p.1 

OAR Box 1313 

Preppedby LaTeiaShed 

Document Number: 

27) ll-B-1 

Docket Number: 

A-88-02 

Printed 6/12/2008 9:03:28 AM Sheet 27 of 99 
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M?"i>2 

MIDWEST RESEARCH INSTITUTE 

4505 Creedmoor Road 

Raleigh, N.C. 27612 

Telephone (919) 781-5750 

Date: March 6, 1986 

(Finalized May 12, 1986) • 

Subject: Site Visit—Duall Industries, Inc. 

Chromium Electroplating NESHAP li'-ii •-.-.• \ 8 irZ ; 

EPA Contract 68-02-3817; ESED Project 85/02ja

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MRI Project 7717-K \ L~—- —

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To: Al Vervaert 

ESED/ISB/SSS (MD-13) 

U. S. Environmental Protection Agency 

Research Triangle Park, N.C. 27711 

I. Purpose 

The purpose of this site visit was to gather background information 

about control devices manufactured by Duall for controlling chromium 

electroplating emissions and to obtain names of plants that properly 

operate and maintain Duall control devices that could serve as possible 

test candidates. 

II. Place and Date 

Duall Industries, Inc. 

700 South McMillian Street 

Owosso, Michigan 48867 

(517) 725-8184 

January 8, 1986 

III. Attendees 

Dual! Industries, Inc. 

Phil Welch, Co-owner 

Don Stanton, Sales Manager 

U. S. Environmental Protection Agency 

Al Vervaert, ISB 

Midwest Research Institute 

Randy Strait 

/• 
P.3 

IV. Discussion 

We arrived at the plant at 1:30 p.m. The visit consisted of a tour 

of the manufacturing facility and discussions about control devices 

manufactured by Duall to control chromium electroplating emissions and 

about plants that properly operate and maintain Duall control devices that 

could serve as possible test candidates. 

A. General 

Duall was founded in 1964 and has installed air pollution control 

systems at over 6,800 facilities. A notebook of brochures describing the 

various types of control equipment was provided. 

Duall manufactures mist eliminators, packed-bed wet scrubbers, and 

moisture extractors that are used by chromium platers to control chromium 

emissions. These control devices are made of Type I or II polyvinyl 

chloride (PVC) or polypropylene to protect against corrosion by chromic 

acid. Type I PVC is used when fluorides are used as a catalyst in the 

chromium plating bath because fluorides will corrode Type II PVC. 

Otherwise, either Type I or II PVC is acceptable. Mr. Welch and 

Mr. Stanton believe that most chromium platers have installed some type of 

control equipment. 

B. Control Device Information 

1. Mist eliminators. Duall manufactures chevron-blade and mesh-pad 

mist eliminators that are used to control chromium emissions. A schematic 

of chevron blades is presented in Figure 1. The exhaust gas is drawn 

through the chevron blades by an induced draft fan. The blades cause 

abrupt changes in the direction of the flow of the exhaust gas, which, in 

turn, causes chromium droplets to impinge onto the blades at the 

overlapping points or edges. The chevron blades should be washed down 

about once per day to prevent edge buildup and possible pass through. 

Control efficiencies are estimated to range from 80 to 85 percent if the 

unit is properly operated and maintained. Mr. Stanton said that he would 

recommend the chevron-blade over the mesh-pad mist eliminator because it 

is easier to maintain. 

The mesh-pad mist eliminator contains a woven mesh pad on which the 

chromium particles impinge. Depending on the application, the pad can be 

made of various types of plastics and can be designed for droplets of any 

size. Control efficiencies are estimated to range from 80 to 85 percent 

and possibly up to 90 percent. Duall recommends mesh-pad mist eliminators 

for hydrochloric and hydrofluoric acid mist but not for chromic acid mist 

because of their tendency to clog with more viscous and heavier mists. 

Installation and operating instructions for Duall PVC mist eliminators are 

presented in the attachment to this report. 
P.4 

AIRFLOW 

DIRECTION 

OVERLAPPING 

POINTS 

/ v \ 

Figure 1. Schematic of chevron blades, 
P.5 

2. Packed-bed wet scrubbers. Mr. Stanton said that Duall generally 

recommends a single packed-bed scrubber for the control of chromium 

emissions. Duall does not believe that a double packed-bed scrubber is 

necessary because of the relatively high solubility of hexavalent chromium 

compounds in water. Control efficiencies for the single packed-bed 

scrubber are estimated to range from 98 to 99 percent if the proper amount 

of water is used. 

Installation, operation, and maintenance instructions for Duall 

scrubbers also are presented in the attachment to this report. The 

scrubber should not have to be washed down under normal operating 

conditions. However, if chromium deposits build up Inside the unit over a 

period of time, the unit should be shut down and chemically cleaned. 

Many plants pump scrubber water to a holding tank and recirculate 

the water to the scrubber. Mr. Stanton said that it would be Important to 

monitor the concentration of chromic ad d in the holding tank during a 

test because continued recirculation of the scrubbing water can result in 

the buildup of chromic acid concentrations high enough to decrease the 

overall control efficiency of the scrubber. 

C. Test Data and Candidate Plants 

Duall has a research and development laboratory that has conducted 

performance tests of its scrubbers and mist eliminators. Mr. Welch said 

that he would review the test data and determine if he could release it 

for review by EPA. He also said that he would try to identify plants that 

may be amiable to an EPA test of Duall equipment. 

Attachment 
attaciimeriL 

INDUSTRIES, INC. 

P.6 

DUALL PVC MIST 

ELIMINATOR 

INSTALLATION AND 

OPERATING INSTRUCTIONS 

NO. 121-8 ELM 

TECHNICAL 

BULLETIN 

1/85 

The Duall Mist Eliminator must be installed in a horizontal 

section of duct/ i.e. air enters at one side and exits at the 

opposite side. The eliminator will normally require transitions to adapt to your duct. The inlet and outlet are standard with 1-%" flanges which should be drilled to match the 

configuration on your transitions or a minimum of 5/16" holes 

at 4' c c. An acid resistant mastic or foam type gasket 

material should be used to seal the flanges. 

The eliminator is complete with an integral steel base. This 

base should be securely attached to your platform or floor. 

After proper connection to the duct/ the spray Washdown inlet 

is connected to a fresh water supply with a valve in the line. 

The purpose of this line is for periodic washdown of the 

interior of the mist eliminator. The frequency of the washdown process will vary with the type of mist being removed. 

On an average/ operation of the spray for ten minutes/ once a 

day should be adequate. If the unit is to be installed in an 

area subject to freezing temperatures/ precaution should be 

taken to prevent freeze-up of the fresh water.line. 

The drain should then be connected to your waste drain. A 

goose neck trap should be installed in the drain line ojr the 

end of the drain should be submerged in liquid to prevent air 

entering this line. This line will receive a continual drainage from the mist being removed as well as the water and 

contaminants from the periodic washdown. 

Tfua££ INDUSTRIES, INC. 

Main Office: 

OWOMO, Ml 46867-0769 

(517) 7254164 

TELEX 22-6532 

Fontst City, NC 26043-1000 

(704) 2454725 

TELEX 60-2210 

-S 
P.7 

INDUSTRIES, INC. 

DUALL SCRUBBERS 

INSTALLATION/ OPERATION 

& MAINTENANCE 

INSTRUCTIONS 

121-3 

TECHNICAL 

BULLETIN 

1/85 

AIR FLOW -•=• "--77". 

Units are designed to be on the" suction side of the fan. 

Air flow through units must be in the direction indicated. 

Too large a deviation from the design flow (CFM) vill affect 

the efficiency of the scrubber. Other designs are available/ however/ extra special equipment will be required. 

SUPPORTING THE UNIT 

The scrubber rests on a steel channel base making the unit 

self-supporting. This steel base may be suspended from 

overhead structure or test on any media suitable tb support 

the unit's weight. 

CONNECTION TO VENTILATION DUCT 

To eliminate the possibility of vater running dovn the duct/ 

there should be a minimum of 4 ft. of horizontal duct before 

the scrubber inlet transition. This should be sloped 

slightly towards the bottom of the scrubber. The flanges 

should be field drilled on approximately 4"-5" centers. A 

soft foam type chemically compatible gasket material or 

caulking is recommended between the .scrubber...flange and the 

duct flange. If possible/ caulking inside the scrubber on 

bottom and half way up the sides is recommended before the 

duct is attached. 

ELECTRICAL CONNECTION 

Proper electrical connection complying with local codes 

should be made to the pump motor. 

UNITS WITH INTERNAL RECIRCULATION SYSTEM 

Units should be installed in heated areas or protected from 

freezing. Fresh water must be supplied by connecting the 

supply line to the flowmeter provided. This flowmeter is 

mounted on the side of the scrubber. The make-up water line 

should be valved to provide a maximum of 5% of the 

recirculation rate as shown on the side of the scrubber. 

CAUTION: The scrubber drain is connected to customer's 

waste drain line. If this line must go to a sump/ it must 

be submerged 6"-8n below the lowest expected level/ or a 

plumber's "P" trap installed. This will prevent air from 

flowing into the drain line and interfering with proper 

drainage of the scrubber. Liquid build-up in the scrubber 

can interfere seriously with the proper operation of the 

scrubber. 

T)ua£C INDUSTRIES, INC. 

Main Off Ica: 

Owoaao, Ml 46667-0769 

(517) 7254164 

TELEX 22-6532 

Foraat City, NC 26043-1000 

(704) 2454725 

TELEX 00-2210 
P.8 

INDUSTRIES, INC. 

DUALL SCRUBBERS 

INSTALLATION/ OPERATING 

& MAINTENANCE 

INSTRUCTIONS 

121-5 

TECHNICAL 

BULLETIN 

drain. Pump motor should be interlocked vith fan to provide 

approximately tvo (2) minutes pump operation before fan may 

be started. Pumps should not be started until the scrubber 

base or remote recirculation tank are filled to the overflov 

level. During the early break-in period/ the pump packing 

gland should be checked for proper veeping. If incorrect/ 

check pump manufacturer's instructions for correction procedure. 

8. CHEMICAL ADDITIONS 

In some cases/ liquid caustic (sodium hydroxide solution) or 

an acid solution may be metered into the recirculation system to increase scrubber efficiency. A threaded coupling is 

provided in the side of the self-contained recirculation 

scrubbers for introduction of this chemical addition. 

Chemical addition for scrubbers provided vith remote 

recirculation tanks is made by adding the solution to the 

recirculation tank. When using solid caustic/ care should 

be taken in mixing to assure that no solid material is 

pumped into the scrubber or recirculation tank vhich may 

cause a build-up. The pH of the recirculation tank should 

be maintained in a range that wi-11 achieve the desired 

scrubber efficiency while preventing the appearance of a 

build-up on the packing. A pH control package may be 

purchased from Duall to provide a chemical feed pump and pH 

control to maintain the recirculation solution in the 

satisfactory range. 

9. PERIODIC MAINTENANCE SCHEDULE 

Inspection doors are provided in all scrubber units for 

periodic inspection. Periodic inspection on a monthly basis 

is suggested. This inspection should include the following: 

A. Check spray nozzles with the pump and fan in operation. 

All nozzles should produce a full 360 spray pattern. 

If any nozzles are found to be spraying incorrectly/ the 

pump should be stopped/ the header pipe removed/ and 

each nozzle cleaned individually. When the cleaned 

header system has been replaced/ the pump may be restarted. 

B. Check the face of the scrubber and the spray nozzles for 

ariy indication of a build-up of solids. If a surface 

build-up has occurred/ it may be removed by spraying the 

pack with high pressure water/ by chemical treatment of 

1/85 

INDUSTRIES, INC. 

Main Offlea: 

Owoaao, Ml 46667-0769 

(517) 7254164 

TELEX 224532 

Foraat City, NC 26043-1000 

(704)2454726 -

TELEX 60-2210 

7