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OAR Box 1313 

Prepped by LaTeia Shed 

Document Number: 

35) ll-B-9 

Docket Number: 

A-88-02 

Printed 6/12/2008 9:03:28 AM Sheet 35 of 99 
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A-88-02 

MIDWEST RESEARCH INSTITUTI 

4505 Creedmoor Roai 

Raleigh, N.C. 2761: 

• - .Telephone (919) 781-5751 

Date: July 18, 1986 

(Finalized December 19, 1986) 

Subject: Site Visit—Able Machine Company 

Chromium Electroplating NESHAP 

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

MRI Project 7717-K \ 

From: Randy Strait 

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 the chromium electroplating operation at this plant and to determine 

the suitability of this plant for chromium emissions testing. 

II. Place and Oate 

Able Machine Company 

Post Office Box 675 

Taylors, South Carolina 29687 

(803) 244-0893 

March 27, 1986 

III. Attendees 

Able Machine Company 

Ricky Owens 

U. S. Environmental Protection Aqency 

Al Vervaert, ISB 

Midwest Research Institute 

Randy Strait 

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IV. Discussion 

A. General 

Able Machine Company is a small job shop that performs hard chromium 

electroplating of industrial rolls. 

B. Process Information 

There are two hard chromium plating tanks at this facility. Tank 1 

was installed in July 1985. The tank measures 14 feet (ft) in length, 

4 ft 1n width, and 10 ft 1n depth and holds about 4,180 gallons (gal) of 

plating solution. Tank 2 measures 11.5 ft 1n length, 2.5 ft 1n width, and 

8 ft 1n depth and holds about 1,720 gal of plating solution. 

The plating solution for both tanks consists of chromic ad d (Cr03) 

in a concentration of 28 ounces per gallon (oz/gal) of water. Sulfuric 

a d d (HjSO,..) is used as a catalyst 1n the plating solution 1n a 

concentration of 0.18 oz/gal. The normal operating temperature of the 

plating solution 1s between 110° and 140°F. Both tanks are cooled with 

water. 

An overhead hoist 1s used to transport rolls to and from the plating 

tanks. Tank 1 is operated at full capacity for one 8-hour shift per 

day. Tank 2, which was not operating during our visit, 1s used only when 

Tank 1 is shut down for repairs or when the plant receives a heavy work 

load. Typically, each tank is operated at full capacity when in use. A 

maximum of 12 rolls is plated at a time in Tank 1 for 1.5 hours at 

7.5 volts (V) and 8,000 amperes (amps). A maximum of eight rolls 1s 

plated at a time in Tank 2 for 2 hours at 6.0 V and 6,000 amps. After 

being plated, the rolls are rinsed with water from a hose over the top of 

the plating tank. This rinsing allows excess plating solution on the 

rolls to drain into the plating tank, thus reducing drag-out. It takes a 

total of about 40 minutes to unload and load one plating tank. 

Tank 1 is energized by a single transformer/rectifier equipped with 

a timer and other automatic controls. The timer is set to turn off the 

transformer/rectifier when plating is completed. Other automatic controls 

regulate the voltage and current and turn the transformer/rectifier off 

when the plating bath exceeds normal operating parameters or when the 

plating tank ventilation system malfunctions. Maximum operating voltage 

and current for the transformer/rectifier are 12 V and 12,000 amps, 

respectively. Tank 2 is energized by a single transformer/rectifier 

without automatic controls. Maximum operating voltage and current are 

15 V and 6,000 amps, respectively. 

C. Emission Control 

A schematic of the exhaust systems for Tanks 1 and 2 is shown in 

Figure 1. The capture and control system for Tank 1 was manufactured and 

installed 1n July 1985 by Duall Industries, Incorporated. The tank is 

equipped with a push-pull capture system. The hood installed on the back 

tL 
STACK STACK 

DUALL 

MOISTURE 

EXTRACTOR 

LEGEND 

AIRFLOW 

•e 

WATER FLOW 

WALL DUALL 

MIST 

ELIMINATOR 

^ 

WALL 

KCH 

SINGLE 

PACKED-BED 

SCRUBBER 

Figure 1. Schematic of hard chromium plating operation at Able Machine Company. 

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of the tank 1s 12 ft in length and 6 ft in height and contains 3 rows of 

slots with 15 slots per row. The slots are 10 inches (in.) 1n length and 

1 in. in width. The pusher side of the hood Installed on the front of the 

tank contains 72 holes spaced 2 in. apart. Each hole is 0.125 in. in 

diameter. Both sides of the tank are equipped with baffles 4 ft in length 

and 6 ft in height. Removable panels are placed over the top of the tank 

during plating to enclose the surface of the plating solution to maximize 

capture efficiency. 

Tank 2 also is equipped with a push-pull capture system. The hood 

installed on the back of the tank is 12 ft in length and 3.5 ft 1n height 

and contains 3 rows of slots with 12 slots per row. The slots are 10 In. 

in length and 0.5 1n. in width. The pusher side of the hood contains 

42 holes spaced 2 1n. apart. Each hole 1s 0.125 1n. in diameter. The 

right side of the tank only is equipped with a baffle 3 ft in length and 

2 ft in height. 

Chromium emissions from Tank 1 are vented to a chevron-blade mist 

eliminator located on a mezzanine structure behind the tank. The airflow 

rate of the mist eliminator is 6,000 actual cubic feet per minute 

(acfm). A moisture extractor is installed in the stack downstream of the 

mist eliminator to control chromium emissions that are drawn through the 

mist eliminator. The moisture extractor consists of a stationary set of 

blades that centrifugally forces acid mist or droplets entrained in 

exhaust gas to impinge against the sides of the extractor wall. The 

droplets drain down the sides of the extractor into collection areas and 

then are flushed out of the unit. The mist eliminator and moisture 

extractor are washed down with about 75 gal of water at the end of each 

working day and each morning if the plating tank was operated overnight. 

Wash-down water is drained into a 160-gal holding tank inside the plating 

shop. The plating tanks are equipped with a float that regulates the flow 

of water from the holding tank to the plating tank. 

A single packed-bed vertical-flow wet scrubber is used to control 

chromium emissions from Tank 2. The scrubber was manufactured and 

installed in 1980 by KCH Services, Incorporated. The design gas flow rate 

of the scrubber is 5,000 standard cubic feet per minute, and the operating 

gas flow rate is 6,472 acfm. The design waterflow rate to the scrubber is 

15 gal per minute. The scrubber water is pumped to the rinse tank and 

recirculated to the scrubber on a continuous basis. The rinse tank is 

4 ft 1n length, 3.5 ft in width, and 8 ft in depth and contains a maximum 

of 838 gal. 

D. Conclusions 

Able Machine Company is a small job shop involved in hard chromium 

plating. The capture system on Tank 1 appears to be very effective, and 

the Duall mist eliminator and moisture extractor would be good candidates 

for emission testing for the following reasons: (1) operating parameters 

of the plating tank are typical of those for conventional hard chromium 

plating operations; (2) the type and amount of work plated would generate 

chromium emissions adequate for testing; (3) parameters such as surface 

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area plated and amount of chromium deposited can be easily calculated; 

(4) the plating tank and emission capture and control equipment are less 

than a year old and are well maintained and operated; and (5) there is 

adequate duct length at the inlet and outlet of the mist eliminator and 

moisture extractor for test ports. 

Emission testing of the KCH scrubber on Tank 2 would be possible. 

However, the Inlet location is less than desirable because a test port 

would have to be cut at the inlet of the scrubber next to an elbow. 

Although Tank 2 was not operating during our visit, the design of the 

ventilation system should provide good capture. Also, the type and amount 

of work plated would generate adequate chromium emissions for testing. 

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