ACKNOWLEDGEMENTS

The project leader was Shobna Sahni with ARB Stationary Source Division. The 

sampling team was led by David Todd and included Don Ridgley and Ron Barros with 

the ARB Monitoring and Laboratory Division. Betsy Ronsse and Donald Taylor with 

MLD Northern Laboratory Branch conducted the laboratory analysis. Dominick Nole 

and Paramo Hernandez with Alta Plating provided chrome plating assistance and 

expertise. Paramo Hernandez of Alta Plating provided analyses for plating bath surface 

tension and chromic acid content.

This report presents results based on samples collected and analyzed by the Air 

Resources Board (ARB) staff using ARB test methods. The results have been reviewed 

by the staff and are believed to be accurate within the limits of the methods. However, 

data may have been affected by variables that were not known to staff during sampling 

and review.
California Environmental Protection Agency

AIR RESOURCES BOARD

Monitoring and Laboratory Division

TABLE OF CONTENTS

I. INTRODUCTION.................................................................................................. 1 

II. PROCESS DESCRIPTION................................................................................... 1 

III. ALTA PLATING SOURCE TEST.......................................................................... 1 

IV. TEST METHODS ................................................................................................. 4 

V. QUALITY ASSURANCE / QUALITY CONTROL .................................................. 6 

VI. TEST RESULTS................................................................................................... 8 

FIGURES

FIGURE III-1: Alta Decorative Chrome Plating Tank with ARB Capture Hood............... 3 

FIGURE III-2: ARB Sampling Location........................................................................... 3 

TABLES

TABLE VI-1. ARB Test Results.................................................................................... 9 

TABLE VI-2. Indoor Ambient Cr(VI) Data................................................................... 10

APPENDICES

A. Calculated Results and Field Data Sheets

B. ARB Laboratory Results

C. Chain-of Custody Sheet

D. Plating Tank Data 

E. Sketch of Capture Hood 
(This page is blank.)
Page 1 

California Environmental Protection Agency

AIR RESOURCES BOARD

Monitoring and Laboratory Division

Total and Hexavalent Chromium Emissions from 

Alta Plating and Anodizing 

Decorative Chromium Plating Tank

I. INTRODUCTION

At the request of the Air Resources Board (ARB) Stationary Source Division (SSD), staff 

of the Monitoring and Laboratory Division (MLD) performed emissions testing of a 

decorative chrome electroplating tank operated by Alta Plating and Anodizing located at 

1733 S Street in Sacramento, California. Total and hexavalent chromium emissions 

testing was conducted from January 26 through February 8, 2004.

II. PROCESS DESCRIPTION

Alta Plating performs decorative chromium plating on a variety of small parts. Alta’s 

decorative chrome plating tank has a capacity of 730 gallons and is 96 inches long, 42 

inches wide, and 42 inches deep. The plating tank is equipped with its own rectifier, 

and amperage and voltage into the tank varies with the type and area of the parts to be 

plated. Plating bath temperature was maintained at approximately 105 - 115° F during 

plating operations. SSD staff periodically collected voltage, amperage, bath 

temperature, and amp-hour readings for the plating tank during the source test. These 

readings are found in Appendix D of this report.

Emissions from the plating tank are controlled through the use of a chemical fume 

suppressant, MacDermid's Protab 1000. Before testing the second week, MacDermid’s 

Clepco Chrome Mist Control was added reducing the surface tension from 40 to 30 

dynes/cm. Chemical fume suppressants are used in plating baths to change the 

surface tension and reduce chromic acid mist that is generated during plating 

operations. No plating tank ventilation system or additional emissions controls are used 

(i.e. HEPA filter) at Alta. Any emissions from the tank are emitted into the building and 

subsequently vented out through open doors, windows, and roof top turbine vents. 

According to the Permit to Operate, electrical usage for the decorative chromium plating 

tank may not exceed 42,000 ampere-hours per year. The permit also requires weekly 

recording of the amp-hour totalizer meter readings.

III. ALTA PLATING SOURCE TEST

The source test consisted of six individual sample runs. Three sample runs were 

collected from Alta Plating’s decorative chrome plating tank between January 27-29, 
Page 2 

2004. During these sample runs the surface tension of the plating solution was about 

40 dynes/cm (measured 39.3 – 40.7) which is a normal operating condition for this 

facility. Three additional sample runs were collected February 2, 3, and 4, 2004, when 

the surface tension was about 30 dynes/cm (measured 28.4 – 30.8). The last three 

samples were collected to determine the effect of lower surface tension on emissions. 

Surface tension was lowered by adding 4.0 liters of MacDermid’s Clepco Chrome Mist 

Control to the plating bath between sample runs 3 and 4 (between Jan. 29 and Feb. 2) 

to the MacDermid's Protab 1000 already in the tank.

ARB Method 425 was used to determine hexavalent and total chromium emissions 

collected during the source tests. Each sample was collected continuously over a sixhour period. During sampling, production or “dummy” parts were plated in the tank. 

The mix of production and dummy parts was necessary to obtain a target of about 400 

amp-hours per run. Alta staff prepared each dummy part for plating in the same 

manner as production parts, and repeated the preparation each time the part was to 

reenter the plating tank. 

ARB staff built a ventilation system to carry any chromium emitted by the plating tank to 

the source sampling area. (See Figures III-1 and III-2).) This ventilation system 

consisted of a capture hood with an open bottom, open or plastic-sheeted sides, and a 

plastic-sheeted top. A 12-inch diameter exhaust duct near the top back center of the 

capture hood carried plating tank emissions from the tank and capture hood through a 

sample collection area and then out a nearby exit door. Surfaces of the hood and duct 

assembly were made of plastic sheeting and PVC flex hose and tubing. This system 

was designed to allow droplets to return to the tank but collect fumes that floated above 

the tank. Per South Coast AQMD’s procedures for plating tanks and fume suppressant 

certification, the average "lift" velocity between the tank and the ventilation system was 

designed to be less than 50 feet/minute.

The capture hood was suspended above the plating tank from the ceiling. The open 

bottom of the capture hood was slightly larger than the open top of the plating tank. 

When suspended and in use, the bottom of the capture hood sidewalls along the back 

and sides ranged from 7 to 8 inches above the top lip of the plating tank. The front of 

the tank was open so plating parts could still be placed in the tank without interference. 

Half of the left sidewall was also open to allow parts to transfer from the plating tank to 

the first rinse tank. Based on smoke tests, additional pieces of plastic sheeting were 

suspended from the top of the hood at various locations to prevent emissions "leakage" 

out of the hood (see Figure III-1 below and Appendix E).

Flexible and rigid (straight) 12-inch diameter PVC pipe directed tank emissions from the 

capture hood to the ARB Method 425 sample collection area. Method 425 samples 

were collected from a vertical (12-inch diameter, 67 inches long) PVC pipe sitting on the 

inlet to a fan box. Samples were collected from two, 3-inch diameter holes cut 90 

degrees apart into the vent stack and located 18 inches (11⁄2 diameters) above the fan 

box and 49 inches (4 diameters) below the flexible pipe connected to the capture hood.
Page 3 

Fig III-1: Alta decorative chromium plating tank and rectifier with ARB capture hood, ducting, and 

ambient sampler (on rectifier top). 

Fig. III-2: ARB sampling location behind Alta chrome plating tank, including vertical sampling pipe (12-

inch diameter), fan box with controller, and exhaust ducting. 

Ambient 

sampler

Rectifier

12" Duct

ARB Hood

Chrome 

Plating 

Tank

12" Duct

ARB Hood

Sampling console

Sample probe 

and support 

Sampling Area

Sample 

Impinger Box 

Fan Box w/ Motor 

and Control 

Exhaust 
Page 4 

The fan box includes a variable flow controlled fan with a 5-foot, 12-inch diameter PVC 

rigid pipe to exhaust tank emissions through a door and out of the building. 

The capture hood was designed to capture plating tank emissions with less than 50 feet 

per minute of vertical lift above the plating tank. Fifty feet per minute is a maximum 

standard developed by South Coast AQMD for using a similar capture hood to measure 

emissions from nickel plating tanks and to certify chromium plating fume suppressants. 

At this velocity plating bath drops would fall back into the tank but fumes and vapors 

would be drawn into the ventilation system. Fifty feet per minute under the hood 

equaled 1,367 cubic feet per minute (cfm) at the sample collection site. Actual flow at 

the site during sampling was approximately 1,000 cfm. Smoke tests were conducted 

during each run to ensure no emissions “leakage” out of the hood. The smoke did not 

contain any chromium or other compounds that would interfere with chromium sampling 

and analysis.

Indoor ambient samples were collected concurrently with each source test run. Another 

four indoor samples were collected after sampling was completed and the capture hood 

removed. One of the four was collected on a Sunday when Alta was not plating. The 

sampler did not shut off on Sunday as programmed, but was shut off manually around 

8:00am Monday. As a result, some Monday plating occurred while the ambient sampler 

was running. Indoor samples were collected on sodium bicarbonate-impregnated filters 

with a BGI, Inc. PQ100 ambient sampler. The sampler was set on top of the rectifier 

next to the decorative chrome tank (see Figure III-1). Indoor ambient samples were 

analyzed for hexavalent chromium only. 

IV. TEST METHODS

A. Source Sampling Procedures

Samples were collected and recovered by ARB Stationary Source Testing Branch. 

Stack and duct flows were determined by ARB Stationary Source Test Method 1 

(velocity traverse), Method 2 (stack velocity and flow rate), Method 3 (stack gas dry 

molecular weight), and Method 4 (moisture content). For Method 3, atmospheric 

concentrations of carbon dioxide, nitrogen, and oxygen were used to determine dry 

molecular weight. 

Hexavalent and total chromium samples were collected isokineticaly in accordance 

with ARB draft Method 425, “Determination of Total Chromium and Hexavalent 

Chromium Emissions from Stationary Sources.” ARB Method 425 was originally 

adopted January 22, 1987 and amended August 27, 2002. ARB draft Method 425 

incorporates several approved modifications from the current amended version. 

These include the use of unheated sample lines and probes, the use of 0.1 N 

sodium bicarbonate impinger solution in place of 0.1 N sodium hydroxide solution, 

and deletion of the sample train filter and filter heater. 
Page 5 

Each test day consisted of a six hour run using a single sample train, except for Run 

2 which was lengthened to 8 hours to increase the total amp-hours for the run. 

The chromium sampling train consisted of a 48-inch glass-lined stainless steel probe 

with a 3/8-inch diameter glass nozzle, and attached Pitot tube and thermocouple for 

monitoring stack conditions. A ten-foot Teflon line connected the probe to three 

Greenburg-Smith impingers used to collect and stabilize any chromium sample. The 

first two impingers contained 100 milliliters each of 0.1 normal (N) sodium 

bicarbonate solution. A third, empty impinger was followed by a cylinder of silica gel 

(final moisture collection), and a 50 foot umbilical line connected to an isokinetic 

(Method 5) sampling console. The sampling console includes a vacuum pump, a 

dry gas meter, and additional monitors and controls for collecting a sample 

isokinetically. 

In accordance with Method 1, the sampling location required 24 traverse points (12 

sampling points on each diagonal ninety degrees apart). 

In accordance with Method 2, thermocouples and Type S pitot tubes bundled with 

the sampling probes were used to determine stack velocity. The weight of the 

impinger solutions and silica gel were recorded before and after each test in order to 

obtain the moisture content of the stack gas in accordance to Method 4. In addition, 

stack temperature, ambient temperature, and barometric pressure were measured 

and recorded during each test. Leak checks in accordance with Method 5 were 

performed on each sample train and Pitot tube setup before and after each sample 

collection. Leak check results were documented on the Method 425 run sheets.

After sampling, rinses of the sampling train nozzle, probe and transfer line, as well 

as the catch from the impingers, were recovered into three, 500-ml glass sample jars 

as follows (all sample jars were pre-cleaned and tested to ensure the absence of 

chromium prior to the source test): 

• Container 1 - rinses from the nozzle, sample probe, and transfer line;

• Container 2 – first impinger catch; and

• Container 3 – second and third impinger catches. 

The pH of the sodium bicarbonate solution used for the probe rinse and impingers 

was maintained at ≥ 8.0. Additionally, the impinger solution was chilled with ice to 4 

°C (39 °F) or less during sample collection. All samples were also chilled with ice 

and refrigeration to 4 °C (39 °F) or less during transport and storage prior to analysis 

to minimize the conversion of hexavalent chromium to trivalent chromium. During 

sample recovery prior to analysis, disposable vinyl gloves were worn to help prevent 

contamination. At the conclusion of each sampling day, staff transported the 

collected samples to the laboratory for recovery and analyses.

Amperage and voltage supplied by the rectifier was monitored and recorded by SSD 

staff during the source tests runs. SSD staff also recorded tank temperature and 

totalizer amp-hours. In addition, plating bath samples were collected near the 
Page 6 

beginning and end of each sample run, and analyzed by Alta Plating to determine 

plating bath surface tension and chromic acid content. 

B. Indoor Ambient Sampling

Indoor ambient samples were collected on 47 mm filters using a PQ100 ambient 

sampler. The filters were specially treated with sodium bicarbonate in order to 

preserve the sample for hexavalent chromium analysis . Indoor ambient samples 

were collected in parallel with the plating source test. Because of the capture hood 

interference, additional indoor ambient samples were collected after the hood was 

removed. After sampling, the filters were placed back into their storage cassettes 

using sterile gloves. The filters were then placed in their original container and 

returned to the laboratory for analysis. 

C. Analytical Procedures

The plating tank stack emissions were analyzed for both hexavalent and total 

chromium. The indoor filters were extracted into a solution and analyzed for 

hexavalent chromium only, using the same analytical procedure as the hexavalent 

chromium portion of the stack samples.

Laboratory analyses for hexavalent and total chromium of the collected stack 

samples was performed by ARB’s Northern Laboratory Branch. Hexavalent 

chromium (also known as hex chrome, Cr(VI), or Cr+6) was measured using ion 

chromatography (IC) in accordance with ARB standard operating procedure (SOP) 

MLD039. The limit of detection (LOD) of the analytical procedure for hexavalent 

chromium is 0.2 nanograms per milliliter (ng/ml). Total chromium was determined 

using an atomic absorption/ graphite furnace (GFAA) technique. To deal with the 

high carbonate fixative concentrations, staff used a variation of ARB SOP MLD005. 

The LOD of the analytical procedure for total chromium is 1.0 ng/ml. 

V. QUALITY ASSURANCE / QUALITY CONTROL

To ensure that collected data are consistent, relevant, and defensible, appropriate field 

and laboratory Quality Assurance (QA) procedures were followed throughout the source 

test. A detailed explanation of the ARB’s standard field and laboratory QA procedures 

are contained in ARB Quality Assurance manuals, Stationary Source Test Methods, and 

laboratory SOPs. 

As required by ARB Method 425, all surfaces that came into contact with a sample were 

either glass or Teflon and were pre-cleaned using the following procedure:

• the glassware was first washed with detergent;

• soaked with a 10% solution of nitric acid for several hours;
Page 7 

• flushed with liberal amounts of tap water;

• rinsed with de-ionized water; and

• rinsed with 0.1 N sodium bicarbonate solution. 

To ensure that the sampling equipment was clean and free of chromium contamination, 

a sample of the final sodium bicarbonate rinse was analyzed for total chromium (Cr). If 

any Cr was detected in the final rinse, all affected sampling equipment were re-cleaned 

until a sample of the final rinse contained no detectable Cr. In addition, extra precleaned equipment was deployed to ensure that no equipment needed to be re-cleaned 

or re-used during field sampling. 

Also, blank source tests were performed on the ARB capture hood and ducting before 

and after sampling at Alta. Both tests had "nondetects" for hexavalent and total 

chromium. The pre-test sampling proves that ARB equipment, including the capture 

hood, did not contribute to Alta emissions. The post test sampling proved their was no 

chromium carryover from one sample run to the next by the capture hood and attached 

ducting.

The sampling console used during the source test was pretested on December 23, 

2003. The console post test was conducted on February 10, 2004. The Type S pitot 

tubes used for stack velocity determinations met the required specifications for a 

baseline coefficient of 0.84 as specified in ARB Method 2. The console assembly, 

including pitot tubes, passed leak checks before and after each velocity determination. 

In addition, all sampling train assemblies passed leak checks before and after each 

sample run. 

Prior to deploying to the field, a blank of the sodium bicarbonate solution used for rinses 

and impinger solutions was collected and given to the laboratory staff for analysis and 

correction of field sample results. During the test week, staff collected a field blank of 

the same sodium bicarbonate solution for analysis with the samples. Field blanks are 

not used to correct laboratory results, but would indicate any contamination beyond the 

original laboratory samples that might affect the results. 

 

All test samples were collected using an iced impinger set. After recovery, samples 

were stored in a sample refrigerator or on ice to maintain their temperature at or below 4 

°C (39 °F) as required by ARB Method 425. Collected and recovered samples 

remained on ice while on site and during transport to the laboratory for analyses. Staff 

of the Northern Laboratory Branch ensured that the samples were maintained at or 

below 4 °C (39 °F) while awaiting analysis.

During sample collection and transport, the pH of the sodium bicarbonate solution used 

for the probe rinse and impinger charging was maintained at ≥ 8.0 as required by 

Method 425. This is necessary to ensure that any collected hexavalent chromium is not 

reduced to trivalent chromium. The pH of the impinger solutions was checked before 

and after sampling, and after sample recovery. 
Page 8 

Chain of custody was maintained for all collected samples. A chain of custody sheet 

was prepared for each sample run. A copy of an Alta Plating chain of custody sheet is 

included in Appendix C as an example.

VI. TEST RESULTS

Results of the ARB Method 425 source tests for the Alta Plating decorative chromium 

plating tank are presented in Table VI-1 for surface tensions of 40 dynes/cm and 30 

dynes/cm. At 40 dynes/cm, chromium emission rates ranged from 0.009 to 0.017 

milligrams per amp-hour (mg/amp-hr) for total chromium and 0.006 to 0.012 mg/amp-hr 

for hexavalent chromium. At 30 dynes/cm, chromium emission rates ranged from 

0.004 to 0.007 mg/amp-hr for total chromium and 0.003 to 0.006 mg/amp-hr for 

hexavalent chromium.

Indoor ambient results are presented in Tables VI-2a and VI-2b. Copies of run sheets 

and emissions calculations are in Appendix A. Laboratory results are presented in 

Appendix B. Additional plating tank information is in Appendix D.
Page 9 

Table VI-1

Alta Plating Decorative Chromium Plating Tank

Sampling Dates – January 27-29 & February 2-4, 2004 

Sampling Location 40 dynes/cm Surface Tension 30 dynes/cm Surface Tension

Sample Number A-11 A-12 A-13 A-21 A-22 A-23

Sampling Date 1/27/2004 1/28/2004 1/29/2004 2/2/2004 2/3/2004 2/4/2004

Plating Tank Data

Totalizer (amp-hours) 183 537 393 390 382 383

Production Rate (amp-hrs/hr) 30.5 67.1 65.5 65.0 63.7 63.8

Freeboard (inches to overflow)* 5.8 -.4.5 4.0 - 4.2 4.0 - 4.0 4.75 - 5.0 4.0 - 4.5 4.5 - 4.9

Surface Tension (dynes/cm)* 39.3 – 39.9 40.7 – 39.3 40.1 – 39.7 30.8 – 28.9 30.5 – 28.9 29.2 – 28.4

Chromic Acid Conc. (oz/gal) 37.7 34.3 35.9 35.1 34.5 34.6

Bath Temperature (oF) 110 110 109 104 109 109

Stack Data

Stack Temperature ( 0F) 63 62 61 62 62 61

Velocity (ft/sec) 23 21 21 21 20 21

Static Pressure ("H20) -0.28 -0.25 -0.25 -0.27 -0.25 -0.26

Stack Area (sq. ft.) 0.785 0.785 0.785 0.785 0.785 0.785

Flow Rate (DSCFM) 1102 983 984 972 958 982

Moisture (% of v/v) 1.0 1.0 0.9 1.0 1.2 1.0

Sampling Data

Sampling Time (minutes) 360 480 360 360 360 360

Sample Volume (DSCF) 390.14 485.60 378.17 353.49 349.45 359.83

Chromium Data (ng/sample)

 Total Chromium 3110 4810 5220 1450 2860 1520

 Hexavalent Chromium 2250 3330 3840 1113 2462 980

Isokinetic Rate (%) 101 105 109 103 104 104

EMISSIONS

Concentration (ng/dscf)

 Total Chromium 7.97 9.90 13.8 4.10 8.18 4.23

 Hexavalent Chromium 5.77 6.86 10.2 3.15 7.05 2.72

Emission Rate (mg/hr)

 Total Chromium 0.53 0.58 0.82 0.24 0.47 0.25

 Hexavalent Chromium 0.38 0.41 0.60 0.18 0.41 0.16

Emissions Factors

(mg/amp-hr)**

 Total Chromium 0.017 0.009 0.012 0.004 0.007 0.004

 Hexavalent Chromium 0.012 0.006 0.009 0.003 0.006 0.003

DSCF & DSCFM means dry standard cubic feet and dry standard cubic feet per minute at 68 F and 29.92 inches 

Hg.

* Paired numbers show "start " - "end" of sample run results (i.e. Run A-11 started at 5.8 in. & 39.3 dyne/cm).

** Emissions Factors (mg/amp-hr) = Emission Rate (mg/hr) / Plating Tank Production Rate (amp-hrs/hr)
Page 10

Sample Number: A-11-A A-12-A A-13-A

Sample Date: 1/27/2004 1/28/2004 1/29/2004

Sampling Time (minutes) 226 422 310

Volume Collected (liters) 2260 4220 3100

Cr (VI) collected (nanograms) 160 120 32

Indoor Ambient Concentration (ng/m3) 70 28 10

Sample Number: A-21-A A-22-A A-23-A

Sample Date: 2/2/2004 2/3/2004 2/4/2004

Sampling Time (minutes) 353 313 350

Volume Collected (liters) 3530 3130 3500

Cr (VI) collected (nanograms) 63 50 33

Indoor Ambient Concentration (ng/m3) 18 16 9.3

Table VI-2b

Alta Plating Company

Indoor Ambient Hexavalent Chromium 

30 dyne/cm Surface Tension

Table VI-2a

Alta Plating Company

Indoor Ambient Hexavalent Chromium 

40 dyne/cm Surface Tension
Page 11

Sample Number: A-33-A A-32-A A-31-A** A-30-A

Sample Date: 2/5/2004 2/6/2004 2/8/2004 2/9/2004

Sampling Time (minutes) 339 450 1747** 368

Volume Collected (liters) 3390 4500 17470 3680

Cr (VI) collected (nanograms) 270 190 69 210

Totalizer, amp-hours 130 182 ** 172

Indoor Ambient Concentration (ng/m3

) 79 41 3.9 57

* - These indoor ambient samples were collected after emissions sampling of the plating

tank was completed and the plating tank capture hood removed. 

** - Sample A-31-A was collected on a Sunday when Alta was not plating. However, the

sampler failed to shut off automatically. It was shut down manually at 8:00 am Monday -

after Alta began plating.

Ambient Results with Plating Tank Capture Hood Removed*

Table VI-2c

Alta Plating Company

Indoor Ambient Hexavalent Chromium