in. H20.

       2. Except  for the  0-0.25 and  0-0.50  in.  H2O      6-13
          ranges, the  magnehelic may  be  used  in  any
          orientation and can accept pressures up to
          15 psig without being  harmed.  This property
          allows  gauges  with different ranges  to be
          combined in one instrument package.

       3. Because of  the silicone  rubber diaphragm,
          the ambient temperature range is limited to
          20° to  140°F.  This lower limitation can be
          accommodated when conducting inspections in
          cold environments by keeping the gauge in- a
          location that  is  within  the  range and then
          taking  it  out   briefly   for  making  the
          measurement.

    D. The Magnehelic is not  a  reference instrument,
       so   its   calibration   should   be   checked
       periodically.

       1. The simplest way  of doing this  is to check
          its indications against a  U-tube manometer.
Lesson 6                        6-5                    Measurement

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          Using  a  laboratory  squeeze-bulb  equipped   SLIDES  AND
          with check valves,  pressures from -40 to +40     NOTES
          in. H20 can be easily generated.

       2. The Magnehelic indications should be plotted
          against those of the manometer to check for
          accuracy  and  linearity-   Gauges that  give
          inaccurate or non-linear indications should
          be discarded.

       3. While  using  the gauge,  its zero should  be
          checked  frequently and  adjusted as  needed
          using  the set-screw  on the  front  plate.
          Adjusting  the  zero  will  not  affect  the
          calibration of the gauge.

    E. Static pressure measurements must be made  with
       a square-ended probe placed at a right-angle to
       the flow  direction.   The purpose  of the probe
       orientation is to be sure that no component  of
       velocity  pressure    is  impacting  the probe
       during static pressure measurements.

    F. The area between the probe and the port opening
       should  be sealed  to  avoid errors  associated
       with  flow into  or  out  of  the  duct.    Errors
       resulting from improper  sealing can be as large
       as 10-30 percent.                                   6-10

       1. Flow   into  the  duct  can  result  in  an
          aspiration effect  at  the end of the probe
          that can increase  (make more  negative)  the
          negative pressures being measured.

       2. Flow out of the duct can add a component  of
          velocity  pressure  to  the  measurement  of
          positive pressures.

    G. Several techniques  are  available for sealing
       measurement ports.

       1. For  inspection  ports,   the  best   sealing
          technique is  to  insert the probe through a
          rubber stopper and then place  that stopper
          into or against the port.

       2. For  the  larger  stack-sampling ports,   a
          rubber sanding disc may be used to cover the
          opening.  The probe,  equipped with  a rubber
          stopper, would then be inserted through the
          center  of  the  sanding  disc,  using   the
          stopper to complete the seal.
Lesson 6                       6-6                   Measurement

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    H. To further mitigate port sealing problems,  the   SLIDES AND
       probe  should be extended  well into the  duct     NOTES
       while making measurements.
IV. Temperature measurement                               6-14

    A. There  are  several techniques  available  for
       measuring temperature,  including:  (1)  mercury
       thermometers,  (2)  dial thermometers,
       (3)   thermistors   and   (4)    thermocouples.
       Unfortunately,  each of  these techniques  has
       some limitation when applied to the inspection
       of industrial ventilation systems.

       1. The  mercury thermometer is constructed  of
          glass  and  is  subject  to  breakage,  with
          resulting exposure to a toxic material.

       2. Both the mercury and dial thermometers have
          a  limited   probe   extension,   making  the
          measurement  of  temperatures  across  large
          ducts impossible.

       3. The  thermistor  is  easy   to  use  but  its
          response becomes non-linear over  some part
          of   its  temperature  range,   making  data
          interpretation  difficult.

       4. The potentiometer used to measure the output
          of a thermocouple is not yet available in an
          intrinsically-safe  construction and cannot
          be   used   in  areas  where  explosive   or
          ignitable materials may be present.

    B. Despite  its  limitations, the thermocouple  is
       recommended as the primary method for measuring
       temperatures.  In situations where explosive or
       ignitable materials may be present, use of the
       dial thermometer is suggested.

       1. The  most  common thermocouple,   and  the  one
          recommended  for use in inspections,  is
          Type  K.    The  Type  K  thermocouple  has  a
          temperature range of -400°F to +2,300°F and
          is  constructed  with a  positive  wire  of
          chromel and  a negative wire of  alumel.

       2. The  thermocouple/potentiometer  is  not  a
          reference instrument  and must be
Lesson 6                       6-7                    Measurement

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          calibrated against a National  Institute of  SLIDES AND
          Standards  and  Technology  (NIST)  traceable     NOTES
          to ensure accuracy-
                                                          6-15
          a. Since the equipment required to  do  this
             is  expensive  and  not   likely   to  be
             available to  the inspector,  it  may  be
             necessary   to   send  the   unit   to   a
             specialized laboratory for calibration.

          b. For most inspection  situations, however,
             high accuracy is not required. In these
             cases,  an   acceptable  evaluation   of
             instrument accuracy may be  conducted by
             checking its response in an ice bath and
             a boiling water bath.

    C. There are several potential sources of error in     6-16
       making temperature measurements:

       1. Unrepresentative measurement location

       2. Cooling of the probe by infiltrated air

       3. Impaction of water droplets on probe

    D. Use  of an  unrepresentative  location  can  be
       avoided  by  making  measurements  at  several
       locations  across  the duct  cross-section  and
       averaging them.

       1. To reach locations well within the duct, the     6-17
          thermocouple wire will need to be supported.
          One satisfactory technique is to thread the
          wire through a small diameter copper tube.

       2. Since locations near the wall of a hot  duct
          will  be  cooler  than  near   the  center,
          measurements   made   there  may   not   be
          representative of actual temperatures.

    E. Problems can also occur from  the  cooling  of
       the probe due to air infiltration through the     6-18
       port or through  leaks into the duct upstream of
       the measurement point.

       1. The former problem can be avoided by  sealing
          the port in the manner  described for static
          pressure measurements.
Lesson 6                       6-8                   Measurement

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       2. If  a copper  tube  is used  to support  the  SLIDES AND
          thermocouple, it could  be bent  slightly so     NOTES
          that  it  extends  into  the  oncoming  gas
          stream.

       3. To  avoid problems  from  upstream  leaks,  the
          area near the measurement location should be
          inspected for holes in the duct or leaks in
          inspection hatches or expansion joints.

          a.  If   these  are   found  to  exist,   the
              measurement location should be changed to
              an area where these leaks will have mixed
              into the  flow.

          b.  If this  is not  possible, the  number of
              measurement  points  used to  obtain  an
              average should be increased.

    F. Measurements downstream of evaporative coolers
       or wet scrubbers can be complicated due to the
       presence  of  water  droplets.     Under  these
       conditions,  the most  reasonable option  is to     6-19
       shield the sensor.   It  should be  realized,
       however, that doing this will  likely slow the
       response of the sensor,  requiring longer times
       to make the measurements.
V- Fan speed measurement

    A. Techniques available for the measurement of fan     6-29
       speed include:

       1. Standard tachometers

       2. Strobetachometers

       3. Phototachometers

    B. Strobetachometers  and   phototachometers   afre
       expensive instruments that are not likely to be
       available   to    the    inspector.       Also,
       phototachometers require reflective tape to be
       placed on the drive shaft and this can only be
       done when the shaft is not moving.
Lesson 6                       6-9                    Measurement

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     C.  The  recommended technique  for measuring fan   SLIDES AND
        speed  is the  standard tachometer.                   NOTES

        1. The  easiest   location   for  making   the
          measurement  is on  the end  of the  shaft,
          through the  access hole in the belt guard.

          a.  If  no  access  hole  is  provided,   the
              inspector should  request  the  assistance
              of plant  personnel.

          b.  Under   no   circumstances  should   the
              inspector attempt to obtain access to the
              shaft end by enlarging the mesh covering
              the belt  guard.

        2. An  alternative  measurement  location is  on
          the shaft,  using  the  roller  attachment
          supplied  with  the   tachometer.    However,
          using this method requires knowledge of the
          shaft  diameter  in order  to calculate the
          rotational   speed   from   the   tachometer
          reading.

     D.  An estimate of the  fan speed can be obtained by
        measuring  the diameter of the  fan  and motor
        sheaves and using their ratio,  as follows:          6-30

          Fan rpm = MS(MD/FD)
                                                           6-31
              MD = motor sheave diameter
              FD = fan  sheave diameter
              MS = motor speed  (rpm)

        1. Motors  are   generally  available  in   the
          nominal speeds of 600,  1200,  1800, 2400 and
          3600 rpm.   The actual speed is somewhat less
          than the nominal value and is stamped on the
          motor nameplate.

        2. The  inspector  should  be  aware  of  belt
          squeal, which can  affect fan  rpm,  and severe
          vibration, which can be a safety hazard.
Lesson 6                       6-10                  Measurement

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 VI. Flowrate measurement                              SLIDES AND
                                                          NOTES
    A. Measurement  of   gas   flowrate   in  ducts  is
       accomplished  by  first  measuring  the  average     6-20
       velocity  pressure and temperature of  the gas
       stream   and   then  calculating   the   average
       velocity.     The  flowrate  is   obtained  by
       multiplying this  average  velocity by  the duct
       cross-sectional area.

    B. Procedures for conducting this measurement are     6-21
       contained  in  40CFR60,  Appendix  A, Methods  1
       through  4,  as  part   of  the  procedures  for
       conducting  compliance sampling.     Since  the
       level  of  accuracy reguired for  inspection  of
       industrial ventilation  systems is not  as high     6-22
       as  that  needed for compliance sampling,  some
       variances to these methods will be employed to
       expand  their  application  and  simplify  the
       procedures and calculations, as follows:

       1. Method  1  limits  the  technigue  to  ducts
          larger  than   12   inches  diameter.     For
          inspection purposes, the procedures will be
          applied to ducts of all sizes.  To minimize
          errors, a pitot tube smaller than 5/16 inch
          O.D. should be used in  ducts smaller than 12
          inches diameter.

       2. Method   1   prohibits   the    location   of
          measurement points within 1 inch of the wall
          for ducts larger than 24 inches diameter and
          within  0.5  inch  of  the  wall  for  ducts
          smaller  than   24   inches  diameter.   For
          inspection purposes, measurement points will
          be  at  the  locations  prescribed  by  the
          location  procedures,  with  no  adjustments
          made.

       3. Method 2 requires  the  determination of the
          apparent dry molecular weight using Method
          3 and the moisture  content using Method 4 in
          order  to calculate  the  gas   velocity  and
          flowrate.    For  inspection  purposes,  an
          apparent dry molecular weight of  28.95 and
          a moisture content of zero will be assumed.

       4. Method  2  requires  the measurement  of the
          absolute   stack  pressure   in  order  to
          calculate the  gas velocity and flowrate.
Lesson 6                       6-11                   Measurement

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          For inspection purposes, an  absolute stack  SLIDES  AND
          pressure of 29.92 in. Hg will be assumed.       NOTES

    C. Measurement of  velocity pressure can be  made
       with either a standard pitot tube or an  S-type     6-23
       (Staubscheid) pitot tube.  The S-type pitot is
       preferred when there are particles  in the gas
       stream  that could  plug the  static  pressure
       holes of a  standard pitot.

       1. If  the  construction  of a  standard  pitot
          conforms to Section 2.7  of Method 2, it does     6-24
          not  have  to  be  calibrated  and may  be
          assigned a pitot coefficient, Cp,  of  0.99.

       2. An  S-type  pitot may be assigned a  pitot
          coefficient  of  0.84  if  its  construction
          conforms to Section 4.1 of Method 2.

       3. Procedures for calibrating an  S-type pitot
          may be found in Section 4 of Method 2.

    D. For highest accuracy,  pressures measured  with
       the pitot tube should be read using an inclined
       manometer.  If less accuracy  is acceptable, a
       0-2 in. H2O Magnehelic pressure  gauge could be
       substituted for the manometer.

    E. The  number  of locations  that  are  used  to
       compute the averages depends on the  degree of
       accuracy  desired.     This  figure   provides
       guidance in determining the minimum  number of
       locations.

       1. The number of locations is  first determined     6-25
          for   the  distance   downstream  from   an
          obstruction  by reading vertically  upward
          from the lower x-axis.

       2. The number of  locations is then determined
          for   the   distance   upstream   from   ^n
          obstruction by reading  vertically downward
          from the upper x-axis.

       3. The  larger of  these  two  numbers  is  the
          minimum  number  of  locations  or  traverse
          points.
Lesson 6                       6-12                   Measurement

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    F. For  circular  ducts,  the  number of  traverse   SLIDES AND
       points   determined  is  divided  by   two   to     NOTES
       determine the  number  of  measurement points on
       each diameter.   The location of each traverse
       point is given in this table as a percentage of     6-26
       duct diameter from the inside wall to the point
       location.                                          6-27

    G. With rectangular ducts, the number of traverse
       points   is   determined  using   an  equivalent
       diameter determined from:

          De = 2LW/(L + W)

       The cross-section  is  then  divided into a grid
       of equal rectangular areas  and measurements are
       made in  the  center of each grid element.   The
       grid configuration should  be either
       3x3, 4x3 or 4x4, depending on the number
       of measurement  locations needed.

    H. Downstream   of  such  devices   as   cyclones,      6-28
       inertial  demisters or  ducts  with  tangential
       entry,  a swirling or cyclonic  motion may  be
       encountered.  When high accuracy  is desired, it
       should  be  determined whether  the  degree  of
       cyclonic  flow  is  enough to cause significant
       error in the measurements.  The procedure  for
       accomplishing this is  as follows:

       1. Level and zero  the manometer.

       2. Connect an S-type  pitot to the manometer.

       3. Place the pitot tube at each traverse point
          so that  the openings are perpendicular to
          the  duct cross-sectional plane.    In  this
          position, each tube should be reading static
          pressure,   and  the   indication   of   the
          manometer should be zero.

       4. If the differential pressure  is  not  zero,
          rotate the pitot tube until  a zero reading
          is obtained and record the resulting angle.

       5. Calculate the average  of the absolute values
          of the angles,  including those angles that
          were  zero (no rotation required) .   If  the
          average is greater  than
Lesson 6                       6-13                   Measurement

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          20  degrees,  the  flow conditions  at  that  SLIDES  AND
          location are  not acceptable.                   NOTES

    I. Once   an   acceptable   location   has   been
       identified,   the   velocity    pressure    and
       temperature measurements are performed and the
       averages are calculated.

       1. Average velocity pressure is determined by
          averaging  the  square roots  of  velocity
          pressures   measured  at   the   prescribed
          locations.

       2. The temperature is  measured at the same time
          by  attaching  a thermocouple to the  pitot
          tube,   and   the   average    is   calculated
          arithmetically.

       3. The average gas velocity is determined from:

             V = 2.9C (VP°-5)     (T     )°'5
              v   ^..j^p^vjr  / averagev average'

                V  = average gas velocity  (feet/sec)
                C  = pitot coefficient
                         (dimensionless)
                VP = velocity pressure  (in. H2O)
                T  = gas temperature (°R)

       4. The average gas flowrate is determined from:

             Q = 60VA

                Q = average gas flowrate  (ft3/min)
                A = duct cross-sectional area (ft2)

    J. Other methods are available for determining gas
       velocity  and these are typically  applied to
       measurements at  the  hood face.    To determine
       flowrate  with  these  devices,   it  would  be
       necessary to make several velocity measurements
       across  the  face of  the hood,  determine  an
       average and then multiply it by  the  area of the
       hood opening.

       1. The  rotating  vane  anemometer has  a  small
          lightweight propeller that  rotates as air
          flows   through  the  instrument.      The
          instrument is calibrated in feet and has to
          be used  with  a timing device to determine
          the velocity.
Lesson 6                       6-14                   Measurement

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       2. Inside  the  instrument  case of the swinging   SLIDES AND
          vane  anemometer is an aluminum  vane which     NOTES
          deflects  the   pointer  on  the   scale  in
          proportion  to  the  velocity.    Air  flows
          through the probe  and  connecting tube into
          the case and then through the channel which
          contains the vane.

       3. The Bacharach instrument is a rotating vane
          instrument with a scale which reads directly
          in feet per minute.

       4. The  probe of  the  hot  wire anemometer  is
          provided with a wire element that is heated
          with   current   from  batteries   in   the
          instrument  case.   As  air  flows over  the
          element,  its temperature changes from what
          it was  in still  air and  the  accompanying
          resistance   change  is   translated   into
          velocity  on the indicating  scale  of  the
          instrument.

VII. Horsepower measurement

    A. Estimates  of operating  horsepower can  be made
       in two ways.

       1. The   simplest   method   is  to have  plant
          personnel measure the amperage while running
          at load.  This  value would then  be  divided
          by the full  load amperage from the nameplate
          and then multiplied by the rated  horsepower
          to    obtain   the   estimated   operating
          horsepower.                                     6-32

       2. Another method would  require plant personnel
          to measure both voltage  and amperage while
          running at  load.  For three  phase  motors,
          these values would  then be substituted into:
                                                          6-33
             bhp = 3°-5VAfe/746

                V = voltage
                A = amperage
                f = power  factor
                e = motor  efficiency

          For single phase motors, the square root of
          3 is replaced by one.
Lesson 6                       6-15                   Measurement

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          a. If the  power  factor were also  measured  SLIDES AND
             and the motor efficiency determined from     NOTES
             the manufacturer,  then  a good  value  of
             operating horsepower could be determined
             with this relationship.

          b. However, because of the time involved,  we
             can   usually    only    estimate   these
             parameters and thereby obtain an estimate
             of operating horsepower.

          c. In the  absence  of other  information,  a
             combined factor  of 0.80-0.85 should  be
             used  for the  product   of  power  factor
             times motor efficiency.

    B. Determination  of  operating horsepower  is  an
       involved  process  that  is not likely  to  be
       performed very often.    Also,  because of the
       procedures and measurements required, it should
       be performed only by plant personnel and never
       by   the   inspector.     The   procedure   plant
       personnel should use is as follows:

       1. Prepare  a  graph  like that  shown,   with
          horsepower on the x-axis and amperage on the
          y-axis.

       2. Disconnect  the  motor  from the  fan and
          measure  the amperage  when  running  at  no
          load.  Mark this  reading as point "a" on the
          y-axis.  Divide the no-load amperage by two
          and mark this value  as point  "b" on the
          y-axis.

       3. Read the full load  amperage  from the motor
          nameplate and draw a horizontal line across
          the graph  at  this  value.   Read the  rated
          horsepower  from  the  nameplate  and draw  a
          vertical  line  at  this   value   until  it
          intersects  the  full  load  amperage  line.
          Call this  intersection  point "c".   Draw a
          straight line from "b" to  "c".

       4. Divide the rated horsepower by  two and draw
          a  vertical line  at  this  value until  it
          intersects the line from "b" to  "c".   Call
          this intersection point "d11- Draw a smooth
          curve through points  "a",   "d" and  "c".
Lesson 6                       6-16                   Measurement

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       5. Connect the motor to the fan and measure the  SLIDES AND
          amperage  when running at  load.   Read  the     NOTES
          corresponding  horsepower  from  the  curve
          "a-d-c".

          Once the  relationship  between  amperage  and
          horsepower  is  determined,  it could  be used
          in  subsequent  inspections,   provided  the
          motor has not  been  changed.

VIII. Use of grounding cables                             6-34

    A. When working with portable instruments in areas
       where   potentially  explosive  or   ignitable
       materials are present, all metal probes should
       be  grounded to  the  duct to avoid  a  static
       discharge.

    B. Guidance  on when  to  use  grounding cables  is
       provided by  the following list:

       1. When the moisture content of  the gas stream
          is low.

       2. When  the gas  stream  velocity across  the
          probe is  high.

       3. When the  gas stream contains  a  relatively
          high  mass   concentration  of   small-sized
          particles.

       4. When  there  is  the  possibility  of  dust
          deposits  in the bottom of the  duct.

       5. When there  is any question about the need
          for a grounding cable.

    C. The most  satisfactory  technique  is  to  use  a
       stranded cable  with a pipe clamp attached to
       one end and  a  spring-loaded jaw  clamp  on  the
       other.  The  pipe clamp is firmly attached -to
       the probe  and  the  jaw clamp attached  to  the
       duct,  usually at  a flange or support.

    D. Care  should  be  taken  to  assure   a  good
       connection at the duct and that  all  paint  and
       rust has been penetrated.

       1. One way to check the connection would be to
          measure the  resistance  between  the probe and
          the duct using an explosion-proof ohmmeter.

       2. If the resistance is less than 3 ohms, the
          connection is  good.
Lesson 6                       6-17                  Measurement

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                        PROBLEM SET 6
     MEASUREMENT OF VENTILATION SYSTEM PARAMETERS
 6-1.   A measurement port on a 24  inch diameter duct is 42 inches
       upstream from an elbow and  78  inches downstream from an
       entry.  Determine the minimum  number of measurement
       points and their locations  in  order to make an acceptable
       measurement of flowrate.

       Solution
           Upstream   =    42/24   =   1.75D   (12 points)

           Downstream =     78/24  =   3.25D   (16 points)

           Use 2 traverses  of  8 points each

           Locations in inches from wall:

                         0.77
                         2.52
                         4.66
                         7.75
                        16.25
                        19.34
                        21.48
                        23.23
Lesson 6                       6-18                  Measurement

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6-2.  Measurements on an 18 inch diameter duct with  an  S-type
      pitot  tube give the following readings:
    Location     Parameter              Point Number
    Traverse  1    VP (in.  H20)   0.22   0.23   0.22  0.20  0.23  0.20
                    T (°F)       86.9   87.0   87.3  87.1  86.9  86.8

    Traverse  2    VP (in.  H2O)   0.14   0.20   0.20  0.10  0.14  0.23
                    T (°F)       85.7   85.0   84.9  84.8  84.7  84.7
     Determine  the flowrate at actual conditions.


     Solution

           (VP)0-5    =    0.44

            Tavg      =    86.0 °F
                    =  546 °R


            V   =    2.9 (0.84) (0.44) (546)0'5

                    25.05 ft/sec
                    (60) (25.05) [(7T/4) (18/12)2]

                    2.656 acfm
Lesson 6                        6-19                    Measurement

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 6-3.  The sheave on a fan shaft is 24 inches diameter and the
       sheave on the drive motor is 8 inches diameter.  Estimate
       the fan speed if the motor speed is 1725 rpm.

       Solution

           Fan speed   =   1725 (8/24)

                       =   575 rpm
Lesson 6                       6-20                   Measurement

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                           LESSON 7

              VENTILATION SYSTEM INSPECTION
Goal:
To summarize and organize the inspection points and procedures from
previous lessons.

Objectives:
At the end of this lesson the student should be able to:

    1. Describe  the  four  levels  involved  in inspecting air
       pollution sources.

    2. List the items appropriate for Level 2 inspections  of the
       components of an industrial ventilation system.

    3. List the items appropriate for Level 3 inspections  of the
       components of an industrial ventilation system.

    4. Conduct effective  inspections  of  industrial  ventilation
       systems.
Lesson 7                       7-1                     Inspection

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 List of Slides
 7-1
 7-2
 7-3
 7-4
 7-5
 7-6
 7-7
 7-8
 7-9
 7-10
 7-11
 7-12
 7-13
 7-14
Ventilation system inspection
Level 2
Level 2 items for hoods
        items for ducts
        items for coolers
        items for fans
Level 2
Level 2
Level 2
Level 3
Level
Level
Level
Level
        items for hoods
        items for ducts
        items for coolers
        items for fans
Completed flowchart for soil incinerator
Graph of static pressure profile
Graph of temperature profile
3
3
3
3
Lesson 7
                               7-2
                                                Inspection

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I. Introduction

    A. The efforts  involved in  inspecting air
       pollution  sources are  generally  categorized
       according to a system of "levels",  as  follows:

       1. Level 1 - visual evaluation of stack opacity
          and  fugitive  emissions  from off the  plant
          site.

       2. Level 2 - on-site evaluation of  the control
          system relying on plant  instruments for the
          values of any inspection parameters.

       3. Level 3 - similar  to Level 2, but relying on
          measurements by the  inspector to determine
          missing or inaccurate inspection  parameters.

       4. Level 4 - similar to Level  3,  but including
          the  development  of  a  process  flowchart,
          determination of measurement port locations
          and  evaluation  of  safety  hazards and
          protective equipment needs.   If  the process
          or control  equipment do not change,  this
          level of inspection would only be conducted
          once.

    B. The inspection level that is actually  utilized
       is  dictated by the  individual situation and
       based on the judgement of the inspector.

       1. For  example,  if a  Level  1 inspection
          indicates no  problems,  the inspector may
          elect  to  terminate the  inspection and
          proceed to another facility-

       2. Or,  if  in  the  course   of a Level   2
          inspection,  critical  information is needed
          to complete the evaluation, the inspector
          may  elect to  proceed to Level 3, making
          on-site measurements to obtain the  data.

    C. These same four levels  can also  be  applied to
       the  inspection   of  industrial ventilation
       systems.

       1. Level  1  would  be limited  to an  off-site
          evaluation of  fugitive emissions from  hoods
          and ducts.

       2. Most inspections will be conducted  at  Level
          2, with  the occasional  need for a Level  3
          evaluation,  and would follow the same
          approach used with control devices.
                        SLIDES AND
                          NOTES

                           7-1
Lesson 7
7-3
Inspection

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       3.  The additional items  in  a Level  4 would   SLIDES  AND
          focus  on port locations and safety  issues.      NOTES


II. Level 2 inspections                                   7~2

    A. Hoods                                             7~3

       1.  Capture  efficiency:   visual  evaluation of
          fugitive  losses as  indicated  by escaping
          dust or refraction lines.

       2.  Physical condition:  hood modifications or
          damage that could  affect  performance;
          evidence of  corrosion.

       3.  Fit of "swing-away" joints:  evaluation of
          gap distance between  hood  system and duct
          system on movable hoods.

       4.  Hood position/cross-drafts:    location  of
          hood  relative to  point  of  contaminant
          generation;  effect  of air  currents  on
          contaminant  capture.

    B. Ducts                                             7-4

       1.  Physical  condition:  indications  of
          corrosion,  erosion or physical  damage;
          presence of  fugitive emissions.

       2.  Position of  emergency dampers:   emergency
          by-pass  dampers should be closed  and not
          leaking.

       3.  Position of balancing dampers:  a change in
          damper positions will change flowrates; mark
          dampers with felt pen  to document position
          for later inspections.

       4.  Condition  of  balancing dampers:   damper
          blades can erode, changing system balance;
          remove  a  few dampers to  check  their
          condition.
    C.  Coolers                                            7-5

       1.  Physical condition:    indications  of
          corrosion,  erosion or  physical  damage;
          presence  of  fugitive emissions.
Lesson 7                       7_4                     Inspection

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       2. Outlet  temperature:   observe  plant  SLIDES AND
          instruments to determine cooler effective-     NOTES
          ness;  if controller  is  used,  compare  to
          set-point value.

       3. Spray pattern/nozzle condition:  indications
          of  effective atomization  on evaporative
          coolers.

       4. Water flowrate:   observe plant  flow meters
          or pressure gauges to evaluate  changes  in
          water flowrate on evaporative coolers.

    D. Fans                                              7-6

       1. Physical  condition:   indications  of
          corrosion.

       2. Vibration:   indications of balance problems
          due to material build-up or wheel erosion or
          corrosion;   severely  vibrating  fans are  a
          safety hazard.

       3. Belt squeal:  squealing belts under normal
          operation indicate a  loss of  air volume.

       4. Fan  wheel   build-up/corrosion:    internal
          inspection of non-operating fans.

       5. Condition  of isolation sleeves:   check
          vibration isolation sleeves for holes.

       6. .Rotation  direction:   check rotation
          direction  with  direction  marked on  fan
          housing.
III. Level 3 inspections                                 7-7

    A. Hoods                                             7-8

       1. Estimated volume:  estimate flowrate using
          SPh/  r  and hood configuration.

       2. Actual  volume:   determine  flowrate  by
          measuring VP and  temperature.

    B. Ducts                                             7-9

       1. Change  in  gas  temperature:    measure
          temperature  change across a section of duct
          to. evaluate  air  infiltration.
Lesson 7                       7-5                     Inspection

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       2. Change in static pressure:   measure static  SLIDES AND
          pressure change across  a  duct section  to     NOTES
          evaluate duct  deposits;  compare  measure-
          ments to calculations for clean duct.

       3. Air volume:  determine flowrate by measuring
          VP and temperature.

    C. Coolers                                           7-10
       1. Inlet  and  outlet temperatures:    measure
          inlet  and  outlet  temperature to  evaluate
          cooling effectiveness.

       2. Water requirement:   estimate  water
          requirement for evaporative  coolers  using
          inlet and outlet temperatures and enthalpy
          relationships; compare to actual use
          information supplied by plant personnel.

       3. Water turbidity:  perform settling test  on
          water sample gathered by plant personnel  to
          evaluate particle  size of solids.

       4. Air volume:  estimate air volume in dilution
          cooling systems  using measured temperatures
          and enthalpy relationships;  could  also  be
          determined by measuring VP and temperature.

    D. Fans
       1. Volume changes:  estimate new flowrate using     7-11
          known performance  (Q,  rpm and  r) and new rpm

       2. Estimated volume:   estimate  flowrate using
          rpm,  FSP,  temperature  and  ratings  table;
          could also be done  using  bhp,  FSP,
          temperature and  ratings table.

IV. Use of flowcharts

    A. Organizing inspection  information on  a      7-12
       flowchart of the process aids  interpretation
       and evaluation

    B. One  normally  expects static  pressures  to
       decrease (become more negative)  from the hood
       toward the  fan and to decrease  (become  less      7-13
       positive) from the  fan to the stack.

    C. In  general,  temperatures  should  decrease
       throughout the system, with significant drops
       across  cooling devices.   A  small rise  in      7-14
       temperature  across may  be  noted  due  to
       compression of the  gas.
Lesson 7                       7-6                     Inspection

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                        PROBLEM SET 7

              VENTILATION  SYSTEM INSPECTION

     The students will be "calculated out" by  this  point  in  the
course, so it  is suggested that the instructor use this time to tie
together the inspection procedures by having the class talk through
the  inspection  of several  situations presented to  them.    The
instructor should first present  the  situation  and them  have  the
students list  the various things that could be  causing the problem.
It is helpful  if the  instructor maintains a list of the potential
caused on a blackboard, flip-chart or  overhead transparency.  Once
the potential  causes have been identified,  the instructor  should
have the students  discuss how they would check-out each one.  Some
situations for class discussion  are presented here;  however,  the
instructor may wish to  use examples  from  his  or  her  own
experiences.
Lesson 7                       7-7                     Inspection

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7-1 Emissions from  transfer  points  in an  ambient-condition
    material handling process are  collected  with five hoods  and
    conducted to  a  pulse-jet  fabric  filter collector.   A
    preliminary Level  2 inspection finds dust escaping from all  the
    hoods;  however, the stack visible emissions are in compliance.
    Baseline data  are available for  hood  static  pressures,
    inlet and  outlet  collector  static pressures,  fan speed  and
    stack visible emissions.   What could be causing  the  fugitive
    losses and how would you  check-out each potential cause?


Solution

       This situation  could be caused by modified or damaged hoods;
    but,  since  it  is  affecting  all  five of  them,  this is  not
    likely.   There could also  be an  increase in the "fines" content
    of  the  materials  being processed,  but a  well-designed hood
    should  be  able  to handle this occurrence.   The most likely
    cause for this  situation is decreased air  volume at the hoods.
    This could be confirmed by measuring the hood static pressures
    and comparing them to  the baseline  values.   If the  pressure
    decreases were not proportional, then the problem (or problems)
    could be in the branch ducts to each hood,  or there could be a
    problem  in some  of the  branch ducts in  combination with a
    downstream problem.  Measurements of the air volume could also
    be used to determine decreased  airflow at  the hoods.

         Assuming proportional decreases  in hood static pressure,
    the decreased air  volume could result from a number of causes,
    as indicated  below.

       a.  Holes  in the  main duct leading   to the  collector:
          Evaluate  with a visual inspection (best approach); check
          static  pressure  at  collector  inlet  to see if it  has
          decreased (may not be  a  good indicator-may not change
          substantially or may  be affected  by other problems);
          measure air volume  at positions along duct  looking  for
          unexplained increases  (time consuming).

       b.  Main duct partially plugged:   Check static  pressure at
          collector  inlet to  see if  it  has  increased (best
          approach);  measure  static pressure  at  several locations
          along  duct  and  plot  versus  equivalent  length  (time
          consuming,   but  locates  the  problem);  measure static
          pressure  change across suspect section and compare to
          expected  value-get  H   from estimated  velocity  based on
          change  in hood static pressures (time  consuming-may  not
          be very accurate  because  of estimated  velocity).

       c.  Main duct damaged:    Evaluate  with  a  visual inspection
          (check  upstream and downstream of the collector-damage
          either  place could  reduce volume).
Lesson 7                       7-8                      Inspection

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       d. Fan speed slowed down:  Measure  fan  rpm  and  compare to
          baseline values  (best approach); estimate  fan  rpm  from
          sheave diameters and  compare to baseline  values  (less
          accurate, but cheaper).

       e. Collector  static pressure drop  increased:  Determine
          collector pressure  drop  and compare to  baseline value
          (reasons for increased collector pressure  drop  are  not
          subject of this course - refer to APTI  Course 445).

       f. Air infiltration at collector:  Evaluate  with collector
          inspection procedures  (not a subject of this course-refer
          students to APTI Course 445).

       g. Damper  position changed:   Evaluate  with a  visual
          inspection;  if  damper  is upstream of collector, check
          collector  inlet static  pressure  to see  if  it  has
          increased;  if damper is downstream of collector, check
          collector outlet static pressure  to  see  if it has
          decreased.
Lesson 7                       7-9                     Inspection

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7-2.   Emissions  from transfer  points in  an ambient-condition
       material handling process  are collected with five hoods and
       conducted  to  a  pulse-jet  fabric filter collector.   A
       preliminary Level 2  inspection finds dust escaping from one
       of  the hoods;  however,  the other  hoods  appear  to  be
       collecting well  and the  stack  visible  emissions are  in
       compliance.  Baseline  data  are  available for hood  static
       pressures,  inlet and outlet collector static pressures, fan
       speed and  stack visible emissions.  What  could  be causing
       the  fugitive losses,  and how  would you  check-out  each
       potential cause?

Solution

       As  in  the  previous  problem, this  situation could be  the
       result of decreased  air volume at the one hood.   This could
       be confirmed by measuring  the hood static pressure and com-
       paring it  to the  baseline value.   Measurement of the  air
       volume could also be used  to determine decreased airflow at
       the hood.  Since only one  hood is  affected,  it  is now more
       likely that a modified or damaged hood could be responsible.
       This could be checked by  inspecting the hood to  see  if  it
       conforms  to good  design practices.   Comparison  to
       recommended hood  designs  from  a  reference  text such  as
       ACGIH's Industrial Ventilation could  also be made.

       Assuming the problem is found to be decreased  air volume,
       the following are possible causes  and techniques for their
       evaluation.

       a. Holes in the duct leading from  the hood:   Evaluate with
          a visual inspection(best approach); measure air volume at
          positions  along  duct looking  for  unexplained
          increases(time consuming).

       b.  Duct  partially  plugged:   Measure  static pressure  at
          several locations along duct  and plot versus equivalent
          length  (time consuming, but  also  locates  the problem);
          measure static pressure change across suspect section and
          compare to expected value-get H from estimated velocity
          based on change in hood static pressure (time consuming-
          may not  be very accurate because of estimated velocity).

       c. Duct damaged:  Evaluate with  a  visual inspection.

       d.  Damper position changed:    Evaluate with a visual
          inspection.

    It is  also possible  that  changes  in the  system balance have
occurred because of adjustments made elsewhere in the system.  This
possibility could  be checked by measuring the hood static pressures
of  the  other  hoods and  comparing them  to  the baseline  values.
Increased flow at  some hoods because of  a change in damper position
may be causing decreased flow at  the one  hood.


Lesson 7                      7-10                     Inspection

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 7-3.    Emissions from  transfer points  in an  ambient-condition
        material  handling process are collected with  five hoods and
        conducted to  a pulse-jet fabric  filter  collector.   A
        preliminary Level 2 inspection finds dust escaping from one
        of  the  hoods;  however,  the other  hoods  appear to  be
        collecting well, and the  stack visible emissions  are  in
        compliance.   There are no baseline  data available.   What
        could  be causing the  fugitive  losses,  and  how  would you
        check-out each potential cause?

 Solution

    Since only one emission point is affected, it is possible that
 a  modified  or damaged hood could be responsible.   This  could  be
 checked by inspecting the hood to see if it  conforms  to good design
 practices.  Comparison to recommended hood designs from a reference
 text such as  ACGIH's Industrial Ventilation could also be made.

    As  in the previous problem,  this situation  could also  be the
 result  of  decreased air volume  at  the one hood;  however,  since
 baseline data are not available in  this case, evaluation of  this
 potential   is not as  straight-forward.    If there  is a well-
 functioning identical  transfer  point and hood in  the system, the
 inspector could  measure its hood static pressure and compare it to
 the  measured  hood  static pressure  of the malfunctioning  hood.
 Alternately,  the air volume could be estimated from the hood static
 pressure and  configuration (or from fan performance  or actually
 measured) and used to determine the capture velocity.  This could
 be compared to typical  values or to specific recommendations  from
 reference texts.

    Assuming  the problem is thought to be reduced air volume, the
 following are possible causes and techniques for their evaluation.

        a. Holes  in the  duct leading from the hood:   Evaluate  with
          a visual inspection (best approach); measure air volume
          at positions along duct looking for unexplained increases
          (time  consuming).

        b. Duct  partially  plugged:  Measure  static pressure  at
          several locations along duct and plot versus equivalent
          length (time  consuming, but  also locates the problem);
          measure static pressure change across suspect section and
          compare  to  expected  value- get H    from  estimated
          velocity based on hood static pressure and configuration
          (time  consuming-may not be accurate  because of estimated
          velocity).

        c. Duct Damaged:  Evaluate with a visual inspection.

        d. Damper position  changed:   Cannot  be  evaluated without
          baseline information.
Lesson 7                       7-11                    Inspection

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7-4.   A  constant volume  hot gas  process is  equipped  with an
       evaporative cooler  followed  by a  fixed-throat  venturi
       scrubber.  A preliminary Level 2 inspection finds that stack
       visible emissions have increased above  the baseline value
       but are still  in  compliance.   Baseline  data are available
       for cooler inlet  temperature,  inlet and  outlet collector
       static pressures,  pump discharge  pressures  for the scrubber
       and the cooler,  fan speed and stack visible emissions.  What
       could be  causing  the  increased visible  emissions,  and how
       would you  check-out each potential cause?


Solution
    Since the collector  is a  fixed  throat  design, a reduction in
air flow  would  cause  the performance of the venturi  scrubber to
decrease, leading to an increase in visible  emissions.  To evaluate
this potential,  the inspector should first  look at the process for
any sign of fugitive emissions.  Also, since baseline fan speed is
available, the current fan speed could be measured or estimated and
compared to this value to see if it has been reduced.  In addition,
the inspector could determine the pressure  drop across the venturi
and  compare  this to   the  baseline value;  however,  since  other
parameters (like liguid rate) also affect pressure drop, a definite
conclusion cannot be  made from  a pressure drop change  alone.
Finally, the inspector could measure the air volume.

    Another potential  cause of increased visible emissions is lack
of  sufficient  cooling in  the evaporation  section.    First,  the
inspector should determine the cooler inlet  temperature and compare
the cooling water pump discharge pressure to its baseline value to
determine any changes.  If possible, the condition of the nozzles
should be determined through a visual examination to be sure that
any changes noted in  pump pressure  are  due only to flow changes.
Also,   since  inadequate cooling water  could also result  from an
increase  in  gas  flow,  the  fan  speed  should  be determined  and
compared  to  the  baseline  value,   or  the  gas  flowrate could be
measured.

    Finally,  increased visible emissions could result from the use
of  cooling water containing a  significant  quantity of  fine
particles.   The  inspector  could  check this  by -t>bserving  the
settling rate of particles in a  water  sample  obtained  by plant
personnel.
Lesson 7                       7-12                     Inspection

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APPENDIX A



  SLIDES

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 APPENDIX B
BIBLIOGRAPHY
   B-l

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B-2

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ACGIH, Industrial Ventilation Manual, Twentieth Edition, Cincinnati, 1988.
Alden, J.L., Design of Industrial Exhaust Systems, Industrial Press, New York, 1939.
Aldina, G J., and J.A. Janke, "APT! Course 450: Source Sampling for Paniculate Pollutants
       - Instructor's Guide", EPA-450/2-80-003, February 1980.
AMCA, "Fan Systems", Fan Application Manual, Part 1, Publication 201, Arlington Heights
       (Illinois), 1979.
AMCA, "Field Performance Measurements", Fan Application Manual, Part 3, Publication
       203, Arlington Heights (Illinois), 1976.
AMCA, "Troubleshooting", Fan Application Manual, Pan 2, Publication  202, Arlington
       Heights (Illinois), 1976.
ANSI, "Fundamentals Governing the Design and Operation of Local Exhaust Systems",
       American National Standard Z 9.2-1971, 1972.
ANSI, "Installation of Blower and Exhaust Systems for Dust, Stock and Vapor Removal or
       Conveying", American National Standard Z 33.1, 1961.
ANSI, "Safety Code for the Use, Care and Protection  of Abrasive Wheels", American
       National Standard B 7.1-1970,  1970.
ASHRAE,  Equipment Guide and Data Book, New York, 1972.
ASHRAE, Handbook of Fundamentals, Atlanta, 1985.
ASHRAE, HVAC Systems and Applications, Atlanta, 1987.
Astleford, W., "Engineering Control of Welding Fumes", NIOSH Publication 75-115,1974.
Baliff,  J., L.  Greenburg  and A.C.  Stern,  'Transport velocities  for industrial,  dusts-an
      experimental study", Ind. Hyg. Quar., 9, 85 (1948).
Barr, H.S., R.H.  Hocutt and J.B. Smith, "Cotton Dust Controls in Yarn Manufacturing",
      NIOSH Publication No. 74-114,1974.
Barritt, S.L., "Duct design by programmable calculator", Heating, Piping &. Air Conditioning,
      December 1978, p.28.
Bastress, E., J. Niedzwecki and A. Nugent, "Ventilation Requirements for Grinding, Buffing
      and Polishing Operations", NIOSH Publication 75-107, 1974.
Baturin, V.V., Fundamentals of Industrial Ventilation, Pergamon Press, New York, 1972.
Brandt, A.D., "Should air be recirculated from industrial exhaust systems?", Heating,  Piping
      &Air Conditioning, 19, 69 (1947).
                                         B-3

-------
 Brandt, AD., Industrial Health Engineering, Wiley, New York, 1947.
 Brown, EJ., "How to select multiple-leaf dampers  for proper air  flow control", Heating,
       'Piping & Air Conditioning, April 1960, p. 167.
 Brown, EJ., and H.E. Staub,  "How  to  estimate  system  total  pressure  requirements",
       'Heating, Piping & Air Conditioning, January 1971, p.  12.
 Burgess W.A, and J. Murrow, "Evaluation of hoods for low volume-high velocity exhaust
       systems", AIHA Journal, 37, 546 (1976).
 Burgess, W.A, MJ. Ellenbecker and R.D. Treitman, Ventilation  for Control of the Work
       Environment, Wiley-Interscience, New York, 1989.
 Burton, D J., Industrial Ventilation Work Book, DJBA, Salt Lake City, 1989.
 Caplan,  K.J.,  "Balance with  blast  gates~a  precarious balance", Heating, Piping & Air
       Conditioning, February 1983, p. 47.
 Chamberlin, R., "The control of beryllium machining operations",  Arch. Ind. Health, 19(2),
       231  (1959).
 Chen, S.Y.S., "Design procedure for  duct calculations", Heating, Piping & Air Conditioning,
       January 1981, p.41.
 Cheremisinoff, P.N., and R.A Young, "Fans and blowers", Pollution  Engineering, July 1974,
       p. 54.
 Chicago Blower Corporation, "A Course in Fan Arrangements and  Classes", CBC-300,1981.
 Chicago Blower Corporation, "Air Handling Equipment", 1982.
 Chicago Blower Corporation, "Basic Course in Fan Density Correction", CBC-200,1981.
 Chicago Blower Corporation, "Basic Course in Fan Selection", CBC-100,1981.
 Churchill, S.W., "Friction factor equation span all fluid flow regimes", Chemical Engineering,
       84,56(1977).
 Clapp, D.E., D.S. Groh and J.D. Nenandic, "Ventilation design by microcomputer", AIHA
      Journal, 43,212(1982).
 Conroy, L., MJ. Ellenbecker and M. Flynn, "Prediction and measurement of velocity into
       flanged slot hoods", AIHA Journal, 49, 226 (1988).
 Constance,  J A., "Estimating air friction in triangular ducts", Air Conditioning, Heating and
       Ventilating, 60(6), 85 (1963).
Crowder, J.W., and KJ. Loudermilk, "Balancing of industrial ventilation systems", JAPCA,
      32,115(1982).
Dalla Valle, J.M., "Velocity characteristics of hoods under suction", ASHVE  Transactions,
      38, 387 (1932).
                                     B-4

-------
 Dalla Valle, J.M., and T. Hatch, "Studies in  the design of local exhaust hoods", ASME
        Transactions, 54, 31 (1932).

 Dalla Valle, J.M., Exhaust Hoods, Industrial Press, New York, 1952.

 Danielson, J.A., ed., "Air Pollution Engineering Manual", Second Edition, EPA AP-40, May
        1973.

 Djamgowz, O.T., and S.A.A. Ghoneim, "Determining the pick-up air velocity  of mineral
        dusts", Can, Mining J., July 1974, p. 25.

 Durr, D., N. Esman, C. Stanley and D. Weyel, "Pressure drop in elbows", Appl Ind. Hyg., 2,
        57 (1986).

 Ellenbecker, M.J., R. Gempel  and W.A. Burgess, "Capture efficiency of local exhaust
       ventilation systems", A1HA Journal, 44, 752 (1983).

 Esman, N., D. Weyel and F. McGuigan, "Aerodynamic properties of exhaust hoods", AIHA
       Journal, 47, 448(1986).

 First, M.W., and L. Silverman, "Airfoil pitometer", I & EC, 42, 301 (1950).

 Flanigan, LJ., S.G. Talbert,  D.E. Semones and B.C. Kim, "Development of Design Criteria
       for Exhaust Systems for Open Surface Tanks", NIOSH Publication 75-108,1975.

 Fletcher, B., "Centerline velocity characteristics of local exhaust ventilation hoods", AIHA
       Journal, 43, 626 (1982).

 Fletcher, B., "Centerline velocity characteristics of rectangular  hoods  and slots under
       suction", Ann. Occup. Hyg., 20, 141(1977).

 Fletcher, B., "Effect of flanges on the velocity in front of exhaust ventilation hoods", Ann.
       Occup. Hyg., 21, 265 (1978).

 Fletcher, B., and A. Johnson, "Velocity profiles around hoods and slots and the .effects of an
       adjacent plane", Ann.  Occup. Hyg., 25,365 (1986).

 Flynn, M., and MJ. Ellenbecker, "Capture efficiency of flanged circular local exhaust
       hoods", Ann. Occup. Hyg., 30, 497 (1986).

 Flynn, M., and MJ. Ellenbecker, "Empirical validation  of theoretical velocity  fields into
       flanged circular hoods", AIHA Journal, 48, 380 (1987).

 Flynn, M.,  and M J. Ellenbecker, "The potential flow solution for air flow into a flanged
       circular hood", AIHA Journal, 46,318 (1985).

 Garrison, R., "Centerline velocity gradients for plain and flanged local exhaust inlets", AIHA
       Journal, 42, 739(1981).

Garrison R., "Velocity calculation for local exhaust inlets-graphical design", AIHA Journal,
       44,941(1983).'

                                        B-5

-------
 Garrison  R  "Velocity calculation  for local  exhaust inlets-empirical design equations",
       AIHA Journal, 44, 937 (1983).

 Garrison, R., and D. Byers, "Static pressure and velocity characteristics of circular nozzles
       for high velocity/low volume exhaust ventilation", AIHA Journal, 41, 803 (1980).

 Garrison, R., and D. Byers, "Static pressure, velocity and noise characteristics of rectangular
       nozzles for high velocity/low volume exhaust ventilation", AIHA  Journal, 41, 855
       (1980).

 Geissler,  H.,  "Purchased  fan performance",  Reprint No.  5483,  Westinghouse Electric
       Corporation, Pittsburgh, 1959.

 Goldfield, J  and F.E. Brandt,  "Dust control  techniques in the asbestos industry", AIHA
       Journal, 35, 799 (1974).

 Goodfellow,  H.,  Advanced  Design of Ventilation  Systems for  Contaminant Control,
       Elsevier, New York, 1985.

 Goodier, J.L., E. Boudreau, G. Coletta and R.  Lucas, "Industrial Health and Safety Criteria
       for Abrasive Blast Cleaning Operations", NIOSH Publication 75-112, 1975.

 Guffey, S.E., and J. Hickey, "Equations for redesign of existing ventilation systems", AIHA
       Journal, 44, 819 (1983).

 Guffey, S.G., "An easier calculation system  for ventilation design", AIHA Journal, 44, 627
       (1983).

 Hama, G.M., "A calibrating wind tunnel for air measuring instruments", Air Engineering, 41,
       18(1967).

 Hama, G.M., "Calibration of Alnor velometers",Aff£4/o«mfl/, 19,477 (1958).

 Hama, G.M., and L.S. Curley, "Instrumentation for the measurement of low velocities with a
       pitot tube", AIHA Journal, 28, 204 (1967).

 Hama, G.M., "Ventilation control of dust from bagging operations", Heating and Ventilating,
       April 1948, p.91.

 Hama, G.M., and KJ. Bonkowski, "Ventilation requirements for airless  spray painting",
       Heating, Piping & Air Conditioning, October 1970, p. 80.

Hampl, V., and O.E. Johnson, "Control of wood dust from horizontal" belt, sanding", AIHA
       Journal, 46, 567 (1985).

Hampl, V., O.E. Johnson and D.M. Murdock,  "Application of an air curtain exhaust system
       at a milling process", AIHA Journal, 49,167 (1988).

Hatch, T., "Design of exhaust hoods for dust control systems", /. Ind. Hyg.  ToxicoL,  18, 595
       (1936).

Healy, J.H., M.N. Patterson and E.J. Brown, "Pressure losses through fittings used in return
       air duct systems", ASHRAE Transactions, 68, 281 (1962).


                                       B-6

-------
 Hemeon, W.C.L.. Plant and Process Ventilation, Second Edition, Industrial Press, New
       York, 1963.

 Hogan, E.E., "Design tips for better O&M", Pollution Engineering, March 1983, p. 16.

 Huebener, D J., and R.T. Hughes, "Development of push-pull ventilation", AIHA Journal,
       46,262(1985).

 Huebscher, R.G., "Friction equivalents for round, square and rectangular ducts", Hearing,
       Piping & Air Conditioning, 19, 127 (1947).

 Hughes, R.T., and A~A.  Amendola, "Recirculating exhaust air: guides, design parameters
       and mathematical modeling", Plant Engineering, March 18, 1982, p.47.

 Jorgensen,  Robert,  ed.,  Fan Engineering,  Seventh Edition,  Buffalo  Forge Company,
       Buffalo, 1970.

 Kane, J.M., "Design of exhaust systems", Health and Ventilating, 42, 68 (1947).

 Kane, J.M., "The application of local exhaust ventilation to eiectnc melting furnaces", Trans.
      Am. Foundrymen's Assoc., 52, 1351 (1945).

 Kashdan, E.R., D.W. Coy, JJ. Spivey, T. Cesta and H.D. Goodfellow, 'Technical Manual:
       Hood System Capture of Process Fugitive Paniculate Emissions", EPA-600/7-86-016,
       April 1986.

 Kemner,  W., R. Gerstle and Y. Shah, "Performance Evaluation Guide for Large Flow
       Ventilation Systems", EPA-340/1-84-012, May 1984.

 Koshland, C.P.,  and  M.G.  Yost, "Use of a  spreadsheet in the design of  an industrial
      ventilation system", AppL Ind. Hyg., 2, 204 (1987).

 Kurz, J.L., "Comparison  between electronic and pitot-tube multi-point air velocity sensors
      used in air flow measuring stations", Pollution Equipment News, December  1984, p.
      58.

 Loeffler, JJ., "Simplified equations for HVAC duct friction", ASHRAE J., January  1980, p.
      76.

 Lynch, J.R., "Computer  design  of  industrial exhaust  systems",  Heating, Piping &  Air
      Conditioning, September 1968, p. 44.

 Lynch, J.R., "Industrial ventilation: a new look at an old problem", Michigan's Occupational
      Health, 19(3), 4(1974).

 Madison,  R.D.,  and  W.R.  Elliot,  "Friction  charts  for gases  including correction  for
      temperature, viscosity and pipe roughness", Heating, Piping & Air Conditioning, 18,
      107(1946).

 Malchaire  J.B.,  "Design  of industrial exhaust systems using a  programmable calculator",
      Ann. Occup. Hyg., 24, 217 (1981).

Markert, J.W., "Use of total  pressure in air system design, fan selection", Heating, Piping d
      Air Conditioning, October 1969. p. 70.

                                        B-7

-------
 McDermott, HJ.. Handbook of Ventilation for Contaminant Control, Ann Arbor Science.
       Ann Arbor, 1977.
 Mclnnes, R.G., B.R. Hobbs and S.V. Capone, "Guide for Inspecting Capture Systems and
       Control Devices at Surface Coating Operations", EPA Contract 68-01-6316, Task 3j,
       May 1982.
 Midwest Research  Institute, "Design Review Guide for  Materials Handling Operations:
       Chapter 4 - Capture/Control Systems", EPA Contract 68-01-6314, Task 6, February
       1983.
 Morse, F.B., ed., Trane Air Conditioning Manual, The Trane Company, La Crosse, 1965.
 NIOSH, "Industrial Ventilation 588: Student Manual", August 1986.
 Obler, H., "Ventilation modifications", Hearing, Piping & Air Conditioning, February 1980, p.
       65.
 Ower, E., and R.C. Pankhurst, The Measurement of Air Flow,  Pergamon Press, Oxford,
       1977.
 Pring, R.T., J.F. Knudsen and R. Dennis, "Design of exhaust ventilation for solid material
       handling", I&.EC, 41, 2442 (1949).
 Rajhans, G.S., and  R.W. Thompkins, "Critical velocities of mineral dusts", Can. Mining J.,
       October 1967, p. 85.
 Reason, J., "Fans", Power, September 1983.
 Rennix, C.P., "Computer assisted ventilation design and evaluation", Appl Ind. HVR., 2, 32
      (1987).
 Richards, J., "Air Pollution Source Field Inspection Notebook", Revision 2, USEPA, APT!
      June 1988.
 Rogers, A.N.,  "Evaluation in  fan  selection", Reprint  No. 5037, Westinghouse Electric
      Corporation, Pittsburgh, 1954.
Rogers,  A.N.,  "Selection  of  fan  types",  Reprint No. 5312,  Westinghouse Electric
      Corporation, Pittsburgh, 1957.
Rutgers University, "Industrial Ventilation: Student Manual", August 1989.
Schulte, H.F.,  E.C. Hyatt and F.S. Smith, "Exhaust ventilation for machine tools used on
      materials of high toxicity",^/r/i. Ind. Hyg. Occup. Med., 5, 21 (1952).
Seeal, R., and J.  Richards, "Inspection Techniques for Evaluation of Air Pollution Control
      Equipment", Volume II, EPA-340/l-85-022b, September 1985.
Shorwell, H.P., "A  ventilation design program for hand-held programmable computers"
      AIHA Journal, 45, 749 (1984).
                                       B-8

-------
 Silverman, L., "Centerline velocity characteristics of round openings under suction", /. Ind.
       Hyg. ToxicoL, 24, 259 (1942).
 Silverman, L., "Fundamental factors  in the design of lateral exhaust hoods for industrial
       tanks",/. Ind. Hyg.  ToxicoL, 23,  187 (1941).
 Silverman, L., "Velocity characteristics of narrow exhaust slots",/. Ind. Hyg. ToxicoL, 24, 267
       (1942).
 Sisson, W., "OSHA spray booth air flow requirements", Pollution Engineering,  November
       1975, p. 31.
 SMACNA, HVAC Duct System Design, First Edition, Vienna (Virginia), 1977.
 SMACNA, HVAC  Duct System  Design: Tables and Charts, First  Edition, Vienna
       (Virginia), 1977.
 SMACNA, Manual for the Balancing and Adjustment of Air Distribution Systems, First
       Edition, Vienna (Virginia), 1967.
 Sorg, G.R., "Fan acoustic basics: Part 1", Pollution Engineering, March 1983, p. 34.
 Sorg, G.R., "Fan acoustic basics: Part 2", Pollution Engineering, April 1983, p. 30.
 Staheli, A.H., "Control methods for reducing chlorinated hydrocarbon emissions from vapor
       degreasers", Reprint No. 72-PEM-7, ASME, New York, 1972.
 Thompson, J.E.,  and CJ. Trickier, "Fans and fan systems", Chemical Engineering, March 21,
       1983, p. 48.
 Tracy, W.EL, "Fan connections", Reprint No. 5100, Westinghouse Electric Corporation,
       Pittsburgh, 1955.
 Trickier, CJ., "Effect of system design on the fan", Engineering Letter No. E-4, New York
       Blower, Chicago.
 Trickier, C J~, "Field testing of fan systems", Engineering Letter No. E-3, New York Blower,
       Chicago.
 Trickier, CJ., "Fundamental characteristics of centrifugal fans", Engineering Letter No. E-l,
       New York Blower,  Chicago.
 Trickier, CJ., "How  to get more air from your fan",  Engineering Letter No. E-5, New York
       Blower, Chicago.
Trickier, CJ., "How to select centrifugal fans for quiet operation", Engineering Letter No.
       E-13, New York Blower, Chicago.
USEPA, "Determination  of  Stack Gas  Velocity and  Volumetric Flow Rate",  40CFR60,
       Appendix A, Method 2.
USEPA, "Plant Inspection Workshop Handout: Design, Operation and Maintenance  of
      Fans", July 1979.
                                            B-9

-------
USEPA, "Sample and Velocity Traverses for Stationary Sources", 40CFR60, Appendix A,
      Method 1.

Wright, D.K., "A new friction chart for round ducts", ASHVE Transactions, 51, 312 (1945).

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     APPENDIX C



PSYCHROMETRIC CHARTS
         c-i

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   175 —
   170 —
   165 —
   160 —
O
(X
co  150
Q
   140 —
    130 —
    120 —
    110


    100
                                                                                  Psychrometric Chart for Humid Air


                                                                                     Barometric Pressure 29.92 in. Hg
                                                                                                 Density Factor - Mixture
                            100
                                     200
                                              300
400      500     600     700      800     900


    Dry Bulb Temperature In Degrees F.
1000    1100    1200   1300   1400  1500

-------
O
 I
u>
                                                        Barometric Pressure 29.92 In. Hg

                 •       .        •

                 \      \       \

                 -A	i	3
                          •
v      \

                                                          \

                                                             »


                                          *

                                            -v


                                       *

                                        •
                                        •
                                                  •


                              •
                                                          *
                                                            *

                                                                t
               T
                 \
                                             »
                                               •
                                                      \
                                                       *
                                                        *
                                                          •

                                                                              \
                                                                   \
                                        t
                                          *

                                                                         •


                                                                     *
                                                                      •

                                                                                 •

                                                                                   •
                                                                           \
                                                                                                                          0.30

                                                                                                                          0.25

                                                                                                                          0.20
                                                                                               0.15
                                                                         Vft
                                                                                                                          0.10
o
•o

o
Q.

s.
                                                                                                     O
                                                                                                     M
                                                                                                     TJ


                                                                                                     i
                                                                                               0.05
                                                                                                                    »
                                                                                                                           0.00
           100
                                    200
                                                                  300
                                                                  400
                                                                                            500
                                                   Dry Bulb Temperature In Degrees F.

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             ATTENTION INSPECTOR TRAINING CONTACTS
      The enclosed course package tided "Emission Capture and Gas Handling
System Inspection" is not a final version. Initial peer review has shown a number of
minor revisions and additions need to be done before the manuals are considered
complete.  The manuals were used during the recent telecourse broadcast with
additional figures, tables and example problems added by the instructor to clarify
some lecture points.  These revisions will be made during FY 1994 by the course
instructor, Jerry Crowder, UTA Compliance Training Support Center, Arlington, TX.
The video tape set of the 15 hour telecourse should be available in 6 weeks.  Each
Regional Office and State Office may request a set at that time by contacting Betty
Abramson, APTB, phone 919/541-2371.  Call Kirk Foster, SSCD, phone 919/541-
4571 if you have any questions concerning the course materials.

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                 BACKGROUND INFORMATION AND INVENTORY SHEET FOR
        STATIONARY SOURCE COMPLIANCE TRAINING COURSE/WORKSHOP SERIES

                              PART I - COURSE INFORMATION

Course No.:            AITP #345/APTI #345

Course Title:           Emission Capture And Gas Handling System Inspection (also called
                      Inspection Of Industrial Ventilation Systems)

Course Category:              Air Inspector Training Curriculum  Intermediate Level

Course Type:                 Classroom course, 2-3 days, 1-2 instructors, with course manuals
                             (3), reference manuals (3), technical guides (3)  included in course
                             reference manuals, and slides (250)

Development Status:          Course manuals and  slides were revised March  1993. Course
                             materials are considered up to date.

Course Description:

This course is designed for Federal and State/local agency compliance staff responsible for
inspecting and evaluating the performance of emission capture and collection systems.  The
course provides students  with an understanding of the components of industrial ventilation
systems, including hoods, ducts, gas coolers and fans. Basic ventilation system design principles
are reviewed and  operation and maintenance practices discussed in regards to  their affect on long
term equipment performance.  However, the focus of the course is on inspection and
performance evaluation procedures.  Case studies of various ventilation systems are included to
assist students in  developing trouble-shooting skills.  The importance of properly designed,
operated and maintained emission capture and transport systems to overall control performance is
stressed.

Major Course Topics include:

• Properties of air and air-water vapor mixtures
• Hood types, their  design and performance characteristics,
 and techniques for their evaluation
• Duct design and key failure points
• Gas cooling equipment  design and  performance characteristics
• Fan system design and  fan performance characteristics
• Key ventilation system  operating parameters and
 parameter measurement techniques                          nT^pI  R  ?*SV   "brar?
• Inspection and performance analysis procedures                         Kegion VII

Key Contacts For  Information/Revisions:

   EPA Project Leader: Kirk Foster, SSCD MD-17, EPA, Research Triangle Park, NIC 2771 1,
                      Telephone: 919/541-4571

   Principle Author:    Jerry Crowder,  Crowder Environmental Assoc., 2905 Province Place,
                      Piano,  TX 75075, Telephone: 214/964-7661, Fax: 214/867-3617

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                            PART II - COURSE INSTRUCTOR(S)

Qualified Instructors/Contractors For Course #345:

   Most Experienced Team:   Jerry Crowder, Phd., Crowder Environmental Assoc., without
                            other instructor assistance, (Phone: 214/964-7661, Fax:
                            214/867-3617)

   Other Qualified Teams:

   Team 1:      John Richards, Phd., Richards Engineering, Durham NC, without other instructor
                assistance, (Phone: 919/489-8273)

Qualified Instructors For Related Courses:

   Option 1:     Raymond Manganelli, Phd., Environmental Sciences, Cook College, Rutgers
                University, New Brunswick, NJ. Can be contacted through the Rutgers
                Inspector Training  Center via Mike Gallo, jr. Phone 908/932-7715.  Dr.
                Manganelli is the principle instructor for EPA/Rutgers inspector training course of
                the same title.  The Rutgers course is a modified version of #345 presented in 2
                1/2 days and includes a flow measurement lab session. The course is usually
                presented only at the Rutgers Training Center.

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                       PART III - COURSE MATERIALS INVENTORY SHEET
Course # and Title:
Course 345  Emission Capture And Gas Handling  System Inspection
(Also called Industrial Ventilation System Inspection)
Course Technical Contact:
Course Materials List:
       Kirk Foster, SSCD MD-17, EPA, RTP, NC, Phone: 919/541-4571
               Item/Title
                Manual No.
  Description/Comment
  Instructors Package:

  1.Instructor Manual
  2.Slides set  200 slides
  3.Instructor Reference Material   Fans
  And Fan Systems Manual
  4. Post Test And Post Test Answer
  Sheet
  5.Plus student package
               340/1-92-01 5b

               340/1-92-015e
-Outline w/ notes manual

-Technical papers and reports on fan
system selection, design, and operation
  Students Package:

  1 .Student manual
  2.Slide manual
  3.Reference Volumes:
   1   Industrial Ventilation System
  Inspection Manuals
   2  Guide On Measurement Ports
  Location And Design
               340/1-92-01 5a
               340/1-92-01 5c

               340/1-92-015d
               340/1-92-01 5f
-Text type course manual
-Contains copy of all course slides

-Contains two manuals on industrial
ventilation system design and
inspection (600/7-86-016 & 340/1-84-
012)
-Technical guide on  location and design
of AP control system parameter
measurement ports  (340/1-84-017)
  Optional Course Materials (Student):

  (None)

  (Note: The hot mix asphalt plant
  description in chapter 15 in the Air
  Pollution Engineering Manual (1992)
  reference document has been used as a
  group discussion problem on industrial
  ventilation system and emission
  problems orientation)
 Additional Reference Materials:

 (See "core technical reference
 documents in attached list)

-------
                    PART IV - COURSE REFERENCE DOCUMENTS
               (For Additional Reading  and Technical Reference Library)

I.   Inspection Manuals

    1.  Performance Evaluation Guide For Large Flow Ventilation Systems, EPA 340/1-
        84-012, July 1984"

    2.  Guidelines On Preferred Location And Design Of Measurement Ports For Air
        Pollution Control Systems, EPA  340/1-84-017. September 1984"

II.   Technical Guides

    1.  Technical Manual: Hood System Capture of Process Fugitive Particulate
        Emissions, EPA 600/7-86-01 6, April 1986"

    2.  Air Pollution Engineering Manual, Chapter 6 - Ancillary Equipment for Local
        Exhaust Ventilation Systems, p. 155-205, Air & Waste Management Assoc.,
        Pittsburgh,  1992"

    3.  Air Pollution Engineering Manual, Chapter 3 - Design of Local exhaust systems, p.
        25-87, AP-40, US EPA, May 1973 (out of print)"

    3.  Industrial Ventilation, Twentieth Edition, ACGI, Cincinnati, OH, 1988

III.  Technical Reports And Articles

    1.  Fans  Special Report, John Reason, Power Journal, September 1983

    2.  Fans, Robert Aberbach, Power Journal, March 1968

IV.  Technical Books

    1.  H. D. Goodfellow, Advanced Design of Ventilation Systems for Contaminant
        Control, Elsevier Science Publishing Co., New York, 1987

    2.  Henry McDermott, Handbook of Ventilation Control, Ann Arbor Science, Ann
        Arbor, Ml, 1977

V.  Industrial Publications

    1.  The Fundamentals of the Operation and Maintenance  of the  Exhaust Gas System
        in a Hot Mix Asphalt  Facility, IS-52/87, National Asphalt Pavement Association,
        Revised 1987"m
(1)  Available from: National Asphalt Pavement Association, 5100 Forbes Blvd. Lanham,
MD 20706-4413, telephone (301) 731-4748, price $100 + $7.50 s&h

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