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OAR Box 1313 

Prepped by LaTeia Shed 

Document Number: 

46) ll-B-20 

Docket Number: 

A-88-02 

Printed 6/12/2008 9:03:29 AM Sheet 46 of 99 
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Date: 

Subject: 

From: 

To: 

March 16, 1987 \ 

(Finalized May 28, 1987-)" 

lC-e-"2C 

A-88-02 

MIDWEST RESEARCH INSTITUTE 

4505 Creedmoor Roa< 

Raleigh, N.C 2761: 

Telephone (919) 781-575( 

FILE COPY 

Site Visit—United Metal Finishing, Inc. of Greensboro 

Chromium Electroplating NESHAP 

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

MRI Project 7717-K 

Robin Barker -"--

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 as a test site for evaluating the performance of a mist eliminator with a single and double set of chevron 

blades. 

II. Place and Date 

United Metal Finishing, Inc., of Greensboro 

133 Blue Bell Road 

Post Office Box 16623 

Greensboro, North Carolina 27406 

(919) 272-8107 

December 8, 1986 

III. Attendees 

United Metal Finishing, Inc. 

Claude Church, President 

Jerry C. Messick, Sr., Vice President 

U. S. Environmental Protection Agency (EPA) 

Al Vervaert, ISB 

Midwest Research Institute (MRI) 

Robin Barker 

Amy Kowalski 

Randy Strait 

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IV. Discussion 

The visit consisted of a tour of the plating shop and a discussion 

about the hard chromium electroplating operation and the chromium emission 

capture system. Emission testing on the chevron-blade mist eliminator 

first with a single and then with a double set of blades was also 

discussed. 

A. General 

United Metal Finishing, Inc., 1s a small job shop that began 

operation about 6 months ago. The company performs hard chromium plating 

of industrial rolls and textile machine and hydraulic hoist parts and also 

performs zinc and cadmium plating. A decorative plating line 1s being 

Installed and 1s expected to be operational during the first quarter of 

1987. The hard chromium plating Hn e operates 24 hours/day, 

5 days/week. 

B. Process Description 

There are two hard chromium plating tanks at this facility that are 

arranged as shown in Figure 1. Tank 1 is 6.4 meters (m) (21 feet [ft]) 

long, 1.2 m (4 ft) wide, and 0.9 m (3 ft) deep. Tank 2 is 1.2 m (4 ft) 

long, 1.2 m (4 ft) wide, and 1.2 m (4 ft) deep. The capacities of Tanks 1 

and 2 are 7,120 liters (a) (1,880 gallons [gal]) and 1,820 a (480 gal), 

respectively. An automatic hoist 1s used to transfer parts into and out 

of the tanks. 

The plating solution in the tanks contains approximately 247 grams 

per Uter (g/a) (33 ounces per gallon [oz/gal]) of chromic add . Sulfuric 

acid 1s used as a catalyst in the plating solution 1n a concentration of 

approximately 2.5 g/a (0.33 oz/gal) of solution. 

C. Emission Control 

Both tanks are equipped with single-sided lateral hoods. The hood 

on Tank 1 has one row of slots and two takeoffs. The hood on Tank 2 has 

two rows of slots and one takeoff. During the visit, it was evident based 

on visual observations that the ventilation system on Tank 1 was 

ineffective at capturing the chromic acid mist produced during plating. 

Substantial quantities of mist were observed spilling out of the tank Into 

the plating room and atmosphere. The ventilation system on Tank 2 

appeared to be effective at capturing the chromic acid mist produced 

during plating. Mr. Messick stated that with the building doors closed as 

they are in the winter, there is insufficient makeup air for the 

ventilation system to perform at design specifications. Consequently, a 

negative pressure is created inside the plating shop with respect to 

outside the building. During the summer, the emission capture system 

operates at design specifications because the open plating shop doors 

allow sufficient makeup air to enter the plating shop. 

a-
MOISTURE 

EXTRACTOR ? -T > 

MIST 

ELIMINATOR 

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1 

i 

ZINC PLATING LINE 

r+ 

CHROMIUM 

PLATING 

TANK 2 

SINGLE-SIDED 

LATERAL HOOD 

SINGLE- S1DLD LATERAL HOOTTOD t 

CHROMIUM r-L.TIiK 

TANK 1 

LEGEND 

AIP.rLO..' 

=> 

WATER 

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Figure 1. Schematic of hard chromium plating Tanks 1 and 2. 

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Emissions 

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from both tanks 

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are 

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ducted 

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together 

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and 

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are 

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vented 

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outside 

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The fan is powered by a 10-horsepower motor. The design gas flow rate of 

the system is 566 cubic meters per minute (m /m1n) (2^,000 cubic feet per 

minute [ft/min]). Actual conditions are about 400 m /m1n 

(14,000 ft /min) due to the increased static pressure on the fan resulting 

from the deficiency 1n makeup air supply. The mist eliminator was 

manufactured and Installed by KCH Services, Inc., in April 1986. The mist 

eliminator contains a single set of wave-type blades. The blade assembly 

is about 187 centimeters (cm) (73.5 Inches [in.]) in height, 171 cm (67.5 

1n.) in width, and 25 cm (10 in.) in depth. The design cross-sectional 

gas velocity at the blades is 274 meters per minute (900 feet per 

minute). Actual conditions are lower due to the reduced gas flow rate. 

The mist eliminator is equipped with a spray washdown system to clean the 

blades. The mist eliminator is washed down once per day by plant 

personnel until the washdown water runs clean. The washdown water 1s 

drained back Into Tank 1. 

The pollution control system also 1s equipped with a moisture 

extractor downstream of the mist eliminator. The moisture extractor was 

installed after chromic acid droplets were observed to be breaking through 

the mist eliminator. As an additional precaution, the stack was replaced 

with an inverted U-shaped duct that is funnelled so that any remaining 

chromic acid in the air stream will impinge out and drain into the plating 

tank. The clean air is exhausted outside the building. 

V. Conclusions 

United Metal Finishing, Inc., is a small job shop that performs hard 

chromium electroplating. Although the operating parameters of the plating 

tanks are typical of conventional hard chromium plating operations and the 

type and amount of work would generate chromium emissions adequate for 

testing, several technical issues associated with the capture and control 

equipment will have to be resolved before emission testing could be 

performed. The technical issues include the following: (1) makeup air 

supplied to the plating shop during the winter months is insufficient and 

significantly decreases the performance of the capture system because the 

gas face velocity across the mist eliminator blades is significantly 

reduced below design specifications; (2) there 1s not a sufficient length 

of straight duct at the inlet of the mist eliminator for emission testing, 

and (3) the moisture extractor and ductwork downstream of the moisture 

extractor would have to be removed and replaced with a stack extension for 

outlet testing. Also, the costs and logistics of retrofitting the mist 

eliminator with a double set of blades must be evaluated. The mist 

eliminator can be tested with a single set and a double set of wave-type 

blades to determine the effect of redundancy on the performance of the 

unit. The plant is presently working with KCH Services, Inc., the 

manufacturer and installer of the ventilation system, to correct the 

problem of insufficient makeup air. 

Plant personnel were very cooperative during the visit and are 

willing to allow emission testing of the mist eliminator if the technical 

issues discussed above can be resolved. 

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P.6 

[Note: During a telephone conversation with Mr. Strait of MRI on 

May 27, 1987, Mr. Church stated that a second set of blades was installed 

in the mist eliminator 1n April 1987, by KCH Services, Inc. Mr. Church 

did not provide any other comments on the draft report during this 

contact]. 

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