ENVIRONMENTAL PROTECTION AGENCY
TECHNOLOGY TRANSFER SEMINAR
UPGRADING
METAL FINISHING FACILITIES
TO REDUCE POLLUTION
IN-PROCESS
POLLUTION ABATEMENT PRACTICES
NEW YORK CITY, NEW YORK
DECEMBER, 1972
OXY METAL FINISHING CORPORATION
ENVIRONMENTAL SERVICES GROUP
MADISON HEIGHTS, MICHIGAN
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INTRODUCTION
The threat of air and water pollution to the welfare of the United States has been
recognized only in recent years. The task of determining just how industrial wastes ad-
versely alter the environment is still fraught with unknowns, because this work also has
just begun.
Clear to the metal finishing industry is the fact that its wastes are detrimental to the
environment. The industry wonders about the extent of the detriment, the reasoning behind
regulatory correctional measures, and the steps which industry must take to make per-
manent peace with the environment and still continue to use it.
This paper intends only to assist the metal finisher to understand where his pollution
begins, how to reduce it, and having done so, to have a proper assemblage of facts ac-
cumulated so that his future endeavors at pollution control are not just self-serving, but
technologically sound, and not inclined to obsolescence.
IS METAL FINISHING REALLY NEEDED?
Neither the metal finishing industry nor the importance of its products to the Amer-
ican way of life are very well understood by the public. This is simply because metal-
finished components, though they add to the attractiveness of a major product and enable
it to become functional, in the end receive little attention, and the significance of their
contribution is lost. When the buyer admires the beauty, reliability, comfort, performance
and/or corrosion resistance of his purchase, he does not single out the metal finished
parts for commendation. Yet during all his waking hours, wherever he may be, he has
unwittingly come into contact with literally thousands of items which required metal finish-
ing or have metal-finished parts. They have become so much a part of his daily routine
that he tends not to notice them . . . the alarm clock, his tie pin, and belt buckle, a
drawer pull, the silverware, coffee pot, toaster, stove, dishwasher, refrigerator, lamps,
doorknobs, bathroom fixtures, telephones, radios, TV sets, his tools, automobile, even the
bridgework in his mouth . . . none of these are possible without metal finishing. Industry
itself, computerized, highly sophisticated by automation techniques, must rely on electro-
plated printed circuits, chrome plated dies, electroformed devices, cold formed parts made
possible by phosphate lubricity . . . indeed, it is held together by plated fasteners as is
our entire modern world. With this in mind, the preservation of the environment is not
likely to be achieved by having metal finishing vanish from the American scene. (Though
the term "metal finishing" implies that the basis materials to be "finished" are all
metallic in nature, we have included, as a matter of convenience, plastic basis materials
in this terminology, as plating on plastics has become a representative portion of the metal
finishing industry.)
WHAT IS METAL-FINISHING?
Metal Finishing is utilized to improve the surface of a basis material by:
1. Cleaning it.
2. Hardening or softening it.
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3. Smoothing or roughening it.
4. Depositing another metal on it by chemical exchange.
5. Electroplating another metal or series of metals on it.
6. Converting its surface by chemical deposition.
7. Coating it with organic materials.
8. Electrocoating it with organic materials.
9. Oxidizing by electrolysis.
These processes are more familiarly known as cleaning and pickling, annealing, case
hardening, polishing, buffing, immersion plating, electroplating, phosphating, conversion
coating, oxidizing, painting, electropainting, and anodizing.
The corresponding changes produced by these methods of metal finishing upon the
basis material serve to enhance the value of the treated item by providing such improve-
ments as:
1. Corrosion resistance.
2. Durability.
3. Esthetic appearance.
4. Electrical conductivity.
Such processes also fill many special engineering requirements of industry such as
stress relief, ductility, heat resistance, or the ability to stamp and form metal objects.
TYPE OF METAL FINISHERS
The metal finishing industry may be considered in three segments: large captive shops,
small captive shops, and job shops.
The large captive shop is usually a division of, or operated by, a major manufacturer
whose product requires metal finished items in quantity. These shops are to be found
generally in the automotive and appliance industries and are noteworthy because of the
size of their metal finishing facilities and the magnitudes of their daily production and
chemical consumption.
The small captive shops are usually minor adjuncts to their parent industries. Their
roles are to supply metal finished incidentals to the principal products. An example of
this type of captive shop might be found in the machine tool industry or in many of the
sports equipment manufacturing companies.
Where large corporations find it impractical to maintain their own captive metal fin-
ishing operations, the job shops serve as sources for satisfying their requirements for
metal finished parts.
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The job shops exist solely on profits accrued from metal finishing. Jobs are accepted
for metal finishing on a contract basis, and the job shop owner must be prepared to
serve a variety of industries.
His role does not end with the finishing of his customer's wares. For survival, he is
required to keep abreast of all changes in metal finishing technology and his products'
end-use requirements, thus serving his customers as supplier, inspector, and counsel, a
role which they themselves are loathe to countenance technically or endure financially.
CHEMICALS AND BASIS MATERIALS USED IN THE
METAL FINISHING INDUSTRY
Though the list of chemicals (See Appendix, Fig. 1) is not guaranteed to be compre-
hensive, it represents the great majority of potential pollutants with which we are con-
cerned as we consider plant waste control planning.
The types and quantities of materials and chemicals purchased furnish an excellent
key toward prediction of the process effluent characteristics. They also act as cross-checks
on the accuracy of effluent analyses. An attempt has been made to indicate the expected
environmental impacts of these materials when they become waterborne.
PROCESSING EQUIPMENT USED IN THE METAL FINISHING INDUSTRY
It is not convenient to the scope of this report to discuss entirely the great diversity
of equipment used in metal finishing. It is assumed that the reader needs no further
description of the type of processing which is performed by hand through a great variety
of tank-and-vat assemblies. Rather, it is hoped that the following scan of commonly used
automated equipment will enlighten and also invite increased awareness of the difficulties
to be met and resolved during the application of pollution control technology and equip-
ment to the metal finishing facility.
As is seen in Figures 2 through 7, (Appendix) the applicability of any of the automat-
ic finishing machines is directly dependent upon the quantity of production required in a
given length of time, the physical shape of the work pieces and the means by which they
are to be fixtured for processing, and, of course, the nature of the metal finishing re-
quired. From work pieces so tiny that they may scarcely be observed by the eye to items
weighing many tons apiece, all may be processed in variations of this basic line of
equipment.
From the effluent control standpoint, the type of machine chosen to be the most ef-
fective in fulfilling the desired production requirements will also have a marked effect on
the nature of-the effluent and the cost to handle it. For example, if a return-type auto-
matic is to be selected, it is convenient and inexpensive to incorporate counterflow rins-
ing, as the rinse tanks are very small, handle only a rack or two at a time, and do not
add a costly and- lengthy enlargement to the prospective machine. Programmed hoist
equipment requires rinse tanks large enough to handle a battery of racks, or a single rack
of long parts. To incorporate more rinse tanks so that counterflow water conservation
tactics may be employed inevitably implies larger initial capital outlays. On the other
hand, the motion of the hoist in transporting the work may be much more adaptable than
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the return-type automatic to delayed dwells in the "up" position, or to repeated dunkings
of the work in the same rinse before moving on to the next process.
With existing equipment, any rearrangements which may lend themselves to chemicals
and water conservation techniques should also be closely considered for what effect they
may have on:
a. Cost to make the change.
b. Cycle reprogramming.
c. Foundation updating.
d. Busswork and piping.
e. Ventilation.
f. Structural supports.
SOME METHODS FOR REDUCING OR ELIMINATING CHEMICAL WASTE
IN METAL FINISHING
I Process Substitution:
Wholesale substitution of low-concentration processes for those of high concentration
or processes containing non-toxic materials for those containing toxic constituents has
commenced only in recent years, inspired undoubtedly by the advent of pollution control
requirements. Unfortunately, the chemicals contained in the time-honored processes which
made the greatest contribution to a profitable and efficient metal finishing job were in-
variably the same chemicals causing the greatest adverse impacts to the environment as
wastes in the plant effluents.
Substitution, therefore, became practical only when it did not compromise the quality
of the metal finishing and was able to produce an environmental benefit. Perhaps the most
well known type of substitution in the past few years has involved cyanide plating baths,
principally those related to zinc. Elimination or reduction of cyanide was obtained by using
non-cyanide or low-cyanide-type processes. The non-cyanide baths offered complete free-
dom from cyanide but many of these processes employed chelating and sequestering addi-
tion agents to keep the zinc in a soluble form (one of the jobs formerly performed so well
by the cyanide.) Treatment of the resulting effluent hence became virtually impossible as
no means was at hand to remove the equally undesirable zinc from the waste water
stream. Since cyanide was also a good cleaner, the first few minutes of dwell-time in the
cyanide plating bath were cheerfully accepted as cleaning time to complete the job only
perfunctorily performed by the previous cleaning and pickling cycle. Without any cyanide,
substantial improvements were required in the pre-plating treatment steps to achieve good
metal finishing quality. Many different types of non-cyanide processes are now available.
Applicability of these processes must be weighed with due consideration of effluent im-
provement and process operational changes.
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The low cyanide processing solutions obviously do not offer complete relief from the
onus of cyanide in the effluent, but they can account for a substantial reduction in usage
(90% is achievable) and an equally substantial improvement in effluent quality. These baths
are not really substitutes but dilute versions of the baths they "replace." Tighter process
control is generally required when these baths replace conventional cyanide processes, but
the use of chelates may be avoided and the zinc disposal problem a solvable issue.
Other substitutes have found use in the industry. They are:
a. Non-phosphate cleaners.
b. Non-chromium bearing dips (in conversion coatings and anodizing.)
c. Non-cyanide stripping solutions.
d. Non-chromium bearing bactericides for cooling waters.
e. Non-cyanide gold and copper processes.
Some guideline questions should always be considered when substitution is contem-
plated ...
a. Will I eliminate one effluent problem and create another?
b. Do I fully understand the control problems which might accompany the change?
c. Have I sufficient man-hours available to handle tighter control requirements?
d. Will the substitution affect in any way the final quality of my product?
e. May I expect an increase in cost in my operation, or will I experience a
saving?
f. If I already have a waste treatment facility, what effect will the substitution
have on the treatment system when it is mixed with my normal waste flows?
g. Did I overlook any unforeseen ventilation or OSHA-related problem?
h. Have I calculated the cost of changing my equipment to accept the substitute
process?
II Process Solution Concentration — Minimum Limits:
Most processes offer a range of concentrations in which they may be operated suc-
cessfully. The industry has traditionally selected the midpoint in these ranges as the
operating concentration. With effluent standards and cost savings in mind, serious con-
sideration should be applied to operating the process solutions at their minimum con-
centrational limits. As an example, a standard nickel plating solution has the following
composition limits:
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OPERATING
CHEMICAL RANGE CONCENTRATION
Nickel Sulfate (NiS04.6H20) 40 to 50 oz./gal. 45 oz./gal.
Nickel Chloride (NiC12.6H20) 8 to 12 oz./gal. 10 oz./gal.
Boric Acid (H3B03) 6.0 to 6.5 oz./gal. 6.3 oz./gal.
At the above operating concentrations, a typical small plating shop running an aver-
age of twelve hours per day and two hundred and fifty days per year would experience an
annual loss of nickel salts (due to dragout) of approximately 8500 Ib. Nickel Sulfate and
1900 Ib. Nickel Chloride (based on the processing of 600 square feet/hour and a con-
servative dragout rate of 1.5 gal/1000 square feet.) Had minimum concentrations been
used for the year, the resultant saving in Nickel Salts would have been 950 Ibs. Nickel
Sulfate and 375 Ib. Nickel Chloride or a saving of about eight hundred dollars. If this
shop applied the same thinking to the other process solutions in the plating line, a major
improvement in operating costs is readily obtainable. Not considered in the improvement
is the potential cost savings in effluent treatment. All metal finishing operations merit
this type of assessment. If minimum concentration limits become the practice, tighter
process control should be expected and accommodated. Likewise, any possibility of a re-
duction in product quality due to mediocre process performance should be evaluated.
Ill Control of Dragout
Dragout is defined by KUSHNER1 as "the volume of solution carried over the edge of
a process tank by an emerging piece of work." There are several factors which influence
the rate of dragout. They are:
a. Velocity of withdrawal of the work pieces.
b. The geometry of the work pieces.
c. The positioning of the pieces on the rack or fixture.
d. The drainage time allowed over the process tank.
e. The viscosity and density of the process solution.
f. The temperature of the solution.
Many devices may be successfully used for dragout reduction. The velocity of with-
drawal of work from the process tank is least controllable when the metal finishing cycle
is operated by hand because of human fatigue. An excellent method of circumventing this
obstacle is to place a bar or rail above the process tank where the rack may be suspend-
ed for drainage while its predecessor is removed from the rail and transported to the
next phase of the finishing cycle. If, however, the equipment is automated, withdrawal may
frequently be slowed, without a subsequent loss of production, by reorganizing machine
motion. (Vendors of metal finishing machines can assist on these motion studies.) No
standard rule is available to accurately predict the amount of dragout volume to be saved
by a given reduction in withdrawal speed; noteworthy only is that a saving may be ex-
pected, the degree to be determined by the specific application.
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When the purchase of new equipment is being considered, withdrawal and drainage
times should merit close attention before a final design is chosen. This is especially im-
portant when related to bulk processing or barrel plating. Slow barrel rotation during
withdrawal has reduced dragout volumes by as much as 50%. Machines may be readily
automated to accommodate this type of rotation at the time of design.
In general, as the chemical content of a solution is increased, its viscosity increases,
resulting in a thickening of the film clinging to work withdrawn from the process solution,
and thus contributing not only to a larger volume of dragout, but more chemical wastage
in that volume, and increased difficulty with subsequent rinsing.
Temperature also has an effect on dragout. Elevating the operating temperature of a
process solution will result in diminished dragout by reducing viscosity. Care must be
exercised, when increasing temperatures, that bath performance remains unimpaired and
that the work pieces acquire no adverse surface conditions such as dry-on patterns.
A dilemma historically plaguing the metal finisher, especially in electroplating, has
always been the positioning of work pieces on a rack. The primary consideration in rack-
ing is proper exposure of the work to the anodes so that the coverage and thickness uni-
formity of the electrodeposit may be optimum. Drainage and rinsability figure in the
racking deliberations because of possible damage to the work piece surface by insufficient
or inefficient rinsing, or to succeeding process solutions by drag in of unremoved chemi-
cals from the previous solution. A contemporary consideration of chemical wastage is
now made more critical by potential effluent treatment costs. There is even the possibility
that the reduction of this wastage (and its attendant effluent purification costs) may in
some cases make the incipient difficulties of poorer coverage and plate distribution
acceptable.
Maintenance of racks, fixtures, and rack coatings, as an industry average, has been
generally poor. Transport of chemicals from one process to others underneath loose rack
coatings is not uncommon. Chromium-bearing solutions, for example, appearing in plant
effluents in spite of treatment systems designed to handle the normal chromium discharge
sources, have been traced to rinse tanks and process solutions remotely located from the
chromium discharge points, having arrived in these areas by the loose rack coating route.
Increased attention to rack maintenance will not only eliminate this potential hazard, but
it is certain to contribute to a welcome reduction in the numbers of work pieces rejected
because of poor contact.
KUSHNER1 has summarized dragout loss reduction principles with ten rules:
1. Keep the concentrations of all dissolved materials at the minimum value req-
uisite to the proper operation of the bath.
2. Do not add anything to a plating bath that does not perform a necessary function
in the same.
3. Operate the plating bath as hot as possible.
4. If there is a choice of conducting salts that can be used in a plating bath, use
the salts that give the greatest density and the smallest viscosity per unit
concentration.
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5. Make use of an effective wetting agent in the plating bath.
6. With a given, fixed time period allowed for withdrawal and drainage, use the
largest part of the period for withdrawal.
7. For minimum dragout, rack solid objects so that they are extended in area
rather than in depth.
8. Do not rack objects directly above each other so as to lengthen the drainage
path.
9. Tilt all solid objects with plane or singly curved surfaces so that drainage flow
is consolidated.
10. Every solid object, outside of a sphere, has at least one position in which
dragout will be at a minimum.
Significant chemical losses are also encountered in connection with the batch puri-
fications of process solutions in external storage tanks and the repacking of process filter
equipment. Process liquids entrapped in sludges and in discarded filter packs are re-
coverable by the simple expedient of flushing with water and returning the water, properly
filtered back to the process to replace evaporation losses. Such a practice becomes
doubly valuable when the eventual disposal of the sludges remaining after purification is
considered, as the presence of soluble metals or other toxic materials in these residues,
by today's standards, is generally forbidden by regulations for the disposal of solid wastes
to landfill sites.
PLANNING TO PREVENT POLLUTION CATASTROPHES
There is, of course, a great difference between the type of pollution which causes a
nuisance to the public domain by gradually altering the environment to which it has been
discharged, and a catastrophic pollution which causes not only a sudden and far-reaching
change in the environment, but also poses a direct and immediate threat to the health of
aquatic life and humans.
In the metal finishing plant, nuisance pollution is characterized by the daily flow of
waste rinse waters to the sewer, usually coupled with small-volume spillages incurred in
work piece transport between processes or during the addition of maintenance chemicals
to the processes themselves. Spent process solutions gradually discharged along with
waste rinse waters may also be considered nuisance pollution.
On the other hand, process solutions, containing concentrated toxic materials, dis-
charged suddenly and in large volume to the sewer, constitute potential catastrophic pol-
lution. When these discharges are deliberate, they result from human carelessness and
error, and may be eliminated only by stringent in-plant housekeeping measures. Electro-
mechanical devices strategically located within the plumbing system may sense the pass-
age of such discharges, but serve only to inform of the damaging event after its occurrence.
Accidental discharges of a catastrophic nature are far more insidious because they
are not predictable. Fortunately, they are very rare in this industry.
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Although revision of a plant to prevent both nuisance and catastrophic pollution is
more properly the province of the pollution control systems design engineer, as it is an
integral portion of his entire prospective treatment scheme, control measures should be
at least evaluated by the plant operator prior to design discussion. Such evaluations may
forestall delays and interruptions of his work schedule which otherwise may be caused by
the installation of the treatment systems.
Several general plans may apply as temporary catastrophic pollution prevention
techniques, i. e.:
a. All rinse waters are piped directly to the sewer (with plans to pipe these
rinse waters to their respective treatment plant areas once the waste treatment
system is designed and installed.) Thus, all floor exits to the sewer may be
plugged, preventing the escape of accidental spills of concentrated solutions.
Spent process solutions in this system are pumped to holding tanks for remov-
al by scavenger, or for treatment and gradual discharge. Floor sumps will be
required for sump pumps. Obviously, where both cyanide and chromium solu-
tions are in use, steps must be taken in floor segregation to assure that cy-
anide and alkali spent solutions are prevented from mixing with chromium and
acid wastes, thus avoiding the possibility of generating toxic hydrocyanic acid
gases. Separate drainage, sumps, and holding tanks would be provided for this
condition.
b. Another method is to install a large holding pit or lined lagoon located out-
side. All flows exiting from the plant would pass through this pit or lagoon be-
fore entering the sewer. Electromechanical devices for the measurement of pH
and conductivity would be installed prior to the holding area. Any sudden and
large variations in pH or conductivity sensed by the instruments would sound an
alarm and turn off all incoming water to the processing plant. The retention
time in the pit or lagoon would be sufficient to cushion and absorb the incoming
concentrated solution or "slug" without adverse effect at the outfall. Thus, the
slug would be retained in the holding facility for treatment or disposition.
c. A third means of attack is based on the supposition that the plant in question
has existing floor trenches through which all wastes are conveyed from the
plant, and that these trenches are large enough to be divided lengthwise into
two subtrenches. By this dividing technique, the outer side of the trench could
be used for rinse waters. The headers from the rinse water tanks could go
directly to this portion of the trench which would then be covered over to pre-
vent entry of floor spillage. The other half of the trench would remain open and
would be used as in part "b" above, i.e., ending in a sump. Accordingly, this
open portion of the trench would have no exit to sewer, and would catch all
solution dumps and floor spills for pumping to a disposition point elsewhere.
To increase awareness of potential pollutive sources within the plant, the following
suggestions for an investigative effort are made:
a. Begin by tracking all plant incoming water from its sources to its ultimate
destination.
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b. Don't overlook fume scrubbers, water-cooled rectifiers, heat exchangers,
boilers, heating and cooling coils, air conditioners, and welders.
c. Ascertain that all inlet water lines to process solutions have anti-syphon devices.
d. Inspect all heating and cooling coils for physical condition (conductivity meters
for leak detection will be required when a waste treatment system is installed.)
e. Thoroughly inspect all floors and foundations in the processing areas for pos-
sible leakage and consequent percolation to ground waters.
f. Check all chemical storage areas for compliance with safety regulations and
methods for handling "empty" and broken containers.
g. Make an inspection inside and out of all process tanks and filters for physical
condition. Check especially those tanks where processes are seldom if ever
removed. All piping should also be examined.
h. Record all data acquired with the foregoing steps. It will prove very useful later.
WATER CONSERVATION TECHNIQUES
Rinsing represents the most frequently used process in metal finishing. It is by far
the largest consumer of water, and has been given little or no consideration as a cost or
problem area. Abundance, ready availability, and low cost have historically contributed to
this inattention to plant water usage and to good rinsing practices. Hardening this attitude
has been the absence of any strictly enforced restrictions on the discharge of waste
rinse waters. Rinsing difficulties could always be overcome with more water . . . where
the water went afterward was a matter of no import. But today the environment commands
attention. Water usage and effluent water quality, thus, have become major factors in
profit and loss statements and are the principal determinants of the magnitudes of capital
expenditures for water pollution control systems.
Modern effluent regulations have eliminated any remaining possibility of continuing to
discharge untreated water. Open to question only is the nature and degree of treatment
which will be required. Of great economic consequence, therefore, is any reduction in
water usage which may be achieved through plant re-organization of rinsing practices. In
plants where there has been little attention to rinse flow rates, water conservation studies
have repeatedly shown that each rinse tank flow may usually be reduced by 50% or more
without impairment of rinsability. (In one large plant, a flow of 10,000 GPH was reduced
to 700 GPH before rejected work attributable to poor rinsing was detected.)
The objective of rinsing is to flush away and remove dissolved salts and solids
clinging to work pieces so that:
a. Coatings subsequently applied will bond properly to the work.
b. No unwelcome discoloration or chemical change will occur to the work surface
due to residual films.
c. Contamination of succeeding process solutions may be prevented.
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The objective in water conservation is to get the maximum amount of rinsing with
the least amount of water. Rinsing occurs at the work surface and is influenced by:
a. Exposure time of the work pieces to the water.
b. The amount of "fresh" water which may be brought to work surface during
the exposure time.
c. The temperature of the entering work pieces and the temperature of the rinse
water.
d. The shape of the work and its position on the rack or in the fixture.
Rinse water removes chemical films from work pieces by the process of diffusion.
The rate at which the film is removed is dependent upon the water solubility of the
chemicals in that film. The chemicals are thus absorbed into the body of the rinse water.
From a practical standpoint, there are a number of methods available (though, inexpli-
cably, seldom used) to improve diffusion and hasten the completion of the rinsing proc-
ess. Many of these methods also produce a dramatic reduction in water usage.
The most difficult part of water conservation is the first step, the determination of
minimum water usage for each rinse phase of the metal finishing cycle. "Minimum water
requirements" cannot be based on the supposition that the work pieces must be completely
free of any chemical films, for the amount of water to produce such work piece surfaces
is so great as to be economically intenable and probably unavailable. In actual practice,
a chemical film will almost always remain on the work after rinsing. The amount of film
which may be safely allowed to remain on the work is based upon two considerations:
a. Chemical films remaining after rinsing must not poison the succeeding process
to which the work pieces will be exposed.
b. These post-rinsing chemical films must not produce adverse effects on the
work piece surfaces themselves or cause underlying problems for subsequent
coatings to be applied on the work.
In short, one must reduce rinse water flow until the residual chemical film, because
of its concentration and/or thickness, begins to cause subsequent production problems.
Implicit to these considerations is the fact that each process and each plant is dif-
ferent; its production, work geometry, incoming water quality, processing equipment con-
figuration, even the protective coatings on incoming basis materials and storage prac-
tices, all will influence water requirements. Therefore, each plant operator will be obliged
to determine his own minimum water requirements step by step and rinse by rinse. A
stepwise logical approach might be:
1. Investigate plant chemical consumption records. Peak periods of chemical addi-
tions to process tanks and a rundown on parts which were metal finished dur-
ing these peak periods will help to locate the work producing the most dragout.
2. When this work is being run, select a rinse tank following a process whose
solution is known to be difficult to rinse (chromium or cyanide baths are good
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examples.) The rinse tank must have been cleaned and filled with fresh water
and then turned off. The level should be high enough to allow immersion of the
rack or barrel to the usual depth but should be low enough to prevent water
displaced by the immersion to overflow. Vigorous agitation of the work and/or
the rinse water is suggested. With the volume of water known by simple tank
measurement, and an analysis of the process bath preceding the rinse already
available, an analysis of one process bath constituent in the rinse water pre-
dicts all the other constituents by ratio, and establishes a highest-dragout vol-
ume figure. This figure may be assumed to be the dragout volume from each
of the rest of the metal finishing processes in the cycle where the same racks
or barrels are used. Although it is recognized that 100% removal of the chemi-
cal film may not always be removed in this single stagnant rinse, the operator
may exercise his own judgment on the efficiency of a second stagnant rinse for
dragout determination. A hose might be used (as a second rinsing) as the work
is being withdrawn, the water used to be collected, measured for volume, and
analyzed as before.
3. When the volume of dragout has thus been established, its concentrations in the
case of every process bath should be arithmetically adjusted to the highest
levels at which any of these baths might be operated. A similar dragout deter-
mination should be considered wherever a different line is involved and the
work processing motions and fixtures are likewise different. (Dragout figures
thus achieved are of paramount importance in the successful design of waste
treatment systems.)
4. With the dragout concentrations and volumes now known, reduction of water us-
age in rinse tanks may commence. Existing rinse water flows must be meas-
ured. In the absence of flow meters, two techniques may be used successfully.
The first involves physical measurement of the working volume of the rinse
tank, a lowering of the rinse water level to a measured depth (at the end of
the working day after the water has been turned off) and a measure (at the be-
ginning of the next day when the water is turned on again) of how long it takes
to fill the tank again to operating level. This method is effective when rinse
tank outlet headers are permanently piped into the exit trench or sewer. A
variation of this method is to insert a five gallon bucket into the flowing rinse.
By withdrawing five gallons of rinse water rapidly, one may time the period
required for five more gallons of rinse water in the rinse tank to reach over-
flow levels again. This test must be repeated several times and the results
averaged because it is difficult to visually ascertain the exact time at which
the flow over the overflow dam has reached a stabilized flow condition.
The second method involves a five gallon bucket and a stopwatch for measure-
ments at the overflow outlet. An alternative method is to buy a flow meter and
use it in each of the incoming rinse water lines, one by one, until the neces-
sary information is obtained.
All flow rate measurements should be carefully recorded as well as readings
at the water main. Now the actual reduction of rinse flows may begin. This is
the most difficult phase of the entire conservation and abatement operation. It
is laborious, because each rinse must be carefully observed during the gradual
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day-to-day reduction in flow rate so that the effect on the work and/or the
succeeding process may be duly noted as the moment arrives when poor rins-
ing begins to cause rejections. The strictest discipline must be maintained in
the plant by the operating personnel so that the cause for rejection may be
traced to its true source. Valve settings on rinse water lines must be under
the specific control of the person charged with water conservation, and tam-
pering should not be tolerated. As the maximum reduction in flow rate for each
rinse is revealed and the readings recorded, rinse water flows may be advanc-
ed slightly to prevent further rejection. At this juncture, if no further con-
servation measures are to be considered, flow restrictor valves should be in-
stalled in all rinse tank incoming water lines. Several types are available
which not only restrict water flow to a fixed maximum output, but also will
automatically adjust to changes in water main pressure, even act simultan-
eously as syphon breakers, and are tamperproof. Flow meters may be used,
in conjunction with normal valving, to control flow, having the advantage of
advancing flow rates when desired, but are not tamperproof and are much
more expensive. (It should be duly noted that up to the point of installing valves
or meters, no money has been spent except in the necessary labor. It is also
likely that the average plant, upon concluding this first water conservation ef-
fort, will achieve a reduction of about 50% in its water usage. An average plant
whose total flow rate is 100 GPM can thus save approximately 50 GPM, and,
based on 3000 operating hours per year and a water charge of $0.25/1000 gal.,
an annual saving of over $2000.00 is achieved. The same reduction in water
usage will cut the capital costs of a waste treatment system in half ... for
the average plant, that saving can amount to $40,000.00!)
Further and equally dramatic reductions in water consumption are achievable
through the use of mechanical devices and equipment rearrangements such as:
a. Counterflow multiple tank rinsing. (Appendix, Figs. 8 and 9)
In counterflow rinsing, used water exiting the first tank becomes feed water
for the second, and after being used again, feeds the third tank, and so on.
The advantage of counterflow rinsing is in the repeated exposure of the work
pieces to the water, the increase in dwell time, permitting more diffusion to
occur, and the ability to bring the majority of the water passing through into
more intimate contact with the'work. The results in water saving are gratify-
ing. For example, if a dragout of 1 gal./hour in a given case required a
1000 to 1 dilution in order to produce acceptable work, 1000 gallons of rinse
water per hour would be required in a single rinse tank; in a double counter-
flow rinse system, 30-35 GPH are required, and in a triple counterflow rinse
system, 8-12 GPH are needed. The disadvantage is that the work requires two
or three processing steps instead of one, and more equipment and space is
also mandatory. If multiple counterflow rinsing is designed into prospective
automatic metal finishing equipment, the initial disadvantages are increased
capital expense and space requirements. The ultimate advantage lies not only
in the enormous drop in water costs, but also in a sharp reduction in the
cost of the supporting waste treatment system. Additionally, the curtailment
of water volume makes the use of waste recovery systems more inviting.
13
-------
b. Multiple tank rinsing (Appendix, Fig. 10)
This type of rinsing is merely a battery of single rinses, each with its own
feed waters. The principles are generally the same as in "a" above, although
the total reduction in water consumption will not be as great as with the
counterflow system.
c. Spray rinsing: (Appendix, Fig. 11)
Two categories of spray rinsing may be used. The first, impact spraying,
uses both impact and diffusion to remove contaminant films. It uses little
water compared to immersion rinsing, and may be used in some cases as a
recovery rinse by pumping the collected spray volume into the previous proc-
ess tank, but is disadvantaged when the work pieces have areas inaccessible
to the spray nozzles.
The second method, rinse and spray, employs immersion rinsing followed by
a spray operational only when the work is withdrawn from the rinse tank. It
is advantageous in removing stubborn films by impact and permits lower
water flows in the main body of the rinse tank.
d. Fog rinsing (Appendix, Fig. 12)
Fog rinsing finds utility at exit stations of process tanks. A fine fog is spray-
ed on the work, thus diluting the dragout film and causing a runback into the
process solution. Fog rinsing finds application in those instances where proc-
ess operating temperatures, high enough to produce a high evaporation rate,
allow replacement water to be added to the process in this manner. Fog rins-
ing also prevents dry-on patterns by cooling the work pieces. To be effective,
fog rinsing requires a slow rate of withdrawal of the work from the process
tank.
e. Chemical rinsing (Appendix, Figs. 13 and 14)
The principle of Chemical rinsing has been used by the metal finishing in-
dustry for many years. One of the oldest applications of this principle was
used quite effectively to eliminate staining from the chromium solution, notor-
iously difficult to rinse. By the simple expedient of making the first rinse
after chromium plate a stagnant rinse containing sodium bisulfite, the drag in
of hexavalent chromium was converted to trivalent chromium. Thus, the rins-
aoility of the work in the second rinse was improved considerably by:
a. Changing the chemical nature of the film on the work in the stagnant
rinse, and
b. Reducing film concentrations before attempting to rinse by diffusion. The
same principle is frequently employed in "neutralizing" dips.
The application of chemical rinsing to plant effluent treatment has been well
described by LANCY2,3,4 and PINNER5 and is known as "Integrated Waste
Treatment" in the industry. Aside from the environmental benefits thus
14
-------
achieved, this type of chemical rinsing also prevents the majority of heavy
metal solids formed in the chemical rinse from reaching the succeeding water
rinses by removing these materials in an external settling vessel. This is
accomplished by flowing the chemical rinse solution to a treatment reservoir.
The overflow from the reservoir is pumped back to the rinse tanks forming
a complete closed-loop system. Chemicals are added to the reservoir to pro-
vide a controlled excess of reagent in the solution. The reservoir acts as a
combined reaction and settling tank. Because of the presence of a controlled
excess of reagents in the chemical rinse tank, toxic materials and heavy
metals are removed from the metal finishing sequence and are prevented
from entering the subsequent water rinse. At the same time rinsing is im-
proved due to the fact that the diffusion layer, which is present during con-
ventional water rinsing, is broken down by the chemical reaction.
Such equipment rearrangements and additions, as water conservation measures, are
capable of reductions in water use of up to 90%! Additionally, the saving related to
prospective capital outlays cannot be calculated solely in terms of reduction in equipment
size; it can make the difference between satisfying effluent control demands or closing
the metal finishing plant, if considered only from the standpoint of available plant space.
The basis for future effluent control systems design, likewise, may be radically changed
by the skillful application of conservation techniques.
Other devices which assist in the improvement of rinsing are:
a. Agitation of the work in the rinse tank.
b. Air agitation of the rinse water.
c. Hydraulic agitation of the rinse water.
d. Agitation through mixers or impellers.
e. Ultrasonic agitation.
f. Elevation of rinse water temperature.
g. Use of rinse aids and wetting agents.
h. Recirculation and reuse of rinse water using ion exchange.
No consideration has been given here to the possibilities of reusing treated water
from a prospective effluent treatment facility to achieve yet a further reduction in water
purchases. An accurate assessment of the volume and quality of reuse water from this
source cannot be made until the design concept for a treatment system has been decided.
The treatment methods chosen will determine the quality of the treated water and the
selection of rinse tanks where it may be safely used. Nonetheless, the prospect of re-
covered water must be considered as a factor during water conservation planning
endeavors.
When the foregoing water conservation practices have been concluded, the compiled
data will supply the necessary ingredients to predict rinse water volumes required when
15
-------
the new work pieces and racking produce a change in dragout conditions. Only the new
dragout volume and concentration need be determined by actual analysis (as defined earlier
in this presentation). Formulae6,7,8 may then be applied to calculate the flow rate
required, and the proper restrictor valve settings may then be applied.
UPDATING METAL FINISHING AND POLLUTION CONTROL AT COMPANY X
At a meeting of the Board of Directors of Company X on October 18, 1971, the major
topic of discussion was pollution control and what to do about it Everyone agreed that
something should be done, but since very little pressure had been received by Company
X from the people down at the sewage works to clean up the Company's discharges, (and
besides, there were no clear rules or recommendations to date which pointed the way to
doing a once - and • for • all job on pollution control), there was an understandable
reluctance to spend money when the goal was not clear and it didn't make a profit.
The conclusion of the Board on that day was that it would be necessary to appoint a
responsible member of middle management to the task of finding out what the scope of
their problem was, and then, how they could reduce the amount of pollution and get ready,
once the oncoming regulations applying to them became known, to put in pollution control
systems. If, at the same time, a way could be found to reduce the waste of the Company's
chemicals and water, so much the better.
To accomplish their objectives quickly and expeditiously, they selected an aggressive
young manager. His primary responsibility was to define the plant's environmental prob-
lem ... if time remained to perform his other duties, fine ... if not, those duties
would be assigned to someone else. In addition, he was told that all future environmental
considerations affecting the operations of Company X would be his responsibility ... in
effect, he became the new Pollution Control Officer reporting directly to the President
and Chairman of the Board. He was given the authority to require the cooperation of all
plant personnel to accomplish his mission.
The first step was to develop a Site Plan (See Appendix, Fig. 15) to show
a. Where the waterborne wastes came from and where they were going.
b. Where the plant boundaries were.
c. What usable space was available for future pollution control equipment.
d. What influence the topography might have on drainage.
Several more points were revealed during the site investigation:
a. There was no manhole at the point where the plant industrial sewer joined the
interceptor, and thus, no easy way to sample the effluent for analysis or to
determine the flow rate. A design for a manhole was obtained from the City
Sanitary Department; it included a calibrated V-Notch weir and provisions for
monitoring equipment.
b. It was possible during a rain to have drainage from a chemical storage area
for "empty" containers run into a ditch leading to a small creek.
16
-------
c. The water table at the outside area assigned to future pollution control equip-
ment was more than thirty feet down.
Next came a sketch and study of the Equipment Layout (See Appendix, Fig. 16), which
included:
a. The location of each waste producing piece of equipment
b. The processing cycles.
c. The production from each cycle.
d. The location of accessory equipment.
The geography of the equipment would prove useful when the time came to move pol-
lution control equipment into the plant. Updating of this layout print whenever any equip-
ment changes occurred would prevent the appearance of an obstacle (where no obstacle
was supposed to be) thus confounding the installation engineer. (The importance of this
document to a pollution control systems design engineer is incalculable ... it has a
major influence on the selection of both treatment concept and equipment.) Recorded also
at this time was information concerning:
a. Plant electrical power and capacity.
b. Steam availability.
c. Head space and usability.
d. Support column locations.
Since four major metal finishing lines were to be examined, it was decided to look
at them one at a time. Hence, an individual equipment layout in each case was drawn. The
Nickel-Chromium Plater (See Appendix, Fig. 17) (including its Rack Strip Line) began the
parade. The object was to determine and record what was in each process tank in terms
of major chemical constituents, when spent processes were dumped, how much rinse water
was being used, and what volume of dragout was being developed. To accomplish the first,
a record of purchases of all chemicals and basis materials for 1971 was obtained from
the Chief Buyer, and matched with the Metal Finishing Department's record of additions to
the various tanks. Where proprietary materials were involved, the suppliers of those ma-
terials were contacted for information on the principal ingredients.
Next came the determination of dragout and process dumping schedules (See Appendix,
Fig. 18). In this line, the chromium plating solution was chosen for the measurement, and
used as the criterion for the other process dragout volumes in the line. No substitutions
were contemplated, but plans were made to investigate the applicability of phosphate-free
cleaners. All processes were reduced to their minimum concentrations, and a fog rinse
was installed at the exit station of the nickel.
Attention now turned to the rinse flows (See Appendix, Fig. 19). Gradual reduction
of these flows over a period of five weeks produced an average cutback for the entire
line of 910 GPH or approximately 55%.
17
-------
In the Zinc Plater, (See Appendix, Figs. 20, 21, 22) the same procedure was used.
The Cyanide Zinc solution was replaced with a non-cyanide non-chelated alkaline zinc
process and the chromates were made to last 50% longer by altering the baths with
inhibitors and increasing up-dwell time over them. Double-dunking is now being consider-
ed in selected rinses.
Rinse flow reduction amounted to an aggregate of 1400 GPH or about 45%.
The Phosphater (See Appendix, Figs. 23, 24, 25) did not have any substitution of
process. Rinse water flow was reduced by 750 GPH or about 40%. It was discovered that
the cleaners would last for ten days if small frequent additions of replenishment cleaner
were made. This resulted in a 50% saving by decreasing the frequency of the discard of
spent process.
Only a small saving was realized in the Anodizer (See Appendix, Figs. 26, 27, 28).
The Desmutter was replaced by a chromium-free process and a reduction in water usage
of 80 GPH or about 35% was realized.
After the rinse water conservation program was completed, several remedial meas-
ures were taken to prevent the new housekeeping attitude from having a relapse:
a. All incoming rinse water lines were equipped with restrictor valves.
b. All hoses were spring loaded so that they could not be abandoned in a running
condition.
c. All the rinse water mains leading to each automated line were equipped with
solenoid valves connected to the control panels of each machine. When the ma-
chines were not operating during breaks or lunch periods, the valves auto-
matically shut off rinse water flow.
d. An investigation is now being carried out to determine the advisability of
conductivity cells for the rinse tanks.
e. Areas between adjacent tanks (where spillage and drippage from work in trans-
fer could fall to the floor) were equipped with troughs to catch such drippage
and let it drain back to the process where it had originated.
f. All naked anode rails were taped to prevent erosion of contaminating metals
into the processes they served.
g. Tank covers furnished with original equipment, and long since removed from
the tanks, were returned to their intended purpose.
h. Chemical definitions of all protective oils or drawing and stamping compounds
used either in the plant, or by vendors were obtained, tested for ease of re-
moval, and catalogued. Vendors and plant personnel alike were expressly for-
bidden to change the composition of any of these coatings without notifying the
plant chemist and the pollution control group. Similarly, changes in metal fin-
ishing process compositions could not be made without approval by the pollu-
tion control group.
18
-------
Company X, in the first year of operation since these changes were made, has saved:
a. By lowering water usage $4,300.00
b. By reducing chemical use $5,800.00
c. By a 1.7% drop in overall rejection rate $7,700.00
Total $17,800.00
What is more important, Company X had only a few more chores to perform and it
would be ready for pollution control design. A foundation plan (See Appendix, Fig. 29)
was needed so that a design engineer could make recommendations on the segregation
of accidental spills and also the most convenient disposition of spent processes. The
problem of catastrophe prevention would require a long look at the types of coatings
available for floor and foundation protection. Though Company X had never experienced
a catastrophic spill in its seventeen years of operation, it was painfully evident to the
Board of Directors that the existing foundation plan did not offer safety, should the seven-
teen-year record be inadvertently ended. (And too, the City had just received funds to
erect a secondary treatment system complete with bugs which eat sewage, but don't
much like metal finishing wastes.) The foundation plan, however, did lend itself to the
temporary piping of all rinse waters to the underground pipes leading to the interceptor.
Thus, the trenches could house the rinse water pipes and also be used to convey floor
spills and dumps to blind sumps from which they would be pumped into holding tanks for
disposition. This plan is now being implemented by Company X.
All that now remained was to tabulate each toxic material (See Appendix, Fig. 30) by
reviewing materials purchased and process composition. The tabulation accurately predicts
the quality of the effluent. With the new manhole now installed, Company X is recording
flow rates exiting from the plant. Composite samples are being taken by means of a
twenty-four hour sampler recently purchased. Quantitive results will soon be available.
Because Company X took the time to survey its plant and its chemical usage, the need for
extensive and expensive effluent sampling has been greatly reduced. Effluent sampling
will confirm by analysis the accuracy of the earlier dragout determinations. The record
on the contents of each process and Company X's purchases will tell the analyst what he
must search for in the samples.
The Company has now turned its attentions -to developments in environmental regula-
tions . . . plans for Company growth will be influenced . . . but Company X now has
bought the time to weigh these plans carefully, the time to examine the field for firms
whose capabilities in environmental control design will successfully conclude the work it
has started. Company X is also satisfied that when the control system it chooses is
installed, it will be able to accommodate the work without any serious interruption in
normal production.
Company X reckons that it has spent almost $6,000.00 in manhours, analysis, and
some equipment. It has discovered many serious lapses in production techniques during
the investigation. It has eliminated any reasonable possibility of catastrophic pollution.
Most of all, Company X is ready for the future.
19
-------
BIBLIOGRAPHY
1J. B. Kushner, Metal Finishing, pgs. 59, 60, 61, 64, November and December 1951.
2L. E. Lancy, Metal Finishing, 1951, pgs. 49(2), 56.
3L. E. Lancy and H. F. Hanson, Plating, 1952, pgs. 39, 210.
4L. E. Lancy, Sewage and Ind. Wastes, 1954, pgs. 26,1117.
5R. Pinner, Electroplating and Metal Finishing, 1967, pg. 20, July, August, September.
6 A. F. Mohrnheim, Plating, 1969, June, pgs. 715-718.
7 J. B. Kushner, Metal Finishing, 1955, January, pgs. 715-718.
8J. A. Tallmadge and B. A. Buffham, Journal of Water Pollution Control Federation, 1961,
August, pgs. 817-828.
Prepared by:
Alan E. Olsen
Director, Environmental Services Group
Oxy Metal Finishing Corporation
20
-------
APPENDIX
-------
FIGURE 1
SOME CHEMICALS USED IN THE METAL FINISHING INDUSTRY
CHEMICAL
Aluminum Potassium Sulphate
Aluminum Silicate
Ammonium Acetate
Ammonium Bifluoride
Ammonium Chloride
Ammonium Citrate
Ammonium Hydroxide
Ammonium Molybdate
Ammonium Nitrate
Ammonium Sulfate
Anisic Aldehyde
Antimony Potassium Tartrate
Barium Carbonate
Barium Sulphate
Benzene (Benzol)
Boric Acid
Cadmium Cyanide
Cadmium Sulfate
Calcium Nitrate
Chromic Acid
Citric Acid
Cobalt Carbonate
Cobalt Sulfate
Cupric Sulfate
Diammonium Phosphate
Ferric Nitrate
Fluoboric Acid
Formaldehyde
Glue
Glycerine
Hydrazine Sulfate
Hydrochloric Acid CP
Hydrofluosilicic
Hydrogen Peroxide
Hydroxyacetic Acid
Hypophosphorous Acid
PH
ADJUSTMENT
REQUIRED
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
CYANIDE
OR
CHROMIUM
TREATMENT
REQUIRED
X
X
LEGEND
MS — Metal Sludge NH3 — Ammonia
DS — Dissolved Solids O — Organic Mailer
WASTE PRODUCTS
MS DS
MS DS
DS NH3
MS DS NHg
DS NH3
DS NHg O
DS NHg
MS DS NHg
DS NHg
MS DS NHg
MS DS 0
MS
MS
O
DS
MS DS
MS DS
DS
MS DS
DS O
MS
MS DS
MS DS
MS DS NHg
MS DS
MS DS
O
O
0
DS
DS
MS DS
DS O
MS DS
-------
FIGURE 1 (Cont'd.)
CHEMICAL
Indium Sulfate
Iron Oxide
Isopropanol
Lard Oil
Lead Fluoborate
Lead Oxide
Lime (Calcium Hydroxide)
Magnesium Sulfate
Manganese Carbonate
Manganese Sulfate
Methanol
Monoammonium Phosphate
Nickel Carbonte
Nickel Chloride
Nickel Sulfate
Nickel Sulfamate
Nitric Acid
Oxalic Acid
Phosphorous Acid
Potassium Bromate
Potassium Citrate
Potassium Chloride
Potassium Copper Cyanide
Potassium Cyanide
Potassium Ferricyanide
Potassium Hydroxide
Potassium Phosphate
Potassium Stannate
Potassium Thiocyanate
Sodium Acid Pyrophosphate
Soda Ash (Sodium Carbonate)
Sodium Bicarbonate
Sodium Bisulphite
Sodium Bifluoride
Sodium Citrate
Sodium Copper Cyanide
PH
ADJUSTMENT
REQUIRED
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
CYANIDE
OR
CHROMIUM
TREATMENT
REQUIRED
X
X
X
X
LEGEND
MS— Metal Sludge NH3— Ammonia
DS — Dissolved Solids O — Organic Matter
WASTE PRODUCTS
MS DS
MS
O
O
MS DS
MS
MS
MS DS
MS
MS DS
0
MS DS NH3
MS
MS DS
MS DS
MS DS
DS
MS DS
MS DS
DS
DS O
DS
MS DS
MS DS
MS DS
DS
MS DS
MS DS
DS
MS DS
DS
DS
DS
MS DS
DS O
MS DS
-------
FIGURE 1 (Cont'd.)
CHEMICAL
Sodium Cyanide
Sodium Dichromate
Sodium Fluoborate
Sodium Gluconate
Sodium Hexametaphosphate
Sodium Hypophosphite
Sodium Hydrosulphite
Sodium Hydroxide (Caustic Soda)
Sodium Metasilicate
Sodium Molybdate
Sodium Nitrate
Sodium Orthosilicate
Sodium Polysulfide
Sodium Stannate
Sodium Sulfate
Sodium Sulfide
Sodium Sulfite
Sodium Tripolyphosphate
Stannous Fluoborate
Stannous Sulphate
Stearic Acid
Sulfamic Acid
Sulphur (Liquid)
Sulphuric Acid
Tallow Glyceride
Tartaric Acid
Tetrapotassium Pyrophosphate
Tetrasodium Pyrophosphate
Toluene (Toluol)
Trichlorethylene
Trichloroethane
Trisodium Phosphate
Xylene (Xylol)
Zinc Chloride
Zinc Cyanide
PH
ADJUSTMENT
REQUIRED
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
CYANIDE
OR
CHROMIUM
TREATMENT
REQUIRED
X
X
X
LEGEND
MS— Metal Sludge NHs— Ammonia
OS — Dissolved Solids O — Organic Matter
WASTE PRODUCTS
DS
MS DS
MS DS
DS
MS DS
MS DS
DS
DS
MS DS
MS DS
DS
MS DS
MS DS
MS DS
DS
MS DS
DS
MS DS
MS DS
MS DS
O
DS
MS
MS DS
O
O
MS DS
MS DS
O
O
0
MS DS
0
MS DS
MS DS
-------
d!
TYPE AUTOMATIC
jty Rack Applications
Fig. 2
-------
CONVEYORIZED AUTOMATIC LOADING
AND UNLOADING
Fig. 2A
-------
SIDE ARM RETURN TYPE AUTOMATIC
SYSTEMS
Heavy Duty Applications
-------
PROGRAMMED AUTOMATIC HOIST SYSTEM
Heavy Duty Applications
-------
YPICAI H =AVY DUTY APPIICA1 ION
-------
PROGRAMMED HOIST SYSTEM
Bulk Finishing Applications
-------
PROGRAMMED AUTOMATIC HOIST SYSTEM
Bulk Finishing Applications
Fig. 6
-------
OBLIQUE BARREL AUTOMATIC SYSTEM
Bulk Finishing Applications
-------
SINGLE RINSE
OUTGOING WATER
MOVEMENT
INCOMING WATER
Fig. 8
DOUBLE COUNTERFLOW
OUTGOING WATER
--»--» WORK MOVEMENT
INCOMING WATER
Fig. 8A
-------
TRIPLE COUNTERFLOW
OUTBOARD TRIPLE COUNTER FL
-------
WORK MOVEMENT
INCOMING
WATER
OUTGOING WATER
Fig. 10
-------
SPRAY RINSING
INCOMING
WATER
IMPACT SPRAY
RINSE AND SPRAY
OUTGOING WATER
Fig. 11
-------
ORK MOVEMENT
PROCESS TANK
Fig. 12
-------
CHEMICAL RINSING
WORK MOVEMENT
RINSE WATER
PROCESS TANK
CHEMICAL RINSE
r
,
OUTGOING WATER
PERIODIC BATCH DUMP
Fig. 13
-------
INTEGRATED CHEMICAL RINSE
WORK MOVEMENT
CHEMICAL RINSE
PROCESS
TREATMENT CHEMICAL ADD-
OUTGOING WATER
-------
EMPLOYEE
PARKING
SHIPPING
DOCK
VISITOR PARKING
SHIPPING
& RECEIVING
• FUTURJ :
PUflff"
or EQUIP.
UTSI
AVAILABLE FOR
WASTE TRIATMEN
L
Company X Site Plan
-------
JMPANY X EQUIPMENT LAYOUT
ZINC COOLING SYSTEM
NICKEL-CHROMIUM PLATER (AUTOMATIC)
45 RACKS/HR.-16 HR./DAY
6 SO. FT./RACK. MAX.
WORK PIECES-STEEL STAMPINGS
BARREL ZINC PLATER (AUTOMATIC)
12 BARRELS/HR.-16 HR./DAY
300 LB./BBL. MAX.
WORK PIECES-STEEL FASTENERS
BARRELSIZE-18"x36"
BARREL PHOSPHATER (AUTOMATIC)
10 BARRELS/HR.-16 HR./DAY
500 LB./BBL. MAX.
WORK PIECES-STEEL THREADED FASTENERS
BARREL SIZE-18" x 30"
ANODIZER (MANUAL HOIST)
2 LOADS/HR.-8 HR./DAY
50 SO. FT./LOAD MAX.
WORK PIECES-ALUMINUM STAMPINGS
•3 0
Fig. 16
DEIONIZER
-------
NICKEL-CHROMIUM PLATER
PROCESS COMPOSITION
8 OZ/GAL
SODA ASH
CONC.
NITRIC ACID
(PROPRIETARY
ADDITIVES)
12 OZ/GAL
CAUSTIC SODA
SODA ASH
PHOSPHATES
SILICATES
SURFACTANTS
SAME AS (6)
SAME AS (3)
30% BY VOL.
HYDROCHLORIC
ACID
12 OZ/GAL
CAUSTIC SODA
SODA ASH
PHOSPHATES
SILICATES
SURFACTANTS
[0X0]
50 OZ/GAL NICKEL SULFATE
12 OZ/GAL NICKEL CHLORIDE
7 OZ/GAL BORIC ACID
PROPRIETARY ADDITION AGENTS
O
50 OZ/GAL CHROMIC ACID
CATALYST (SULFURIC ACID
AND FLUORIDES)
(PROPRIETARY)
12 OZ/GAL
CAUSTIC SODA
SODA ASH
SURFACTANTS
PHOSPHATES
GLUCONATES
Fig. 17
-------
NICKEL-CHROMIUM PLATER
AND RACK STRIP
DUMPING SCHEDULE — SPENT PROCESSES
300 GAL.
QUARTERLY
1300 GAL. (EST.)|
MONTHLY
1100 GAL. (EST.)j
MONTHLY
NICKEL STORAGE
190 GAL.
I MONTHLY I
190 GAL.
TWICE
WEEKLY
190 GAL.
WEEKLY
540 GAL.
I MONTHLY!
[o][oi
NOT DISCARDED!
NOT DISCARDED
PROCESS
1. SOAK CLEAN
2. C.W. RINSE
3. ANODIC CLEAN
4. C.W. RINSE
5. C.W. RINSE & SPRAY
6. ACID
7. C.W. RINSE
8. C.W. RINSE & SPRAY
9. ANODIC CLEAN
10. C.W. RINSE & SPRAY
11. ACID
PROCESS
TANK
CAPACITY
1100 GAL.
540 GAL.
190 GAL.
190 GAL.
190 GAL.
PROCESS
12. C.W. RINSE
13. NICKEL PLATE
14. DRAGOUT
15. C.W. RINSE
16. C.W. RINSE
17. CHROME PLATE
18. DRAGOUT
19. C.W. RINSE
20. C.W. RINSE & SPRAY
21. H.W. RINSE
22. LOAD & UNLOAD
PROCESS
TANK
CAPACITY
3300 GAL.
560 GAL.
190 GAL.
=
•
• PRO
I
3
1 J.
1 4.
u
6.
7.
8.
••
RACK STRIP
1. CHROME STRIP
DRAIN
C.W. RINSE
NICKEL STRIP
C.W. RINSE
NEUTRALIZE
C.W. RINSE
H.W. RINSE
RINSE
TANK
CAPACITY
300 GAL.
300 GAL.
300 GAL.
300 GAL.
-------
NICKEL-CHROMIUM PLATER
AND RACK STRIP
RINSE WATER DATA
2 GPH ^B 10 GPH | 10 GPH
10 GPH H^^
RINSE
TANK
PROCESS CAPACITY
1. SOAK CLEAN
2. C.W. RINSE 190 GAL.
3. ANODIC CLEAN
4. C.W. RINSE COUNTERFLOW 190 GAL.
5. C.W. RINSE 190 GAL.
& SPRAY
6. ACID
7. C.W. RINSE] 190 GAL.
8. C.W. RINSE COUNTERFLOW 190 GAL.
& SPRAY
9. ANODIC CLEAN
10. C.W. RINSE & SPRAY 190 GAL.
••^•••••••^•••B
PROCESS
12. C.W. RINSE
•••••••••••••••••••••••I
RINSE
TANK
CAPACITY
190 GAL.
13. NICKEL PLATE
14. DRAGOUT
15. C.W. RINSE
16. C.W. RINSE
190 GAL.
190 GAL.
17. CHROME PLATE
18. DRAGOUT
19. C.W. RINSE
20. C.W. RINSE
& SPRAY ,
21. H.W. RINSE
COUNTERFLOW 190 GAL.
HAUK Sll
PROCESS
1. CHROME STRIP
2. DRAIN
3. C.W. RINSE
4. NICKEL STRIP
5. C.W. RINSE
6. NEUTRALIZE
7. C.W. RINSE
8. H.W. RINSE
______________________
190 GAL.
HP ^^
RINSE
TANK
CAPACITY
300 GAL.
300 GAL.
300 GAL.
300 GAL.
•••••••••••••••
22. LOAD & UNLOAD
11. ACID
-------
ZINC PLATER
PROCESS COMPOSITION
6 OZ/GAL ZINC METAL
10 OZ/GAL CAUSTIC SODA
12 OZ/GAL CYANIDE
CARBONATES
PROPRIETARY ADDITIVES
30% BY VOL.
HYDROCHLORIC ACID
12 OZ/GAL
CAUSTIC SODA
SODA ASH
SURFACTANTS
PHOSPHATES
GLUCONATES
10 OZ/GAL SODIUM DICHROMATE
3 FL. OZ/GAL NITRIC ACID
1 OZ/GAL SODIUM DICHROMATE
2 FL. OZ/GAL NITRIC ACID
12 OZ/GAL
CAUSTIC SODA
SODA ASH
PHOSPHATES
SILICATES
SURFACTANTS
Fig. 20
-------
BARREL ZINC PLATER
DUMPING SCHEDULE — SPENT PROCESSES
BB a a__a
220 GAL.
TWICE
WEEKLY
NOT DISCARDED
265 GAL.
WEEKLY
220 GAL.
DAILY
220 GAL.
TWICE
WEEKLY
300 GAL.
WEEKLY
PROCESS
1. LOAD & UNLOAD
2. SOAK CLEAN
3. C.W. RINSE
4. ACID PICKLE
5. C.W. RINSE
6. C.W. RINSE
7. P.R. ELECTRO CLEAN
PROCESS
TANK
CAPACITY
300 GAL.
220 GAL.
265 GAL.
220 GAL.
DAILY
PROCESS
TANK
CAPACITY
9. ZINC PLATE
10. C.W. RINSE
11. C.W. RINSE
12. CHROMATE I
13. CHROMATE II
14. C.W. RINSE
15. W.W. RINSE
1800 GAL.
220 GAL.
220 GAL.
220 GAL.
8. C.W. RINSE
Fig. 21
-------
BARREL ZINC PLATER
RINSE WATER DATA
300 GPH
3270 GPH
•mi
850 GPH
300 GPH
120 GPH
850 GPH 850 GPH
_J
PROCESS
RINSE
TANK
CAPACITY
1. LOAD & UNLOAD
2. SOAK CLEAN
3. C.W. RINSE 220 GAL.
4. ACID PICKLE
5. C.W. RINSE COUNTERFLOW 220 GAL.
6. C.W. RINSE 220 GAL.
7. P.R. ELECTRO CLEAN
8. C.W. RINSE 220 GAL.
PROCESS
9.
10.
11.
12.
13.
14.
ZINC PLATE
C.W. RINSE
C.W. RINSE
CHROMATE
CHROMATE
C.W. RINSE
COUNTERFLOW
1
II
RINSE
TANK
CAPACITY
220
220
220
GAL.
GAL.
GAL.
15. W.W. RINSE
220 GAL.
Fig. 22
-------
PHOSPHATER
PROCESS COMPOSITION
I
502/GAL
ZINC PHOSPHATE
PHOSPHORIC ACID
NITRATES
(PROPRIETARY)
13% BY VOL.
HYDROCHLORIC ACID
AND ANTIMONY
(PROPRIETARY)
SAME AS (2)
EMULSIFIED
MINERAL OIL
J
10% BY VOL.
SULFURIC ACID
12 OZ/GAL
CAUSTIC SODA
SODA ASH
SURFACTANTS
PHOSPHATES
GLUCONATES
Fig. 23
-------
PHOSPHATER
DUMPING SCHEDULE — SPENT PROCESSES
NOT
DISCARDED
225 GAL.
WEEKLY
270 GAL.
DAILY
o
310 GAL.
WEEKLY
270 GAL.
WEEKLY
270 GAL.
DAILY
iLJ
NOT
DISCARDED
PROCESS
1. LOAD SHUTTLE
2. SOAK CLEAN
3. SOAK CLEAN
4. C.W. RINSE
5. HOT SULFURIC PICKLE
6. C.W. RINSE
7. PRE DIP
PROCESS
TANK
CAPACITY
310 GAL.
310 GAL.
270 GAL.
225 GAL.
PROCESS
8. W.W. RINSE
9. PHOSPHATE
10. C.W. RINSE
11. C.W. RINSE
12. H.W. RINSE
13. SEAL & OIL
14. UNLOAD STAND
PROCESS
TANK
CAPACITY
270 GAL.
1080 GAL.
270 GAL.
270 GAL.
-------
BARREL PHOSPHATER
RINSE WATER DATA
1920 GPH
240 GPH
1
120 GPH j
1
F20 GPH
720 G
I
PH
120 GPH
I
LJ
PROCESS
RINSE
TANK
CAPACITY
1. LOAD SHUTTLE
2. SOAK CLEAN
3. SOAK CLEAN
4. C.W. RINSE
5. HOT SULFURIC PICKLE
6. C.W. RINSE
7. PRE DIP
225 GAL.
225 GAL.
PROCESS
RINSE
TANK
CAPACITY
8. W.W. RINSE 270 GAL.
9. PHOSPHATE 225 GAL.
10. C.W. RINSEl-COUNTERFLOW 225 GAL.
11. C.W. RINSEj 225 GAL.
12. H.W. RINSE 270 GAL.
13. SEAL & OIL
14. UNLOAD STAND
Fig. 25
-------
ANODIZER
PROCESS COMPOSITION
3 OZ/GAL
ORGANICS
VARIABLE
DILUTE
CONCENTRATION
NICKEL ACETATE
15% BY WEIGHT
SULFURIC ACID
SURFACTANT
16% OZ/GAL
CAUSTIC SODA
AND
PROPRIETARY
ADDITIVES
5% BY VOL.
CHROMIC ACID
NITRIC ACID
Fig. 26
12 OZ/GAL
CAUSTIC SODA
SODA ASH
SURFACTANTS
PHOSPHATES
GLUCONATES
-------
ANODIZER
DUMPING SCHEDULE — SPENT PROCESSES
320 GAL.
VARIABLE
(AVG.
QUARTERLY)
320 GAL.
WEEKLY
320 GAL.
TWICE
MONTHLY
320 GAL.
WEEKLY
47S GAL.
QUARTERLY
320 GAL.
WEEKLY
PROCESS
TANK
CAPACITY
1. SOAK CLEAN
2. RINSE
3. CAUSTIC ETCH
4. RINSE
5. RINSE
6. DESMUT
7. RINSE
320 GAL.
320 GAL
320 GAL
PROCESS
PROCESS
TANK
CAPACITY
8. ANODIZE
9. RINSE
10. D.I. RINSE
11. DYE
12. RINSE
13. HOT WATER SEAL
14. WARM D.I. RINSE
475 GAL.
320 GAL.
320 GAL.
-------
ANODIZER
RINSE WATER DATA
245 GPH
45 GPH
45 GPH 45 GPH
L I I
45 GPH
RINSE FLOWS
PROCESS
1.
2.
3.
4.
5.
6.
7.
RINSE
TANK
CAPACITY
SOAK CLEAN
RINSE
320
GAL.
CAUSTIC ETCH
RINSE
RINSE
COUNTERFLOW
DESMUT
RINSE
320
320
320
GAL.
GAL.
GAL.
1
PROCESS
8.
9.
10.
11.
12.
13.
14.
ANODIZE
RINSE
D.I. RINSE
DYE
RINSE
HOT WATER SEAL
WARM D.I. RINSE
RINSE
TANK
CAPACITY
320
320
320
320
GAL.
GAL.
GAL.
GAL.
Fig. 28
-------
FOUNDATION LAYOUT
OUTSIDE
BUILDING
WALL
NDERGROUND PIPE
NICKEL-CHROMIUM PLATER
OPEN TRENCH
Fig-29
-------
FIGURE 30
ITEMS TO BE EXPECTED IN PLANT EFFLUENT OF COMPANY X
Metals
Nickel
Chromium
Copper
Iron
Antimony
Aluminum
Lead
Zinc
Organics
Soluble Oils
Immiscible Oils
Gluconates
Dyes
Proprietary Additives
Dissolved Solids
Calcium
Sodium
Potassium
Borates
Carbonates
Nitrates
Chlorides
Sulfates
Fluorides
Silicates
Phosphates
-------
METAL FINISHING OPERATIONS
VENTILATION
AND
AIR POLLUTION CONTROL
CONSIDERATIONS, DESIGN, EQUIPMENT
\
AND
SYSTEM INTEGRATION
PREPARED
FOR
ENVIRONMENTAL PROTECTION AGENCY
TECHNOLOGY TRANSFER PROGRAM
DESIGN SEMINAR
Ceflcoie
THE CEILCOTE COMPANY • 140 SHELDON RD. BEREA. OHIO 44017
-------
TABLE OF CONTENTS
PART I: INTRODUCTION PAGE 1
PART II: VENTILATION PAGE 3
PART III; AIR POLLUTION CONTROL PAGE 20
DEVICES
PART IV: CONCLUSION PAGE 33
APPENDIX, INCLUDING FLOOR PROTECTION
-------
I. Introduction
In the discussion of any ventilation system for a
metal finishing operation, two distinct areas should be covered.
These areas are:
1. The ventilation of the fumes from the work
area, and
2. The removal of any contaminants from the
exhaust stream that can cause an air pollution
hazard.
In addition to a general discussion of these points,
this paper will also deal.with some of the operating and design
principles upon which ventilation and air pollution control
equipment is based. It is mandatory that the owner and
operator of the metal finishing equipment have a general idea
of the principles involved so that he can make the best
selection of design and equipment for his own application.
In the final analysis, the owner is the one responsible for
the proper operation and function of the equipment.
Even if he has recourse back to the supplier, the
owner should never assume that a vendor's "guarantee" absolves
-------
Introduction Page 2
him of all responsibility. The owner should also carefully
consider all vendors on the basis that if legal recourse is
required, the vendor is economically strong enough to back
up his "guarantee".
The owner should also be able to understand the
operating and design principles behind the vendor's equipment
well enough so that he has a high degree of technical con-
fidence in the vendor's guarantee. It is ludicrous not to
be able to judge the technical merits of the design and operation
of any vendor's equipment when the owner is the one responsible
to the pollution control authorities for the proper operation
of his plant and equipment. For this reason alone, the owner
should be competent enough to be able to analyze and compare
the vendor's equipment and quotation beyond the simple "first
cost price comparison". When the control authorities want
to padlock your door for creating an air pollution hazard,
they will not be impressed by how much money you saved by
purchasing the least expensive equipment.
To prevent action by any air pollution authority,
you must be confident that the equipment you select will
perform satisfactorily for many years, will satisfy the
existing air pollution requirements, and will meet all other
codes and regulatory requirements, including OSHA.
-------
Page 3
II. Ventilation
A. OSHA Considerations
The Occupational Safety and Health Act (OSHA), as
published in the Federal Register, Volume 36, No. 105, May 29,
1971, has specific guidelines for the design and evaluation
of exhaust systems.
The primary requisite for any ventilation system
as required by OSHA is to assure that any air borne toxic
material be held below the threshold limit value (TLV) or the
maximum allowable concentration (MAC). Both the TLV and MAC
mean essentially the same thing in that it has been experi-
enced that this concentration of toxic materials will not
materially affect the health of any worker exposed to same for
a period of 8 hours per working date for his entire working
life. The values of the TLV are as determined by various
governmental agencies, and the OSHA act does include a listing
of these as published by the American Conference of Governmental
Industrial Hygienists.
In addition to the requirement that all ventilation
systems "be adequate to reduce the concentration of the air
contaminant to the degree that a hazard to the worker does
-------
Ventilation Page 4
not exist", OSHA also lists a specific method for determining
exhaust rates from each tank. This determination is as pub-
lished by the Committee on Industrial Ventilation's "Industrial
Ventilation Handbook, 12th edition" as published by the American
Conference of Governmental Industrial Hygienists. It should be
noted here that in most cases the ventilation rates recommended
in this 12th edition are higher than those listed for identical
applications in previous editions. OSHA in effect states that
in many cases additional exhaust volumes are needed to control
the contaminant less than the TLV in the area immediately sur-
rounding the tanks being exhausted.
In the past, lower rates have accomplished this in most
applications. However, care must be exercised in the initial
design to provide an area where cross drafts are a minimum. To
do this, the location of windows and doors becomes extremely
critical and should be carefully watched in the vicinity where
exhaust of the metal finishing tanks is required. Other consid-
erations, such as traffic patterns, work flow, method'of work
movement, and location of personnel must all be studied.
-------
Ventilation Page 5
When planning a new system or revising an existing
system, special emphasis should be placed on how workers are
exposed to possible contaminants. Obviously; the farther
away you can keep your workers, the greater the internal
dilution, the lower exhaust rate required to keep contaminants
below the TLV level. Fresh air movement into the area should
be controlled such that it flows past the worker at his work
station(s).
These then are the considerations that should be
taken into account in order to comply with OSHA.
B. Other Factors
In addition to the above considerations, there should
be other factors which will help in the overall design of the
exhaust system designed and installed.
One of the most critical items in any ventilation system
is the proper amount of makeup air that is provided. The
amount of makeup air should be slightly less than the total
volume being exhausted, but the amount of this difference
should be less than 2-5%. Many ventilation manuals state
that the amount of makeup air should be greater than the amount
of exhaust air. However, when dealing with toxic contaminants
-------
Ventilation Page 6
and air pollution control requirements, it is mandatory to
keep control of the toxic fumes in the area where they•can be
effectively removed.
Having a positive pressure within this area means
that wherever windows are open or doors are open, air flow
will be out of the immediate area, and consequently toxic
contaminants can find their way into other areas of the
building. In any building, it is suggested that the metal
finishing operation where tanks are involved be segregated
somewhat from the remainder of the area. In this fashion,
makeup air can be supplied to the remaining portion of the
building at an excess quantity with sufficient air makeup .
to cover the slight negative values that would be found in
the metal finishing tank area. This then will insure that all
air borne contaminants would be carried through the ventilation
system in the metal finishing area which has been specifically
designed and constructed to handle these contaminants.
C. Materials of Construction
Obviously, the ventilation system in the metal
finishing area should be constructed of corrosion resistant
materials that are also fire-retardant. Some of the con-
siderations that should be given to materials of construction
would be the following:
-------
Ventilation Page 7
1. Corrosion resistant to contaminants being
handled
2: Physical strength of the materials
3. Fire-retardancy
4. First cost and installation cost
5. Ease of modification
Over the past 15 years, it has been proven that
solid plastic materials of construction used in ventilation
systems offer many of these advantages at low first cost,
and they are readily installed by most personnel. Solid
plastic materials available include PVC, polyethylene, poly-
propylene, and glass reinforced polyester, as well as other
glass reinforced thermosetting materials.
The first three materials listed are thermoplastics
which are by their very nature susceptible to heat degradation
at high temperatures but are effective when it is expected
that operating temperatures within the system are kept well
below the upper operating limits generally recommended. These
operating limits are as follows:
PVC - 140° F
Polyethylene -200° F
Polypropylene - 230° F
-------
Ventilation Page 8
Thermosetting resins, such as glass reinforced
polyesters, do not exhibit the same physical strength loss
with increase in temperature and do expand at a slightly lower
rate than most of the thermoplastics. Glass reinforced
polyesters used in ventilation systems have operated successfully
at temperatures in excess of 250° F. They can be made fire-
retardant and will contain fire and smoke, should a fire occur.
Although PVC is generally regarded as non-combustible,
it does give off copius quantities of HC1 when burned, and will
drop flaming globules when exposed to a fire. In several
cases, PVC fires have snuffed themselves out in a relatively
short period of time, but extensive structural steel damage
has been caused by the large amount of HCl generated. In
other cases, it has been shown that PVC has spread the fire
by dripping these flaming globules of molten PVC plastic.
Polyethylene is combustible and is generally not recommended
where fire-retardancy is a prime requisite—which should always
be the case in a metal finishing operation. Polypropylene
is available in fire-retardant grades, but this material will
burn at a faster rate than a comparable glass reinforced
polyester.
-------
Ventilation Page 9
The key to the effective design of any ventilation
system is to follow some specific guidelines. The "Industrial
Ventilation Manual", mentioned earlier, offers excellent advice
about the basic components of the ventilation system.
In addition to this information, it is generally
recommended that duct velocities in the range of 2,500 to
3,500 feet per minute be used for ventilation systems for metal
finishing operations. This generally keeps the static pressure
in the total duct system to a reasonable amount, generally
in the range of 1.5" to 3" w.g.
D. Hoods
Exhaust hoods should be designed to insure capture
of all of the fumes generated from the tanks. It is important
to remember that the maximum fuming occurs when the work is
placed into the tank and as the work is removed from the tank.
Therefore, it is mandatory that the pickup points be arranged
to capture the fumes in these areas. If the tank is hot, the
fumes tend to rise and, therefore, pickup points should be
installed above the point where the maximum height of work
occurs during this- transferring operation.
In addition to consideration for the pickup points,
additional consideration should be given to providing some
-------
Ventilation Page 10
type of baffles around the immediate hood itself. The addition
of 12" or more of baffles beyond all extremities of the hood
can materially increase the effectiveness of the removal of
the contaminants from the tank area. It is surprising how
much more effective a hood can be when it is baffled and when
the pickup points are located properly.
In general, for most metal finishing operations,
slot hoods are used as these tend to give equal distribution
to the suction of the fumes across the width of the tank.
Slot velocities in these slot hoods are generally kept in
the range of 2,000 to 3,000 feet per minute due to the high
static pressure created with this type of an arrangement.
A slot hood with this velocity will generally have no more
than 1/2" to 3/4" static pressure for the hood itself.
The design of the hood in the duct system should
be based on the following premises:
1. Containment of the fumes. The fumes should be
kept in the tank area until they can be"thoroughly
picked up by the exhaust hood. Additional baffles
or artificial walls will assist in this operation.
Baffles tend to eliminate the cross drafts and also
-------
Ventilation Page 11
help to contain the fumes in the tank area. It is
sometimes evident that baffles are also required
directly above the maximum height of work to control
the fumes from rising too rapidly before they are
picked up into the exhaust hood.
2. Controlled air flow into the fuming area. The
placement of the tanks within the room and location
of items which can contribute to cross drafts should
be carefully studied. The objective is to maintain
the flow of air into the tank area in such a fashion
that it constantly flows past the work stations
and towards the exhaust hoods. A study on paper
of the location of windows and doors, as well as
location of the tanks themselves in relationship
to .these openings, is important. Consideration
for baffles and rearrangement of tanks within a
given area can sometimes eliminate problems and
reduce the total amount of ventilation required to
keep the contaminants below the TLV in the work
area. Baffles extended on either side .of the tanks,
as well as between all hpods, as mentioned above,
help the orderly flow of air into this area and
generally assist the exhaust system in performing
-------
Ventilation Page 12
its vital function, i.e. removal of the con-
taminants .
3. Removal of the fumes from the tank area. Although
this seems redundant, it is important that this third
item be included with the first two because the
amount of exhaust air utilized for a given tank or
tanks must be adequate enough to remove the fumes
in the area in which they are being contained as
quickly as possible. Obviously, an inadequate amount
of exhaust air allows the fumes to linger in the
exhaust area for too long a period of time permitting
their eventual escape into the room itself and pos-
sible contamination of the entire working area.
In general, the exhaust volume should be 100 to
200 CFM for heated tanks and not less than 50 to
75 CPM for cool tanks. However, the Industrial
Ventilation Manual or OSHA should be studied before
any exhaust volumes are defined in a given situation.
These values can only be used if the fumes are con- ~
tained and the air flow into the area is controlled
as indicated above.
-------
Ventilation Page 13
E. Ductwork
In addition to the design and location of the hoods
and other items, some consideration should be given to the
runs of ductwork themselves. The duct runs should be sloped
and drainage points provided so that condensation on the interior
of the duct walls can be controlled. The duct material of
construction should be such that if a leak occurs due to physical
damage, repairs can be easily effected to eliminate this potential
sour6e of pollution into a sewer system not equipped to handle
toxic contaminants. In general, the design of the duct system
should follow the guidelines outlined in the "Industrial Ventila-
tion Manual" with some consideration given to standard practices
within the plastics industry. For instance, in most instances
plastics fabricators utilize an elbow turning radius of 1-1/2
times the diameter of the duct rather than the 2 times the
diameter recommended in the Industrial Ventilation Manual.
This is merely a compromise between static pressure loss and
initial cost of materials.
F. Fans
The exhaust fan is the heart of any exhaust system.
Without the fan providing the necessary suction and the necessary
air movement through the hoods, duct system, scrubber, and
stack, there can be no exhaust system.
-------
Ventilation Page 14
The exhaust fan should be sized to handle the full
exhaust volume at the static pressure for which the system is
designed. Since metal finishing installations traditionally
are modified over the years, it is suggested that the fan
selected be of such a size that additional capacity can be
added at a future date by changing the motor and drive arrange-
ment.
The fan manufacturer should be consulted to make
certain that the fan selected is at the "midpoint" of the
performance range for the particular fan size. Make certain
that the fan is constructed so that this additional capacity
can actually be realized at a future date. Beware of furnishing
a Class I fan when an increase in CFM or slight change in the
static pressure would require Class II construction. This
also applies to the differential between Class II and Class
III, especially where metal fans are involved. In some cases,
solid plastic fans also have similar restrictions and care
must be exercised in making these selections.
In any metal finishing ventilation system, it is
advisable to make certain that the fan is completely corrosion
resistant on the inside as well as the outside of the fan
itself. Corrosion of the exterior housing surfaces of a fan
-------
Ventilation Page 15
leading to premature failure of .same when the interior has
an expensive corrosion resistant system is humorous but some-
times all too true and unnecessarily expensive.
The most critical part of the fan is the impeller
itself. It is important to make certain that the impeller
is of adequate design and structurally strong to handle any
increase in capacity at any future date.
The impeller should be constructed of materials which
are completely corrosion resistant to the expected fumes that
the fan will handle. If the fan is supplied with a coated
impeller, it should be specified that the coating installer
must spark test this fan after it has been -balanced. If the
coating so applied is a thermoplastic coating, this coating
should be supplied in adequate thickness for the corrosion
protection involved. Particular attention should be made to
the tip speed of the impeller. Make certain that the centri-
fugal forces do not exceed the bond strength of the coating
material causing the coating to fling off and fail prematurely.
If the fan impeller is constructed of a thermosetting
FRP, then it is important that it is in fact solid plastic
construction and that it is built of the same resin as the
remainder of the duct system. Again, particular care should
-------
Ventilation Page 16
be made to make certain that the resin selected has adequate
corrosion resistance to all the contaminants the fan is expected
to handle.
Construction of the fan should include an inspection
door and housing drain. The housing drain helps to insure
adequate drainage of the condensation which is caused by the
natural centrifugal force of the fan impeller rotating within
the housing. Since in many cases the exhaust stream coming
from the metal finishing operation is heavily saturated with
liquid droplets, you can expect liquids to build up within
the fan housing very rapidly. Therefore, a drain should always
be used on any fan involved on a metal finishing application.
This drain should be connected to a seal leg so that it can
properly drain away the liquid without having to overcome
the negative static pressure that may be encountered on the
inlet side of the fan. An access door on the side of the
fan housing should be provided so that inspection of the fan
impeller can be accomplished with minimum difficulty. This
also permits cleaning of the fan impeller by washing or similar
type of action. Cleaning of the fan impeller will help to
extend the service life of the fan itself.
After the fan impeller, the fan housing is the next
-------
Ventilation Page 17
most critical item to which attention should be paid. The
interior of the fan housing should be coated with the same
material as the fan impeller. If all internal surfaces are
coated as mentioned above, it is recommended that the exterior
of the fan be provided with some type of corrosion protection
as well.
If the fan housing is steel to which a coating will
be applied, then it should be so constructed that the coating
can be applied with integrity. This means that all welds should
be ground smooth with a slight radius in all corners. (Note
that a steel impeller must have similar preparation.) All
coatings should be spark tested after they are applied to the
fan housing and the coating should be carried through to the
outside of all flanges and should overlap the edges of all
corners.
If the fan housing is solid plastic, then it should
be stiffened adequately to withstand the negative static pres-
sures that may be encountered during normal operation or at
some future date.
In addition to the above considerations, both the
fan housing and impeller should be constructed of materials which
are basically fire-retardant. In the remote event of a fire
-------
Ventilation Page 18
occurring in the ventilation system, the fan should be kept
on to remove the smoke and fumes from the burning area through
the exhaust system to the outside of the building. Smoke
damage within the building itself sometimes can be more costly
than the fire damage to a localized area of the exhaust system.
There are several additional accessory items which
should be provided to facilitate installation and operation
of the fan. One such additional item is flexible connectors.
Flexible connectors to connect the ductwork to the inlet and
discharge side of the fan should be considered to isolate the
fan from the remainder of the duct system. This tends to
reduce the sound transmitted to the entire ventilation system
by the fan, and it also will reduce any vibration which the
fan may transmit to the duct system.
Another additional accessory item used with fans
should be vibration isolators. Depending on the location
of fan mounting and the type of mounting supports, vibration
isolators should be definitely included in all fan instal-
lations. This serves the same function as the flexible
connectors, that is, it tends to reduce the transmission of
noise and vibration from the fan to surrounding systems.
-------
Ventilation Page 19
G. Drains
In conjunction with the exhaust system and fan,
condensate drains have been mentioned. It should be pointed
out that these condensate drains should be connected to the
waste treatment area. This is a potential source of toxic
contaminants/ and special provisions made to connect these
drain systems will prevent these contaminants from entering
the normal sanitary drain system or storm water system. Note
that some hoods are also provided with condensate drains.
These should be connected to a seal leg or capped for periodic
drainage. This will prevent exhaust air from being drawn into
this drain thus reducing the effectiveness of the hood. These
drains should also be connected to the metal finishing waste
treatment system.
-------
Page 20
III. Air Pollution Control Devices
A. Introduction to Problem
Metal finishing operations that are carried on within
liquid tanks create in general two different types of emissions.
One is emissions of a gaseous nature, and the other is emissions
of entrained liquid particulate. In a very rare instance, mists
are formed, but these occurrences are so infrequent that they
will not be the subject of any discussion within this paper.
Gaseous contaminants can be defined as those specific
contaminants which are composed of gas molecules which are
controlled by their brownian movement and are generally in the
range of less than 0.01 micron in particle size.
Entrained liquid particles are those contaminants which
are released from a bath due to air agitation, drippage, mechanical
agitation, etc. and which are generally 10 microns in size and
larger.
A micron is defined as one-millionth of a meter which
is equivalent to roughly 1/25,000 of an inch. For reference
purposes, it should be noted that the smallest individual
particle that can be detected with the naked eye has been
reported to be between 60 and 100 microns in size. The average
human adult red blood cell is 7.5 ± 0.3 microns in particle size.
-------
Air Pollution Control Devices Page 21
Tobacco smoke is generally defined as composed of solid particles
that range from 0.01 micron to'l micron in particle size.
This would give the metal finishing operator some appreciation
for the size of the particles with which he is dealing.
The amount of air pollution control equipment required
and the efficiency with which this air pollution control equip-
ment must work will be dictated by local, state and federal
EPA regulations. However, due to the nature of the specific
contaminants and the myriad of possible chemicals involved
in metal finishing operations, the present regulations are not
specific enough to permit a discussion in this paper of the
maximum emission levels for individual chemicals. In some
cases, emission levels are specified as a maximum rate per pound
of work processed. In other cases, there is no specific mention
of any of the normal contaminants found in a metal finishing
operation. Some states do have emission regulations for such
items as hydrogen fluoride, sulfuric acid, and hydrochloric
acid, where a large segment of the state industrial complex
handles such items.
There is a trend by the EPA to spell out in some
detail, limitations on specific contaminants. It is expected
that such limitations will be established in detail for the
-------
Air Pollution Control Devices Page 22
metal finishing industry in the very near future. In the
meantime, some companies, in an effort to anticipate tentative
goals, have established that the scrubber or pollution control
device they install shall have an outlet concentration of
the contaminants which does not exceed the threshold limit
value (TLV).
There have been specific cases in the past where
metal finishers have been subjected to the "nuisance" clause.
The "nuisance" clause is generally included in most regulations,
and it is specifically included so that no industry or company
can interfere with the right of any individual to the pursuit
of his happiness and well-being or cause a nuisance which
interferes with that basic right. There have been specific
cases where metal finishers have chromic acid emissions which
have caused damage to nearby property and houses, and these
have forced the particular company involved to make restitution
for this damage. Subsequently, the company involved has been
obligated to install pollution control equipment which will
specifically remove all the chromic acid contaminants passing
through the system. There have been other similar cases
involving other types of contaminants, but it should be noted
here that proper planning and care in the design of the exhaust
system as well as selection of the air pollution control device
will preclude such instances.
-------
Air Pollution Control Devices Page 23
As mentioned above, because of the fact that most
contaminants coming from a metal finishing operation are
either gaseous or entrained liquid particulate in nature,
wet scrubbers have generally been utilized for this type of
operation. Wet scrubbers are considered to be a chemical
type of pollution control device (as opposed to a mechanical
or electrical device).
A packed tower is generally recommended for control
of gaseous contaminants. There are some scrubbers available
on the market which do provide a limited amount of gas absorption
through some other means other than a packed bed. However, the
amount of absorption provided is limited, and if the objective
is to reach the TLV on the discharge side of the wet scrubber,
then a packed tower absorption device will definitely be required.
The packed tower scrubber generally uses a recirculation system
to recirculate the absorbing liquid through and across the packed
bed. There are several different geometric modes of configuration
for a packed tower. The geometric mode concerns itself with
the manner in which the liquid comes in contact with the gas.
In a countercurrent packed column, the liquid enters the top
of the column and flows countercurrent to the gas stream which
enters the bottom of the packed column. In a crossflow packed
column, the gas flows horizontally through a packed bed, while
-------
Air Pollution Control Devices Page 24
the liquid flows from the top of the packed bed down to the bottom
of the packed bed and discharges at the bottom while the gas
discharges through the rear of the packed bed. See Figures
1 and 2 attached.
For liquid entrainment removal, wet scrubbers of
various designs have been effectively employed to obtain
efficiencies in the range of 99+% removal. The nature of the
liquid entrainment coming off the metal finishing operation
must be studied carefully. If the tank is at room temperature,
the entrainment will generally be relatively large, that is,
probably 100 microns or larger. For this particular type of
liquid entrainment, a simple air washer, which is essentially
an entrainment removal device with a washing action to keep
the concentration of the contaminants to a minimum, is all
that is required. If the tank is heated, however, there is
some concern that smaller particles will be generated. In
this particular case, the air washer or entrainment separator
should be selected with care since there is a possibility
that liquid particulate matter as small as 10 microns in size
can be emitted.
In the case of chromic acid fumes, it is important
to remember that even a very small particulate droplet of
chromic acid can cause damage to painted surfaces. For this
-------
Air Pollution Control Devices Page 25
reason, an entrainment removal device which is efficient down
to the range of 3 to 5 microns is generally recommended.
B. Recovery of Contaminants
There have been many installations where the recovery
of contaminants from a metal finishing operation has proven
to be economical. In general, in order to economically recover
the contaminants, the water which is used for washing and dilution
must be evaporated to increase the concentration of the con-
taminant to a level where it can be reused back into the metal
finishing process.
An evaporator, utilizing a supply of heated water,
is generally recommended for such applications as nickel plating
and chrome plating operations where recovery can be economical.
The attached chart shows the results of such an evaporator
design and indicates the approximate range of inlet concentrations
over which an evaporator can be economically effective.
-------
TYPICAL OPERATING DATA FOR CHROME AND
NICKEL PLATING EVAPORATOR/SCRUBBER SYSTEMS*
RECOVERY DATA
Parameter
AVERAGE VALUE OVER
TEST PERIOD
Inlet Air
Rate - CFM
Temp./R.H.
Steam Usage Ib./min. @ 25 psi
Total Electrical Usage Amps @ 440V
Recycle Rate - GPM
Heat Exhanger Temp.
Reservoir Temp.
Evaporation Rate - GPM
Return Rate to Tank - GPM
Output Air Temp.
R.H.
Hourly Reclaim Rate (Ib./hr.)
expressed as chrome or nickel
solution
Chrome
10,000 CFM
77° F/40%
120
200
225
150-155° F
114° F
9.5
1.5
131° F
100%
215
Nickel
10,000 CFM
77° F/40%
120
200
225
150-155° F
114° F
9.5
1.5
131° F
100%
83
Operating Costs
Item
Electrical @ 1.54 KWH
Steam @ $1.50/1000 Ib.
Total Cost/hr.
Reclaim Cost $/lb.
Orig. Chrome cost/lb.
Cost $/hr.
$0.35
$10.75
$11.10
5.2«/lb.
$0.50/lb.
Cost $/hr.
$0.35
$10.75
$11.10
13.4$/lb.
$1.50/lb.
*Based on actual case study using countercurrent flow packed
bed scrubber containing 4 feet of 1" Tellerettes.
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Air Pollution Control Devices Page 26
There have been many cases where an evaporator can
be effectively combined with a wet scrubber. That is, the
wet scrubber serves a dual function—removal of contaminants
as well as recovery of same. In order to effectively accomplish
this, additional equipment must be provided. This additional
equipment involves a heat exchanger and extra piping as well
as arrangements to run a batch operation through the evaporator/
wet scrubber system. In this particular case, the scrubbing
liquid is heated to a point where water is evaporated from the
air stream while the contaminant is being removed within the
packed bed.
There are some cases where a separate evaporation
system can be economically justified. A separate evaporation
system will be employed where a number of small scrubbing
installations are handled separately and the liquid from each
of these is fed to a single evaporator system.
C. Water Consumption
A wet scrubber, to be efficient, must raise the
relative humidity of the exitting air to the saturation level.
Since the relative humidity on the inlet side of the scrubber
is generally less than the saturation level, evaporation of
water is taking place within the scrubber itself. For this
-------
Air Pollution Control Devices Page 27
reason, a makeup supply of some type of relatively "fresh"
water must be added to the scrubber recirculation system.
The amount of water used as makeup must be greater than the
evaporative losses that can be expected within the scrubber
itself.
If the contaminant being removed is of a gaseous nature,
then the amount of fresh water added to the system must be of
sufficient quantity and quality to permit the recirculation
solution to be kept well below the level where the concentration
of the contaminant in the liquid phase does not interfere with
the gas absorption rate. For most metal finishing operations,
this amounts to a makeup rate of approximately 5-10% of the
total amount being recirculated in the scrubber system.
In addition to the above considerations, there may
be a consideration to have the concentration of the contaminant
in the overflow of the scrubber in the range where it can be
effectively handled by the waste water treatment system which
is installed.
Since the overall consumption of water for any metal
finishing operation is limited to keep the capital investment
of the waste water treatment system to a minimum, the source
of "fresh", water for the scrubbing system should be carefully
-------
Air Pollution Control Devices Page 28
studied. While it is best to use fresh city water for the
scrubbing solution, in some cases this "fresh" water can be
the clarified water from the waste treatment system. That is,
the treated water from your waste treatment system could be
returned to the scrubbers as the fresh water supply, conse-
quently leading to recycling of the stream. This will tend
to reduce the amount of city water being used in the system.
In addition to this arrangement, there have been other
arrangements where the rinse water from the secondary or tertiary
rinse tank can be used as the fresh water makeup for the scrubber.
The concentration of the contaminants in the fresh water makeup
to the scrubber must be kept to a sufficiently low value to
preclude any release of this contaminant to the air stream
in the scrubber itself. In some cases, even the primary rinse
tank may have a sufficiently low enough concentration to be
able to use this water as the makeup water to the scrubber.
>
As a further water conservation practice, there have
been cases where the overflow from the scrubber is used as
makeup for a primary rinse tank. This would be especially
beneficial when more than one rinse tank is employed in a
process.
-------
Air Pollution Control Devices Page 29
The exact nature of the supply of fresh water makeup
for a scrubber system can only be determined upon detailed
examination of the specific application. Each application
must be weighed carefully with all the alternatives mentioned
above carefully considered, and the final selection based upon
the merits of the specific case in point.
With the recirculation piping, drain line piping,
and other piping connections on the scrubber, care should be
taken that all of these are connected to the waste water treat-
ment system.
D. Costs
The attached table illustrates typical costs for the
installation of ventilation and air pollution control equipment
for some typical metal finishing operations.
-------
TYPICAL COSTS OF VENTILATION SYSTEM
BASIS OF COMPARISON
1) 10,000 CFM for all systems
2) Static pressure loss in all air handling systems exclusive of scrubber is 2.5 inches w.g.
3) Fan efficiency - 55%
4) Pump efficiency - 50%
5) Annual operating days - 300
6) Power cost - 1.5C per KWHR
7) All scrubbers 95% efficient or better
TOTAL
ANNUAL INSTALLED
PRESSURE DROP LIQUID RATE HORSEPOWER FIRST COST POWER COST
METAL
FINISHING
OPERATION
Chrome
Nickel
Zinc
Phosphate
Coat
TYPE OF
OF OF SCRUBBER PUMP
SCRUBBER SCRUBBER TOTAL RECIRCULATED* (A)
Counter cur rent 2"
Air Washer 1"
Crossflow 1.5"
Air Washer 0.7"
4.5"
3.5"
4.0"
3.2"
120
60
60
50
0.7
0.4
0.4
0.3
FAN
(B)
12.8
9.4
11.5
9.1
SCRUBBER
APPROX.
S
6000
3500
7000
3000
COST
$
(0
1490
837
1024
810
COMPLETE
SYSTEM
S
12,000
9,000
13,000
8,000
(A) - Pump HP = 8.33 H s (gpm) (B) - Fan HP = .000157 Q (in. w.c.) (C) Operating Cost =
33000 (50% eff) 55% eff.
Hrs (HP) (.746) (1.5)
*NOTE: Fresh makeup rate will be from 5 to 10% of this but no less then 3 gpm.
-------
Air Pollution Control Devices Page 30
The number of tanks being exhausted, as well as
exhaust rate, together with the size of the individual equip-
ment selected, will control the actual installation and operating
costs.
Care should be exercised in the selection of the air
pollution control equipment so that the operating cost is not
excessive. It is important to remember that as a rule-of-thumb
the operating costs of each motor used on the ventilation and
air pollution control system will range from $50 to $100 per
brake horsepower per year depending upon your local electrical
costs. On a large system, this cost can quickly mount up to
a point where the savings of several inches of static pressure
of resistance within the system by careful selection of the
pollution control equipment and design of the ventilation system
can save many thousands of dollars of operating costs in a
year's period of time.
E. Other Considerations
Contained within the appendix of this paper are some
examples of ventilation systems employing air pollution control
devices which have been installed in metal finishing operations
at various locations throughout the country.
-------
Air Pollution Control Devices Page 31
In addition to the design considerations listed
above, there are several additional items which should be
mentioned in the ventilation of metal finishing operations
which should be taken into account on any installation.
If the metal finishing operation includes cyanide
salts as one type of metal finishing solution and the cyanide
tanks must be exhausted, then the exhaust system for the cyanide
solutions should be kept separate from any exhaust system that
incorporates acid solutions. This will preclude the formation
of any hydrogen cyanide within the exhaust system itself,
which could lead to potential problems.
Normally, if there are alkali solutions which must
be exhausted which do not contain cyanide salts, these can
be combined with exhaust systems handling acid solutions so
that some neutralization within the duct system prior to the
scrubber can be effected. This will serve to reduce the load
of acid contaminants entering the waste water treatment system.
However, this step should not be taken if recovery of the
acid contaminants is being attempted.
There are some metal finishing operations which
utilize an ammonium based alkali within the tank system.
Any exhaust system which is venting an ammonia tank should
-------
Air Pollution Control Devices Page 32
be kept separate from an exhaust system that is handling hydro-
chloric acid. The combination of ammonia and hydrochloric
acid in an exhaust system forms the compound ammonium chloride
(NH4C1). Ammonium chloride, when it is formed, becomes a
submicron particulate matter which is impossible to remove
in any of the wet scrubbers discussed in this presentation.
Ammonium chloride can appear as a dense white cloud which can
lead to serious problems. The metal finishing operator who
has an ammonium chloride effluent may find himself faced with
complaints from local citizens due to the reduced visibility
in the plant area. The simple expedient of separating these
two exhaust stream internally and making certain that the
hydrochloric acid vapors are removed to a high efficiency
and then separating the exhaust points of these two by as wide
a distance as possible will help to preclude this possibility.
-------
Page 33
IV Conclusion
The design of a ventilation system for me'tal finishing
operation should be based on OSHA considerations within the
building. The specific manner in which the exhaust fumes are
contained within the area and removed through the exhaust system
should be carefully studied so that the contaminants are kept
within a confined area. The flow of fresh air should be con-
stantly past all work stations so that the TLV of the contaminants
is not exceeded.
The exhaust system should be designed so that it
utilizes a minimum of static pressure resistance to keep the
operating costs down. Use of corrosion resistant materials of
construction should be combined with fire-retardant characteristics
so that the effectiveness of the exhaust system does not
deteriorate with age.
The fan and the pollution control device selected should
be constructed of similar corrosion resistant and fire-retardant
materials. The air pollution control device selected should be
efficient enough to allow operation under existing codes. Some
provisions can be made in many scrubber designs to increase the
efficiency at a later date. However, care must be used in this
-------
Conclusion Page 34
selection so that the fan capacity can be increased at slight
additional costs at some future date.
condensate drains and drain line connections to
the vet scrubber should be directed to the waste treatment
system to prevent contamination of ground water, sanitary or
storm sewer effluents.
Careful consideration of the fresh water makeup to the
wet scrubber system should be included in the overall planning of
the waste water treatment system.
A detailed evaluation of any vendor's proposal for the
complete exhaust system and/or pollution control devices should
include the major points covered in this paper.
-------
APPENDIX
INCLUDING
FLOOR PROTECTION
-------
I. Floor Protection
In the consideration of any waste water system,
some means of surface protection of the floor area around
the tanks is always included. Surface protection of the
floor is required to protect the substrate (actual floor
material) from damage due to spills, splash, drippage, over-
flow, or catastrophe. In the event of a catastrophe, it
is imperative that the liquids involved be all contained within
the area serviced by the waste water treatment system provided
for same. Depending on the specific design utilized and the
extent of the catastrophe, spill, or other problem, the liquids
involved may have to be contained within this area for from
several minutes to several hours. Obviously, the liquids
could cause severe damage to the substrate and even the
building and/or building foundation if the area is not prop-
erly protected.
The type of material selected for this service
should be based on the following considerations:
1. Substrate material
2. Type of traffic, if any, that will be
using this floor area
-------
Floor Protection Page 2
3. Broad range corrosion resistance
4. First cost
5. Ease of installation and its cost
6. Repairability
There are many different types of materials
available on the market. Most of these materials are con-
sidered to be monolithics and are based on the use of a
thermosetting resin. Thermosetting resins are those resins
which utilize a catalyst system. They start off as a liquid
at room temperature to which the catalyst is added and,
depending upon the amount of catalyst and the temperature
and humidity, the resin "sets up" or becomes a solid with
an exothermic reaction within from 5 minutes to several hours.
Once this exothermic reaction is complete and the heat has
dissipated, the resin is fully cured and can usually be treated
in the same manner as the substrate. The complete cure may
be complete within several hours, but most materials should
not be subjected to anything other than foot traffic for
from 24 to 48 hours after being fully installed. Thermo-
setting resins include epoxies, polyesters, and furans,
although most floor protection materials are based on either
epoxies or polyester resins.
-------
Floor Protection Page 3
It is imperative to point out that there are prob-
ably well over 100 different epoxy resins available as well
as over 500 different polyesters. However, limiting the
materials to the considerations listed above will probably
reduce these numbers to 20 and 100 respectively for epoxies
and polyesters. With this variety still available, the ideal
material should be selected based on these parameters:
1. Corrosion resistance to a wide range of acids
and alkalis
2. Low first cost and installation cost
3. High resistance to impact damage
4. High bond strength to substrate
5. Can be inspected visually and repaired easily
The only other consideration is the amount of traffic
•«»
or type of load to which the material will be subjected.
In some cases, the materials are applied using nothing more
than an aggregate or other type of filler. The aggregate
is used to enhance impact strength, thermal expansion char-
acteristics, and to provide additional thickness of material.
In other cases, the same materials or slightly different
formulations are used in conjunction with some type of addi-
tional reinforcement such as glass cloth.
-------
Floor Protection Page 4
Reinforcement with glass cloth markedly increases
the impact strength of the material. It also enhances other
properties which overall make this type of addition very
valuable in many instances.
When taking all factors into consideration, a material
which approaches the ideal would be a modified glass rein-
forced polyester. It has the following properties:
A. It is corrosion resistant to the vast majority
of plating solutions.
B. It has a total installed cost of from $2.00
to $3.00 per square foot which makes it
economical.
C. It bonds tenaciously to the substrate and
discourages undercutting so that cracks and
damage are contained within a localized area.
D. The glass reinforcement provides high impact
strength and permits the material to bridge
minor shrinkage cracks in the substrate.
E. Cracks, if they do occur, can be repaired
readily by maintenance personnel with minimum
training.
-------
Floor Protection Page 5
F. Cure is complete within hours so that downtime
for repairs or interruption of initial con-
struction can be held to minimum.
G. This material can also be applied to vertical
surfaces so that curbs and walls can be given
the same corrosion protection. Thus, any
chemicals involved in a catastrophic spill can
be contained within the designated area serviced
by the water treatment system.
The best material selected for this service is
wasted if the proper consideration is not given to the overall
design of the substrate, the method of installation of the
material, and the surface preparation. Areas that warrant
particular attention include floor drains, joints between
walls and floors, etc. Illustrated here are the methods
that are generally used to handle these potential trouble
areas.
Note that before the installation of any monolithic
material the substrate must have the surface preparation
recommended by the manufacturer. For most monolithics, when
concrete is the substrate, the surface preparation is generally
a steel trowel finish followed by acid etching of the fully
cured concrete.
-------
Page 6
II. Protection of Equipment
In addition to protection of the floor under the
tanks, consideration should also be given to protection of
other areas. Whenever corrosive chemicals are used, all
equipment exposed to the same atmosphere or in direct contact
with the chemicals is subjected to rapid degradation. Equip-
ment and areas in this category include:
a) The exterior of the tanks
b) All surfaces of a plating machine
c) Structural steel used anywhere in the vicinity
of the corrosive chemicals
d) Utility connections or pipelines that are located
within the area where floor protection is provided.
Equipment installed in a metal finishing operation
is expensive to replace. It is also extremely expensive
if the equipment must be repaired constantly.
One of the best questions that is always asked in
conjunction with any discussion of catastrophes in a plating
area is "How could they occur?". There is probably no better
response or more likely occurence than through the forces of
corrosion and neglect. Therefore, it is economic folly when
considering floor protection not to investigate the possibility
-------
Protection of Equipment Page 7
of providing similar protection to all equipment contained
within the floor area which will be protected.
With the normal maintenance that will be required
by your treatment plant and equipment, as well as the plating
equipment itself, corrosion protection of tanks, machinery,
and structural steel will reduce maintenance on these items
freeing your people to maintain critical equipment. It will
also materially lessen the chances of a catastrophic event.
Corrosion protection for these parts and areas
can be provided by coatings which are readily applied by
brush or spray and which have the same properties and cor-
rosion resistance as the monolithics used on the floor.
Typical of such materials is a flake reinforced
polyester. These are available in the same grades as the
monolithics and can be applied to a thickness of from 15 to
30 mils at a nominal cost. The typical installation will
range from $0.80 to $1.50 per square foot, depending on the
amount of surface area being covered and the complexity of
shape. This means this material is competitive with most
epoxy, vinyl, or similar paint systems used as coatings.
The advantage of this type of coating is its superior impact
resistance, better thermal shock resistance, lower expansion
coefficient, and resistance to undercutting.
-------
Protection of Equipment Page 8
These coatings have been field proven in years of
trouble-free service where they have eliminated the usual
annual reapplication of materials that is normal with most
paint systems in corrosive areas. They are also readily
cleaned with a water flush and could even be brushed with
a stiff bristle brush without fear of damage.
-------
Page 9
III. Other Considerations
It is obvious that the area occupied by the waste
water treatment should receive the same considerations.
Although the function here is one of neutralization of cor-
rosives, it should also be realized that the same type of
spills, leaks, splash and other minor occurences could cause
serious damage to floors, tank exteriors, structural work, etc.
In addition, serious consideration should be given
to the manner and means in which the liquid effluent from
the metal finishing area is transported to the treatment
plant. Pipelines must be properly installed and completely
corrosion resistant both inside and out. Trenches, if used,
should be similarly protected.
In all cases, wherever corrosive chemicals are
used within the plant, careful attention should be given to
corrosion protection of all surfaces in those areas where
the chemicals are received, stored, consumed, transported
to the waste treatment plant, and where they are finally
neutralized.
-------
3.31 Expansion Joints
for monolithic floor
3.321 Drains
for monolithic floor
3.322 Drains
for brick floor
Monolithic Topping
Expansion Joint
[wr«$fl
&&$$
W3C.iOty£
SXS ^ *N 'SS + /// \W^/ \\\
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Pre-formed Joint
Expansion Joint
Monolithic Topping
Expansion Joint Material
Acidproof Brick
Acidproof
Cement
Membrane
Concrete slab
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Fig. Ill ACIDPROOF BRICK &
MEMBRANE CONSTRUCTION
Membrane seals and protects concrete
substrate.
Acidproof brick protects membrane from
impact, abrasion, and thermal shock.
•Acidproof cement bonds brick solidly in
place and prevents liquids from seeping
through to the membrane.
^^
Acidproof Membrane,
Brick & Cement Construction
Fig. IV GROUTED
BRICK CONSTRUCTION
Ribbed bottom vitrified tile or brick set in
uncured base of cement and sand.
Tiles tamped evenly in place with W joint
spacing.
Joints grouted flush with acidproof cement
after base cures.
Grouted Brick Construction
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3.331 Brick Wall Coving
Flexible resin-based membrane pro-
tecting the concrete substrate is carried
up the wall behind coving. All joints
are made with acidproof cement.
Brick
Acidproof Cement
Joints
Membrane
3.332 Monolithic Wall Coving
Lining for wall is applied first and
feathered down over the floor. Mono-
lithic floor topping is then trowelled up
to the side wall and the joint is addi-
tionally protected with polysulfide
sealant.
Monolithic Wall Lining
Expansion Joint Sealant
Monolithic Topping
3.34 Brick & Monolithic Column Bases
Both types are treated essentially the same as side-
wall covings for the respective materials.
Mor
i
lolithic Topping
Monolithic
Lining
\ A
Expansion ^
Joint
r *
i
Expansion Joint
'%
^
i —
3
^-—
^
Acidproof
Brick
/Monolithic
Membrane
* 1 1 IV
3.351 Monolithic Floor Combined
With Acidproof Brick Trenches
Trench is lined with flexible membrane. Brick is then
layed up with acidproof cement. Glass reinforced
monolithic floor topping is trowelled across the
header course to completely seal the joint between
the concrete trench and its brick lining.
Reinforced Monolithic Topping
a • a. • A
•a • a .
4 '
•a
—
-
Membrane
1 1 1 1^1 1 1 1
=1
i
3.352 Monolithic Trenches
Consists of reinforced monolithic lining material
specially formulated for vertical surfaces. Note that
lining runs up on to the floor, and that the floor top-
ping is brought to the edge of the trench to com-
pletely seal the monolithic joint.
Monolithic Topping
\ ^
Monolithic Lining
4 Glass Cloth
Reinforcement
&:X '
'• A
3.36 Monolithic Pump Base
Top and sides of the base are covered with mono-
lithic lining which is feathered over the floor. Mono-
lithic floor topping is then trowelled on floor area and
lapped up the side of the base. Use of reinforcement
is determined by service conditions.
Monolithic Flooring
Monolithic Lining
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Cleaned
Gas
Contaminated
Gas
\] Liquid Inlet
Counter-Current Flow
-------
Liquid
Inlet
=^>
Contaminated
Gas
Cleaned
Gas
Crossflow
-------
FIELD JOIMT AT ROOF
ROOF SKIRT BY Cf iLCOTi
G IN ROOF
FIELD JOINT
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t—
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in
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ro
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-------
CUSTOMER
DCSCRIPTION
CU5T. DWG. No.
OPERATING CONDITIONS
PRESSURE- DESIGN
PRESSURE.OPERATING
CONSTRUCTION
THE CEILCOTE CO.. INC.
140 SHELDON RO. BEREA (CLEVELAND), OHIO
tUOTE No. [ S. O. »MT. OF
JHAWN CV-S CHK'D. I APPH. -_ «*•
^^ I I f^
>AT£ DAT! | DATE V>"
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DURACOR VENTILATION SYSTEM
THE CEILCOTE
140 SHELDON ROAD
CO., INC.
BEREA (CLEVELAND) OHIO
STEEL CO.
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