PB82-227539
Evaluation and Documentation of
Mechanical Reliability of Conventional
Wastewater Treatment Plant Components
Southwest Research Inst.
San Antonio, TX
Prepared for
Municipal Environmental Research Lab.
Cincinnati, OH
Mar 32
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CJ/M Jfdl
EVALUATION AND DOCUMENTATION OF MECHANICAL RELIABILITY OF
CONVENTIONAL WASTEWATER TREATMENT PLANT COMPONENTS
by
David W. Shultz
Van B. Parr
Southwest Research Institute
San Antonio, Texas 78284
Contract No. 68-03-2712
Project Officer
Jon Bender
Wastewater Research Division
Municipal Environmental Research '.aboratory
Cincinnati, Ohio 4526E
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
hpdooucco tr
NATIONAL TECHNICAL
INFORMATION SERVICE
US Of COUf'SCt
VIMCJIUD, »». 221M
EPA-600/2-82-044
March 1932
P £62-22753 5
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TECHNICAL REPORT DATA
(Tlczie read tnuniclionx on the revene before eomplrttncf
REPORT NO.
EPA-600/2-82-044
ORD Report
3. Rf c; p i c n i s/•- ccu> na.
PB32 2 2253 H
<. TITLE AMD SUBT I T LE
Evaluation nnd Documentation of Mechanical Reliability
of Conventional Wastewater Treatment PlanCcomponents
5 REPORT OATP
March 1982
6. PERFORMING ORGANIZATION CODE
AUTHOMISI :
David W. Shultz
Van B. Parr
a PEHFOMMING ORGANISATION REPORT NO
3 PERFORMING ORGANIZATION NAME AND AODRESS
Southwest Research Institute
6220 Culebra Koad
San Antonio, Texas 78284
10. PROGRAM CLEMENT NO.
AZB1B
11. CON IRACT/GnANT NO.
EPA Contract No. 68-03-2712
'2. SPONSORING AGENCY NAME ANO AODHESS
Municipal Environmental Research Laboratory - Cin., OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 4526S
13. TYPE OF RCPORT ANO PEHIOO COVERED
Fina 1
14. SPONSORING AGENCY CODE
EPA/600/1-
15. SUPPLEMENTARY NOTES
EPA Project Officer: Jon H. Bender
(513) 6fl4-?6Q7
'6 ABSTRACT
This study was initiated to determine the in-service reliability, maintainability
and availability of selected critical wastewater treatment plant cor.pnnents. Compo-
nents were considered critical if their failure caused an immediate impact on effluent
quality.
Treatment plant components selected included pumps, power transmissions, motors,
compressors, valves, and controls. Components were those from four tvpes of wastewate
treatment plants. The four types of plants were air activated sludge, oxygen acti-
vated sludge, trickling filter, and rotating biolopical contactor (RI'C). Operation
and maintenance data obtained from nine operating plants wore used lo estimate failure
rates, mean-time-between-failures, mean-tine-to-repair, and availability for each
component. These performance statistics .ire by component type, size tan^e, and appli-
cation. Performance statistics were calculated from operating data for 119 pumps,
249 power transmissions, 285 motors, 17 compressors, 13 valves, and 269 controls.
Calculated performance statistics can be utilized by design engineers and plant
operators to assist in the selection of new equipment. The development .of a perform-
ance data base and subsequent proper utilization of the data should result in improve-
ments in treatment plant performance. Thes? data allow estimates to be made of
performance to be expected from certain equipment in certain applications.
KEY 'I/OnOS ANO DOCUMENT ANALYSIS
J DESCRIPTORS
b.tOENTIFlERS/OPEN ENOEO TERMS
l\ COSATJ IVl'J/Croup
1*) QISTHmUTlON SIAILMtNT
Release Co Public
19 SCCUniTY CLASS ( i his f\fportf
line lnss i f i od
21. NO Of- ('AGtS
235
20 SECURITY CLASS {Tins past)
Unc 1 .nss i f i od
22 PRICE
CPA form 2220-1 U-73)
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publica-
tion. Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade nair.es or commercial products constitute endorsement or
recommendation for use.
ii
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FOREWORD
The Environmental Prot-nrion Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people. Noxious air, foul water, and spoiled
land are tragic testimony to the deterioration of our natural environment.
The complexity of that environment and the interplay between its components
require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem solu-
tion and it involves defining the problem, measuring its impact and searching
for solutions. The Municipal Environmental Research Laboratory develops
new and improved technology and systems for the prevention, treatment, and
management of wastewater and solid and hazardous waste pollutant discharges
from municipal and community sources, for the preservation and treatment of
public drinking water supplies, and to minimize the adverse economic, social,
health, and aesthetic effects of pollution. This publication is one of the
products of that research; a most vital communications link between the re-
searcher and the user community.
In the report, performance statistics for various mechanical components
found in four types or secondary wastewater treatment plants are presented.
These statistics were derived utilizing equipment service records from nine
wastewater treatment plants. Results indicate a wide range of performance
characteristics for similar equipment in different applications. Example
problems are presented with appropriate solutions to explain how these types
of statistics can serve as a valuable design and operations tool.
r- Francis T. !,ayo, nire;c j-"
Municipal Environmental kesearch
Laboratory
Si 1
_s !
ii i
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ABSTRACT
This research program was initiated to determine the ir.-service reli-
ability, maintainability and availability of selected critical wastewater
treatment plant components. Components were considered critical if their
failure caused an immediate impact on effluent quality.
Treatment plant components selected included pumps, power transmissions,
motors, compressors, valves, and controls. Components were those from four
types of wastewater treatment plants. The four tvpes of plants were air
activated sludge, oxygen activated sludge, trickling filter, and rotating
biological contactor (R3C). Operation and maintenance data obtained from
nine operating~pi ants were used to estimate failure rates, mean-tirce-between
failures, mean-time-to-repair and availability for each component. These
performance statistics are by component type, size range, and application.
Calculated performance statistics can be utilized by design engineers
and plant operators to assist in the selection of new equipment. The
development of a performance data base and subsequent proper utilization
of the data should result in improvements in treatment plant performance.
These data allow estimates to be made of performance to be expected from
certain .equipment in certain applications.
This report was submitted in fulfillment of Contract No. 68-03-2712 by
Southwest Research Institute under the sponsorship of the U.S. Environmental
¦ Protection Agency. This report covers the period September, 1978 to March
1981.
iv
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CONTENTS
Pa^e
Foreword iii
Abstract iv
Figures vi
Tables vi
List of Abbreviations vii
Acknowledgements viii
1. Introduction 1
2. Conclusions 3
3. Recommendations ~ 5
4. Project Objectives 6
5. Research Approach 7
Criticality Analysis 7
Data Source Selection 14
Data Acquisition 15
Data Analysis 16
6. Results and Discussion 25
7. Comparison of Reliability Data from Wastewater Treatment
Plant Study to Data from Two Other Sources 31
8. Performance Statistics Utilization 33
References 39
Appendices
A. Data Numbering System 40
B. Results of Criticality Analysis 51
C. Mechanical Equipment Priority Ranking 70
D. Summary of Performance Statistics Calculated on
Critical Components 74
E. Wastewater Reliability Analysis Program Users Manual 133
v
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FIGURES
Number Page
1 Flow Diagram - Typical Trickling Filter System 8
2 Flow Diagram - Typical Oxygen Activated Sludge System 9
3 Flow Diagram - Typical Activated Sludge Treatment System 10
4 Flow Diagram - Typical Rotating Biological Contactor
Treatment System 11
5 Sample of a Field Data Collection Form 17
6 Percent Deviation of One Sided Lower Confidence Limits
from Point Estimate of MTBF vs. Number of Failures 21
7 Example of Chi-Square Distributions; Percentiles and
Confidence Limits 30
TABLES
Number Page
1 Treatment P'ants Included in Reliability Study 15
2 Comparison of MTBF for Components from Three Data Sources 32
vi
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LIST OF ABBREVIATIONS
Abbreviations
POTW -- Publicly Owned Treatment Works
EPA -- Environmental Protection Agency
GAO -- General Accounting Office
BOO -- biochemical oxygen demand
MTBF — mean time between failure
MTTR -- mean time to repair
WRAP — Wastewater Reliability Analysis Program
PM — preventative maintenance
CM -- corrective maintenance
AVI -- inherent availability
AVO -- operating availability
vii
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ACKNOWLEDGEMENTS
Joe N. Pyle, P.E., and Stuart D. Whitford, P.E., of Seligmann and Pyle,
Consulting Engineers, Inc., San Antonio, performed the data collection.
This work was supported by the U.S. Environmental Protection Agency,
Wastewater Research Division, under Contract 68-03-2712. Mr. Jon H. Bender
of the EPA Municipal Environmental Research Laboratory, Cincinnati, Ohio,
was the Project Officer. The authors wish to acknowledge the help of Messrs.
John Smith, Frank Evans and Ms. Janet Houthoofd of the EPA, and especially
the help and support of Mr. Jon Bender who worked closely with project per-
sonnel throughout the project. The assistance of plant personnel at the
wastewater treatment plants visited during this project is also acknowledged.
vi i 1
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SECTION 1
INTRODUCTION
There are approximately 21,000 publicly owned municipal treatment plants
(POTWs) operating me, with 1000-1200 new plants
billion have been awarded to help state and local governments construct these
treatment plants. Once constructed, local governments become responsible for
plant operation in accordance with effluent discharge permit requirements
established by the National Pollutant Discharge Elimination System (NPDES).
Many POTWs are apparently not meeting NPDES permit requirements. The
General Accounting Office (GA0) concluded in 1970 that operation and mainte-
nance problems with POTWs had be^n widespread for many years and had resulted
in inefficient plant operations^. A 1975 EPA analysis of 954 P0TW inspec-
tions showed 386 plants had sufficient design and operational performance
data to determine whether the plant was meeting design criteria for biochemi-
cal oxygen demand (500) removal. 40 percent of the 386 plants failed to meet
design BOD removal. 49 percent of 305 plants were operating below design
criteria for suspei'iued solids removal. Other studies have indicated signifi-
cant problems of r.on-compl iance by POTWs with NPDES permi ts(4) (5) (6).
In recognition of these operational and maintenance problems, the U.S.
EPA initiated a national research program dealing with performance and relia-
bility of POTWs. A significant part of the effort involves determining the
reliability of various mechanical components used at POTWs.
This study was conducted to quantify the in-service reliability of
critical mechanical components found in four types of secondary wastewater
treatment plants. The four types of plants included in this study were air
activated sludge, oxygen activated sludge, trickling filter, and rotating
biological contactor. Component reliability statistics calculated were .T.ean
time between failure (MTBF), mean time to repair (MTTR), and availability as
a fraction of scheduled operating time.
To determine the in-sorvice reliability of critical mechanical compo-
nents, the first step was to identify the critical components. The following
components were identified as critical (i.e., failure would have an immediate
impact on effluent quality):
(1) Pumps
(2) Power transmissions
(3) Motors
being constructed
Federal grants exceeding 20
1
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(4) Compressors
5) Diffusers
6) Valves
(7) Controls
(8) Pressure vessels
(9) Conveyors.
A criticality analysis was then conducted to determine which applica-
tions of these components should be included in the study. This effort
served to identify the field data collection requirements.
Nine treatment plants were then selected from a candidate list of
approximately <10 plants. These nine plants were visited and data collected
from plant maintenance records. Reliability statistics were then calculated
using these data.
2
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SECTION 2
CONCLUSIONS
Based upon the results of the performance data collection and analysis
effort conducted during this project, the following conclusions are made:
(1) Three types of performance statistics (reliability, maintainability,
and availability) have been determined for mechanical components of
wastewater treatment plants, (p. 25)
(2) These performance statistics were not available in the literature,
from manufacturers, or owners of equipment, (p. 31)
(3) These performance statistics can be used by design engineers as a
tool to (a) compare and predict performance of generic equipment
in various applications, and (b) design reliability into new treat-
ment plants, (p. 33)
(4) These data can be used by operators of wastewater treatment plants
to help develop spare parts inventories for new equipment and
establish preventative maintenance programs, (p. 37)
(5) The majority of the 200 plants contacted by phone or visited during
the screening process did not maintain adequate records necessary
for collection of data needed in this study, (p. 14)
(6) This data base does not cover all the size ranges or types of
equipment typically found in the 21,000 treatment plants operating
in the U.S. Therefore, performance statistics for many of the
components found in smaller plants are not available in the djta
base. It was found that these records are not routinely kept by
the smaller plants surveyed during this study, (p. 14)
(7) The quality of data obtained from the nine treatment plants was
good. The form of record keeping sometimes required judgments
as to appropriateness with respect to project data requirements,
(p. 16)
(8) The nine treatment plants from which the data were collected main-
tained records for equipment for a variety of reasons, including
ordering spare parts, scheduling preventative maintenance, and
preparing annual budgets.
3
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(9) The nine plants visited had preventative maintenance programs which
appeared to be effective.
(10) Performance statistics can provide design engineers and plant
operators with additional information to help select and specify
equipment. Training will be required to help these people know
how to utilize such data. For maximum effect, the data base should
be expanded to cover all major types and size ranges of equipment
found at treatment plants presently operating in the U.S. The data
base should be maintained for at least a five year period.
4
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SECTION 3
RECOMMENDATIONS
Based upon the results of this study, the following recommendations
are offered:
(1) EPA should encourage the use of performance results of this
study by designers or operators as an additional tool for the
selection of equipment and the prediction of performance from
mechanical components.
(2) EPA should conduct a series of technical seminars to (1) present
the results of this project to design engineers and plant oper-
ators, and (2) explain the basic reliability and availability
analysis methodologies. Their feedback could be used to help
formulate and define future EPA policy regarding the Federal
role in the WWTP performance statistic data base management.
(3) EPA should conduct a study to determine the feasibility of
implementing a continuous performance data collection program
from selected treatment plants representing a sufficient cross
section of the nearly 21,000 plants in the U.S. by plant type
and design flow. Mechanism and cost should be determined.
(4) Based upon favorable results of recommendations (2) and/or
(3) above, EPA should initiate a program to collect performance
data on a continuous basis for use by design engineers and
treatment plant operators.
5
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SECTION 4
PROJECT OBJECTIVES
Major project objectives were as follows:
(1) Quantify in-service reliability, maintainability and availability
on mechanical components used in four types of secondary wastewater
treatment plants.
(2) Show how the component application affects its reliability,
maintainability and availability.
(3) Quantify in-service reliability, maintainability and availability
of the s^dge processing unit operations at wastewater treatment
plants.
6
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SECTION 5
RESEARCH APPROACH
The research approach utilized to accomplish the objectives of this study
involved a series of major tasks which are discussed in detail in the follow-
ing sections. Briefly, the first step, the Criticality Analysis, involved
the identification of the important mechanical components in conventional
secondary wastewater treatment plants az defined by their potential impact
on effluent quality should they fail. Once these components were identified,
the criticality of each component was determined and ranked by conducting a
failure mode and effects analysis. From this effort, the desirable informa-
tion needed from actual operating treatment plant records was identified.
The Plant Selection step involved developing a candidate lir.t of treat-
ment plants to be visited. From this list, nine treatment plants were
selected and subsequently visited to collect data. These data were then
analyzed to determine the important performance statistics, i.e., mean time
between failure, mean time to repair, and availability.
5.1 CRITICALITY ANALYSIS
The objective of the criticality analysis was to determine the mechani-
cal components in conventional wastewater .treatment plants which would have
the most inmediate impact on final effluent quality if they failed.
The procedure used in this phase was to define the conventional second-
ary wastewater treatment plants - air activated sludge, oxygen activated
sludge, trickling filter and rotating biological contactor in terns of the
respective flow diagrams. These flow diagrams are presented as Figures 1
through 4.
Sludge processing systems were included in the study. These included
vacuum filters, aerobic and anaerobic digestion and dissolved air flotation.
Data for components of sludge processing equipment were not collected. Only
data for those sludge processing systems found at the treatment plants visited
were collected.
The flow diagrams defined the various treatment systems of interest.
Each system was then divided into the following unit operations:
- Headworks
- Primary settling
- Secondary treatment (biological units)
- Final settling
7
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FIGURE I
FLOW DIAGRAM - TYPICAL TRICKLING FILTER SYSTEM
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FIGURE 2
FLOW DIAGRAM - TYPICAL OXYGEN
ACTIVATED
SLUDGE SYSTEM
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FIGURE 3
FLOW DIAGRAM - TYPICAL ACTIVATED SLUDGE TREATMENT SYSTEM EXAMPLE
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FIGURE 4
FLOW DIAGRAM - TYPICAL ROTATING BIOLOGICAL CONTACTOR TREATMENT SYSTEM
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- Sludge processing
- Disinfection
The broad classifications of mechanical equipment that could be identi-
fied in each unit operation were then defined. These classifications are:
Pumps
Power transmission
Motors
Compressors
Diffusprs (air/water)
Valves
Controls
Pressure vessels
Conveyers (unconfined materials handling)
A numbering system was developed to aid in performing the criticality
analysis and data collection. The numbering system is presented in Appendix
A. In developing the numbering system, the generic groups, applications,
size ranges, subcomponents and other pertinent information were preliminarily
identified. Examples of these categories are presented in Appendix A. The
system was developed with the flexibility to add additional information during
field collection of data. This is the reason for the use cf the two, three
and four digit columns to identify a specific component. Additionally, to
allow for data sorting by computer, it was necessary to eliminate any mixing
of equipment type or application between columns.
The following steps were then used in the criticality analysis:
(1) Identification of the broad classification in each plant unit
operation for each type of plant.
(2) Identification of the applications for each broad classification
defined in step 1 above.
(3) Assignment of a criticality factor as a function of failure on
effluent quality and the time ot the effect.
In performing the criticality analysis, it was assumed that there was no
equipment duplication and the plant was operating at design conditions. For
example, it was assumed that there was only one raw wastewater pump in the
headwords, only one final clarifier in the final settling unit operation, and
no additional hydraulic capacity in either component.
A rating was assigned to each plant type, unit operation, broad classifi-
cation ana application combination. The rating consisted of two parts:
(1) Relationship between Failure and Effluent Quality
. A - Significant impact
. B - Minimal impact
. C - No impact
12
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(2) Time Factor
1 - 0-4 hours
. 2 - >4-12 hours
3 - >12-24 hours
4 - >24 hours
Using this approach, if a combination was rated "A-l," the failure of the
mechanical component would likely result in a significant impact on effluent
quality within four hours. If the rating was "C," the failure would probably
have no impact on effluent' quality. The results of the criticality analysis
are presented in Appendix B.
The results of the criticality analysis were then reviewed and ranked
according to priority by those that v/ould have the most significant impact
in the shortest time period. The results of this ranking are presented in
Appendix C.
The critical components for inclusion in the study were selected as those
with an assigned criticality factor of either A-l, A-2, A-3 or B-l. If the
impact of failure of a mechanical component was minimal (i.e., B) and it oc-
curred within four hours, that component was also considered to be critical
and included in the data collection effort. The following presents a summary
of those mechanical components selected for inclusion in the data collection
phase:
- Raw and intermediate wastewater pumps, power transmission and motors
for al 1 pi ant types
- Return activated sludge pumps, power transmission and motors for air
and oxygen activated sludge
- Recirculation pump, power transmission and motors for trick!inq
filter and rotating biological contactors
- Motors and power transmission for final clarifiers for all plant
types
- Motors, power transmission, compressors, valves, controls and dif-
fusers jsed in dissolved air production application and mechanical
aerators in air activated sludge plants
- Motors, power transmission, recirculation pumps, controls, diffusers
and valves used in oxygen generation, application and recirculation
in oxyyen activated sludge plants
- Liquid application systems for trickling filter plants
- Compressors, motors, power transmission and controls used in rotating
biological contactors in RBC planus
- Motors, pumps, pow^r transmission and controls used in primary
13
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clarifiers and primary sludge pumping in trickling filter and RBC
plants
- Recirculation pumps controls used in secondary treatment in RBC plants
- Raw and intermediate wastewater pump controls used in all plant
types and valves used in raw and intermediate pumps in trickling
filter plants
- Controls used in dosing siphon in secondary treatment in trickling
filter plants
- Controls used in final clarifiers for all plant types
- Pumps, motors, power transmission and pressure vessels used in dis-
infection for all plant types.
Having defined the data collection requirements, the next step involved
the selection of treatment.plants having adequate records from which these
data could be collected.
5.2 DATA SOURCE SELECTION
The Criticality Analysis described in Section 5.1 defined the mechanical
components for which performance data were needed. The next step was to
select the treatment plants where this information could be obtained. This
data source selection process involved the following tasks:
o Develop a list of candidate plants.
o Select plants for one-day screening visits.
o Conduct the one-day visits.
o Select study plants.
A candidate list of approximately 200 treatment plants was developed
utilizing information from the U.S. EPA s^aff, equipment manufacturers and
sales representatives, SwRI and subcontractor contacts, treatment plant
operators and the literature. The criteria used to develop this list were
primarily (1) that the plants satisfied the plant type requirement (i.e.,
air or oxygen activated sludge, RBC, or trickling filter); (2) there was an
indication these plants would be willing to participate in the study; and (3)
maintenance records were available.
Using information about these plants, forty-two plants were selected for
direct contact by telephone. Project objectives and available maintenance
records were discussed with appropriate personnel at each facility. The
majority of the plants contacted did not maintain historical records on the
plant components by component type. To access these data, extensive on-site
time would have been necessary. Other plants did not maintain maintenance
records. This was more often the case with smaller plants. Seventeen plants
were identified for further consideration. One-day screening visits were
then scheduled for each plant. The one-day visits were made to discuss the
14
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project with plant personnel and verify the suitability of plant records
for the study.
Following the one-day visits, the treatment plants to be included in the
data acquisition effort were selected. Criteria used to make the selection
wer.e as follows:
(1) Existence of adequate and complete preventative and corrective
maintenance records for all major equipment components at each
plant;
(2) Existence of plant equipment typical of the generic equipment found
in the four types of treatment plants under consideration;
(3) An indication that plant operations and maintenance personnel were
willing to cooperate in the data collection effort.
Table 1 shows the design flow and age of the nine plants included in this
study.
TABLE 1. TREATMENT PLANTS INCLUDED IN RELIABILITY STUDY
Plant Type Design Flow (MGD) Age (Years)
Air Activated Sludge
93
15
75
7
36
8
60
4
Oxygen Activated Sludge
72
5
300
7
Trickling Filter
45
20
150
30
Rotating Biological Contactor
24
2
5.3 DATA ACQUISITION
The objective of the data acquisition phase of this study was to obtain
failure and me ntei.ance data on the critical mechanical component/application
combinations shown in Appendix C, "Mechanical 'equipment Priority Ranking"
(see Section 5.1). A schedule was developed for visiting the plant locations
identified in Section 5.2. Plant managers/superintendents were contacted to
establish the time for the visit and confirm that the appropriate plant
employees would be available at that time.
Upon arrival at each plant, the data collection team (engineer/operator
and engineering technician) met with the plant staff involved. This meeting
15
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provided an opportunity for the data collection team to further explain the
project and discuss possible uses of the project results. The methodology of
the data collection effort was discussed. The plant staff was asked to out-
line the details of their maintenance management system, work order system,
spare parts program, contract maintenance, and problems encountered. These
discussions were important to facilitate proper collection of the data from
plant records. Following this interview, a plant tour was made to familiarize
the data collection team with plant layout, sub-processes, equipment, flow
patterns, flow rates, and controls.
Ac this puint, data collection uas started. Maintenance records for
each critical component were reviData collection forms were used to
code all data. An example is shown in Figure 5. Required data elements are
shown at the top of this form. All data collected in the field were encoded
using the numbering system discussed in Section 5.1 (see Appendix A). These
codes are shown in the appropriate columns in Figure 5. For example, column
one contains the code number 04-8731. The first two digits, 04, identify
t'.ie plant location. The second four-digit number represents a record number
i^sed to identify that specific piece of equipment. Column two, plant type,
shows the number 05, -which identified this plant as a combination air/oxygen
activated sludge plant. Codes for each of the remaining 23 columns are shown,
•with a description of what each code means shown below the code. Column 23
was for recording actual down time of sludge processing systems. Data for
the sludge processing systems at eich facility visited were recorded as shown
at the bottom of Figure 5. These data allowed calculation of the mean time
between failure and availability of the system.
The data collection from plant records often required a degree of judg-
ment and interpretation. This was especially true when deciding when equip-
ment had actually failed. A mechanical component failure is classified as
an event which occurs when a subcomponent 'ceases to perform its function, and
must be repaired or replaced to restore the component to a normal operating
condition. An example of a failure is a seized bearing on a pump shaft which
must be replaced before the pump can be restored to an operating condition.
In contrast, an equipment malfunction was defined as situations where the
equipment could be placed back into service by minor cleaning and/or adjust-
ments. Only data for down time considered to be caused by failure were re-
corded. Malfunctions including pump blockages, reduction in blower capacities
due to dirty air filters, and plugging of air diffusers were not recorded.
If interpretation of maintenance records was questionable, the data collection
team conferred with plant maintenance staff to decide whether a failure had
occurred.
5.4 DATA ANALYSIS
A computer program entitled "Wastewater Reliability Analysis Program -
WRAP" was written to handle the sorting.and analysis of the relatively large
data base. Complete details of the logic, fortran listings, and capabilities
of WRAP are contained in Appendix E of this report. Reliability, maintain-
ability, maintenance and availability statistics were calculated from the
data base across all plants for:
16
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-------
(1) Components
(2) Components by application
(3) Components by size
(4) Ccmponents by generic group
(5) Components by generic group by application
(6) Components by generic group by size.
In addition, failure distribution information by subcomponent type for
the first four categories listed above were also calculated. Also, relia-
bility and availability statistics were calculated for sludge processes.
Included in Appendix E is a computer printout by plant, and across all
plants of reliability, maintainability, maintenance and availability statistics
for components by generic group by application by size.
The statistics calculated from the data serve as the best sumary of
the data base in terms of the reliability, maintainability, maintenance,
availability and subcomponent failure distribution parameters for the nine
wastewater treatment plants. This information should be useful to other
plant owners and operators, equipment manufacturers, and plant designers.
A description of the algorithms and methods used to calculate the esti-
mates of the parameters which appear in the tables in Appendix D of this
report follows.
5.4.1 Number of Units
The number of units in the data base for each category of component
groupings was calculated by summing the number of units reported in the data
base across the appropriate grouping.
5.4.2 Number of Failure;
The number of failures (Column 12 in Figure 5) was calculated in the
same manner as the number of units.
5.4.3 Operating Hours (in millions of hours)
The total operating hours (OH) for the units in each category of com-
ponent groupings was calculated by the following formula:
N
OH = (8760 2 )/l ,000,000
i=l
where
Y, is the number of years'between the instil*ation date (Column
10 in Figure 5) and the date the data were taken or the
unit was taken out of service (Column 24 in Figure 5),
for the ith unit in the category,
18
-------
P.j is the percent of the time the unit was operating
(Column 11 in Figure 5), and
N is the number of units in the category.
5.4.4 Overall MTBF (in millions of hours)
The point estimate for the overall mean-time-between-failures (MTBF)
was calculated by the following formula:^)
MTBF =
X0.5;2r+2
where,
T is the total operating hours (OH) from Section 5.4.3,
r is the number of failures frcm Section 5.4.2, and
Xq 5.2r+2 is the value a chi-square distribution^) with
2r+2 degrees of freedom at the fiftieth percentile.
This method yields a slightly more conservative estimate of the MTBF than
the usual method of dividing the operating hours by the number of failures.
This method also allows an estimate of the MTBF, even when no failures have
occurred.
5.4.5 Minimum MTBF (in millions of hours)
The minimum MTBF for a particular category is the least MTBF calcu-
lated in a subcategory of the category. For example, In a grouping of
components by generic group by size, there may be several subcategories by
application. The smallest value of MTBF from this subcategory is listed as
the minimum MTBF. This information serves as a lower bound on the range of
the subcategory MTBF's. Wnere there is only one data point in the subcate-
gory, the entry is left Dlank.
5.4.6 Maximum MTBF (in millions of hours)
The maximum MTBF is calculated in a similar manner to the minimum
value and serves as an upper bound on the range of subcategory values. The
difference between the maximum and minimum values car. be interpreted as a
measure of dispersion about the overall MTBF estimate. If one assumes that
these estimates are normally distributed,^8' then an estimate for the standard
deviation is one-sixth of the range of the minimum to maximum values. The
smaller the ratio of the estimate of the standard deviation to the MTBF, the
more precise is the estimate of the MTBF.
5.4.7 Overall 90% Confidence Level (in millions of hours,)
The overall 90% confidence level (M(.90)) for the MTBF is ca^ul^ted
19
-------
by the formula:(?)
M( .90) = ^
X2
.90;2r+2
where,
T is the total operating hours (OH) from Section 5.4.3,
r is the number of failures from "ectioti 5.4.2, and
O
.90-2r+2 v3''116 °f a chi-square distribution with
2r+2 degrees of freedom at the ninetieth percentile.
The meaning of the 90% confidence limit is that one can be 90% confi-
dent that the true value of the MTBF is at least as great as the calculated
90% confidence limit.
The percent deviation of the confidence limit value from the point
estimate value of the MTBF is a function of the number of failures.Figure
6 is a graph showing the percent deviation from the point estimate of the
lower confidence limit, as a function of the number of failures. Figure 6
was derived using the following formula:
x2
Percent Deviation =1 —
(CL); (2r+2)
From Figure 6, for a lower 90% confidence limit, the following infor-
mation can be derived as to the approximate percent deviation of the lower
90% confidence limit from the point estimate of the MTBF as a function of
the number of failures.
Approximate Percent
Number of Failures Deviation
1 -57%
2 -49%
3 -44%
4 -41%
5 -38%
10 -31%
20 -24%
100 -12%
The percent deviation is also a measure of the precision of the point
estimate.
20
-------
-10 -20 -30 ¦ -40 -50 -60
PERCENT DEVIATION (PRECISION)
-70
Figure 6. Percent Deviation of One Sided Lower Confidence Limits
From Point Estimate of MTBF vs. Number of Failures
21
-------
5.4.8 Preventative Maintenance Hours per Unit per Year (PM-HRS/UNIT/YEAR)
The preventative maintenance (scheduled maintenance) hours per unit per
year (PH) for each unit category are calculated by the formula:
PH = ( 2 PM)/[(Y) (m)]
p=l J
where,
m is the number of units in the category, (taken from
Section 5.4.1)
Y is the number of operating years on the m units (taken
from Section 5.4.3), and
PM-: is the number of preventative maintenance hours reported
on the jth unit.
5.4.9 Corrective Maintenance Hours Per Unit Per Year (CM-HRS/UNIT/YEAR)
The corrective maintenance (unscheduled maintenance due to failures)
hours per unit per year (CH) for each category are calculated by the formula:
m
CH = ( 2 CMi)/[(Y)(m)] ,
j=l J
where,
m is the number of units in the category (taken from
Section 5.4.1)
Y is the number of operating years (EY-jP^, taken from Section
5.4.3) on the m units
CMj is the man hours spent on corrective maintenance for
the jtri unit (Column 16 in Figure 5).
5.4.10 Mean-Time-To-3epair (MTTR) in hours
The mean time to repair a unit in a category is calculated by the
formula
N nj N nj
MTTR = (22 Cii)/( 2 2rii)
j=l i=l J j=l i=l 1J
22
-------
where,
N 1s the number of units in the category,
n,- is the number of corrective maintenance actions due to
failures on the jtfl unit
C^j is the number of calendar hours during which repair
actions were being made (Column 15 in Figure 5) due to
the ith failure on the jth t:nit.
r.jj is the ith failure on the unit, that is,
N nj
2 £ r,-,• is the total number of failures
j=li=l J
(or corrective maintenance actions) on the N units in the
category.
5.4.11 Inherent Availability (AVI)
The inherent availability for each of the component groupings is
calculated by the formula:
AVI - ^
MTBF+MTTR
The inherent availability of a component is a measure of the fraction
of time that the component can be expected to be operational, excluding pre-
ventative maintenance downtime.
5.4.12 Operating Availability (AVO)
The operating availability for each of the component groupings was
calculated by the formula:
AVO - ™-THD •
TH
where,
N
™ ~ ^^Yj)(8760) = total hours for all units in category, and
23
-------
THD = total downtime over all units due to corrective and
scheduled maintenance.
Thus, the operating availability is calculated from th.e operating
history of the units, and is a measure of the fraction of the Calendar time
which the unit was operating.
5.4.13 Component Failure Statistics by Subcomponent Type
For each of the first four component groupings listed in Section 5.4,
the number of failures of the components due to failures of subcomponents was
determined. The relative frequency of failures by subcomponent type was cal-
culated. These frequency distributions for the dominant subcomponent failures
are listed in Appendix D, Part 2.0.
5.4.14 Reliability and Availability Statistics for Sludge Processes
Data on the following five sludge process were obtained.
(1) Sludge treatment external to the wastewater treatment process
(2) Anaerobic digestion
(3) Incineration
(41 Sludge Thickening Dissolved Air Floatation
(5) Vacuum filter
Statistics calculated by plant and across all plants are: operating
hours, number of failures, MTBF, 90% confidence limits on MTliF and operating
availability. These statistics for sludge processes were calculated in a
manner similar to their counterparts for components, and are presented in
Appendix D, Part 3.0.
24
-------
SECTION 6
RESULTS AND DISCUSSION
The performance statistics on critical components and sludge processes
which were calculated from the data gathered at nine wastewater treatment
plants are presented in Appendix D. The statistics which were calculated
are as follows:
RELIABILITY STATISTICS
o Overall mean time between failures (Overall MTBF)
o Maximum mean time between failure (Max IiTBF)
o Minimum mean time between failure ^Min MTBF)
o Lower limit 90% confidence level for the mean time between failure
point estimate (overall 90% CL)
MAINTAINABILITY AND MAINTENANCE STATISTICS
o Mean tine to repair (MTTR)
o Preventative maintenance man hours per unit per year (PM-HRS/Unit/YR)
o Corrective maintenance man hours per unit per year (CM-HRS/Unit/YR)
AVAILABILITY STATISTICS
o Inherent availability (AVI)
o Operating availability (AVO)
These statistics, presented in Part 1.0 of Appendix D, have been grouped
as follows:
o By component (component is synonymous with broad classification
as used in the data numbering system)
o By component by generic group
o By component by application
o By component by size/capacity
o By component by generic group by application
o By component by generic group by size/capacity
25
-------
The definitions and methods used to calculate the performance statistics
are presented in Section 5.4 of this report. A discussion of Tables
1.1.1 and 1.1.2 of Appendix 0 follows.
Table 1.1.1 presents the reliability statistics for the eight components
(or broad classifications) included in the data base. The overall point
estimate of the mean time between failures for pumps was 32,066 hours,
or approximately 3.7 years. This estimate is for all types of pumps
of various size raises in a variety of applications. To obtain the MTBF
estimate for a specified type of pump in a certain application, say an
open impeller pump being used for raw wastewater pumping, one refers
to Table 1.5.1.1. The lower limit 90% confidence level MTBF value for
pumps in Table 1.1.1 is 28,630 hours, or approximately 3.3 years. As
discussed in Section 5.4, this means there is a 90% chance that the true
MTBF value is greater than 3.3 years. The true MTBF value would be that
value calculated from operating data for all critical pumps in all wastewater
treatment plants throughout the United States. Since this history is
not presently available, the 90% value, combined with the overall point
estimate, provides a reasonable range for predicting component performance.
The minimum and maximum MTBF values shown in Table 1.1.1 represent
the smallest and largest estimated MTBF values calculated for subcategories
of pumps. The difference between these values can be interpreted as
a measure of the dispersion about the overall MTBF estimate for pumps.
In summary, the estimate of the true MTBF value for pumps based
upon data collected is 32,066 hours. The smallest and largest MTBF values
calculated were 21,652 hours and 74,191 hours, respectively in the sub-
category of generic group. There is a 90% chance that the true MT3F
value is at least 28,630 hours. The same conclusions can be made for
the other components listed in the tables presented-in Part 1.0 of Appendix
0.
Table 1.1.2 presents the maintenance statistics for components.
For pumps, the preventative maintenance (scheduled) hours/unit/year spent
at all the treatment plants included in the study averaged .00227 hours.
The corrective maintenance (breakdown) hours per unit per year were .05177
hours. These numbers might appear to be low. However, it must be recognized
they are based upon a large number of pumps (119) operating for a combined
total of 442 years. Many units operated for ten years with few failures,
and required minimal scheduled maintenance. The corrective maintenance
value is based upon the active man hours required to disassemble, correct,
and reassemble the unit, excluding time parts may have spent in the shop
or time spent waiting for a new part to be received.
The AVI, or the inherent availability, is a measure of the fraction
of time that the component can be expected to be operational, excluding
preventative maintenance downtime. The AV9, or the operating availability,
is a measure of the same fraction of time, but is based upon the operating
history of the units, including preventative and corrective maintenance.
26
-------
For pumps, the AVI and AVO fractions from Table 1.1.2 are .99968
and .99116, respectively.
The tables in the other five groups provide a further breakdown
of the reliability and maintenance statistics.
Part 2.0 of Appendix D contains tables presenting the number and
relative frequency of failures of subcomponents for the eight components
or broad classifications. For example, Table 2.1.1 lists the types of
subcomponents which caused pump failures, ranked according to the number
of failures. There were 17 impeller wear ring or plate failures. The
relative frequency was .177. This means one should expect that approximately
17 percent of the subcomponent failures for pumps will be due to impeller
wear rings or plates.
Part 3.0 of Appendix D presents reliability and availability statistics
for the various sludge processes located at the treatment plants visited
during this study. Table 3.1-1 presents for the five sludge processes
listed, total operating hours, number of failures of the process, the
mean time between failure, the 90% confidence level lower limit and the
operating availability. The first process listed, sludge process external
to wastewater treatment process, includes primary, secondary, waste activated,
and digester gas recirculation pumping. The other processes listed are
self-explanatory.
MTBF Comparison Method
In order to select the component type for an application with the
highest CTBF, it is necessary to compare the MTBF statistics for the
candidate component type. Since one is comparing estimates of the true
MTBF, it is useful to derive an estimate of the level at which a given
MTBF value is statistically different from another MTBF value.
One method is to utilize an "F" test(®) based on the fact that the
statistic
2rm , where
m
r is the number of failures,
m is the print estimate for MTBF, and
m is the true MTBF,
has a Chi Square distribution with 2r degrees of freedom.^) The ratio
of two of these statistics has an "F" distribution^"' with 2r^, 2r? degrees
of freedom, and a test of the hypothesis that the true MTBF's of tne
populations from which the estimates came are equal can be made.
27
-------
Another less precise method is Illustrated in the following paragraphs,
using data taken from Tables 1.2.1, 1.5.2.1, and 1.5.2.9.
Generic Group
No. of Failures •
MTBF
90% CL
Concentric Reducer
Belt Drive
2
5
122,640
91,101
61,898
55,640
The significance level at which the two MTBF's are statistically
different is a measure of the risk that one is wrong in saying that the
component with the highest point estimate value MTBF has a true MTBF
that is actually higher than the point estimate value MTBF of the ether
component.
A less precise method (than the F test) for determining the significance
level at which the concentric reducer can be judged to have a higher
MTBF than the belt drive is outlined below:
Step 1. Compare the 90% confidence limit value MTBF of the concentric
reducer to the point estimate value MTBF of the belt drive.
If the 90% confidence limit value MTBF of the concentric
reducer (61,898 hours) is greater than the point estimate
MTBF value of the belt drive (91,101 hours), there is less
than a 10% chance of being wrong if one decides that the
true MTBF of the concentric reducer is greater than the
point estimate value MTBF of the belt drive; the significance
level would be less than 10%. However, since the 90% confidence
limit value MTBF of the concentric reducer is less than
the point estimate value MTBF of the belt drive, one nust
go on to Step 2 to determine the approximate significance
level.
Step 2. Use the graph in Figure 6 to determine the % confidence
limit value MTBF of the concentric reducer which is greater
than the point estimate value MTBF of the belt drive.
From Figure 6, the deviation from the point estimate for
80% CL with 2 failures is .376, and for 60% CL with 2 failures
is .140. The confidence limits are:
80% = (1-.376)(122,640) = 76,520
60% = (1-.140)(122,640) = 105,460
At the 60% CL, the concentric reducer MTBF value is 105,460
hours, which is greater than the point estimate value MTBF
of 91,101 hours for the belt drive. However, at the 80%
CL, the concentric reducer MTBF value of 76,520 hours is
less than the point estimate value MTBF of 91,101 hours
for the belt drive.
28
-------
Thus, there is a risk oF greater than 20% and less than
40% of being wrong if one decides that the true MTBF of
the concentric reducer is greater than the point estimate
value MTBF of the belt drive power transmission.
The actual significance level for this example is 32.6% as determined
by the "F" test method.
The Chi-Square distributions and the percentiles v**om which the same
calculations could be rade are shown in Figure 7, along .vith a linear
graph of the confidence level comparisons. Tables of the appropriate
Chi-Square distributioiis could be used to determine confidtnce levels
for MTBF, using the formula in section 5.4.7.
Figure 6 can also be used for this type of determination for any
of the MTBF values presented in the tables of Appendix 0, Part 1.0.
When the 90% Confidence Limit value MTBF of one equipment type is greater
than tr.e point estimate value MTBF of another equipment, there is less
th?.n a 10% chance of being wrong in deciding that the first equipment
type has a higher MTBF than the second.
29
-------
X
(o) CHI-SQUARE DISTRIBUTION WITH
6 DEGREES OF FREEDOM
(b) CHI-SQUARE DISTRIBUTION WITH
12 DEGREES OF FREEDOM
125 100 75 50
I 1 1 I HOURS (Thousands)
53% 60% 80% 90%
I 1 1 1 CL MTBF EST FOR BELT DRIVE
50% 60% 80% 90%
I 1 1 1 CL MTBF EST FOR CONCENTRIC
REDUCER
(c) CONFIDENCE LIMIT ON BELT DRIVE
AND CONCENTRIC REDUCER
Figure 7.
EXAMPLE OF CHI-SQUARE DISTRIBUTIONS;
PERCENTILES AND CONFIDENCE LIMITS
-------
sect i or; 7
COMPARISON OF RELIABILITY DATA FROM WASTEWATER TREATMENT PLANT STUDY
TO DATA FROM TWO OTHER SOURCES
A comparison of reliability data from other sources to the reliability
data from the-Wastewater lreatment Plant Study is useful in assessing
how similar components perform in different applications. Two other
data sources were identified which contained data on components that
were similar in size and/or generic group to those in the Wastewater
Treatment Plant Study. These data sources are, "The Non-Electric Parts
Reliability Data'V9' "The Nuclear Plant Reliability Data System" (Edison
Elec^^ Institute, operated by Southwest Research Institute, San Antonio,
Pertinent performance data were selected from each of the two sources.
Mean time between failure (MTBF) calculations were made, using the same
methods as were employed for the Wastewater Treatment Plant Study. The
results are shown in Table 2.
For most components, there were many more operating hours contained
in each of the other two data sources. The wastewater treatment plant
MTBF values were lower than for the other two sources, for all the components
listed. This could be expected, since the components reported in the
Nuclear Plant Reliability Data System are all in the safety class of
the nuclear steam supply system. In addition, many of the components
from the Non-Electric Parts Reliability Data were qualified to military
specifications and were used in military applications. The added safety
and/or reliability requirements for components in these types of applications
may have contributed to the higher MTBF values.
Various manufacturers and equipment owners were contacted during
the study to solicit reliability/performance data on plant components.
These manufacturers indicated they did not calculate these statistics.
31
-------
TABLE 2. COMPARISON OF MTBF FOR COMPONENTS FROM THREE DATA SOURCES
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-------
SECTION 8
PERFORMANCE STATISTICS UTILIZATION
There are a variety of uses for the reliability, maintainability
and availability statistics presented in Section 6. For example, design
engineers c^n utilize these data as an additional tool to be used for the
selection of equipment, determination of the reliability and availability .
of unit operations as well as entire treatment systems, and the prediction
of operational performance of equipment in various applications. Plant
owners/operators can utilize preventative and corrective maintenance data
to help refine overall future maintenance budget and staffing projections.
Knowledge of equipment failure rates and subcomponent failures can provide
input into determining spare parts inventories. The following problems
and their solutions are presented to demonstrate how inservice performance
statistics can be used in these ways.
AVAILABILITY ESTIMATION
Problem: Determine the expected availability of an existing wastewater
pumping station.
Given: Peak demand 150,000 gpm
Existing pumps 3 at 55,000 gpm each
MTBF of each pump 7500 hours
MTTR of each pump 100 hours
Solution:
Derive the system event tree state-capacity matrix.
Determine the availability versus capacity for each set of states.
Availability (A) for each pump
A = MT6F+MTTR = 7500+100 = -9868421053
A system event tree is developed showing each operating state, pumping
capacity at each stato., and the percent of the peak demand flow that
£an jae handled at each state. Ai, A2 and A3 define each pump availability.
Aj, A£ and A3 indicate the pump is unavailable or out of service.
33
-------
System Event Tree
Operating
State Capacity % of Peak
55,000 gptn 36.67
^1^2^3 55,000 gpm 36.67
AiA2A3 55,030 gpm 36.67
AjA^ 110,000 gpm 73.33
^1^2^3 110,000 gpm 73-33
A1A2A3 110,000 gpm 73.33
^1^2^3 165,000 gpm 110.0
There are 4 capacity states. The percentage of the operating time
that.the system is in each state can be found using the binomial distribu-
tion^'' since:
A^ = A2 = A3 and A^ - A2 = A3 = 1 — A
Let R = A and Q = A, then
(R + Q)3 = 0 r3Q° + 1 ^ + 2 r1Q2 + 3 R°Q3
= R3 + 3R2Q + 3RQ2 + Q3
Replacing R by A and Q by A and evaluating the binominal expansion yiel
the state versus time proportion matrix shown below, for each term yields
the proportion of the time that the system will be in the respective state.
The state capacity is obtained by multiplying the number of available pumps
34
-------
by the pump capacity.
The state-time proportion matrix is shown below.
State Time Proportion
165,000 gpm .9610434283
110,000 gpm .0384417371
55,000 gpm .0005125565
0 .0000022781
Thus, in a one year period, on the average, the number of hours in each
state would be:
State Hours per Year
165,000 gpm 8418.740432
110,000 gp.ii 336.749617
55,000 gpm 4.48999494
0 .019956156
The number of hours in one year is 8760. Therefore, the estimated number
of hours per year that this pump station could not be expected to pump at
a combined rate of 165,000 gpm would be 8760 - 8419 or 341 hours (14.2 days).
Problem
Determine the state capacity matrix versus probability for the pumping
station described in the previous problem with an added pump of 55,000 gpm
capacity.
Solution:
The binomial equation for the
capacity-probability states is:
(J) A4 1° + (J) A3 A1 + (4) A2 J? + (4) A1 I3 + (J) A0 S4 = 1
35
-------
where
The first term capacity is 4(55,000) = 220,000 gpm
The second term capacity is 3(55,000) = 165,000 gpm
The third term capacity is 2(55,000) = 110,000 gpm
The fourth term capacity is 1(55,000) = 55,000 gpm
The fifth term capacity is 0(55,000) = 0
The matrix below is calculated using the individual pump availability
(A) of .9868421053.
State
220,000 gpm
165,000 gpm
110,000 gpm
55,000 gpm
0 gpm
Time Proportion
.9483981201
.0505812331
.0010116247
.0000089922
.0000000299
Hours per Year
8307.967532
443.0916017
8.861832034
.078771672
.000261924
Thus, the addition of a pump has reduced the time that station would
be expected to be below the peak demand capability from 341 hours to 8760
- (8308+443) or 9 hours.
There are existing analytical methods^) to determine the effect of adding
new equipment to any existing unit operation, i.e., primary and secondary
clarification, aeration, etc. These methods are also useful for determining
reliability and availability of the entire treatment plant system. By having
access to appropriate performance statistics, designers and operators can
develop reliabilities and availabilities for treatment plant designs comprising
various types of equipment and identity the design which appears to offer
the lowest life cycle cost. This approach to design and equipment component
evaluation has been practiced in the electrical and electronics industry since
the early 1950's. At the present time, approximately 50 percent of the nuclear
power plants in the U.S. participate in a reliability, maintainability and
availability data base program. Since Three Mile Island, the industry has
begun to evaluate this data base to determine how these data can help prevent
similar system failures.
36
-------
MAINTENANCE COST ESTIMATION
Problem:
Estimate the average maintenance costs for the raw wastewater pumps
(excluding motors) in the previous example.
Given: Number of pumps 3 at 55,000 gpm
Preventative Maintenance (PM)/
Unit/Year 10 manhours
Corrective Maintenance (CM)/
Unit/Year 20 manhours
Labor Costs (average) $15/hour
Solution: PM hours/yr = (3 units) 10 manhours/unit/yr
- 30 hours/yr
CM hours/yr = (3 units) 20 manhours/unit/yr
= 60 hours/yr
PM and CM Cost/yr = ($15/hr) 90 hrs/yr
= $1350/yr, or $450/pump/yr
These estimates could be made for all equipment at a planned or existing
treatment plant. The results form a base to which the design engineer or
owner may apply his own experience, to estimate maintenance costs and staff
levels.
SPARE PARTS ESTIMATION
Problem:
Determine the replacement rate for those subcomponents failing most
frequently, using the pumps included in the previous example.
Given: No. of pumps 3 at 55,000 gpm each
MTBF 81,635 hours
Solution:
The failure rate for each pump is
Failure rate = 1
MTBF
1
81,635 hours
37
-------
= 1.23x10"^ failures/hr/pump
For three pumps, the expected number of failures/yr are
No. of failure? = 3(1.23xi0"5) 8760
year
= 3.23x10"* failures/yr
The distribution of subcomponent failures from the tables in Appendix D,
Part 2.0 are
Impeller wear ring 19.7%
Seal, packing, oil lubricated 18.4%
Bearings, ball, double row 7.9%
The parts needed per year are
Impeller wear rings/yr = (.197)3.23x10"^
= 0.1
Seals, packing/yr = (.184)3.23x10"*
= 0.1
Bearings/yr = (.079)3.23xl0_1
= 0.03
Thus, an impeller wear ring and packing should require replacement
approximately every ten years. A pimp bearing should require replacement
only every thirty-three years, due to ranaom failure between scheduled
preventative maintenance activity.
These are point estimates of the parts needed per year. Confidence
intervals.can be placed around this point estimate using the Poisson distri-
bution.The Poisson distribution can also be used to determine the number
of spares required for a 90% confidence level of having a spare when needed.
38
-------
REFERENCES
1. Smith, J. M., F. L. Evans, and J. H. Bender. Improved Operation
and Maintenance Opportunities at Municipal Treatment Facilities.
Wastewater Research Division, MERL, EPA, Cincinnati, Ohio, 1980.
45 pp.
2. U.S. EPA, Clean Water Report to Congress, Washington, D.C., 1975-
1976.
3. Comptroller General of the United States. Continuing Need for Opera-
tion and Maintenance of Municipal Waste Treatment Plants. Report to
Congress, Washington, D.C., CED-77-46, April 1977.
4. Hegg, B. A., K. L. Rakness, J. R. Schultz. Evaluation of Operation
and Maintenance Factors Limiting Municipal Wastewater Treatment
Plant Performance. EPA 600/2-79-034, June 1979.
5. Gray, A. C., P. E. Paul, H. D. Roberts. Evaluation of Operation
and Maintenance Factors Limiting Biological Wastewater- Treatment
Plant Performance, EPA 600/2-79-078, July 1979.
6. Ball, R. 0. Manual for Identification and Correction of Typical
Design Deficiencies at Municipal Wastewater Treatment Facilities.
EPA Contract No. 68-03-2775, December 1979.
7. Bagovski, Igor. Reliability Theory and Practice, Prentice-Hall,
Inc., Englewood Cliffs, N.J., 1961.
8. Ostle, Bernard. Statistics in Research, The Iowa State University
Press, Ames, Iowa, 1960.
9. "Nonelectric Parts Reliability Data," Reliability Analysis Center,
Rome Air Development Center, Griffiss AFB, NY 13441, Summer 1978.
10. "Nuclear Plant Reliability Data System 1978 Annual Reports of Cumulative
System and Component Reliability," prepared by Southwest Research
Institute, San Antonio, Texas.
39
-------
APPENDIX A
DATA NUMBERING SYSTEM
COLUMN 1 (6 Digits)
First 2 digits plant ID Number
COLUMN 2 (2 Digits)
00
01
02
03
04
05
COLUMN 3 12 Digits)
00
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
COLUMN 4 (2 Digits)
00
01
02
03
04
05
06
07
08
09
PLANT AND RECORD NUMBER
Last 4 digits component record number
TYPE PLANT
No information
Air Activated Sludge
Oxygen Activated Sludge
Trickling Filter
Rotating Biological Contractor
Combination Air/Oxygen Activated Sludge
PLANT UNIT OPERATIONS
No information
Head Works
Primary Settling
Secondary Treatment (biological unit)
Final Settling
Disinfection
Sludge Processing outside the Waste Treatment Process
Anaerobic Digestion
Aerobic Digestion
Heat Treatment
Incineration
Sludge Thickening Gravity
Sludge Thickening DAF
Centrifuge, Solid Bowl
Centrifuge, Basket
Centrifuge, Nozzle
Vacuum Filter
Belt Press
BROAD CLASSIFICATION OF MECHANICAL COMPONENTS
No information
Pumps (without motor)
Power Transmission
Motors
Compressors
Diffusers air/water
Valves
Controls
Pressure Vessels
Conveyor (unconfined materials handling)
40
-------
APPENDIX A
DATA NUMBERING SYSTEM (Cont'd)
COLUMN 5 (4 Digits)
GENERIC GROUPS
Pumps
0000
No information
0100
No information
0101
Self-priming Centrifugal Pump
0102
Submersible Centrifugal
0103
Screw Pump
0104
Progessing Cavity
0105
Diaphragm
0106
Piston
0107
Gear
0108
Air Operated
0109
Open Impeller Centrifugal
0110
Closed Impeller Centrifugal
0111
Open Impeller Centrifugal Close Coupled
0112
Closed Impeller Centrifugal Close Coupled
0113
Pump with Integral Motor
0114
Propeller Pumps, Axial Flow
Power Transmission
0200
No information
0201
Concentric Reducer
0202
Parallel Shaft
0203
Right-angle Shaft
0204
Vertical Shaft
0205
Variable Speed Drive Belt Type
0206
Variable Speed Drive Hydraulic
0207
Variable Speed Drive Other
0208
Gear Box
0209
Chain Drive
0210
Cyclo Drive (Wemco Sells)
0211
Belt Drive
0212
Flexible Coupling
Motors
0300
No information
0301
Single Phase
0302
Multi Phase
0303
Air Drive
0304
Hydraulic Drive
0305
Variable Speed, A.C.
0306
Variable Speed, D.C.
0307
D.C. Exciter
0308
Gas Engine
41
-------
APPENDIX A
DATA NUMBERING SYSTEM (Cont'd)
Compressois
0400
0401
0402
0403
0404
0405
0406
Diffusers, air/water
0500
0501
0502
0503
0504
0505
0506
0507
0508
Valves
0600
0601
0602
0603
0604
0605
0606
0607
0608
0609
Controls
0700
0701
0702
0703
0704
0705
Pressure Vessels
0800
0801
0802
No information
Single Stage Centrifugal
Multi Stage Centrifugal
Rotary, Lobe
Rotary Vane
Rotary Water Seal Ring
Multi Stage High Pressure
No information
Spargers, Large Bubble, Mechanical
Small Bubble Ceramic
Small Bubble Plastic
Small Bubble Mechanical
Static Tube
Circular (for mechanical aerators)
RBC Shaft
Waste to media
No information
Gate
Ball
Butterfly
Globe
Needle
Relief (safety)
Check
Sluice Gate
Plug
No information
Electrical
Mechanical
Pressure (fluid)
Pressure (air)
Chlonnators
No information
Chemical Containers
Reactors
-------
APPENDIX A
DATA NUMBERING SYSTEM (Cont'd)
Conveyor tJJnconfinsd materials handling)
0900 No information
0901 Belt
0902 Screw
0903 Pneumatic
0904 Bucket
0905 Chain (Bar Screen)
0906 Skimmer
0907 Sludge Collector (includes cross collector)
COLUMN 6 (2 Digits) APPLICATIONS
Headworks
00
01
02
03
04
05
Primary and Secondary Seltling
06 Clarifier Circu'3r Center Drive
07 Clarifier Circular Peripheral Drive
08 Clarifier Square/Rectangular Center Drive
09 Clarifier Square/Rectangular Peripheral Drive
10 Scum and Grease Removal
Secondary Treatment (Biological)
11 Return Activated Sludge Handling
12 Recirculation Pumping
13 Oxygen Generation/Storage
14 Dissolved Air Production
15 Dissolved Air/O Application
16 Trickling Filter Rotary Distributor
17 Dosing Siphon
18 Trickling Filter Fixed Distributor
19 Rotating Biological Contactor
20 Mechanical Aerators
No information
Flow Measurement
Raw Wastewater Pumping
Intermediate Wastewater Pumping
Screening/Communition
Grit Removal
43
-------
APPENDIX A
DATA NUMBERING SYSTEM ICont'd)
Sludge Handling
30
31
32
33
34
Disinfection
50
51
52
Mechanical Mixers
61
62
63
64
65
66
COLUMN 7(2 Digits)
00
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Primary Sludge Pumping
Secondary Sludge Pumping
Waste Activated Sludge Pumping
Other Sludge Pumping
Digester Gas Recirculation Pumping
Chlorine, Gaseous
Chlor-ne, Hypo
Other, Oj, UV, Br2
High Speed Fixed
Low Speed Fixed
High Speed Floating"
Low Speed Floating
Submerged Turbine
Fixed Rotor
SIZE (CAPACITY)
No information
0-10,000 gallons per minute
10,001-20,000 gallons per minute
20,001-100,000 gallons per minute
Over 100,000 gallons per minute
0-1 horsepower
2-5 horsepower
6-16 horsepower
26-100 horsepower
101-500 horsepower
Over 500 horsepower
0-10 cfm
11-20 cfm
20-25 cfm
26-100 cfm
101-1000 cfm
1001-10,000 cfm
10,001-20.000 cfm
Over 20,000 cfm
0-6"
7-12"
13-24"
25-48"
Over 48"
Under 2000 lbs chemical
Over 2000 lbs chemical
44
-------
APPENDIX A
DATA NUMBERING SYSTEM (Uo..;'H)
COLUMN 8 (3 Digits) SUBCOMPONENT
000
No information
001
Pump Impeller
002
Impeller Wear Ring or Plate
003
Shaft Sleeve
004
Shaft, Drive
005
Shaft Key
006
Seal, Single Mechanical
007
Seal. Double Mechanical
008
Seal, Packed, No Lubricated
009
Seal. Packed, Water, Oil, Grease Lubricated
010
Seal, Other
011
Coupling
012
Drive Belt
013
Pulley, Belt Drive
014
Bearing Ball, Single Row
015
Experimental/Prototype Bearing
023
Bearing, Ball. Double Row
024
Bearing, Thrust
025
Bearing, Needle
026
Bearing, Cast, Pillow
027
Chain. Pintle
028
Gear for Chain Drive
029
Gear, Worm
030
Gear, Spur
031
Gear, Rack
032
Gear, Pinion
033
Gear, Internal
034
Gear, Miter
035
Gear, Bevel
036
Gear, Helical
037
Magnetic Starter
038
Relay
039
Overload Relay
040
Electrical Timer
041
Switch. Electric
042
Motor Armature
043
Motor Windings
044
Case, Motor
045
Case, Pump
046
Case, Gear
047
Case, Blower
048
Case, Electric or Control Device
049
Controller
050
Brushes
051
Cylinder, Piston Pump
45
-------
APPENDIX A
DATA NUMBERING SYSTEM (Cont'd)
COLUMN 8 (3 Digits)
052
053
054
055
056
057
058
059
060
061
062
063
064
065
COLUMN 9 (2 Digits!
00
01
02
03
04
COLUMN 10
COLUMN 11
COLUMN 12
00
99
01
02
03
04
05
COLUMN 13
(4 Digits)
(2 Digits)
(2 Digits)
SUBCOMPONENT (Con'td)
Collector Mechanism
Conveyor Belt
Skimmer
Solenoid Valve
Control Valve
Shear Pin
Rake Guides
Cables
Tie Rod
End Gjte
Complete Bearing
Replace Piston
Plastic Chain and Flights
Pipe Broken
CRlTICALITY
No information
Effluent impact within 4 hours
Effluent impact from 4 to 12 hours
Effluent impact from 12 to 24 hours
Effluent impact after more than 24 hours
DATE INSTALLED Month and Year (1072)
ACTUAL PERCENT OF TIME OPERATING
Record actual percentage
FAILURES
No information
No failures
One fialure
Two failures
Three failures
FAILURE MODE
No information
46
-------
APPENDIX A
DATA NUMBERING SYSTEM (Cont'd)
COLUMN 14 (2 Digits) CONTRIBUTORY CAUSE OF FAILURE
00 No information
01 Automatic Lubrication System Failure
02 Misalignment
03 Mechanical Seals
04 Packing Fdilure/lmproper Installation
05 Overload Protection Failure
06 Control System
07 Corrective Maintenance Inadequate or Incomplete
08 Normal Wear
09 Climatic Conditions
10 Unsuitable for Environment
11 Improper Application
12 Preventative Maintenance Inadequate
13 Bad Part
14 Improper Protection from Environment
15 Swapout of Parts trying to cure a problem
UMN 15(2 Digits) CALENDAR DOWN TIME OF FUNCTION
00 No information
01 1 hour or less
02 1 to 6 hours
03 6 to 24 hours
04 24 to 168 hours
05 Over 168 to 720 hours
06 Over 720 to 4320 hours
COLUMN 16 (2 Digits) MANHOURS TO REPAIR
CO No information
01 0 to 1 hour
02 Over 1 to 6 hours
03 Over 6 hours to 24 hours
04 Over 24 to 168 hours
Where more than one failure is shown, times to repair are averaged
COLUMN 17 (2 Digits) ENVIRONMENTAL FACTOR
00
1 Jo information
01
Outdoors, Ambient
02
Outdoors, Heaters
03
Basement, Humid
04
Basement, Dry
05
Subject to Corrosive Splash
06
Subject to Spiash
47
-------
APPENDIX A
DATA NUMBERING SYSTEM (Cont'd)
COLUMN 17(2 Digits)
07
08
09
10
11
12
COLUMN 18(2 Digits)
00
01
02
03
04
COLUMN 19(3 Digits)
000
001
002
003
004
005
006
007
008
009
010
011
012
013
014
015
016
017
018
019
020
021
022
023
024
025
ENVIRONMENTAL FACTOR (Cont'd)
Submerged in Water or Sewage
Corrosive Atmosphere
Submerged in Corrosive Fluid
Subject to Freezing
Subject to Excessive Heat
Indoor Controlled
PART DISPOSITION
No information
Repaired in Place
Replaced
Replaced and Discarded
Sent out (or Repair
SUBCOMPONENT MANUFACTURER
No information
New Departure
Hyatt
Fafnir
Norma Hoffman
Falk
Fast
Thomas
John Crane
U. S. Varidriva
Reeves Varidrive
GETeledyr,e
Dodge
Link Belt
Rex
Dorr Oliver
GE
Bristol
Roots
U.S. Electric
Marlow
Falk
Westinghouse
Electric Machinery
Climax
Ideal
48
-------
APPENDIX A
DATA NUMBERING SYSTEM (Cont'd)
COLUMN 20 (3 Digits)
000
001
002
003
004
005
006
007
008
009
010
011
012
013
014
015
016
017
018
019
020
021
022
023
024
025
026
027
028
029
030
031
032
033
034
035
036
COLUMN 21 (2 Digits)
00
01
02
03
04
COMPONENT MANUFACTURER
No information
Gorman Rupp
PACO
HydroMatic
Crown
Fairbanks Morse
Allis Chalmers
Worthington
GE
Roots
Door Oliver
Komlinc Sanderson
U.S. Electric
Marlow
Hoffman
Chicago Pump Co.
Marathon Elec.
Falk
Westinghouse
Envirex
Dodge
Reliance
WEMCO
FMC
Lightnin
Clark
DeLaval
Midland
Eimco Envirotech
Ralph B. Carter Co.
Louis Allis
Electric Machinery
Wallace and Tiernan Division
Autotrol
Climax
Ideal
Fischer and Porter
INVENTORY INFORMATION
No information
Stocked at Plant
Available Locally (1 to 6 hours)
Available within 24 hours
Over 24 hours
49
-------
APPENDIX A
DATA NUMBERING SYSTEM (Cont'd)
COLUMN 22 (2 Digits)
TYPE OF MAINTENANCE
00
01
02
COLUMN 23 (5 Digits)
COLUMN 24 (4 Digits)
COLUMN 25 (4 Digits)
No information
Preventative Maintenance
Corrective Maintenance
ACTUAL DOWN TIME OF UNIT OP (Sludge Processing Only)
Record actual time in hours
COLLECTION OR DECOMMISSIONING DATE
First 2 digits are month
Second 2 digits are year
ACTUAL ACTIVE CLOCK TIME TO REPAIR
Record the sum of the clock time (in hours) when someone worked on
unit.
50
-------
APDCNDIXB
RESULTS OF CRITICALITY ANALYSIS
Effects
TABLE 1. CRITICALITY ANALYSIS
Time Factors
A—Significant Impact
1-0-4 hrs
B—Minimal Impact
Type Plant —Air Activated Sludge 01
2—>4—12 hrs
C—Nc Impact
Unit Operation —
HeadworksOl
3—>12—24 hrs
4->24 hrs
Broad Classification
Relationship between
Time
of Equipment
Applications
Failure and Effluent Quality
Factor
Pumps 01
02
A
1
03
A
1
05
C
Power Transmission 02
02
A
1
03
A
1
05
C
04
C
Motors 03
02
A
1
03
A
1
05
C
04
C
Valves 06
01
C
02
B
4
03
B
4
05
C
Controls 07
01
C
02
B
1
03
B
1
04
C
05
C
Conveyors 09
05
C
51
-------
Effects
TABLE 2. CRITICALITY ANALYSIS
Time Factors
A —Significant Impact
1 —0—4 hrs
B —Minimal Impact
Type Plant—Trickling Filter 03
2 —>4— 12 hrs
C —No Impact
Unit Operation — Headworks 01
3 —>12 —24 hrs
4->24 hrs
Broad Classification
Relationship between
Time
of Equipment
Applications Failure and Effluent Quality
Factor
Pumps Ci
02
A
1
03
A
1
05
C
Motors 03
02
A
1
04
C
05
C
03
A
1
Power T ransmission 02
02
A
1
04
C
05
C
03
A
1
Conveyor 09
04
C
05
C
Controls 07
01
C
02
B
1
03
B
1
04
C
05
C
Valves 06
02
B
1
03
B
1
05
C
01
C
52
-------
Effects
TABLE 3. CRITICALITY ANALYSIS
Time Factors
A— Significant Impact
1 —0—4hrs
B—Minimal Impact
Type Plant —Rotating Biological Contractor 04
2—>4— 12 hrs
C— No Impact
Unit Operation-
HcadworksOl
3—>12 —24 hrs
4->24 hrs
Broad Classification
Relationship between
Time
of Equipment
Applications
Failure and Effluent Quality
Factor
Pumps 01
02
A
1
03
A
1
05
C
Power Transmission 02
02
A
1
03
A
1
04
C
05
C
Motors 03
02
A
1
03
A
1
04
C
05
C
Conveyor 09
04
C
05
C
Controls 07
01
C
02
B
1
03
B
1
04
C
05
C
Valves 06
02
B
4
03
B
4
05
C
01
C
53
-------
Effects
TABLE 4. CRITICALITY ANALYSIS
Time Factors
A—Significant Impact
1—0—4 hrs
B—Minimal Impact
Type Plant—Air Activated Sludge 01
2—>4— 12 hrs
C—No Impact
Unit Operation —
Primary Settling 02
3—>12—24 hrs
4—>24 hrs
Broad Classification
Relationship between
Time
of Equipment
Applications
Failure and Effluent Quality
Factor
Pumps 01
22
B
3
10
C
Motors 03
06
B
3
07
B
3
08
B
3
09
B
3
10
C
22
8
3
Power Transmission 02
06
B
3
07
B
3
08
B
3
09
B
3
10
C
22
B
3
Valves 06
10
C
22
B
4
Controls 07
06
B
3
07
B
3
08
B
3
09
B
3
10
C
22
B
3
54
-------
Effects
TABLE 5. CRITICALITY ANALYSIS
Time Factors
A—Significant Impact
1-0-4 hrs
B—Minimal Impact
Type Plant — OAS 02
2—>4—12 hrs
C—No Impact
Unit Operation-
Primary Settling 02
3 —>12—24 hrs
4 —>24 hrs
Broad Classification
Relationship between
Time
of Equipment
Applications
Failure and Effluent Quality
Factor
Power Transmission 02
06
B
3
07
B
3
08
B
3
09
B
3
10
C
22
B
3
Motors 03
06
B
3
07
B
3
08
B
3
09
B
3
10
C
22
B
3
Valves 06
10
C
22
B
4
Pumps 01
10
C
22
B
3
Controls 07
22
B
10
C
06
B
3
07
B
3
08
B
3
09
B
3
55
-------
Effects
TABLE 6. CRITICALITY ANALYSIS
Time Factors
A—Significant Impact
1 —0—4 hrs
B — Minimal Impact
Type Plant -
•Trickling Filter03
2— >4—12 hrs
C—No Impact
Unit Operation-
- Primary Settling 02
? —>12—24 hrs
.,->24 hrs
Broad Classification
Relationship between
Time
of Equipment
Applications
Failure and Effluent Quality
Factor
Motors 03
06
A
3
07
A
3
08
A
3
09
A
3
10
C
22
A
3
Pumps 01
10
C
22
A
3
Power Transmission 02
06
A
3
07
A
3
08
A
3
03
A
3
10
C
22
A
3
Valves 06
10
C
22
B
4
Controls 07
06
A
3
07
A
3
08
A
3
09
A
3
10
f.
22
A
3
56
-------
Effects
TABLE 7. CRITICALITY ANALYSIS
Time Factors
A —Significant Impact
1 —0—4 hrs
B— Minimal Impact
Type Plant— RBC 04
2 —>4—12 hrs
C —No Impact
Unit Operation-
Primary Settling 02
3—>12—24 hrs
4->24 hrs
Broad Classification
Relationship between
Time
of Equipment
Applications
Failure and Effluent Quality
Factor
Pumps 01
10
C
22
A
3
Motors 03
06
A
3
07
A
3
C8
A
3
09
A
3
10
C
22
A
3
Power Transmission 02
05
A
3
07
A
3
08
A
3
09
A
3
10
C
22
A
3
Valves 06
10
C
22
B
4
Controls 07
06
A
3
07
A
3
08
A
3
09
A
3
10
C
22
A
3
57
-------
Effects
TABLE8. CRIT'CALITY ANALYSIS
Tine Factors
A—Significant Impact
1 — 0—4 hrs
B—Minimal Impact
Type Plant
— Air Act Sludge 01
2—>4—12 hrs
C— No Impact
Unit Operation -
Secondary Treatment 03
3 —>12—24 hrs
4 —>24 hrs
Broad Classification
Rela;ionship between
Time
of Equipment
Applications
Failure and Effluent Quality
Factor
Pumps 01
11
A
1
Power Transmission 02
11
A
1
14 (blower)
A
2
20
A
2
Motors 03
11
A
1
14 (blower)
A
2
20
A
2
Compressors 04
14
A
2
20
A
2
Diffusers 05
15
A tSubm Turbine)
2
Valves 06
11
B
4
14
A
2
15
A
2
Controls 07
11
A
1
14
A
2
15
A
2
20
A
2
58
-------
Effects
TABLE 9. CRITICALITY ANALYSIS
Time Factors
A —Significant Impact
1 —0—4 hrs
B— Minimal Impact
Type Plant —OjAS 02
2 —>4—12 hrs
C— No Impact
Unit Operation —
Secondary Treatment 03
3 —>12 —24 hrs
4 —>24 hrs
Broad Classification
Relationship between
Time
of Equipment
Applications
Failure and Effluent Quality
Factor
Motors 03
13
A
2
15
A
2
12 Recir. O
A
2
20
A
2
11
A
1
Power Transmission 02
13
A
2
15
A
2
12
A
2
20
A
2
11
A
1
Pumps 01
11
A
1
12
A
2
Diffusers 05
15
A (Subm Turbine)
2
Pressure Vessels OS
13
B
4
Controls 07
11
A
1
12
B
4
13
A
2
15
A
2
20
A
2
Valves 06
11
B
4
13
A
2
15
A
2
59
-------
Effects TABLE 10. CRITICALITY ANALYSIS Time Factors
A —Significant Impact
1 —0—4 hrs
B —Minimal Impact
Type Plant
— Trickling Filter 03
2—>4—12 hrs
C— No Impact
Unit Operation-
Secondary Treatment 03
3—>12 —24 hrs
4->24 hrs
Broad Classification
Relationship between
Tim ¦
of Equipment
Applications
Failure and Effluent Quality
Factor
Pumps 01
12
A
1
Power Transmission 02
12
A
1
Motors 03
12
A
1
Valves 06
12
B
3
Controls 07
12
A
3
17
B
1
Diffusers 05
16 (Actual Arm)
A
2
17
A
2
18
A
2
60
-------
Effects
TABLE 11.CRITICALITY ANALYSIS
Time Factors
A— Significant Impact
1—0 — 4 hrs
B — Minimal Impact
Type Plant-
RBC04
2 —>4—12 hrs
C— No Impact
Unit Operation — Secondary Treatment 03
3—>12—24 hrs
4->24 hrs
Broad Classification
Relationship between
Time
of Equipment
Applications
Failure and Effluent Quality
Factor
Pumps 01
12
A
1
Power Transmission 02
12
A
1
19
A
2
14
A
2
Motors 03
12
A
1
19
A
2
14
A
2
Compressors 04
14
A
2
Diffusers05
19
C
Valves 06
12
B
3
14
B
4
Controls 07
12
B
4
19
A
2
14
B
4
61
-------
Effects
TABLE 12. CRITICALITY ANALYSIS Time Factors
A —Significant Impact
1-0—< hrs
B —Minimal Impact
Type Plant — Air #>ct Sludge 01 2—>4—12 hrs
C—No Impact
Unit Operation —
Final Settling 04 3—>12—24 hrs
4->24 hrs
Broad Classification
Relationship between Time
of Fquipment
Applications
Failure and Effluent Quality Factor
Power Transmission 02
06
A 1
07
A 1
08
A 1
09
A 1
Motors 03
06
A 1
07
A 1
08
A 1
09
A 1
Controls 07
06
B 1
07
B 1
08
B 1
09
B 1
62
-------
Effects
TABLE 13. CRITICALITY ANALYSIS Time Factors
A— Signil'.I Impact
1 — 0—4 hrs
B — Minima: Impact
Type Plant — O^AS 02
2— >4— 12 hrs
C — No Impact
Unit Operation— cinal Settling 04 3 —>12 —24 hrs
4—>24 hrs
Broad Classification
Relationship between Time
of Equipment
Applications Failure and Effluent Quality Factor
Motors 03
06
A 1
07
A 1
08
A 1
09
A 1
Power Transmission 02
06
A 1
07
A 1
08
A 1
09
A 1
Controls 07
06
B 1
07
B 1
08
B 1
09
B 1
63
-------
Effects
TABLE 14. CRITICALITY ANALYSIS
Time Factors
A —Significant Impact
1 —0—4 hrs
B — Minimal Impact
Type Plant-
Trickling Filter 03
2 —>4—12 hrs
C —No Impact
Unit Operation — Final Settling 04
3— >12 —24 hrs
4->24 hrs
Broad Classification
Relationship between
Time
of Equipment
Applications
Failure and Effluent Quality
Factor
Motors 03
06
A
1
07
A
1
08
A
1
09
A
1
Power Transmission 02
06
A
1
07
A
1
08
A
1
09
A
1
Controls 07
06
B
1
07
B
1
08
B
1
09
B
1
64
-------
Effects
TABLE 15. CRITICALITY ANALYSIS
Time Factors
A —Significant Impact
1—0—4 hrs
B — Minimal Impact
Type Plant
-RBC04
2 — >4—12 hrs
C—No Impact
Unit Operation-
Final Settling 04
3 —>12 —24 hrs
4—>24 hrs
Broad Classification
Relationship between
Time
of Equipment
Applications
Failure and Effluent Quality
Factor
Motors 03
06
A
1
07
A
1-
03
A
1
09
A
1
Power Transmission 02
06
A
07
A
1
08
A
1
09
A
1
Controls 07
06
B
1
07
B
1
08
B
1
09
B
1
65
-------
Effects TABLE 16. CRITICALITY ANALYSIS Time Factors
A—Significant Impact 1—0—4hrs
B —Minimal Impact Type Plant —Air Act Sludge 01 2— >4—12 hrs
C — No Impact Unit Operation —Disinfection 06 3—>12—24 hrs
4->24 hrs
Broad Classification Relationship between Time
of Equipment Applications Failure and Effluent Quality Factor
Pumps 01 12 B
50 B
51 B
52 B
Motors 03 12 B
50 B
51 B
52 B
Diffusers 05 50 C
51
52
Valves 06 50 B
51 B
52 B
12 B
Controls 07 50 B
51 B
52 B
12 B
Power Transmission 02 50 B 1
52 B 1
51 B 1
12 B 1
Pressure Vessels 08 50 B 1
52 B 1
66
-------
Effects
TABLE 17. CRITICALITY ANALYSIS Time Factors
A— Significant Impact
1—0—4 hrs
B —Minimal Impact
Type Plant
-OjAS 02 2—>4— 12 hrs
C—No Impact
Unit Operation —
Disinfection 06 3—>12 —24 hrs
4->24 hrs
Broad Classification
Relationship between Time
of Equipment
Applications
Failure and Effluent Quality Factor
Pumps 01
12
B 1
50
8 1
51
B 1
52
B 1
Motors 03
12
B 1
50
B 1
51
B 1
52
B 1
Diffusers 05
50
C
51
C
52
C
Valves 06
50
B 4
51
B 4
52
B 4
12
B 4
Controls 07
50
B 4
51
B 4
52
B 4
12
B 4
Power Transmission 02
50
B 1
51
B 1
52
B 1
12
B 1
Pressure Vessels 08
50
B 1
52
B 1
67
-------
Effects
TABLE 18. CRITICALlTY ANALYSIS
Time Factors
A—Significant Impact
1—0—4 hrs
B —Minimal Impact
Type Plant —
Trickling Filter 03
2—>4—12 hrs
C —No Impact
Unit Operation — Disinfection 06
3->12-24 hrs
4 —>24 hrs
Broad Classification
Relationship between
Time
of Equipment
Applications
Failure and Effluent Quality
Factor
Pumps 01
12
B
1
50
B
1
51
B
1
52
B
1
Motors 03
12
B
1
50
B
1
51
B
1
52
B
1
Diffusers 05
50
C
51
52
Valves 06
50
B
4
51
B
4
52
B
4
12
B
4
Controls 07
50
B
4
51
B
4
52
B
4
12
B
4
Power Transmission C2
50
B
1
52
B
1
51
B
1
12
B
1
Pressure Vessels 08
50
B
1
52
B
1
68
-------
Effects
TABLE 19. CRITICALITY ANALYSIS
Time Factors
A—Significant Impact
1—0—4 hrs
B— Minimal Impact
Type Plant
— RBC 04
2—>4—12 hrs
C—No Impact
Unit Operation-
Disinfection 06
3->12- 24 hrs
4->24 hrs
Broad Classification
Relationship between
Time
of Equipment
Applications
Failure and Effluent Quality
Factor
Pumps 01
12
B
1
50
B
1
51
B
1
52
B
1
Motors 03
12
B
1
50
B
1
51
B
1
52
B
Diffusers 05
50
C
51
52
Valves 06
50
B
4
51
B
4
52
B
4
12
B
4
Controls 07
50
8
4
51
B
4
52
B
4
12
B
4
Power T ransmission 02
50
B
1
51
B
1
52
B
1
12
B
1
Pressure Vessels 08
50
B
1
52
B
1
69
-------
Plant
Type
01
01
01
01
01
01
02
02
02
02
02
02
03
03
03
03
03
03
04
04
04
04
04
04
01
01
01
02
02
02
C3
03
03
04
04
04
01
01
01
01
01
01
01
0-i
02
02
APPENDIX C
MECHANICAL EQUIPMENT PRIORITY RANKING
TABLE 1. MECHANICAL EQUIPMENT PRIORITY RANKING
Unit Broad Classification Time and Effect
Operation of Equipment Application Relationship
01
01
02
A1
01
01
03
A1
01
02
02
A1
01
02
03
A1
01
03
02
A1
01
03
03
A1
01
01
02
A1
01
01
03
A1
01
03
02
A1
01
03
03
A1
01
02
02
A1
01
02
03
A1
01
01
02
A1
01
01
03
A1
01
03
02
A1
01
03
03
A1
01
02
02
A1
01
02
03
A1
01
01
02
A1
01
01
03
A1
01
02
02
A1
01
02
03
A1
01
03
02
A1
01
03
03
A1
03
01
11
A1
03
02
11
A1
03
03
11
A1
03
03
11
A1
03
02
11
A1
03
01
11
A1
03
01
12
A1
03
02
12
A1
03
03
12
A1
03
01
12
A1
03
02
12
A1
03
03
12
A1
04
02
06
A1
04
02
07
A.I
04
02
08
A1
01
02
09
A1
04
03
06
A1
04
03
07
A1
04
03
08
A1
04
03
09
A1
04
02
06
A1
04
02
07
A1
70
-------
Plant
Type
02
02
02
02
02
02
03
03
03
03
03
03
03
03
04
04
04
04
04
04
04
04
01
01
01
01
01
01
01
01
01
01
01
01
02
02
TABLE 1. MECHANICAL EQUIPMENT PRIORITY RANKING (Cont'd)
Unit Broad Classification Time and Effect
Operation of Equipment Application Relationship
04
02
08
A1
04
02
09
A1
04
03
06
A1
04
03
07
A1
04
03
08
A1
04
03
09
A1
04
02
06
A1
04
02
07
A1
04
02
08
A1
04
02
09
A1
04
03
06
A1
04
03
07
A1
04
03
08
A1
04
03
09
A1
04
02
06
A1
04
02
07
A1
04
02
08
A1
04
02
09
A1
04
03
06
A1
04
03
07
A1
04
03
08
A1
04
03
09
A1
03
02
14
A2
03
02
20
A2
03
03
14
A2
03
03
20
A2
C3
04
P.
A2
03
04
20
A2
03
05
15
A2
o:'.
06
1«:
A2
03
06
15
A2
03
07
14
A2
03
07
15
A2
03
07
20
A2
03
03
13
A2
!5
A2
12
A2
20
A2
03
02
13
A2
02
15
A2
02
12
A2
02
20
A2
o:
12
A2
05
15
A2
07
13
A2
07
15
A2
71
-------
"ABLE 1. MECHANICAL EQUIPMENT PRIORf'Y RANKING (Ccnt'd)
Plant
Ur:t
Broad Classification
Time and Effect
Type
Operation
of Equipment
Application
Relationship
02
03
07
20
,\2
06
13
A2
06
15
A2
03
03
05
16
A2
05
17
A2
05
18
A2
04
03
02
19
A2
02
14
A2
03
19
A2
03
14
A2
04
14
A2
07
19
A2
03
02
03
06
A3
03
07
A3
03
08
A3
03
09
A3
02
06
A3
02
07
A3
02
08
A3
02
09
A3
07
06
A3
0/
07
A3
07
08
A3
07
09
A3
03
06
A3
03
07
A3
03
08
A3
03
09
A3
02
06
A3
C2
07
A3
02
Od
A3
07
08
A3
07
09
A3
03
03
07
12
A3
01
01
07
02
B1
03
B1
02
01
07
03
B1
03
B1
03
01
07
02
81
03
B1
03
01
06
02
B1
03
B1
04
01
07
02
B1
03
B1
03
03
07
17
B1
01
04
07
06
B1
72
-------
TABLE 1. MECHANICAL EQUIPMENT PRIORITY RANKING (Cont'd)
Plant Unit Broad Classification Time and Effect
Type Operation of Equipment Application Relationship
01
04
07
B1
08
B1
09
B1
02
04
07
06
B1
07
81
08
B1
09
81
03
04
07
06
81
08
B1
09
B1
04
04
07
06
B1
07
B1
08
B1
09
B1
01-02
05
01
12
B1
03-04
50
B1
51
B1
52
B1
03
12
B1
50
B1
51
B1
52
B1
02
12
B1
50
B1
51
B1
52
BV
01-02
05
08
50
B1
03-04
52
B1
01-02
02
01
22
B3
01-02
02
03
06
B3
07
B3
08
B3
09
B3
22
B3
01-02
02
02
06
B3
07
B3
08
B3
09
B3
22
B3
01-02
02
07
06
B3
07
B3
08
B3
09
B3
22
B3
04
03
06
12
B3
-------
APPENDIX D
SUMMARY OF PERFORMANCE STATISTICS CALCULATED ON
CRITICAL COMPONENTS
1.0 Reliability, Maintainability and Availability Statistics for Components
1.1 By Component
1.1.1 Reliability (Table 1.1.1)
1.1.2 Maintainability and Availability (Table 1.1.2)
1.2 By Component by Generic Group
1.2.1 Reliability (Table 1.2.1)
1.2.2 Maintainability and Availability (Table 1.2.2)
1.3 By Component by Application
1.3.1 Reliability (Table 1.3.1)
1.3.2 Maintainability and Availability (Table 1.3.2)
1.4 By Component by Size/Capacity
1.4.1 Reliability (Table 1.4.1)
1.4.2 Maintainability and Availability (Table 1.4.2)
1.5 By Component by Generic Group by Application
1.5.1 Pumps (Tables 1.5.1.1 and 1.5.1.2)
1.5.2 Power Transmissions (Tables 1.5.2.1 through 1.5.2.9)
1.5.3 Motors (Tables 1.5.3.1 through 1.5.3.4)
1.5.4 Compressors (Tables 1.5.4.1 thrcuon 1.5.4.3)
1.5.5 Diffusers, Air/Water (Tables 1.5.5.1 and 1.5.5.2)
1.5.6 Valves (Tables 1.5.6.1 through 1.5.5.4)
1.5.7 Controls (Tables 1.5.7.1 through 1.5.7.5)
1.5.8 Conveyors (Tables 1.5.8.1 and 1.5.8.2)
1.6 By Component by Generic Group by Size/Capacity
1.6.1 Pumps (Tables 1.6.1.1 and 1.6.1.2)
1.6.2 Power Transmissions (Tables l.fi.2.1 through 1.6.2.9)
1.6.3 Motors (Tables 1.6.3.1 through 1.6.3.4)
1.6.4 Compressors (Tables 1.6.4.1 thrown 1.6.4.3)
1.6.5 Diffusers, Air/Water (Tables 1.6.5.1 and 1.6.5.2)
1.6.6 Valves (Tables 1.6.6.1 through 1.6.6.4)
1.6.7 Controls (Tables 1.6.7.1 through 1.6.7.5)
1.6.8 Conveyors (Tables 1.6.8.1 and 1.6.8.2)
2.0 Component Failure Statistics by Subcomponent Type
2.1 By Component (Tables 2.1.1 through 2.1.8)
2.2 ."y Component by Generic Group
2.2.1 Pumps (Tables 2.2.1.1 and 2.2.1.2)
2.2.2 Power Transmissinni (Tables 2.2.2.1 through 2.2.2.3)
74
-------
2.2.3 Motors (Tables 2.2.3.1 through 2.2.3.4)
2.2.4 Compressors (Tables 2.2.4.1 and 2.2.4.2)
2.2.5 Diffusers, Air/Water (Table 2.2.5.1)
2.2.6 Valves (Table 2.2.6.1)
2.2.7 Controls (Tables 2.2.7.1 through 2.2.7.4)
2.2.8 Conveyors (Table 2.2.8.1)
2.3 By Component by Application
2.3.1 Pumps (Tables 2.3.1.1 through 2.3.1.4)
2.3.2 Power Transmissions (Tables 2.3.2.1 through 2.3.2.3)
2.3.3 Motors (Tables 2.3.3.1 through 2.3.3.6)
2.3.4 Compressors (Tables 2.3.4.1 and 2.3.4.2)
2.5.5 Diffusers, Air/VJater (Table 2.3.5.1)
2.3.6 Valves (Tables 2.3.6.1 and 2.3.6.2)
2.3.7 Controls (Tables 2.3.7.1 through 2.3.7.8)
2.3.8 Conveyors (Table 2.3.8.1)
2.4 By Component by Size
2.4.1 Pumps (Tables 2.4.1.1 through 2.4.1.4)
2.4.2 Power Transmissions (Tables 2.4.2.1 through 2.4.2.5)
2.4.3 Motors (Tables 2.4.3.1 through 2.4.3.4)
2.4.4 Conpressors (Tables 2.4.4.1 through 2.4.4.3)
2.4.5 Diffusers, Air/Water (Table 2.4.5.1)
2.4.6 Valves (Tables 2.4.5.1 and 2.4.6.2)
2.4.7 Controls (Tables 2.4.7.1 through 2.4.7.5)
2.4.8 Conveyors (Table 2.4.8.1)
3.0 Reliability and Availability Statistics for Sludge Processes
3.1 3y Sludge Process (Table 3.1.1)
75
-------
APPENDIX D
PART 1.0
RELIABILITY MAINTAINABILITY AND AVAILABILITY
STATISTICS FOR COMPONENTS
TABLE 1.1.1. MEAN TIME BETWEEN FAILURE (MTBF) FOR COMPONENTS
Overall Min Max Overall
MTBF MTBF MTBF S0% CL
Component (x 10* Hrs) (x 106 Hrs) 106 Hrs) (x 10s Hrs)
Pumps
.032066
.021662
.074191
.028630
Power transmissions
.03562
.01785
.71091
.03317
Motors
.06670
.01088
.11432
.06122
Compressors
.00714
.00562
.08392
.00631
Diffusers, air/water
.01813
.01263
1.834
.01C67
Valves
.01444
.00893
.03259
.01040
Controls
.08358
.00393
.10064
.07569
Conveyor (unccnfined
materials handling)
.14848
.06175
.35856
.11690
TABLE 1.1.2. MAINTENANCE STATISTICS FOR COMPONENTS
PM-Hrs/
CM-Hrs/
MTTR
Components
Unit/Yr
Unit/Yr
(Hrs)
AVI
AVO
Pumps
.00227
.05177
9.541
.99968
.99116
Power transmissions
.00032
.00469
2.273
.99994
.99898
Motors
.00098
.00660
6.854
.99939
.99816
Compressors
.033S9
.17843
0.960
.99987
.99306
Diffusers, air/water
.00065
.04664
8.305
.99951
.99875
Valves
.0Cj84
.73845
11.615
.99879
.96446
Controls
.00025
.00261
3.696
.99996
.99370
Conveyer (uncon fined
materials handling)
.00055
.10086
4.768
.99996
.99980
76.
-------
TABLE 1.2.1. WEAN TIME BETWEEN FAILURES (MTBF) FOR COMPONENTS BY GENERIC GROUP
Overall
Min
Max
Overall
MTBF
MTBF
MTBF
S0% CL
Component
Generic Group
(x 10® Hrs)
(x 10® Hrs)
(x 10® Hrs)
(x 10s Hrs)
Pumps
Open impeller, centrifugal
.02166
.01530
.03569
.019105
Propeller, axial flow
.074191
.02415
.7528
.05762
Power transmission
Concentric reducer
.12264
.02814
.3764
.05190
Parallel shaft
.71091
.01996
1.867
.35381
Right angle shaft
,01<*48
.00993
2.512
.01772
Vertical shaft
.03147
.01925
.06091
.02611
Variable speed drive, hydraulic
.3495
.1020
Variable speed drive, others
.01842
.00784
.02689
.01075
Gear box
.04578
.00982
.6313
.03932
Chain drive
.01785
.01091
Belt drive
.09101
.05564
Motors
Multiphase
.0680
.02102
4."339
.0620
Variable speed, AC
.11482
.01081
.4033
.05795
Gas engine
.02380
.01023
Compressors
Single stage, centrifugal
.02242
.01934
.02173
.01359
Multi stage, centrifugal
.00562
.00544
.02689
.00495
Multi stage, high pressure
.08392
.02933
.05459
.02449
Diffusers, air/water
RBC Shaft
1.834
.5352
Waste to media
.01263
.01160
Valves
Gate
.00893
.00702
.01353
.00627
Ball
.01146
.00493
Butterfly
.03253
.01408
Plug
.02852
.00832
Controls
Electrical
.10064
.01859
4.6849
.03994
Mechanical
.03123
.01705
.03334
.01282
Pressure (fluid)
.03578
.03140
.06485
.02676
Pressure—air
.01869
.01272
Chlorinators
.00393
.00262
Conveyor (unconfined
materials handling)
Chain (bar screen)
.06175
.04688
Sludge collector
.35856
.2202
1.570
.23345
77
-------
TABLE 1.2.2. MAINTENANCE STATISTICS FOR COMPONENTS BY GENERIC GROUP
PM-Hrs /
CM-Hrs/
MTTR
Component
Generic group
Unit/Yr
Unit/Yr
(Hrsl
AVI
AVO
Pumps
Open impeller centrifugal
.00343
.09477
7.82S
.99962
.98955
Propeller, ajtial flow
.00627
.11411
16.780
.99975
.<*9311
Power transmission
Concentric reducer
.01187
.00S90
2.000
.59998
.99998
Parallel shaft
.00224
.01203
32.000
.99995
.99990
Right ang'e shaft
.00103
.01244
1.400
.99395
.99989
Vertical shaft
.00122
.03331
2.023
.99994
.99688
Variable speed drive, hydraulic
.01865
0.0
1.0
1.0
Variable speed drive, others
.39460
.61080
2.500
.99976
.99952
Gear box
.00045
.05956
3.523
.99993
.99952
Chain drive
0.0
1.3840
8.000
.9996
.9345
Belt drive
0.0
.03488
1.800
1.0
.9916
Motors
Multiphase
.00068
.00633
6.853
.99989
.99837
Variable speed, AC
.01258
.05034
8.000
.99996
.99936
DC exciter
1.62196
1.59310
3.667
.9967
.99035
Gas engine
10.57
10.57
24.000
.9990
.9342
Compressors
Single stage, centrifugal
.16854
.31990
3.800
.99981
.99541
Multistage, centrifugal
.06513
.44723
0.813
.99987
.99179
Multi stage, high pressure
.07767
0.0
1.0
1.0
Drffusers, air/water
RBC Shaft
.00356
0.0
1.0
1.0
Waste to media
.00008
.1591
8.305
.9993
.9982
Valves
Gate
0.0
1.40743
3.636
.99947
.95633
Ball
0.0
43.89
110.000
.90S
.8685
Butterfly
.05999
.12005
1.000
.99997
.99933
Plug
.2286
0.0
1.0
1.0
Controls
Electrical
.00028
.00211
2.893
.99998
.99922
Mechanical
.04385
.96717
8.000
.99956
.99339
Pressure ((laid)
.00405
.12830
8.236
.93975
.98322
Pressure—air
.00970
.1309
3.556
.9998
.9998
Chlorinalors
0.0
17.82
5.375
.9986
.9982
Conveyor lunconfined
materials handling)
Chain (bar screen)
0.0
.1371
0.947
1.0
.9999
Sludge collector
.00098
.16507
15.14
.99994
.399751
78
-------
TABLE 1.3.1. MEAN TIME BETWEEN FAILURES (MTBF) FOR COMPONENTS BY APPLICATION
Overall
Mm
Max
Overalt
MTBF
MTBF
MTBF
90% CL
Component
Application
(x 10»Hre>
(* 10® Hre)
(* 10* Hrs)
(* 10® Hrsl
Pumps
Raw Wastewater Pumping
.01530
.01303
Intermediate Wastewater Pumping
.08588
.01727
.09255
.06318
Return Activated Sludge Hand'ing
.05336
.7528
.03569
.04235
Recirculation Pumping
.Ol.415
.01759
Power Transmission
Raw Wastewater Pumping
.CI 884
.00784
.05919
.01303
Intermediate Wastewater Pumping
.18881
.02689
.1678
.05679
Clanfief. Circular Center Onve
.01605
.00993
.09101
.01329
Clanfier, Square/Rectangular Peripheral
.C8C14
.00982
2.512
.06760
Return Activated Sludge Handling
.7037
.3495
.3764
.2118
Oxygen Generation/Storage
.09289
.02740
Dissolved Air Production
.1763
.08847
Rotating Biological Contactors
1.867
.5449
Mechanical Aerators
.06136
.04735
.06091
.04365
Motors
Raw Wastewater Pumping
.02192
.01163
.02380
.01754
Intermediate Wr-tewater Pumping
.06523
.006764
.3331
.04380
Screening/Con«numtion
1.8100
.5283
Clarifier, Circular Center Onve
.1236
.09442
Clarrfier, SQuare/Rectangular Peripheral
4.4935
.5650
2.512
1.756
Return Activated Sludge Handling
.02642
.„1081
.4033
.02214
Recirculate Pumping
.0531
.03362
Oxygen Generation/Storage
.08392
.02449
Dissolved Air Production
.02319
.01858
.022*2
.01792
Dissolved Air/O; Application
.01353
.006789
Rotating Biological Contactor
.02215
.01876
Mec ha rxal Aerators
.6711
.1959
Secondary Sludge Pumping
.1513
• .0216
.3226
.0650
Compressors
Dissolved Air Production
.00575
.00544
02173
.005069
Dissolved Air/07 Production
.02321
.01934
.02689
.01172
Oxygen Generation/Storage
.08392
.02449
Dttfusers, Air/Water
Rotating Biological Contactor
1.834
.5352
TnckJing Filter Rotary Distnbutor
.01263
.01160
Vatves
Raw Wastewater Pumping
.00997
.00702
.02852
.00694
Intermediate Wastewater Pumping
.01353
.00679
Oxygen Generation/Storage
.05459
.01523
Dissolved Air/Oj Production
.01081
.00465
Controls
Raw Wastewater Pumping
.03898
.03334
.03742
.02834
Intermediate Wastewater Pumping
.14729
.01705
.1907
.09589
Screening/Communition
1.810
.5288
Ctanfter, Circular Center Onve
.1144
.01081
.1191
.0879S
Clarrfier, Square/ Rectangular Peripheral
4.609
.5270
2.512
1.345
Return Activated Sludge handling
.01859
.00043
.01895
.0157B
Recirculation Pumping
.04618
.03008
Oxygen Generation/Storage
.08392
.02449
Dissolved Air Production
.04871
.03315
Rotatinq Biological Contactor
1.867
.5449
Mechan»cj| Aerators
.05620
.01031
.00116
.0374d
Secondary Sludge Pumping
.09866
.06485
.09497
.05404
Chlorine, Gaseous
.02193
.01869
.03140
.01772
Conveyor (Unconfirmed
Materials Handling)
Screening/Communition
.06175
.04688
Clarrfier, Square/Rectangular Peripheral
.35856
.2202
1.570
.23345
79
-------
TABLE 1.3.2. MAINTENANCE STATISTICS FOR COMPONENTS BY APPLICATION
Component
Application
PM-Hrs/
Unu/Yr
CM-Hrs/
Unit/Yr
MTTR
Hrs
AVI
AVO
Pumps
Raw Wastewater Pumping
00944
.3178
8.483
.9994
.9845
Intermediate Wastewater Pumping
.03301
.47335
13 334
99977
99087
Return Activated Sludge HdnCtmg
.00232
03377
6.786
.99337
99387
neorculation Pumping
.003S3
.5945
14.710
.9994
.9719
Power Transmission
Raw Wastewater Pumping
.01092
.00138
2.800
.93385
99977
Intermediate Wastewater Pumping
.17227
0.0
1.0
99389
Clarifrer, Circular Center Drive
.00072
.01971
1.775
.99991
.99759
Clanfier, Square/Rectangular Peripheral
.00058
.03355
2.787
.99998
.99556
Return Activated Sludge Handling
.00898
0.0
1.0
1.0
Oxygen Generation/Storage
,06342
0.0
1.0
1 0
Dissolved Air Production
.00620
.5953
32.000
.9938
.9996
Rotating Biological Contactors
.00349
0.0
1.0
1 0
Mechanical Aerators
.00228
.04797
4.833
.9939
.9999
Motors
Raw Wastewater Pumping
.07434
.30876
8 871
.99957
.99061
Intermediate Wastewater Pumping
.00302
.03782
4.400
.99999
59930
Screening/Communition
00360
0.0
1.0
1.0
Clanfier, Circular Center Drive
.00957
.01893
2.600
1.0
.9983
Ctarif.er, Square/Rectangular Penpheral
.00140
0.0
1.0
.9999
Return Activated Sludge Handling
.00202
07879
5.368
.99977
99943
Recirculation Pumping
.00795
.2385
12 500
.9998
9842
Oxygen Generation/Storage
.07767
0.0
1.0
1.0
Dissolved Air Production
.0485
5214
8 455
.9996
9912
Dissolved Air/O, Production
.06061
.2424
1.000
.9999
.9999
Rotating Biological Contactor
00
.1047
7.857
.9996
9933
Mechanical Aerator
.00971
0.0
1.0
1.0
Secondary Sludge Pumping
.01608
.00742
2.000
1.0
1.0
Com pressors
Dissolved Air Production
.07405
.38760
0.887
.99385
.93108
Dissolved Air/0? Production
.02020
.29631
2.750
.99992
.99967
Oxygen Generation/Storage
.07767
0.0
1.0
1.0
DiHusers. Air/Water
Rotating Biological Contactor
.00356
0.0
1.0
1.0
Trickling Filter Rotary Distributor
.00008
.1591
8 305
.9993
.9382
Valves
Raw Wastewater Pumping
.00539
2.15610
13.400
.93800
93513
Intermediate Wastewater Pumping
0.0
3 63G5
4.500
.9993
.99695
Oxygen Generation/Storage
.1134
0.0
1.0
1.0
Dissolved Air/Oj Production
0.0
1.455
1.000
.9999
9998
Controls
Raw Wastewater Pumping
00453
.14466
4 543
.99986
.99953
Intermediate Wastewater Pumping
00907
.08034
6.571
.99996
99744
Screening/Communition
.00360
0.0
1.0
1.0
Clanfier, Circular Center Drive
.00130
.00580
2.000
.99999
99999
Clanfier, Square/Rectangular Peripheral
.00147
0.0
1.0
.999*19
Return Activated Sludge Handling
.00074
.05812
2.607
99989
999b 1
Recirculation Pumping
00795
.07351
5.571
.9999
.9845
Oxygen Generation/Storage
07767
0.0
1.0
1.0
Dissolved Air Production
.00155
.1457
1.333
1.0
.9999
Rotating Biolog>cal Contractor
.00349
0.0
1.0
1.0
Mechanical Aerators
.00069
.03977
1.750
.99338
.99938
Secondary Sludge Pumping
.01152
.01037
2.667
1.0
.99871
Chlorine, Gaseous
.00125
.21428
6.425
.99367
98380
Conveyor (Unconfrned
Materials Handling)
Screening/Communitioi.
0.0
.1371
0.947
1.0
.3099
Clanfier. Square/Rectangular Peripheral
.00038
.165U7
15.14
.99394
.99975
80
-------
TABLE 1.4.1. MEAN TIME BETWEEN FAILURES (MTBF) FOR COMPONENTS BY SIZE
Overall
Min
Max
Overall
MTBF
MTBF
MTBF
90% CL
Component
Application
(* 10>Hrs)
(* 10» Hrs)
|x10»Hrs>
1* 10® Hrs)
Pumpa
1-1.0C0 Gallons Per Minute
.03S8
.03569
.1678
.03146
10.001 -20.000
.031130
.01378
.5377
.02442
20,001-100.000
.081635
.02602
.1833
.061515
Over 100,000
.008366
.005068
.2151
.007010
Power Transmission
0-1 Horsepower
.02537
.00993
2.5120
.02341
1-5
.01101
.00982
.01785
.00912
6-25
1.3764
.6316
1.867
.59387
26-100
.05862
.03476
06091
.04176
101-500
.07838
.00784
.3764
.05420
Over 500
.20645
.02689
.1763
.10373
Motor?
0-1 Horsepower
.2147
.1236
2.512
.1349
1-5
.5648
.1648
6-25
.0621
.0222
1.010
.0527
26-100
.0460
.0210
1.334
.0347
101-500
.06463
.02380
.4033
.04903
Over 500
.02058
.01088
.0231
.01685
Compressors
101-1,000 Cubic Feet Per Minute
.05459
.01593
1.001-10.000
.02744
.01954
.02933
.01602
10,1-20.000
.01487
.00817
Over 2*,.TOO
.00535
.02173
.00530
.00471
Diffusers, Air/Water
6-25 Hors .-power
1.834
.5352
10,001 -2T ,000 Gallons Per Minute
.01487
.01160
Vat
0-6 Inches
.05459
.01593
13-24
.01081
.00465
25-46
.01907
.00812
.02852
.01044
Over 48
.00750
.00627
.01081
.00510
Over 48 Inches
.06175
.04638
Controls
0-1 Horsepower
2.0092
.1191
2.512
.15686
1-5
.50950
.15362
6-25
4.6849
1.570
1.887
1.41258
26-100
.026103
.01895
.06116
.02252
101 -500
.09939
.01061
.6144
.07587
Over 500
.03770
.00434
.08392
.02796
Over 2000 lbs. Chemical
.02193
.03408
.5232
.01772
Conveyor (Unconfirmed
Materials Handling)
0-1 Horsepower
.2202
.1434
6-25 Horsepower
1.570
.4583
81
-------
TABLE 1.4.2. MAINTENANCE STATISTICS FOR COMPONENTS BY SIZE
PM-Hrs/
CM-Hrs/
MTTR
Component
Application
Unit/Yr
Unit/Yr
Hrs
AVI
AVO
Pumps
1-1,000 Gallons Per Minute
.00199
.07576
6.786
.99922
99981
10,001-20.000
.00349
.17403
7.800
.99974
.99831
20.001-100.000
.00133
17748
26.722
.99964
S3925
Over 100.000
.07379
.83854
9.368
.99931
.96080
Power Transmission
0-? Horsepower
.00042
.01266
1.815
.9S994
.99847
2-5
.00288
.29455
2.116
.99384
.99789
6-25
.00187
.00597
25.000
1.0000
.99982
26-100
.00180
.05849
5.000
.99995
.99969
101-500
.00490
.00700
2.600
.99996
.99995
Over 500
.02579
.25385
32.000
.99381
.99959
Motors
0-1 Horsepower
.00522
.01009
2.600
1.0000
.99890
2-5
.01152
0.0
1.0000
1.0000
6-25
.00016
.03261
7.857
.99985
.99575
26-100
.00108
.03098
4 9685
.99987
.99962
101-500
.01221
.06992
12.685
.99980
.99239
Over 500
.04174
.20070
7.658
.99959
.98971
Compressors
101-1,000 Cubic Feet Per Minute
.1194
0.0
1.0000
1.0000
1,001-10.000
.02136
.18805
2.750
.99993
.99972
10.001-20,000
.03211
1.4450
6.000
.99960
.99930
Over 20.000
.12567
.58143
0.723
9b^88
.99020
Diffusers, Air/Water
6-25 Horsepower
.00356
0.0
1.000G
1.0000
10,001-20,000 Gallons Per Minute
.00008
.15910
8.305
.9993
.998?
Vah/es
0-6 Inches
.1194
00
1.0
1.0
1?24
0.0
1.455
1 000
.9999
.9993
25-48
.01565
3 9437
42.000
.99702
.56357
Over 48
0.0
2.15075
2.667
.99960
.93850
Controls
0-1 Horsepower
.00083
.00296
2.050
1.0
.99992
2-5
.01325
"0
1.0
1.0
6-25
.00124
0.0
1.0
1.0
26-100
.00034
.02615
2.377
.99993
.99988
101-500
.00258
.01876
5.450
.99995
.99692
Over 500 Horsepower
.00310
.11783
3.125
.99990
.99551
Over 2000 lbs. Chemical
.00125
.21428
6.425
.99967
.93980
Conveyof (Unconfined
Materials Handling)
Over 48 Inches
0.0
.1371
0.947
1.0
.9999
0-1 Horsepower
.00097
.4359
15.14
.9999
.9936
6-25 Horsepower
.00415
0.0
1.0
1.0
82
-------
TABLE 1.5.1.1. RELIABILITY AND MAINTENANCE DATA FOR PUMPS-OPEN
IMPELLER CENTRIFUGAL BY APPLICATION
Application
No of
Units
No of
Failures
Opo/atmg
Mrs
I* 10* Hrs)
Overall
MTBF
1» 10® Hrsl
M.n
MT0F
{* 10s Hrs)
Mox
MTBF
t* lO'Hrs)
Overall
90% CL
(* 104 Hrs)
PM Hrs/
Unit/
Yoar
CM Hrs/
Unit/
Yoor
MTTR
(Hrs)
AVI
AVO
Raw Wastewater Pumping
34
60
9277
.01530
-
-
.C1303
.009442
.3179
8 483
.994
.9845
Intermediate Wastewater
Pumping
9
9
.1669
01727
-
-
.01175
.1079
.7871
6.667
.9996
.9543
Return Activated Sludge
Handling
27
28
1.023
.03569
-
-
.02335
.001745
.1028
6.786
.9938
9998
TOTAL
70
97
2 1176
.02166
.01530
.03569
.01911
.003428
.094773
7 825
.90962
9S355
TABLE 1.5.1.2. RELIABILITY AND MAINTENANCE DATA FOR PUMPS-PROPELLER,
AXIAL FLOW BY APPLICATION
Application
No of
Units
No of
Failures
Operating
Hrs
1* 10* Hrs)
Overall
MTBF
|x 106 Hrs)
Min.
MTBF
I* 10»Hrsl
Max
MTBF
1* 10® Hrs)
Overall
90% CL
1* WHrs)
PM-Hrs/
Unit/
Yoar
CM-Hrs/
Unit/
Year
MTTR
(Hrs)
AVI
AVO
Intermediate Wastewater
Pumping
7
9
.8947
.09255
_
_
.06238
06364
1.035
20.00
.9998
.9976
Return Activated Sludge
Handling
28
0
.5059
.7528
-
-
.2197
.008656
0 0
-
1.0
1.0
Recirculation Pumping
14
14
.3541
02415
-
-
.01759
.003534
.5955
14.71
.9934
9719
total
49
23
1.7547
.074)9
02415
.7528
.05763
.006265
.1140107
16.783
99975
.99311
-------
TABLE 1.5.2.1. RELIABILITY AND MAINTENANCE DATA FOR POWER TRANSMISSION - CONCENTRIC
RFDUCER BY APPLICATION
Application
No r'
¦
No of
Failures
Operating
Hrs
l« I0« Hi*)
Overall
MTOF
(« W Hrsl
Min.
WIHF
1* 10» Hrsl
Max
MTOF
(« 10" Hrsl
Overall
90% CL
(* 1C Hrs)
PM-Hrs/
Unit/
Year
•-.M Hrs/
Unit/
Yoar
MTTR
(Hrs)
AVI
AVO
Clanfier Circular Center
Drive
4
• 2
.07516
.02814
-
_
01412
.02314
.1748
2.0
.9399
.9999
Reutrn Activated Sludge
Handling
14
0
.2529
.3764
-
-
.1099
01732
00
1.0
« 0
TOTAL
18
2
.32806
.12264
.02814
.3764
.061638
.01187
00890
2.0
.99998
99998
TABLE 1.5.2.2. RELIABILITY AND MAINTENANCE DATA FOR POWER TRANSMISSION-PARALLEL
SHAFT BY APPLICATION
Application
No. of
Units
No. of
Failures
Operating
Hrs
(« 10« Hrsl
Overall
MTBF
(k 10»Hrsl
Min.
MTBF
<* 10» Hrsl
Max.
MTBF
(x 10« Hrsl
Overall
90% CL
I* 10s Hrs)
PM-Hrs/
Unit/
Yuar
CM-Hrs/
Unit/
Year
MTTR
IHra)
AVI
AVO
Intermediate Wastewater
Pumping
6
0
.1127
.1678
_
_
.04836
.03885
0.0
1.0
1.0
Oxygen Generation/
Storage
S
0
.06309
•093G9
-
-
.02740
.06942
0.0
-
1.0
1.0
Dissolved f 'r Production
6
2
.4709
.1763
-
-
.08847
.005201
.6953
320
.9998
.9996
Rotating Biological
Contactor
56
0
1.255
1.867
-
-
.5449
.003*91
00
-
1 0
1 0
TOTAL
73
2
1.90169
.71091
,09389
1.867
35081
002241
.012075
32 0
.99995
.99990
-------
TABLE 1.5.2.3. RELIABILITY AND MAINTENANCE DATA FOR POWER TRANSMISSION-
RIGHT ANGLE SHAFT BY APPLICATION
Application
No of
Units
No. of
Failures
Operating
Hrs
1* 10»Hrs)
Overall
MTBF
(x 10« Hrs)
Min
MTBF
(« 10* Hrs)
Max
MTBF
(« 10* Hrs)
Overall
SO% CI
(* 10® Hrs)
Prd-Hrs/
Unit/
Year
CM-Hrs/
Unit/
Year
MTTR
(Hrs)
AVI
AVO
Raw Wastewater Pumping
2
0
.03978
.05319
—
-
.01720
.1101
0.0
-
1.0
1.0
Clanfier Circular Confer
Drive
41
180
1.793
.009929
—
-
.009035
.001907
.03039
1.4
.9099
9938
Clarifior Square/
Rectangular Peripheral
8
0
1 .ess
2.512
-
-
.7332
.002594
00
-
1.0
1.0
TOTAL
51
180
3.52078
.019479
.009929
2.512
.017747
.301025
.01244
1.4
.99S95
•999R9
TABLE 1.5.2.4. RELIABILITY AND MAINTENANCE DATA FOR POWER TRANSMISSION -
VERTICAL SHAFT BY APPLICATION
Operating
Overall
Min.
Max,
Overall
PM-Hrt/
CM-Hrt/
No. of
No ot
Hrs
MTBF
MTBF
MT0F
90% CL
Unit/
Unit/
MTTR
Application
Units
Failures
(* 10* Hrs)
(* lO* Hrs)
(* :0^ Hrs)
1* 10« Hrs)
(x 10« Hrs)
Year
Yoai
(Hrs)
AVI
AVO
Clanfier Circular Center
Drive
9
32
.6287
.01925
-
-
01551
.002322
.1455
.9683
1.0
.9931
Mochanical Aerators
42
12
.7762
.06128
.04735
.06091
.04365
.002284
.04797
4.833
.9999
.9999
TOTAL
51
44
1.4049
.031465
.01925
.06128
.026113
.001223
03331
2 023
99994
99666
TABLE 1.5.2.5. RELIABILITY AND MAINTENANCE DATA FOR POWER TRANSMISSION -
VARIABLE SPEED DRIVE, HYDRAULIC BY APPLICATION
Operating
Overall
Min.
Max.
Overall
PM-Hrs/
CM Hrs/
No. of
No. of
Hrs
MTBF
MTBF
MT0F
90% CL
Unit/
Unit/
MTTR
Application
Units
Fsifuros
(* 10" Hrs)
»* 10* Hrs)
1" 10® Hrs)
(k 106 Hrs)
1* 10® Hrs)
Yoar
Yoor
IHrs)
AVI
AVO
Roturn Activated Sludge
Handling 13
0 2349 3495
.1020 01655 00
1.0 1 0
-------
TABLE 1.5.2.6. RELIABILITY AND MAINTENANCE DATA FOR POWER TRANSMISSION -
VARIABLE SPEED DRIVE-OTHER BY APPLICATION
Operating Ovorall Mm Ma*. Overall PMHri/ CM-Hrs/
No. of No. of Hrs MT6F MTBF MTBF 90% Ct Unit/ Unit/ MTTR
Application Units Failures (* I0» H.s) I* 1C Hrsl (* 10» Hrsl I* 10» Hrsl (* 10» Hrsl Year Year (Hrs) AVI AVO
Raw Wastewater Pumping 3 B .05796 .007641 - _ .005230 .02148 1.031 2 5 .9097 9936
IntDimedisie Wastewator
Pumping 1 0 01807 . 02683 - - 007847 - 7.273 0 0 1.0 . 9992
TOTAL 4 8 .0CGO3 .018422 .007841 .02609 010754 3946 . 6100 2 5 . 93976 . 99952
TABLE 1.5.2.7. RELIABILITY AND MAINTENANCE DATA FOR POWER
TRANSMISSION-GEAR BOX BY APPLICATION
Application
No. of
Units
No. of
Failuros
Operating
Hra.
(x 10« Hrsl
Overall
MTBF
<* 10* Hrsl'
Mm.
MT0F
(X 10* Hrsl
Max.
MTQF
(» 10* Hr«)
Overall
90% CI
(* 10* Hrsl
PMH^/
Unit/
Year
CM-Hr»/
Unit/
Year
MTTR
(Hrsl
AVI
AVO
Raw Wastewater Pumping
1
2
.09236
.03476
-
-
.01745
.6600
4.0
.9999
.9993
0.0
Clarifier Circular Center
Drive
8
21
8439
.03924
_
—
.03016
.2512
6.19
.9998
.9997
.000921
Clvifier Square/
Ractanguiar Peripheral
23
42
2.067b
.04648
000816
.6313
.04008
.0833
2.1666
.999332
.99944
.0004S47
TOTAL
32
65
3.1026
.0457BJ
.03476
.04848
.039323
.059550
3 523
.99993
.99952
-
-------
TABLE 1.5.2.8. RELIABILITY AND MAINTENANCE DATA FOR POWER TRANSMISSION -
CHAIN DRIVE BY APPLICATION
Application
No. ol
Units
No. ol
Failures
Operating
Hrs
(* 10* Hrs)
Overall
MTBF
I* 10® Hrs)
Min.
MTBF
(* 10* Hrs)
Max.
MTBF
(x 104 Hrs)
Overall
90% Cl
I* 10* Hrs)
PM-H s/
Uni./
Yf ar
CM-Hrs/
Unit/
Year
MTTR
(Hrs)
AVI
AVO
Clarlfier Square/
Rectangular Peripheral
4
5
.1012
.01785
-
-
.01091
0.0
1.364
8.0
.9998
.9945
TABLE 1.5.2.9. RELIABILITY AND MAINTENANCE DATA FOR POWER TRANSMISSION-
BFLT DRIVE BY APPLICATION
CO
•vi
Application
No. ol
Units
No. ol
Failures
Operating
Hrs
t» 10* Hrs)
Overall
MTBF
(* 10s Hrs)
Min.
MTBF
l« 10«Hrs)
Max
MTBF
1* 10* Hrn
Overall
30% CL
1* 10»Hrs)
PM-Hrs /
Unit/
Yeer
CM-Hrs/
Unit/
Year
MTTR
iHrsI
AVI
AVO
Clarifter Circular Center
Drive
3
5
.5160
.09101
.05564
00
.08408
1.8
1.0
9916
-------
TABLE 1.5.3.1. RELIABILITY AND MAINTENANCE DATA FOR MOTORS
Mean Time Between Failures (MTBF) By Application
Broad Classification — Motors
Generic Group—Multiphase
Application
No. of
Units
No. of
Failures
Opercung
Hrs
(» 10* Hrs)
Overall
MTBF
1* 10® Hrs)
Min.
MTBF
1" 10» Hrsl
Max.
MTSF
(x 10® Hrs)
Overall
90% CI
(» 106 Hrsl
Raw Wastewater Pumping
25
26
.5997
.02249
.00983
.02795
.01772
intemvxjiate Wastewater
Pumping
14
2
1.050
.3331
.0422
1.334
.1973
Screening/ Commuruson
3
0
1.216
1.810
-
-
.5283
Clsnfter, Circular Center
Drive
62
20
2.553
.1236
-
—
.09442
~arifier. Square/
Rectangular Peripheral
23
0
3.1224
4.4935
.5650
2.512
1.356
Return Activated Sludce
Handling
27
48
1.0227
.02102
-
-
.01759
Recirculation Pumpmg
14
6
.3541
.0531
-
-
.03362
Oxygen Generation/
Storage
5
0
.00563
.03392
-
—
.02449
Dissotvec' Air Production
11
22
.5255
.02319
.01858
.02282
.017S2
Dissolved Air/Oj
Application
2
2
.0361
.01353
—
—
.006789
Rotating Biological
Contactor
56
56
1.255
.02215
—
—
.01876
Mechanical Aerators
24
0
.4510
.6711
-
-
.1959
Secondary Sludge
Pumping
14
1
.2529
.1513
.0218
.3226
.0650
TOTAL
28S
183
12.4947
.0680
.02102
4.4935
.0620
88
-------
TABLE 1.5.3.2. RELIABILITY AND MAINTENANCE DATA FOR MOTORS
Maintenance Statistics By Application
Broad Classification —Motors
Generic Group — Multi Phase
Applicant
No. of
Units
Operating
Hra
(X 10« Hrsl
No. of
Failures
PM-Hrs/
Unit/
Year
CM-Hra/
Unit/
Year
MTTR
(Hrsl
AVI
AVO
Raw WartuwalOT Pumping
2S
.59965
29
.01139
.3653
8.885
.9996
.9936
Intermediate Wastewater
Pumping
14
1.04999
2
.003575
.01788
6.000
1.0000
.9999
Screening/Commiinition
3
1.216
0
.003601
-
-
1.0000
1.0000
Clarrfier Circular Center
Drive
62
2.553
20
.009573
.01893
2.600
1.000
.9933
Clarifier Square/
Rectangular Ponpherol
2a
3.1224
0
.001403
-
-
1.0000
.9959
Return Activated Sludge
Handling
27
1.022679
48
.001745
.1562
5.313
.9997
.9933
Recirculation Pumying
14
.3541
6
.007951
.2335
12.50
.9998
.9842
Oxygen Generation/
Svorage
5
.05639
0
.07767
—
-
1.000
1.000
Dissolved Air Production
Dissolved Air/Gj
Production
11
2
.52S46
.03813
22
2
.04850
.06061
.5214
.2424
3.455
1.000
.9999
.9912
.9999
Rotating Biological
Contactor
56
1.2S5
56
0.0
.1047
7.857
QOAfi
,9>Kn)
.9993
Mechanical Aerators
24
.4510
0
.009713
-
-
1.000
1.000
Secondary Sludge
Pumping
14
.25293
1
.01608
.007421
2.000
1.000
1.000
TOTAL
335
12.494729
183
.000682
6.85266
.998
.0069
-------
TABLE 1.5.3.3. RELIABILITY AND MAINTENANCE DATA FOR MOTORS-
VARIABLE SPEF.D, AC BY APPLICATION
Operating Ovorsll Mm. Max. Overoll PM-Hra/ CM-Hra/
No of No. of Hit MTBF MTBF MTBF 90% CL 'Jmt/ Unit/ MTTR
Application Unit* Failures (*10* Mrs) (x'O^Hrs) (xlO^Hn) (" 101 Hrs) 1*10" Hra) Yev Year IHra) AVI AVO
Intermeddle Waatewator
Pumpina 1 ! .01907 .0181 - - .00465 0.0 7.273 8.00 .9303* .9392
Return Activated Sludge
Handling 16 1 .28307 .1729 .01081 .4033 .07432 .01420 .02841 8.0C 1.00 .9999
TOTAL 17 2 .30714 .11482 .01081 .1729 .05795 .01267 8.00 999 .0503 9993
TABLE 1.5.3.4. RELIABILITY AND MAINTENANCE DATA FOR MOTORS -
DC EXCITER BY APPLICATION
Operating Overall Win. Ma*. Overall PM-Hrs/ CM-Hrs/
No. of No. ol Hn> MTBF MTBF MTBF 90% CL Unit/ Unit/ MTTR
Application Uniu Failuros I* 10" Hra) (» 10« Hr») (*10«Hri| (x 10" Hral (k 10" ;
-------
TABLE 1.5.4.1. RELIABILITY AND MAINTENANCE DATA FOR COMPRESSORS-
SINGLE STAGE CENTRIFUGAL BY APPLICATION
Application
No. of
Units
No. of
Failures
Operating
Hrs
l» 106 Hrsl
Overall
MTBF
1* 10* Hrsl
Min.
MTBF
1« 10® Hrsl
Max.
MTBF
t» 10® Hrsl
Overall
90% CL
(* 10® Hrsl
PM Hr»/
Unit/
Year
CMHrs/
Unit/
Year
MTTR
(Hrsl
AVI
AVO
Dmolved Air Production
3
1
.03532
.02173
-
-
•U00337
1.487
1.206
8.00
.9909
.9850
Diisoived Air/02
Application
5
4
09034
.01934
-
-
.01130
.01939
4267
2.75
.9999
9996
TOTAL
8
5
.12606
.02242
.01934
.021/3
.01359
.16854
.3199
3 80
.9399
.9955
TABLE 1.5.4.2. RELIABILITY AND MAINTENANCE DATA FOR COMPRESSORS-
MULTI STAGE CENTRIFUGAL DY APPLICATION
Application
No. of
Unit!
No. of
Failures
Operating
Hrs
(x 10® Hrs)
Overall
MTBF
(» 10® Hrs)
Mm
MTBF
(* 10® Hrsl
Max.
MTBF
(» 10® Hrsl
Overall
90% CL
(« 10® Hrs)
PM-Hrs/
Unit/
Year
CMHrs/
Unit/
Yoar
MTTR
(Hrsl
AVI
AVO
Dissolved Air Production
11
96
.52547
.005438
.005030
.01487
004785
.0727
.5040689
.8125375
.99987
.99150
Oiuotved Air/Oj
Production
1
0
.01807
.02609
-
-
.007847
.2424
0.0
_
1.0
1.0
TOTAL
12
96
.54354
.005618
.00V38
02689
.004952
.0651
.4723294
.8125375
.99987
.99179
TABLE 1.5.4.3. RELIABILITY AND MAINTENANCE DATA FOR COMPRESSORS-
MULTI STAGE- HIGH PRESSURE BY APPLICATION
Aoplication
No of
Units
No of
Failures
Operating
Hrs
(x 10* Hrt)
Overall
MTBF
(« 10® Hrs)
Min.
MTBF
l« 10® Hrsl
Max.
MTBF
(« 10® Hrt)
Overall
90% CL
(« 10® His)
PM-Hrs/
Unit/
Year
CMHrs/
Unit/
Year
MTTR
(Hul
AVI
AVO
Oxygen Gonerption/
Storage
5
0
.05639
.083S2
.02933
00459
.02449
.0776659
00
-
1.0
1 0
-------
TABLE 1.5.5.1. RELIABILITY AND MAINTAINABILITY DATA ON DIFFUSERS,
AIR/WATER-RBC SHAFT BY APPLICATION
Application
No. Of
Units
No. of
Failures
Operating
Hrs
(* 10« Hrs)
Overall
MTBF
(* 10® Hrs)
Min.
MTBF
10" Hrs)
Max
MTBF
(* 10« Hrs)
Overall
90% CL
(* 10* Hr»)
PMHrs/
Unit/
Yoar
CMHr»/
Unit/
Yoar
MTTR
(Hrs)
AVI
AVO
Rotating Biological
Corrector
55
0
1 232
t 834
-
-
.5352
.003555
-
-
1.0
1.0
TAELE 1.5.5.2. RELIABILITY AND MAINTAIN ABILITY DATA ON DIFFUSERS,
AIR/WATER-WASTE TO MEDIA BY APPLICATION
Application
No. of
Units
No. of
Failures
Opoiaiing
Hrs
(* 10* Hrsl
Overall
MTOF
(* 106 Hrsl
Min.
MTBF
10* Hrs)
Mai.
MTBF
(*10® Hrsl
Overaii
90% CL
(# 10* Hrs)
PMHri/
Unit/
Year
CM-Hrs/
Unit/
Year
MTTR
(Hrs)
AVI
AVO
Trickling Filter —
Rotary Distributor
40
223
1.2824
.01263
-
-
.01263
.000078
.1591
8 305
.9393
.9982
TABLE 1,5.6.1. RELIABILITY AND MAINTAINABILITY DATA ON VALVES
--GATE BY APPLICATION
Application
No. of
Units
No of
Failufijs
Operating
Hrs
<* 10* Hrsl
Overall
MTBF
1* 10« Hrsl
Mm.
MTBF
(* 10» Hrs)
Max.
MTBF
(x 10* Hrs)
Overall
90% CL
(* 10» Hrs)
PM-Hrj/
Unit/
Year
CM Hrs/
Unit/
Year
MTTR
(Hrs)
AVI
AVO
Raw Wastewater Pumping
5
9
06 78J
007023
.006266
.008123
004779
00
2 245
2 667
9906
9356
Intermediate Wastewater
Pumping
2
2
03613
01353
.01081
.01081
.006769
0 0
3 636
80
.9994
.9969
TOTAL
7
11
.10402
008029
.007023
.01353
.006266
00
1.4074
3.6363
.99947
.95693
-------
TABLE 1.5.6.2. RELIABILITY AND MAINTAINABILITY DATA ON VALVES- BALL BY APPLICATION
Application
No of
Units
No. of
Failures
Operating
Hrs
10* Hrs)
Overall
MTBF
<* I06 Hrs)
Mm.
MTBF
(* 10° His)
Max.
MTBF
(« 10* Hrs)
Overall
90% CL
(x 10s Hrs)
PM-Hrs/
Unit I
Year
CM Hrs/
Unit/
Year
MTTR
(Hrs)
AVI
AVO
Paw Wastewater Pumping
1
1
.01916
01146
-
-
004927
00
43 89
1100
9905
.8085
TABLE 1.5.6.3. RELIABILITY AND MAINTAINABILITY DATA ON
VALVES-BUTTERFLY BY APPLICATION
Application
No. of
Units
No. o*
Failures
Operating
Hrs
t* 10* Hrs)
Ovora'l
MTBF
i- 10« Hts>
Mm.
MTBF
t* 10« His)
Max.
MTBF
(x 10s H»s)
Overall
$0% CL
I* \Q* Hrs)
PM-Hrs/
Unit/
Year
CM Hrs/
Unit/
Yea*
MTTR
(Hrs)
AVI
AVO
OxvQftn Generation/
Storage
3
0
.03668
.05459
_
..
.01533
.1194
_
1.0
1.0
D-ssolved Air/Oj
Production
1
1
.01007
.01081
-
-
004045
00
1 455
1 0
9999
.9998
TOTAL
4
1
05475
-
-
-
-
.05339
.12005
f 0
.999967
.999934
TABLE 1.5.6.4. RELIABILITY AMD MAINTAINABILITY PATA ON VALVES
-GATE BY APPLICATION
Application
No. of
Units
No. of
Failures
Operating
Mis
|x 106 Hrs)
Overall
MTBF
(x 10* Hrs)
Mm.
MTBF
(« 106 Hrs)
Mox
MTBF
(* 10® Hrs)
Overall
90% CL
(X 10» Hrs)
PM Mrs/
Unit/
Year
CM Hrs/
Unit/
Year
MTTR
(Hrs)
AVI
AVO
Raw Wastewater Pumping
1
0
01916
02G52
-
-
008322
2286
-
-
1 0
1. *
-------
TABLE 1.5.7.1. RELIABILITY AND MAINTENANCE DATA FOR CONTROLS
Mean Time Between Failures (MTBF) By Application
Broad Classification— Controls
Generic Group— Electical
Application
No. of
Units
No. o(
Failures
Oporating
Hrs.
(* 10* Hrs)
Overall
MTBF
(* 10® Hrs)
Mm.
MTBF
|x 10» Hrs)
Max.
MTBF
(x 10« Hrs)
Overall
90% CL
|X 10* Hrs)
Raw Wartffwater Pumping
21
14
.5487
.03742
.03268
.03888
.02726
Intermediate Wastewater
Pumping
15
5
1.0812
.1907
.01161
.6144
.1166
Screenmg/Communition
3
0
1.216
1.810
-
-
.5283
Clarilier Circular Center
Drive
S3
21
2.47307
.1144
.01081
.1191
.08796
Clanfier Square/
Rectangular Peripheral
27
0
3.0*71
4.609
.5270
2.512
1.345
Return Activated Sludge
Handling
28
56
1.0547
.018585
.000432
.01895
•0157&:
Recirculation Pumping
14
7
.3541
.04618
-
-
.03008
Oxygen Generation/
Storage
5
0
.05639
.08392
-
-
.02449
Dissolved Air Production
6
9
.4709
.04871
-
-
.03315
Rotating Biological
Contactor
56
0
1.255
1.807
—
_
.5449
Mechanical Aerator*
26
3
.4871
.05620
.01081
.06116
.03748
Secondary Sludgo
Pumping
15
2
.2537
.09497
-
—
.04766
TOTAL
?^9
122
12.35396
.100643
.018585
4.609
.039939
94
-------
TABLE 1.5.7.2. RELIABILITY AND MAINTENANCE DATA FOR CONTROLS
Maintenance Statistics By Application
Broad Classification —Controls
Generic Group — Electrical
Application
No. of
Uniti
Operating
Hr*
(x 10« Hnl
No. ot
Failures
PM-Hra/
Unit/
Year
CM-Hrs/
Unit/
Year
MTTR
(Hrs)
AVI
AVO
Row Wastewater Pumping
21
.5487
14
.004562
.157737
4.643
.383854
.999509
Intermediate Wastewater
Pumping
15
1.0812
5
.010005
.084259
6.0
.999975
.997439
Screening/Communition
=
1.216
0
.003601
00
-
1 0
1.0
Clarifier Circular
Center Onve
53
2.47907
21
.001300
005302
2.00
999999
.999999
Clarifier Square/
Rectangular Peripheral
27
3.0971
0
.001466
0.0
-
1.0
.999891
Return Acrvsted Sludge
Handling
28
1.05472
56
.000/41
.058123
2.00705
.999888
.999809
Recirculation Pumping
14
.3541
7
.007951
.07951
5.571
.9999
.9845
Oxygen Generation/
Storage
5
.05639
0
.07767
00
-
1.0
1 0
Disaolveti Air Production
6
.4709
9
.00155
1457
1.333
1 0
.9999
Rotating Biological
Co Hoc Tor
56
1.255
0
.003491
0.0
-
1 0
1.0
Mechanical Aerator?
26
.46707
8
.000692
.039774
1.749963
.923974
.S99985
Secondary Sludge
Pumping
15
.2537
2
.01496
.01381
2.5
1 0
.9982
TOTAL
269
12.35395
122
.000231
002114
2 B93366
.989979
.999225
95
-------
TABLE 1.5.7.3. RELIABILITY AND MAINTENANCE DATA FOR CONTROLS -
MECHANICAL BY APPLICATION
Application
No ol
Unit*
No. of
Failures
Opening
Hn
(* 10* Hn)
Overall
MTBF
<* 10* H.s)
M.n.
MTBF
(« 10* Hn)
Mai
MTBF
I* 10* Hn)
OvenB
90% CL
(« 10* Hn)
PMHn/
Unit/
Y«r
CM-Hn/
Urvt/
Yoif
MTTR
IHn)
AVI
AVO
R*w Wastewaisr Pumping
t
0
.02240
.03334
-
-
.00973
.1955
00
-
1 0
1.0
Inform Wa»)ewrato«
Pumping
3
2
.04553
01705
-
-
00CS&4
.06413
1.324
80
.S395
.S976
TOTAL
4
2
.0G793
.03123
01705
.033*4
.012S17
.04835
.907103
60
.92)7
.33833
TABLE 1.5.7.4. RELIABILITY AND MAINTENANCE DATA FOR CONTROLS-
PRESSURE (FLUID) BY APPLICATION
Application
No of
Urvu
No of
Failurtt
Operating
Hn
I* 10*Hr»l
Overall
MTBF
l» 10* Hn)
Mm.
MT0F
(» 101 Hn)
Mai.
MTBF
I-IO* Hrt)
Ov#r«B
DO% CL
1* 10® Hn)
PM Hn/
Unit/
Y«r
CM Hn/
Urnt/
Yoar
MTTR
IHn)
AVI
AVO
Secondary SHxjg#
Pumptng
6
1
.1064
.06435
_
—
.02707
.04714
.0404
30
1.0
.9999
CNormt. G«mou«
6
18
.52J2
.03140
-
-
.02331
00
3014
8663
9097
.9C:-3
total
12
17
.6316
.03570
.03140
.06405
.02576
00406
.128303
8.Z3S76
.03375
.983219
TABLE 1.5.7.5. RELIABILITY AND MAINTENANCE DATA FOR CONTHOLS-
PRESSURE-A1R BY APPLICATION
Appl.catton
No of
Units
No of
Failures
Operating
Hn
(* 10* Hrt)
OvoifB
MTBF
I* 10* Hn)
Win
MTBF
(« IO Hn)
Mm.
MTBF
l» 10* Hn)
Ov&ioti
DO* CL
(x 10* Hrsl
PM Hn/
Unrt/
You
CM Hn/
Unit/
Yoar
MTTR
(Hn)
AVI
AVO
Oosecua
10
9
.1007
.01063
-
-
.01272
.occo:7
1339
3
3CC8
3009
-------
TABLE 1.5.7.6. RELIABILITY AND MAINTENANCE DATA FOR CONTROLS-
CHLORINATORS BY APPLICATION
Appbcttion
Nc of
Unit*
No o*
Fatluies
Operating
Hrt
<» lO^Hrs)
Qvmatt
MT0F
(* 10* Hf»)
Mm
MTBF
(* 10* Hri)
Ms*
WT6F
1" 10»Hr*)
Owotl
90% CL
(- 10* Hr»)
PM-Hf*/
Unil/
Year
CM Hr»/
Unit/
Year
MTTR
(Hr*»
AVI
AVO
Chlorine. Gj&coi'S
3
8
.oMoa
.003932
-
-
.CO2£23
00
17 E2
b.375
SS36
.££32
TABLE 1.5.8.1. RELIABILITY AND MAINTENANCE DATA FOR CONVEYORS-
CHAIN (EAR SCREENI BY APPLICATION
Appli&ttttn
No. of
Units
No. of
Farfurea
Operating
Hr»
(« 10® Hr*)
OvoijK
MTBF
I* 103 Hr»)
Mm.
MTBF
<¦ 10«Hr»>
Mai.
MTBF
(« 10* Hral
Owrall
90% CL
(¦ 10* Hril
PM-Hrt/
U ritf
Yfiv
CM Hri/
Unrt/
Year
MTTR
(Hral
AVI
AVO
Sc r Domn 3 / C ont m u r> 11 ion
3
19
1.214
06175
-
-
.0*03
00
1371
W74
1 0
0003
TABLE 1.5.8.2. RELIABILITY AND MAINTENANCE DATA FOR CONVEYORS-
SLUDGE COLLECTOR BY APPLICATION
Appk'.atton
No ol
Un.ti
No. ol
Failure*
Operating
Hn
<« 10« Hul
OvtiaU
MTBF
I" 1C Hrt)
M.n
MTBF
(- 10* Hrt)
Ms*.
MTBF
<¦ 10* Hri)
Ovot ii!l
93Tb CL
10* Hr»)
PMHra/
Unjt/
Y
-------
TABLE 1.6.1.1. RELIABILITY AND MAINTENANCE DATA ON PUMPS- OPEN
IMPELLER CENTRIFUGAL BY SIZE
Sir*
(Gtfiana Par Minuta)
No. of
Units
No. of
Failure*
Opwaurtg
Hr«
<" iPHrs)
Overall
MTBF
(« 10* Hr»»
Mm
MTBF
M«i.
MTBF
(« 10* Hril
Overall
00% CL
<« 10»Hri)
PM-Hrt/
Urui/
Ywi
CM Hrt/
Urvt/
Ywr
MTTR
U3
CO
TABLE 1.6.1.2. RELIABILITY AND MAINTENANCE DATA ON PUMPS-
PROPELLER. AXIAL FLOW BY SIZE
. — ¦
Sat
(Gtflona Per Minul*)
No. of
Units
No of
Future*
QparftUng
Hr».
(» 10"Hr*»
Overall
MTBF
(«10* Mn)
Mm.
MT8F
(» 10- Hrt!
Max.
MTBF
[* l0>Hra)
OvOfftU
S0%CI
I* ICf Hfi(
PM-Hr»/
Unit/
Ymt
CM Kr»/
L'rw/
VMT
MTTR
IHra)
AVI
AVO
10.001 20.000
22
3
.41 IBS
.1173
.01378
.6377
.061470
.01212
_
__
1.0
SS337
20.WM0Q.000
17
16
.074256
.0JG02
.1633
0WS58
.001108
-22/JT/
17.467
BSC 75
£0035
Ovw 100.000
10
6
.1E0C3
03197
.006374
2161
01&o28
.237616
1.334614
4.0
.8GC23
00218
total
49
23
1.7S4C2
074197
.0CG3.4
.63^7
0C7d23
.0CC266
.114107
16 783
.80S 76
.03311
-------
TABLE 1.8.2.1. RELIABILITY AND MAINTENANCE DATA ON POWER TRANSMISSIONS -
CONCENTRIC REDUCER BY SIZE
su«
(Gallon! Par Minute]
No. of
Units
No. of
Failure*
Operating
Hr».
(' 10s Hill
Overall
MTBF
l« 10s Hoi
Min.
MTBF
l« 10° Hrel
Man.
MTBF
l« 10* Hra)
Overall
80% CL
l« 10* Hra)
PM-Hra/
Unit/
Year
CM-Hra/
Unit/
Year
MTTR
(Hral
AVI
AVO
O-t
4
2
.07518
.02814
-
-
.01412
.02314
.1748
2.0
.9339
.3933
101-600
14
0
.2629
.3704
-
-
.04298
.01732
00
1.0
1.0
TOTAL
18
2
.32006
.12704
.02314
.3784
.001CS8
.01187
.atso
2.0
coooa
.85008
TABLE 1.6.2.2. RELIABILITY AND MAINTENANCE DATA ON POWER TRANSMISSIONS-
PARALLEL SHAFT BY SIZE
Sli*
IGltOfil P* Mlnuiel
No. of
Unite
No. of
ftllu'M
Operating
Hri.
(< 10* lira)
OwiH
MTBF
I' 10* Hrel
Mm.
MTBF
1' 10* Mill
Mai.
MTBF
1* IbMlnl
Ovorall
90% CL
<« lOllill
PM-Hra/
Unit/
Year
CM-Hra/
Unit/
Y««f
MTTfl
(Hl»l
AVI
AVO
6-2S
M
0
1.2 M
1.067
-
-
.M49
.003491
00
-
1.0
1.0
101-600
e
0
.1127
.1678
-
-
.0*396
•03S38
0.9
-
1.0
1.0
Ovtf GOO
ii
2
.63339
.01S3S
.09334
.1763
.11076
00471
.2843
3i.O
.9938
.9936
TOTAL
73
2
1 901G9
.7109
.01953
1.607
3683
.002241
.012076
320
.90336
.92030
TABLE 1.6.2.3. RELIABILITY AND MAINTENANCE DATA CN POWER TRANSMISSIONS -
RIGHT ANGLE SHAFT BY SIZE
Sit*
(Golloria Per Minute)
No. of
Unlti
No. of
Foiluree
Operating
Hra.
(« 10»Hral
Overall
MTBF
(« 10« Hra)
Mln.
MTBF
1" 10*Hril
Max.
MTBF
(« 1C.« Hra)
Overall
90% CI
l« 10* Hral
iff
CM Hra/
Unit/
Yaar
MTTH
(Hra)
AVI
AVO
0-1
49
100
3.481
.03357
.00-3929
2.612
.03305
.001027
.01310
1.4
.83936
.WJO
101 600
2
0
.03378
.06919
-
-
.CI 728
.1101
00
-
1.0
1.0
TOTAL
61
too
3.62078
010479
.03667
.01*319
.017747
.001025
.01244
1 4
90336
.99309
-------
TABLE 1.6.2.4. RELIABILITY AND MAINTENANCE DATA ON POWER TRANSMISSIONS-
VERTICAL SHAFT BY SIZE
Slzo
(Gallon® Por Minute)
No. of
Units
No. of
Failures
Operating
Hrs.
10>Hfs>
Overall
MT0F
(« 10»Hrs)
Mm.
MT0F
(x10*Hr»)
Max.
MTUF
(« 10*Hrs)
Ovorall
CL
<*10*Hrs)
PM-Hrs/
Unit/
Year
CM-Hra/
Unit/
Year
MTTR
(Hrm)
AVI
AVO
0-1
9
32
.6287
01325
-
-
.01561
.002322
.1466
.0633
1.00
.9031
26 100
33
10
6-W7
.06001
-
-
.04217
002119
.00016
6.2
.OK*
.9J09
101 600
7
2
.1206
.04736
-
-
.02376
.023G8
.OM37
3.0
.0009
.9033
total
61
44
1.4043
.03146
.01926
.00001
.02311
.001223
.03331
2 023
.99394
.93£a6
TABuE 1.6.2.5. RELIABILITY AND MAINTENANCE DATA ON POWER TRANSMISSIONS-
VARIABLE SPEED DRIVE, HYDRAULIC BY SIZE
H-•
o
o
Opersting
GveraU
Min.
Max.
Overall
PM-Hrs/
CM-H'S/
SU«
No. of
No. of
Hrs.
MTBF
MT8F
MTQF
90% CL
Unit/
Unit/
MTTR
(GaJIcni Por Minute)
Unitr
Foiluroi
(x 10® Hrs)
(x 1Q1 His)
(x 10® Hrs)
(x 10* Hrs)
(x 10s Hrs)
Year
Year
(Hrs)
AVI
AVO
101-600
13
0
.2349
34S6
-
-
.1020
.01805
00
-
1.0
1.0
TABLE 1.6.2.6. RELIABILITY AND MAINTENANCE DATA ON POWER TRANSMISSIONS -
VARIABLE SPEED DRIVE, OTHER BY SIZE
Operating
Overall
M:n.
Max.
Ovorall
PM-Hii/
CM Hrs/
SUe
No. of
No. of
Hrs.
MTQF
MT0F
MTBF
80% CL
Unit/
Unit/
MTTR
(Gallons Por Minute)
Units
Failures
(x 10* Hrs)
<* 10* Hrs)
(x 10» Hra)
f< 10* Hrs)
(x 10* His)
Yosr
Year
(Mrs)
AVI
AVO
101-100
3
6
.00/00
00/041
-
-
.CCj23
.02148
1 031
2 6
WO 7
.eo'j6
OvertOO
1
0
01007
02G39
-
-
007CW7
7.273
0.0
-
1.0
-9C32
TOTAL
4
8
,03603
01C122
.007041
.02003
010754
.3046
.6100
26
.90976
90052
-------
TABLE 1.6.2.7. RELIABILITY AND MAINTENANCE DATA ON POWER TRANSMISSIONS-
GEAR BOX BY SIZE
Operating
OtoraO
Min.
Mai.
Overall
PM-Hra/
CM-Hn/
su»
No. ol
No. of
Hn.
MTBF
MTBF
MTBF
00% CL
Unit/
Unit/
MTTH
(Gallons Por Minutoj
Urtlta
Failures
(« IO»Hr.)
Hr*>
l« 10>Hr»)
Vo«
Yosr
IHral
AVI
AVO
0-1
11
24
1.483
.00016
.03324
.1725
.04333
0.0
¦ 1K8
6.04
•SSCSJ
.03374
IS
16
38
.3784
.003616
-
-
.0OCO41
,oo4aie
.3750
1.342
.6339
.8334
0 26
6
1
1.006
.6313
-
-
.2713
.003321
MM
28.0
1.0
.8300
20 100
1
2
.00200
.03476
-
-
.01746
0.0
.6080
4.0
0038
G338
TOTAL
32
66
3.01026
.045783
.000616
.6313
.003323
.000*56
.C6SI30
3.623
.03333
83M2
TABLE 1.6.2.8. RELIABILITY AND MAINTENANCE DATA ON POWER TRANSMISSIONS-
CHAIN DRIVE BY SIZE
Operating
Overall
Min.
Mai.
Overall
PM-Hri/
CM-Hra/
Slia
No. of
No. of
Hra.
MT0F
MTUF
MTBF
00% CL
Unit/
Unit/
MTTR
IGellona Par Minute)
Unita
Failurea
I« 10» Hra)
1* 10* Hra)
l« 10* Hra)
(» 10* Hra)
l» 10* Hra)
Year
Yaar
(Hr»l
AVI
AVO
1-6
4
6
.1012
01785
-
-
.01091
00
1.304
80
.9008
.9945
TABLE 1.6.2.9. RELIABILITY AND MAINTENANCE DATA ON POWER TRANSMISSIONS-
BELT DRIVE BY SIZE
Six*
(Gallona Per Minute)
No. ol
Units
No ol
Failurea
Operating
Hr».
(» 10« Hra)
Overfill
MTBF
(*10«Hrtl
Mm.
MTBF
(« 10«Hral
Mcx.
MTOF
<» 10* Hra)
Overall
00% CL
[« ICKn)
PM-Hra/
Unit/
Year
CM-Hrs/
Ur.lt/
Year
MTTR
(Hra)
AVI
AVO
0-1
3
6
.6100
.03101
.0516*
00
.0C4S)
1.8
1 0
9316
-------
TABLE 1.6.3.1. RELIABILITY AND MAINTENANCE DATA ON MOTORS-
MULTIPHASE BY SIZE
IHorsepowtr)
No. of
Unit*
No. of
Feiluree
Operating
Hra.
(x 108 Hr»)
Overall
MTBF
(x10«Hrs)
Min.
MTBF
(* 10* Hra)
M*k,
MTBF
(x 10" His)
Overall
90% CL
{x 10* Hra)
PMHra/
Unit/
Yoar
CM-Hra/
Unit/
Year
MTTR
(Hra)
AVI
AVO
0-t
70
20
4 241
.2147
.1236
2 612
.1340
.00522
.01009
20
1.0
.85330
1-6
16
0
.3734
.5648
-
-
.1646
.01162
00
-
1.0
1 0
8-25
64
66
3.520
.0021
.0222
1 81
.0627
.00016
.03261
7 857
.99388
.99975
26-100
GO
69
2.702
.04CO
.0210
1.334
.0347
.C0103
.03038
4.9C65I
.95388
.99062
101-600
62
18
.9590
.0540
.0135
3228
.0332
.00323
.10699
12 0S617
95377
.90332
Ov.rSOO
24
30
.6870
.0231
.00033
.09331
.0157
.02633
.24917
8 433
.93360
.90914
TOTAL
206
103
(2.4347
.OCOO
.0231
.6616
.0620
.00068
.00036
e.eseoi
.99383
.93338
TABLE 1.6.3.2. RELIABILITY AND MAINTENANCE DATA ON MOTORS-
VARIABLE SPEED, AC BY SIZE
su*
(Hor*epow«rl
No. of
Untu
No. of
Failure*
Operating
Hra.
(x 100 Hn\
Overall
MTBF
<* 10*Hr»)
Mm.
MTBF
<*10» Hr»i
Max.
MTBF
\* 10»H«)
Ovoro!)
30% CL
(x 10® Hr»)
PMHra/
Unit/
Year
CM-Hra/
Unit/
Year
MTTR
IHn)
AVI
AVO
101-600
16
0
.2710
.4033
-
-
.1177
.01618
-
-
1.0
1.0
Over bpO
2
2
.03614
.01351
.01061
.01061
.00082
0.0
3.6365
80
.9933
.9332
TOTAL
17
2
.30714
.11402
.01351
.4033
.05706
.01258
.060340
8.0
.09902
.89991
TABLE 1.6.3.3. RELIABILITY AND MAINTENANCE DATA ON MOTORS-
DC EXCITER BY SIZE
Size
iHortepowor)
No. of
Unit*
No. of
Failures
Operating
Hrt.
(x 10® Hrtl
Overall
MTBF
fx 10* Hra)
Mm.
MTBF
I- 10* Hrt)
Max.
MTBF
(x 10® Hrt)
Overall
90% CL
(x 10»Hral
PM-Hrs/
Unit/
Year
CM-Hra /
Unit/
Yoar
MTTR
(Hrt)
AVI
AVO
Over 600
6
6
.07230
.010304
,000704
.01103
.000361
1.6213*60
1 53DOG31
3.6GCG87
9036749
.930340
-------
TABLE 1.6.3.4. RELIABILITY AND MAINTENANCE DATA ON MOTORS -
GAS ENGINE BY SIZE
SUa
(Hortopcwsr)
No. of
Units
No. of
Failures
Operating
Hn.
("10* Hrs)
Ovsrell
MTBF
("10* Hrs)
Mln.
MTBF
(MP Hrs)
Max.
MTBF
("10»Hrs)
Overall
00% CL
(* 1G1 Hrs)
PM Mrs/
Unh/
Yoar
CMHrs/
Unit/
Ywr
MTTR
(Hrs)
AVI
AVO
101-600
2
1
.03978
.02300
-
-
.01023
10.67
10.57
24.00
-S3G0
.8342
TABLE 1.6.4.1. RELIABILITY AND MAINTENANCE DATA ON COMPRESSORS-
SINGLE STAGE CENTRIFUGAL BY SIZE
Six*
(Cubic Feet Ppr
Minute)
No of
Units
No. of
Failures
Operating
Hrs.
{* 10* Hrs)
OvereU
MTOF
<* 10* Hrs)
Min.
MTOF
1* 10* Hrs)
Mai.
MTBF
(* 10* Hrs)
Ovaretl
CC%Cl
(« 10s Hrs)
PM-Hrs/
Unit/
Yojr
CM-Hfs/
Unit/
Year
MTTR
(Hrs)
AVI
AVO
O
OJ
001-10.000
&
4
.00034
.01934
-
-
.01130
.01939
.4267
2.76
.9933
.CS90
Over 20,000
3
1
.03632
.02173
-
-
.009337
1.437
1.206
8.0
.8996
.S8M
TOTAL
8
&
.12666
.02242
.01934
.02173
.01369
.16364
.313338
3.80
.9996
.9954
TABLE 1.6.4.2. RELIABILITY AND MAINTENANCE DATA ON COMPRESSORS-
MULTI STAGE CENTRIFUGAL BY SIZE
Sue
Operating
Overall
Min.
Max.
i^sereM
PM-Hrs/
CMHrs/
(Cubic Feet Per
No. of
No. of
Hrs.
MTBF
MTBF
MTBF
90% CL
Unit/
Unit/
MTTR
Minute)
Units
Failures
<*10* Hrs)
(x 10»Hre)
(* 10* Hrs)
(» 10* Hrs)
<« 10* Hrs)
Year
Year
(Hrs)
AVI
AVO
1,001-10.000
1
0
.01609
.02083
-
-
.007*47
.2424
00
-
1.0
1.0
10,001-20.000
6
3
05457
.01487
-
-
003IG3
.03211
1.445
6.0
£336
8303
Over 20,030
6
9
.47030
.005030
-
-
.004417
.1457
.8323
06452
99CO
9323
TOTAL
12
96
.54354
.OOWJ18
.005030
.02CS9
004S52
.C6513
.44723
012&4
SM07
99179
-------
TABLE 1.6.4.3. RELIABILITY AND MAINTENANCE DATA ON COMPRESSORS-
MULTI STAGE HIGH PRESSURE BY SIZE
Sua
(Cubic Foot Per
Minutol
No. of
Unlia
No. of
Faiiur&e
Oporeilng
Hra.
|m 10* Hra)
Overall
MTBF
(k io® Hra)
Win.
MTBF
(* 10* Hra)
Max.
MTBF
Hra)
Overall
90% CL
(x 10» Hral
PM-Hn/
Unit/
Year
CM-Hr*/
Unit/
Y«*r
mtti;
(Hn)
AVI
AVO
A-25 Horsepower
S5
0
1.232
1.834
-
-
.BC62
.01263
-
-
.on eo
-
TABLE 1.6.5.2. RELIABILITY AND MAINTENANCE DATA ON DIFFUSERS. AIR/WATER —
WASTE TO MEDIA BY SIZE
Sue
Operating
PMHra/
CM-Hra/
(Gallon* por
No. of
Hra
No. of
Unit/
Unit/
MTTR
Minute)
Unlta
I* 1C*>
Failure*
Yoar
Year
(Hra)
AVI
AVO
10.001-20,000 40 2.&24 223 .000078 .1531 8.305 .9233 .8632
-------
TABLE 1.6.6.1. RELIABILITY AND MAINTENANCE DATA ON VALVES-
GATE BY SIZE
Siidlnchea)
No. ol
Unit!
No. of
Failurea
Operating
Hra
(» 10* Hra)
Overall
MTBF
(« 10»Hr»l
Min.
MTBF
C 10* Hra)
Ma*.
MTBF
(«10«Hra)
Overall
90% CL
l« 10°Hral
PM-Hra/
Unit/
Year
CM Hra/
Unit/
Year
MTTR
(Hra)
AVI
AVO
25-48
2
2
.03165
.01183
.01081
.01146
.005972
0.0
4.15224
8.00
.959169
9S9004
Over 48
5
9
.07230
.007501
.006266
.01081
¦005C37
0.0
2.10675
2 6C87
.99360
.9X500
TOTAL
7
It
.10403
.003923
.007023
.01353
.003268
0.0
1.40743
3 8394
.85547
.05633
TABLE 1.6.6.2. RELIABILITY AND MAINTENANCE DATA ON VALVES-
BALL BY SIZE
Sixt (Inchea)
No. of
Unlit
No. of
Failure*
Operating
Hr».
(« 1C«Hrel
Overall
MTBF
(x IO*Hn)
Mm.
MTUF
> ICMril
Mai
MTBF
<« ICMnl
Overoll
80% CL
(« 10* Hra)
FM Hra/
Unit/
Y tar
CM Hra/
Unit/
Year
MTTR
IHra)
AVI
AVO
25-43
1
1
.01918
.01148
-
-
.0040Z7
0.0
43.89
110.0
.9306
.esse
TABLE 1.6.6.3. RELIABILITY AND MAINTENANCE DATA ON VALVES-
BUTTERFLY BY SIZE
SUe (Incheal
No. ol
Uivti
No. of
Failure!
Operating
Hre
(« ICHrel
Overoll
MTBF
(k 10«Hra)
Min.
MT0F
(« 10" Hrsl
Max.
MT8F
(<10*Hrtl
Overall
£0% CL
fx 10»Hra)
PM-Hra/
Unit/
Year
CM Hra/
Unit/
Yoar
MTTR
IHra)
AVI
AVO
04
3
0
QDC68
.06459
-
-
,oua3
.1194
-
-
1.0
1.0
13-24
1
1
.01807
.01081
-
-
.004645
0.0
1.455
1.00
.8339
SSS8
TOTAL
4
1
.05475
rmrsn
.01081
C6459
.014075
.0329
.12006
1.00
9SS067
.993334
-------
TABLE 1.6.6.4. RELIABILITY AND MAINTENANCE DATA ON VALVES-
PLUG BY SIZE
SU« (Inches)
No. of
Units
No. of
Failures
Operating
Hrs.
(x 10« Hnl
Ovortll
MTBF
(x 10* Hrs)
Min.
MTBF
(«10» Hrs)
Mai.
MTBF
(> 10* Hrs)
Overall
80% CL
fx 10« Hrs)
PM-Hrs/
Unit/
Vur
CM-Hrs/
Unit/
Yoor
MTTH
(Hrs)
AVI
AVO
25-«
1
1
.01316
.02CS2
-
-
000122
.2128
-
-
1.0
1.0
TABLE 1.6.7.1
. RELIABILITY AND MAINTENANCE DATA ON CONTROLS-
ELECTRICAL BY SIZE
Size
IHorsopoww)
No. of
Unit*
No. of
Failures
Operating
Hrs.
|x 10* Hrs)
Overall
MTBF
|x 10> Hrs)
Min.
MTBF
(x 10* Hrs)
Mu,
MTBF
(x 10* Hrs)
OvorsU
90% CL
(x 10>Hrsl
PM-Hrs/
Unit/
Year
CM-Hrs/
U.-ut/
Year
MTTH
(Hrs)
AVI
AVO
0-1
60
20
4.143
.20032
.1131
2.612
.160C6
.00063
.0Q2S6
206
1.0
.83332
t-6
14
0
.3541
.6C3SO
-
-
.15362
.01325
0.0
-
1.0
1.0
6-25
64
0
3.626
4.6W9
1.670
1.887
1.41258
.00124
00
-
1.0
1.0
26-100
W
69
1.8211
.023109
•01B3S
.06116
.022521
.00035
.02316
2.37672
.539 ca
.99393
101-600
60
19
1.92154
.09779
.01031
.6144
.07419
.00274
.02216
6.67236
.9SS72
.93336
Over 6CO
IS
14
.66221
.03374
.034324
.06332
CC339
.00301
.12236
2.92Q79
.80636
.95593
TOTAL
269
122
12.35395
.100643
.026100
4.6049
033339
.00023
.00211
2. (£337
.90323,
.93322
TABLE 1.6.7.2.
. RELIABILITY AND MAINTENANCE DATA ON CONTROLS-
MECHANICAL DY SIZE
Ske
IHors»ptwe>)
No. of
Units
No. of
Failures
Opercting OvsroU
Hru. MTBF
(*1&»Hrsl («10>Hr>)
Min.
MTBF
(x 1C Hrs)
Max.
MTOF
(x 10> Hnl
OvoraU
SO^CL
(x 10»Hrsl
PM-Hrs/
Ur.it/
Yott
CM-Hrs/
Unjt/
Year
MTTR
(Hrsl
AVI
AVO
101500
1
0
.0224
.03334
-
-
00373
.1005
0.0
-
1 0
1.0
Over BOO
3
2
•WS63
.01706
-
-
,003j64
.0C413
1.324
8.0
•80S3
.9976
TOTAL
4
2
.03723
.03123
.01706
.03334
.012317
.0C33S
.80717
80
.93964.
.83C39
-------
TABLE 1.6.7.3. RELIABILITY AND MAINTENANCE DATA ON CONTROLS-
PRESSURE (PLUID) BY SIZE
Sua
No. of
Unto
No. of
Failures
Operating
Hr>.
(* 10» Hra)
Ovorall
MTEF
1* to* Hra)
Min.
MTBF
1* 'Onira)
Mai.
MTQF
(xlCMIra)
OvorcB
80% CL
t*10»Hra)
PM-Hra/
Unit/
Yoir
CM-Hra'
Unit/
Voir
MTTR
IHra)
AVI
AVO
I01-6COIHPI
•
1
,10
-------
TABLE 1.6.8.1. RELIABILITY AND MAINTENANCE DATA ON CONVEYORS-
CHAIN (BAR SCREEN) BY SIZE
S'ut
No. of
Units
No. ol
Failures
Creralmg
Hrs.
|x 10" Hnl
OvoraU
MTBF
I* 10« hrsl
Mm.
MTBF
(x 10* Hr«)
Ma*.
MT0F
l« 10* Kid
Overall
eo% ci
l» 10* Hnl
PM Hrtl
Unh/
Voir
CM-rtrs/
Unit/
Year
MTTfi
IHll
AVI
AVO
Ov*r43lnch«a 3 18 !.2U .06175 - - .0468J 0.0 .1371 .9474 1.0 .8899
TABLE 1.6.8.2. RELIABILITY AND MAINTENANCE DATA ON CONVEYORS-
SLUDGE COLLECTOR BY SIZE
t—1
O
oo
Slzt
(Honepower)
No. of
Uruu
No. of
Failures
0 periling
Hrt.
(x IO«Hrsl
OvoraU
MTQF
(x 10> Hrs)
Min.
MTBF
(« 10* Hrs)
Mai.
MT0F
(x 10* Hrs)
Overall
90% CL
(x ,0* Hnl
PM-Hrs/
Unh/
Year
CM-Hrs/
Unh /
Year
MTTH
(Hnl
AVI
AVO
0-1
6
7
10.03
.2202
-
-
.1434
.000729
.436a
16.14
S339
.9336
e-s
S
0
l.OtS
1.670
-
-
.4583
.004161
-
-
1.000
1.000
TOTAL
13
7
2.743
WM
7X13
1.670
.23345
.000382
.160)76
16.14
•B2S93
.(£976
-------
TABLE 2.1.1. PUMPS-DISTRIBUTION OF SUBCOMPONENT FAILURES
No. Of
Relative
Rank
Subcomponent Type
Failures
Frequency
1
Impeller Wear Ring, or Plate
17
.177
2
Solenoid Valve
16
.167
3
Bearng, Ball, Single Row
14
.146
4
Bearing, Ball, Double Row
8
.083
5
Controller
8
.033
6
Bearing, Cast, Pillow
5
.052
7
Complete Bearing Replacement
5
.052
8
Seal, Pocked, not Lubricated
3
.031
9
Coupling
3
.031
10
Bearing, Thrust
3
.031
11
Pump Impeller
2
.021
12
Drive Belt
2
.021
13
Case, Pump
2
.021
TABLE 2.1.2. POWER TRANSMISSIONS— DISTRIBUTION OF
SUBCOMPONENT FAILURES
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Drive Belt
133
.453
2
Bearing, Ball, Double Row
48
.163
3
Shear Pin
39
.133
4
Seal, other
24
.082
5
Bearing, Ball, Single Row
11
.037
6
Shaft, Drive
9
.031
7
Controller
8
.027
8
Coupling
5
.017
9
Chain, Pintle
5
.017
10
Pulley, Belt Drive
4
.013
11
Skimmer
2
.007
109
-------
TABLE2.1.3. MOTORS -DISTRIBUTION OF SUBCOMPONENT FAILURES
Rank
Subcomponent Typo
No. Of
Failures
Relative
Frequency
1
Complete Bearing Replacement
58
.347
2
Brushes
38
.228
3
Coupling
19
.114
4
Motor Windings
16
.038
5
Bearing, Ball, Double Row
11
.066
6
Controller
4
.024
7
Shaft Sleeve
3
.018
8
Relay
3
.018
9
Motor Armature
3
.018
10
Seal, Packed, not Lubricated
2
.012
11
Bearing, Ball, Single Row
2
.012
12
Bearing, Thrust
2
.012
13
Overload Relay
2
.012
14
Case, Motor
2
.012
TAELE 2.1.4. COMPRESSORS-DISTRIBUTION OF SUBCOMPONENT
FAILURES
No Of
Relative
Rank
Component Type
Failures
Frequency
1
Coupling
3
.231
2
Bearing, Ball, Single Row
3
.231
3
Switch, Electric
3
.23*
4
Pump Impeller
2
.154
6
Brushes
1
.077
6
Pipe Broken
1
.077
110
-------
TABLE2.1.5. DIFFUSERS, AIR/WATER-DISTRIBUTION OF
SUBCOMPONENT FAILURES
No. of Relative
Rank Subcomponent Failures Frequency
1
Tie Rod
107
.480
2
Seal, Single, Mechanical
49
.220
3
Bearing, Thrust
36
.161
4
Bearing, Ball, Single Row
25
.112
5
End Gate
5
.022
6
Experimental/Prototype Bearing
1
.005
TABLE 2.1.6. VALVES - DISTRIBUTION OF SUBCOMPONENT FAILURES
No. Of
Relative
Rank
Componont Type
Failures
Frequency
1
Seal, Packed Water, Oil, Grease Lubricated
7
.538
2
Control Valve
3
.231
3
Seal, other
1
.077
4
Coi .roller
1
.077
5 Solenoid valve 1 .077
111
-------
TABLE2.1.7. CONTROLS-DISTRIBUTION OF
SUBCOMPONENT FAILURES
No. Of Relative
Rank Subcomponent Type Failures Frequency
1
Controller
46
.371
2
Magnetic Starter
26
.210
3
Overload Relay
13
.105
4
Relay
11
.089
5
Switch, Eloctric
11
.089
6
Seal, Single, Mechanical
3
.024
7
Seal, other
3
.024
8
Complete Bearing Replacement
3
.024
9
Electrical Timer
2
.016
10
Control Valve
2
.016
TABLE 2.1.8. CONVEYOR-DISTRIBUTION OF SUBCOMPONENT FAIL-
URES
No. Of R6'ative
Rank Subcomponent Type Failures Frcq jency
1 Rake Guides 19 .731
2 Collector mochanism 5 .IS 2
3 Plastic chain and Flights 1 .038
4 Pipe Biokon 1 .038
112
-------
1
2
3
4
5
ar
1
2
3
4
5
6
TABLE2.2.1.1. PUMPS-OPEN IMPELLER CENTRIFUGAL
No. Of Relative
Subcomponent Type Failures Frequency
Impeller Wear Ring or Plate
15
.197
Seal, Packed, Watfer, Oil, Grease Lubricated
14
.184
Solenoid Valve
14
.184
Bearing, Ball, Double Row
6
.079
Bearing, Cast, Pillow
5
.066
TABLE2.2.1.2. PUMPS-PROPELLER, AXIAL FLOW
No. Of Relative
Subcomponent Type Failures Frequency
Controller
4
.200
Complete Bearing Replacement
4
.200
Impeller Wear Ring or Plate
2
.100
Bearing, Ball, Double Row
2
.100
Bearing, Thrust
2
.100
Solenoid Valve
2
.100
113
-------
TABLE2.2.2.1. POWER TRANSMISSION-RIGHT ANGLE SHAFT
No. Of Relative
Rank Subcomponent Type Failures Frequency
1 Drive Belt 127 .706
2 Bearing, Ball, Double Row 45 .250
3 Pulley, Belt Drive 3 .017
4 Coupling 2 .011
TABLE2.2.2.2. POWER TRANSMISSION-VERTICAL SHAFT
No. Of Relative
Rank Subcomponent Type Failures Frequency
1 Seal, other 20 .445
2 Bearing, Ball, Single Row 11 .245
3 Shaft, Drive 8 .178
TABLE 2.2.2.3. POWER TRANSMISSION-VARIABLE SPEED DRIVE,
OTHER
No. Of Relative
Rank Subcomponent Type Failures Frequency
1 Controller 8 .8S9
2 Brushes 1 .111
114
-------
TABLE2.2.2.4. POWER TRANSMISSION-GEAR BOX
No. Of Relative
Rank Sbucomponent Type Failures Frequency
1 Shea: Pin 38 .826
2 Seal, other 4 .087
3 Coupling 3 .065
4 Complete Bearing Replacement 1 .022
TABLE2.2.3.1. MOTORS-MULTI-PHASE
No. Of Relative
Rank Subcomponent Type Failures Frequency
1 Complete Bearing Replacement 57 .385
2 Brushes 24 .162
3 Couplinp 19 .123
4 Motor Windings 16 .103
5 Bearing, Ball, Double Row 10 .063
TABLE2.2.3.2. MOTORS-VARIABLE SPEED AC
No. Of Relative
Rank Subcomponent Type Failures Frequency
1 Bearing, Ball, Double Row 1 .500
2 Controller 1 .500
115
-------
TABLE2.2.3.3. MOTORS-DC EXCITER
No. Of
Relative
Rank
Subcomponent Type
Failures
Frequency
1
Brushes
14
.933
2
Motor Armature
1
.067
TABLE 2.2.3.4. MOTORS-GASOLINE
No. Of
Relative
' Rank
Subcomponent Type
Failures
Frequency
1
Complete Bearing Replacement
1
.500
2
Replaced Piston
1
.500
TABLE2.2.4.1. COMPRESSORS-SINGLE STAGE CENTRIFUGAL
No. Of
Relative
Rank Subcomponent Type
Failures
Frequency
1 Bearing, Ball, Single Row
3
.429
2 Switch, Electric
2
.286
3 Coupling
1
.143
4 Brushes
1
.143
L
116
-------
TABLE2-2.4.2. COMPRESSORS-MULTI STAGE CENTRIFUGAL
'Jo. Of
Relative
Rank
Subcomponent Type
Failures
Frequency
1
Pump Impeller
2
.333
2
Coupling
2
.333
3
Cose, Motor
1
.167
4
Pipe Broken
1
.167
TABLE2.2.5.1. DIFFUSERS, AIR/WATER
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Tie Rod
107
.480
2
Seal, Single, Mechanical
49
.220
3
Bearing, Thrust
36
.161
4
Bearing, Ball, Single Row
25
.112
5
End Gate
5
.022
6
Experimental/Prototype Bearing
1
.005
TABLE 2.2.6.1. VALVES-GATE
No. Of
Relative
Rank Subcomponent Type
Failures
Frequency
1
Seal, Packed, Water, Oil, Grease Lubricated
7
.636
2
Seal, other
1
.091
3
Controller
1
.091
4
Solenoid Valve
1
.091
5
Control Valve
1
.091
117
-------
Rank
1
2
3
4
5
Rank
1
2
Rank
1
2
3
TABLE 2.2.7.1. CONTROLS —ELECTRICAL
Subcomponent Type
No. Of
Failures
Relative
Frequency
Contro^er
Magnetic Starter
Overload Relay
Switch, Electric
Relay
32
23
13
10
9
.348
.250
.141
.109
.098
TABLE 2.2.7.2. CONTROLS-MECHANICAL
Subcomponent Type
No. Of Relative
Failures Frequency
Switch, Electric
Motor Windings
.500
.500
TABLE2.2.7.3. CONTROLS-PRESSURE, FLUID
Subcomponent Type
No. Of Relative
Failures Frequency
Controller
Magnetic Starter
Complete Bearing Replacement
.385
.231
.231
118
-------
TABLE2.2.7.4. CONTROLS-CHLORINATORS
Rank Subcomponent Type
No. Of
Failures
Relative
Frequency
1 Seal, other
3
.375
2 Relay
2
.250
3 Control Valve
2
.250
4 Gear, Rack
1
.125
TABLE2.2.8.1. CONVEYOR-SLUDGE COLLECTOR
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Collector Mechanism
5
.714
2
Plastic Chain and Flights
1
.143
3
Pipe Broken
1
.143
TABLE2.3.1.1. PUMPS-RAW WASTEWATER PUMPING
No. Of
Relative
Rank Subcomponent Type
Failures
Frequency
1
Impeller Wear Ring, or Plate
15
.246
2
Seal, Packed, Water, Oil, Grease Lubricated
14
.230
3
Solenoid Valv a
14
.230
4
Bearing, Cast, Pillow
5
.082
5
Seal, Packed, not Lubricated
3
.049
119
-------
TABLE 2.3.1.2. PUMPS-INTERMEDIATE WASTEWATER PUMPING
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Controller
8
.572
2
Seal, other
1
.071
3
Coupling
1
.071
4
Drive Belt
1
.071
5
Relay
1
.071
6
Switch, Electric
1
.071
7
Brushes
1
.071
TABLE 2.3.1.3. PUMPS-RETURN ACTIVATED SLUDGE HANDLING
No. Of Relative
Rank Subcomponent Type Failures Frequency
1 Bearing, Ball, Double Row 5 .714
2 Coupling 2 .286
TABLE 2.3.1.4. PUMPS-RECIRCULATION PUMPING
No. Of
Relative
Rank Subcomponent Type
Failures
Frequency
1 Complete Bearing Replacement 4 .286
2 Impeller Wear Ring, or Plate 2 .143
3 Bearing, Bali, Double Row 2 .143
4 Bearing, Thrust 2 .143
5 Solenoid Valve 2 .143
120
-------
TABLE2.3.2.1. POWER TRANSMISSION —CLARIFIER CENTER
CIRCULAR DRIVE
Rank
Subcomponent Typa
No. Of
Failures
Relative
Frequency
1
Drive Belt
133
.596
2
Bearing, Ball, Double Row
45
.202
3
Seal, other
20
.090
4
Shaft, Drive
9
.040
5
Bearing, Ball, Single Row
5
.022
6
Pulley, Drive Belt
4
.018
TABLE2.3.2.2. POWER TRANSMISSION-CLARIFIER
SQUARE/RECTANGULAR, PERIPHERAL
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Shear Pin
38
.809
2
Chain, Pintle
5
.106
3
Coupling
3
.064
4
Complete Bearinc, Replacement
1
.021
TABLE 2.3.2.3. POWER TRANSMISSION- MECHANICAL AERATORS
No. Of
Relative
Rank Subcomponent Type
Failures
Frequency
1
Bearing, Ball, Single Row
6
.461
2
Seal, other
4
.308
3
Seal, Single Mechanical
1
.077
4
Seal, Packed, Water, Oil, Grease Lubricated
1
.077
G
Bearing Ball, Double Row
1
.077
121
-------
TABLE 2.3.3.1. MOTORS-RAW WASTEWATER PUMPING
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Brushos
16
.381
2
Motor Windings
13
.310
3
Relay
3
.071
4
Motor Armature
3
.071
5 Controller 2 .048
TABLE2.3.3.2. MOTORS-INTERMEDIATE WASTEWATER PUMPING
No. Of
Relative
Rank
Subcomponent Type
Failures
Frequency
1
Brushes
2
.667
2
Controller
1
.133
TABLE 2.3.3.3. MOTORS —CLARIFIER CIRCULAR CENTER DRIVE
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Coupling
19
.826
2
Bearing, Ball, Single Throw
2
.087
3
1
Bearing, Ball, Double Throw
2
.087
122
-------
TABLE 2.3.3.4. MOTORS - RETURN ACTIVATED SLUDGE HANDLING
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Brushes
9
.500
2
Bearing, Ball, Double Row
5
.278
3
Seal, Packed, not Lubricated
2
.111
TABLE2.3.3.5. MOTORS-RECIRCULATION PUMPING
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Shaft, Sleeve
2
.333
2
Bearing, Ball, Double Row
2
.333
3
Bearing, Thrust
1
.167
4
Complete Bearing Replacement
1
.167
TABLE2.3.3.6. MOTORS-DISSOLVED AIR PRODUCTION
No. Of Relative
Rank Subcomponent Type Failures Frequency
1 Brushes 11 .688
2 Motor Windings 2 .125
3 Case, Motor 2 .125
4 Bearing, Ball, Double Row 1 .062
123
-------
TABLE2.3.4.1. COMPRESSORS-DISSOLVED AIR PRODUCTION
No. Of
Relative
Rank
Subcomponent Type
Failures
Frequency
1
Coupling
3
.333
2
Pump Impeller
2
.222
3
Switch, Electric
1
.111
4
Case, Motor
1
.111
5
Brushes
1
.111
S
Pipe Broken
1
.111
TABLE2.3.4.2. COMPRESSORS-DISSOLVED AIR/O, APPLICATION
No. Of
Relative
Rank
Subcomponent Type
Failures
Frequency
1
Bearing, Ball, Double Row
3
.750
2
Switch, Electric
1
.250
TABLE2.3.5.1. DIFFUSERS, AIR/WATER
No. Of
Relative
Rank
Subcomponent Type
Failures
Frequency
1
Tie Rod
107
.480
2
Seal, Singie, Mechanical
49
.220
3
Bearing, Thrust
38
.161
4
Bearing, Ball, Single Row
25
.112
6
End Gate
5
.022
6
Experimental/Prototype Bearing
1
.005
124
-------
TABLE2.3.6.1. VALVES-RAW WASTEWATER PUMPING
No. Of
Relative
Rank
Subcomponent Typo
Failures
Frequency
1
Seal, Packed, Water Oil, Grease Lubricated
7
.700
2
Seal, other
1
.100
3
Controller
1
.100
4
Control Valve
1
.100
TABLE2.3.6.2. VALVES-INTERMEDIATE WASTEWATER PUMPING
No. Of
Relative
Rank
Subcomponent Type
Failures
Frequency
1
Solenoid Valve
1
.500
2
Control Valve
1
.500
TABLE 2.3.7. t. CONTROLS - RAW WASTEWATER PUMPING
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Magnetic Starter
11
.846
2
Switch, Electric
1
.077
3
Solenoid Valve
1
.077
125
-------
TABLE 2.3.7.2. CONTROLS-INTERMEDIATE WASTEWATER PUMPING
No. Of Relative
Rank Subcomponent Type Failures Frequency
1 Relay 2 .222
2 Overload Relay 2 .222
3 Switch, Electric 2 .222
4 Controller 2 .222
5 Motor Windings 1 .111
TABLE2.3.7.3. CONTROLS-CLARIFIER CENTER CIRCULAR DRIVE
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Magnetic Starter
8
.421
2
Overload Relay
5
.263
3
Switch, Electric
4
.211
4
Relay
1
.053
5 Controller 1 .053
TABLE2.3.7.4. CONTROLS-RETURN ACTIVATED SLUDGE HANDLING
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Controller
22
.786
2
Magnetic Starter
4
.143
3
Electrical Timor
2
.071
i.26
-------
TABLE2.3.7.5. CONTROLS- RECIRCULATION PUMPING
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Overload Relay
3
.429
2
Seal, Single, Mechanical
2
.286
3
Switch. Electric
1
.143
4
Controller
1
.143
TABLE2.3.7.6. CONTROLS-DISSOLVED AIR PRODUCTION
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Controller
4
.445
2
Switch, Electric
3
.333
3
Relay
2
.222
TABLE 2.3.7.7. CONTROLS- MECHANICAL AERATORS
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Relay
4
.500
2
Overload Relay
3
.375
3
Switch, Electric
1
.125
127
-------
TABLE2.3.7.8. CONTROLS-CHLORINE, GASEOUS
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Controller
13
.448
2
Seal, other
3
.103
3
Magnetic Starter
3
.103
4
Complete Bearing Replacement
3
.103
5
Relay
2
.069
6
Control Valve
2
.069
7
Seal, Single. Mechanical
1
.035
8
Ge?r, Rack
1
.035
9
Gear, Pinion
1
.035
TABLE 2.3.8.1. CONVEYOR —CLARIFIER SQUARE/RECTANGUI.AR
PERIPHERAL DRIVE
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Collector Mechanism
5
.714
2
Plastic Chain and Flights
1
.143
3
Pipe Broken
1
.143
TABLE2.4.1.1. PUMPS-OTO 10,000GALLONS PER MINUTE
No. Of
Relative
Rank
Subcomponent Type
Failures
Frequency
1
Bearing, Ball. Double Row
5
.714
2
Coupling
2
.286
128
-------
TABLE2.4.1.2. PUMPS-10,001 TO 20.000 GALLONS PER MINUTE
Rank
Subcomponent Typo
No. Of
Failures
Relative
Frequency
1
Impeller Wear Ring, or Plate
15
.600
2
Seal. Pecked, not Lubricated
2
.080
3
Bearing, Thrust
2
.080
TABLE2.4.1.3. PUMPS-20.001 TO 100,000 GALLONS PER MINUTE
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Complete Bearing Replacement
4
.308
2
Impeller Wear Ring, or Plate
2
.154
3
Bearing, Ball. Double Row
2
.154
4
Solenoid Valve
2
.154
TABLE2.4.1.4. PUMPS-OVER 100,000 GALLONS PER MINUTE
No. Of
Relative
Rank Subcomponent Type
Failures
Frequency
1
Seal, Packed. Water, Oil, Grease Lubricated
14
.269
2
Solenoid Valve
13
.250
3
Controller
8
.154
4
Bearing, Cast, Pillow
5
.096
5
Drive Belt
2
.038
129
-------
TABLE2.4.2.1. POWER TRANSMISSION —0 TO 1 HORSEPOWER
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Drive Belt
133
.588
2
8earing, Ball, Double Row
45
.139
3
Seal, other
20
.088
4
Shaft. Drive
9
.040
5
Coupling
5
.022
6
Bearing, Ball, Single Row
5
.022
7
Pulley, Belt Drive
4
.018
TABLE 2.4.2.2. POWER TRANSMISSION-2 TO 5 HORSEPOWER
No. Of
Relative
Rank
Subcomponent Type
Failures
Frequency
1
Shear Pin
38
.884
2
Chain, Pintle
5
.116
TABLE2.4.2.3. POWER TRANSMISSION-26 TO 100 HORSEPOWER
No. Of
Relative
Rank
S ubcomponent T ype
Failures
Frequency
1
Bearing, Ball, Single Row
6
.600
2
Seal, other
4
.400
130
-------
TABLE2.4.2.4. POWER TRANSMISSION-101 TO 500 HORSEPOWER
No. Of Relative
Rank Subcomponent Type Failures Frequency
1 Controller 8 .727
2 Seal, Single, Mechanical 1 .091
3 Seal, Packed, Water, Oil, Grease Lubricated 1 .091
4 Bearing, Ball, Double Row 1 .091
TABLE2.4.2.5. POWER TRANSMISSION-OVER 500 HORSEPOWER
No. Of Relative
Rank Subcomponent Type Failures Frequency
1 Bearing, Ball, Double Row 2 .667
2 Brushes 1 .333
TABLE2.4.3.1. MOTORS-OTO 1 HORSEPOWER
No. Of Relative
Rank Subcomponent Type Failures Frequency
1 Coupling 19 .826
2 Bearing, Ball, Single Row 2 .087
3 Bearing, Ball, Double Row 2 .087
131
-------
1
2
3
4
5
6
an
1
2
3
4
5
6
7
an
1
2
3
4
5
6
TABLE 2.4.3.2. MOTORS-26 TO 100 HORSEPOWER
No. Of Rotative
Subcomponent Type Failures Frequency
Motor Windings
11
.393
Brushes
9
.321
Bearing, Ball. Double Row
4
.143
Seal, Packed, not Lubricated
2
.071
Shaft, Sleeve
1
.038
Controller
1
.036
TABLE2.4.3.3. MOTORS- 1C1 TO 500 HORSEPOWER
No. Of Relative
Subcomponent Type Failures Frequency
Bearing, Ball, Double Row
4
Shaft, Sleeve
2
Bearing, Thrust
2
Overload Relay
2
Motor Windings
2
Brushes
2
Complete Bearing Replacement
2
.222
TABLE2.4.3.4. MOTOr.S-OVER 500 HORSEPOWER
No. Of Relative
Subcomponent Type Failures Frequency
Brushes
27
.643
Relay
3
.071
Motor Windings
3
.071
Controller
3
.071
Motor Armamre
2
.048
Case, Motor
2
.048
132
-------
TABLE2.4.4.1. COMPRESSORS-1,001 TO 10,000 CUBIC
FEET PER MINUTE
No. Of
Relative
Rank
Subcomponent Type Failures
Frequency
1
Bearing, Ball, Single Row 3
.750
2
Switch, Electric 1
.250
TABLE2.4.4.2. COMPRESSORS-10,001 TO20,000CUBIC
FEET PER MINUTE
No. Of
Relative
Hank
Subcomponent Type Failures
Frequency
1
Coupling 2
.667
2
Pipe Broken 1
.333
TABLE2.4.4.3. COMPRESSORS-OVER20,000CUBIC
FEET PER MINUTE
No. Of
Relative
Rank
Subcomponent Type Failures
Frequency
1
Pump Imp.eller 2
.333
2
Switch, Electric 2
.333
3
Coupling 1
.167
4
Brushes 1
.167
133
-------
TABLE2.4.5.1. DIFFUSERS, AIR/WATER-10,001 TO20,000
GALLONS PER MINOfE
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Tie Rod
107
.480
2
Seal, Single, Mechanical
43
.220
3
Bearing, Thrust
36
.161
4
Bearing, Ball, Single Row
25
.112
5
End Gate
5
.022
6
Experimental/Prototype Bearing
1
.005
1SSH1JI OD-li.R
TABLE 2.4.6.1. VALVES-25 TO 48 INCHES
No. of
Relative
Rank
Subcomponent Type
Failures
Frequency
1
Seal
1
.333
2
Solenoid Valve
1
.333
3
Control Valve
1
.333
TABLE2.4.6.2. VALVES-OVER 48 INCHES
No. of
Relative
Rank
Subcomponent Type
Failures
Frequency
1
Seal, Packed, Water, Oil, Grease Lubricated
7
.778
2
Controller
1
.111
3
Control Valve
1
.111
134
-------
1
2
3
4
an
1
2
3
4
5
ar
1
2
3
4
5
TABLE2.4.7.1. CONTROLS-OTO 1 HORSEpOWER
No. Of. Relative
Subcomponent Type Failures Frequency
Magnetic Starter 8 .444
Overload Relay 5 .278
Switch, Electric 4 .222
Relay 1 .056
TABLE2.4.7.2. CONTROLS-26 TO 100 HORSEPOWER
No. Of Relative
Subcomponent Type Failures Frequency
Controller 21 .512
Magnetic Starter 11 .268
Relay 4 .038
Overload Relay 2 .049
Electrical Timer 2 .049
TABLE2.4.7.3. CONTROLS-101 TO 500 HORSEPOvVER
No. Of Relative
Subcomponent Type Failures Frequency
Controller 6 .300
Overload Relay 5 .250
Magnetic Starter 4 .200
Seal, Single, Mechanical 2 .100
Switch, Electric 2 .100
135
-------
TABLE2.4.7.4. CONTROLS-OVER 500 HORSEPOWER
Rank
Subcomponent Typ9
No. Of
Failures
Relative
Frequency
1
Controller
6
.375
2
Relay
4
.250
3
Switch, Electric
4
.250
TABLE2.4.7.5. CONTROLS-OVER2000 POUNDS CHEMICAL
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Controller
13
.448
2
Seal, other
3
.103
3
Magnetic Starter
3
.103
4
Complete Bearing Replacement
3
.103
5
Relay
2
.069
6
Control Valve
2
.069
TABLE2.4.8.1. CONVEYOR-OTO 1 HORSEPOWER
Rank
Subcomponent Type
No. Of
Failures
Relative
Frequency
1
Collector Mechanism
5
.714
2
Plastic Chain and Flights
1
.143
3
Pipe Broken
1
.143
136
-------
TABLE 3.1.1. WWTP REPORT-RELIABILITY OF SLUDGE PROCESSES
Process
Operating
Hours
(x TO8 Hrs)
No. of
Failures
MTBF
(x 1C6 Hrs)
90% CL
(x 10® Hrs)
Avail.
Sludge Process External to
WW Treat. Process
.780
400
.001S5
.00133
.897
Anaerobic Digestion
.678
40
.0167
.0137
1.000
Incineration
.374
454
.000824
.000776
.723
Sludge Thickening DAF
.400
702
.000577
.000583
.994
Vacuum Filter
.697
1150
.000806
.000583
.931
-------
- 16-%
DATE DUE
DATE DUE
I
si-
------- |