Date: January 18, 2012

Subject: Draft – Development of Revised Surface Tension Limits for Chromium 

Electroplating and Anodizing Tanks Controlled with Wetting Agent Fume 

Suppressants

Emission Standards Technical Support and Post Promulgation Activities 

Contract No. EP-D-11-084; EPA Work Assignment No. 0-07

RTI Project No. 0213199.000.007

From: Gabrielle Raymond

Breda Munoz

Richard Marinshaw

To: Phil Mulrine, EPA/OAQPS/SPPD/MMG

The purpose of this memorandum is to summarize the data and analysis used to develop 

revised surface tension limits for chromium electroplating and chromium anodizing tanks 

controlled with wetting agent fume suppressants (WAFS). Section I of this memorandum 

provides background information on the use of WAFS by the chromium electroplating industry. 

The data and methodology used to develop the revised limits are discussed in Section II. Results 

are presented in Section III.

I. Background

Wetting agent fume suppressants (WAFS) are used in most decorative chromium 

electroplating and chromium anodizing tanks and in many hard chromium electroplating tanks to 

comply with the requirements of the National Emission Standards for Chromium Emissions from 

Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks (Chromium 

Electroplating NESHAP, 40 CFR 63, subpart N). As an alternative to meeting the emission 

limits specified in the NESHAP, sources that use WAFS as the primary emission control method 

can maintain the surface tension of the electroplating or anodizing tank liquid (i.e., the bath) 

below certain limits, depending on the type of instrument used to measure surface tension. If a 

stalagmometer is used, the surface tension limit is 45 dynes per centimeter (dynes/cm), and, if a 

tensiometer is used, the surface tension limit is 35 dynes/cm.

However, we note that most hard chromium plants and some anodizing and decorative 

plants rely at least partially on add-on control devices to comply with the emissions limits in the 

current NESHAP. Moreover, some sources may not be able to use WAFS for plating or 

operational reasons and therefore rely on add-on control devices. 
2

 

II. Data and Methodology

Emissions Data Used in Analysis

An extensive data collection effort was conducted between February and April 2011 to update the 

chromium electroplating database and available information on the chromium electroplating industry. A 

total of 28 State and local agencies were contacted for facility-specific information on the chromium 

electroplating industry, and data were received from 24 States and local agencies. Additional information 

was obtained from State websites. The new data included emission test reports and summaries, annual 

emission estimates, types of electroplating processes used, electroplating tank design and operating data, 

emission control methods, exhaust flow rates, and permit requirements. The technical memorandum, 

Information on Chromium Electroplating Facilities Collected from State and Local Agencies January to 

March 2011, identifies the State and local agencies contacted, the types of data provided by each, and a 

complete list of references obtained.

For this analysis, the available chromium emission concentration data from chromium 

electroplating sources controlled with WAFS were compiled in units of milligrams per dry standard cubic 

meter (mg/dscm), which is the format specified in the Chromium Electroplating NESHAP. The data 

compiled included plant name and location, test date, exhaust flow rate, emission concentration for each 

test run, and surface tension measured for each test run. In addition, the type of instrument used to 

measure surface tension was identified.

There are two instruments commonly used to measure surface tension in chromium electroplating 

and anodizing tanks: stalagmometers and tensiometers. These instruments use different measurement 

principles for quantifying surface tension, and, as a result, do not provide measurements that are directly 

comparable. Stalagmometers are used to count the number of drops formed when a specified volume of 

liquid passes through an orifice. Tensiometers measure the force needed to lift a metal ring from the 

surface of a liquid. In general, tensiometers provide lower surface tension readings than do 

stalagmometers. For this reason, the NESHAP specifies different surface tension limits, depending on 

whether a stalagmometer or tensiometer is used.

The first step in the analysis was to normalize the concentration data for exhaust flow rate to 

account for differences in exhaust flow rates from one system (source) to the next, similar to the practice 

of correcting concentration data for combustion sources to a specified oxygen percentage. Because the

concentration of a pollutant in an exhaust stream is inversely proportional to the exhaust flow rate, 

comparisons made between concentrations from different sources should account for differences in the 

flow rates for the exhaust system. For example, if the concentration of chromium from an electroplating 

tank is 0.020 mg/dscm, and the exhaust flow rate is then doubled, the resulting chromium concentration 

will be 0.010 mg/dscm. Although chromium electroplating emission control systems are designed to 

ensure minimum recommended ventilation rates, exhaust flow rates can vary significantly among sources. 

Furthermore, for some of the emission data compiled for the analysis, the tests were conducted on tanks 

that were equipped with temporary hoods and exhaust systems that were not necessarily designed to 

ensure minimum ventilation rates.

For this analysis, the data were normalized using a ventilation rate of 250 cubic feet per minute per 

square foot of tank surface area (ft3

/ft

2

), which is a standard design ventilation rate for electroplating 

tanks. Table 1 summarizes the resulting data set used for the analysis. As indicated in the table, data 

were obtained over a wide range of surface tensions. For measurements made using a stalagmometer, the 
3

surface tensions ranged from 19.9 to 78 dynes/cm. For tensiometer measurements, the surface tensions 

ranged from 18 to 72.5 dynes/cm. The variations in surface tension are due to the concentration of WAFS

in the electroplating tank baths. Surface tensions greater than about 70 dynes/cm indicate that no WAFS 

have been added to the tank bath. The data also illustrate that surface tensions can be achieved that are 

significantly below the limits specified in the NESHAP (i.e., well below 45 dynes/cm for stalagmometer

measurements and 35 dynes/cm for tensiometer measurements), depending on the concentration of WAFS 

in the bath. It should also be noted that the facilities tested reported no adverse effects on product quality, 

even at the lower levels of surface tension observed. 

As was explained in the rulemaking for the 2004 amendments to the NESHAP (69 FR 42885,

July 19, 2004), which established the current surface tension limits, emissions are a function of the 

surface tension. In other words, the lower the surface tension, the lower the emissions from a chromium 

electroplating tank, regardless of the specific chemicals used to achieve the lower surface tensions.

Graphical Representations of the Data

Several scatter plots (see Appendix) were created to provide a graphical representation of the 

relationship between surface tension and emission concentrations. The surface tension values were 

plotted on the x-axis, and the chromium concentration values were plotted on the y-axis. Exhibit 1 of the 

appendix graphically shows the concentration data points for decorative electroplating as a function of 

surface tension measured using a stalagmometer. Exhibit 2 shows the data for decorative chromium 

electroplating concentration and surface tension measured by tensiometer. Exhibits 3 and 4 show the 

same types of data for hard chromium electroplating concentration and surface tension measured by 

stalagmometer and by tensiometer, respectively. No data were available for chromium anodizing.

The data from for decorative chromium electroplating emissions and surface tension measured by 

a stalagmometer (Exhibit 1) include uncontrolled data, which are indicated by the data points with surface 

tensions greater than 60 dynes/cm. To preclude results that are driven by these uncontrolled data points, 

they were removed, and the remaining data were re-plotted, as shown in Exhibit 5. The ranges of the 

reduced dataset were 19.9 to 55.4 dynes/cm for surface tension, and, for concentration, were 0.00002 to

0.0044 mg/dscm. 

Because the surface tension limits in the NESHAP do not distinguish between process types, the 

decorative chromium and hard chromium electroplating datasets were combined by similar surface 

tension device type. The combined dataset for measurements made using a stalagmometer is illustrated in 

Exhibit 6, and Exhibit 7 shows the plot of all data based on tensiometer measurements. The resulting 

ranges for stalagmometer-based surface tensions and emission concentrations are 19.9 to 55.4 dynes/cm

and 0.00002 to 0.00673 mg/dscm, respectively. For data based on tensiometer measurements, the ranges 

are 18.0 to 31.4 dynes/cm and 0.0001 to 0.0044 mg/dscm, respectively.

Note that the combined data based on stalagmometer measurements include a few large values for 

emission concentration corresponding to surface tension ranges of 30 to 35 dynes/cm and from 35 to 

40 dynes/cm. These extreme values tend to skew the data analysis because the statistical procedure used 

is based on the mean and standard deviation calculated in intervals of surface tension, and it is well 

documented that the mean and standard deviation are affected by extreme values. Another factor that may 

affect the results is the sample size; when there are only a small number of values within any surface 

tension range, the t-value used to calculate the t-statistic will be large affecting the precision of the 

estimates.
4

Upper Tolerance Limit Calculation

Statistical tolerance limits provide a range in which some percentage of all emission concentration 

measurements will lie with some confidence. A tolerance limit can be used to predict emission 

concentrations with a high amount of accuracy. A tolerance limit will ensure that the coverage of the 

interval would at least be 95 percent with a high amount of confidence (e.g., 99 percent). In particular, 

the 95 percent upper tolerance limit (UTL) with 99 percent confidence level is the value for which we can 

conclude with 99 percent certainty or confidence that at least 95 percent of the data points lie below. 

Following the approach by Bhaumik and Kulkarni1

, tolerance limits were calculated as follows:

The surface tension data were divided into intervals (e.g., all data ≤ 35 dynes/cm) with enough 

data points to calculate the mean and standard deviation. The UTL was then calculated as:

x − KsS 1+ R

where:

∑=

=

k

i

i i w x

w

x

1

1 denotes a weighted average of the interval means;

k is the number of classes;

∑=

= i n

i

i

i

i x

n

x

1

1 is the average of the i-th interval;

ni denotes the sample size in each interval;

∑=

=

k

i

N ni

1

is the total number of measurements in the dataset;

w R i i = n + − 1 1 is a weighting factor for each interval;

∑=

=

k

i

w wi

1

1

2 2

2

−

+ = NS S S B I is the variance of the data that takes into account the between interval variability,;

( 2 SB ), and within interval variability, ( 2 SI );

∑ ( ) =

= −

k

i

B i i S w x x

1

2 2 is the between interval variability;

∑∑( ) = =

= −

k

i

n

j

I ij i

i

S x x

1 1

2 2 is the within interval variability;

( )

R w

t

K N

s

(1 )

, 1

+ = − δ γ

 1 D. K. Bhaumik and P. M. KulkarniSource. 1996. A Simple and Exact Method of Constructing 

Tolerance Intervals for the One-Way ANOVA with Random Effects. The American Statistician, 

50(4):319-323. 
5

(δ ,γ ) N−1 t is the (100-γ)th percentile of the non-central t distribution with N-1 degrees of freedom 

and non-centrality parameter δ.

R is the variance ratio defined as the ratio of the between intervals variability and between 

measurements variability. It represents the proportion of measurement variability explained by the 

intervals.

R is estimated as: = ( − − 2)− λ 2

2

N k

S

S R

I

x

∑=

=

k

i i k 1 n

1 1 λ

∑=

− − =

k

i

x i x x

k

S

1

2 2 ( ) 1

1

∑=

=

k

i

i x

k

x

1

1 .

After evaluating possible outliers and removing some measurements classified as such, several 

interval classifications were explored, and the UTLs were calculated. The results are shown in Table 2. 

For example, when the surface tension is less than or equal to 30 dynes/cm measured with a 

stalagmometer, we expect 95 percent of future values of emission concentration measurements to be less 

than 0.0050 mg/dscm with 99 percent confidence. In other words, in 99 out of 100 samples, 95 percent of 

the test runs with a surface tension less than or equal to 30 dynes/cm will be less or equal than 

0.0050 mg/dscm.

II Results

The results of the UTL analysis of surface tension measurements using stalagmometers and 

tensiometers indicate concentration values for specified surface tension values. Based on the results of 

the analysis, it was concluded that, for stalagmometer measurements, maintaining a surface tension limit 

no more than 40 dynes/cm would limit emissions to less than 0.006 mg/dscm (which is rounded from 

0.0055 mg/dscm). For tensiometer measurements, a surface tension limit of less than or equal to 

33 dynes/cm (rounded from 32.5 dynes/cm to account for the fact that tensiometers measure in integer 

increments) would correspond to comparable emissions concentrations of 0.0060 mg/dscm (rounded from 

0.0047 mg/dscm). However, as stated previously, some sources use add-on control devices and may not 

be able to use WAFS for plating or operational reasons. 

In summary, it was concluded that maintaining these surface tension limits (40 dynes/cm by 

stalagmometer and 33 dynes/cm by tensiometer) in chromium electroplating and anodizing baths would 

be equivalent or lower to the proposed emission limits for all the chromium electroplating and anodizing 

source categories.
6

Table 1. Summary of Emissions Data Used for Surface Tension Analysis

Company Location Test Date

Type of 

Electroplating Run

Cr Emission 

Conc., 

mg/dscm

Normalized

Cr Emission 

Conc., 

mg/dscm

Flowrate,

DSCFM

Tank 

Surface 

Area, 

ft2

Surface 

Tension, 

dynes/cm Instrument

Alta Plating and Anodizing Sacramento, CA 1/27/2004 Decorative 1 2.81E-04 4.62E-05 1,102 28 39.60 Stalagmometer

Alta Plating and Anodizing Sacramento, CA 1/28/2004 Decorative 2 3.50E-04 5.12E-05 983 28 40.00 Stalagmometer

Alta Plating and Anodizing Sacramento, CA 1/29/2004 Decorative 3 4.87E-04 7.14E-05 984 28 39.90 Stalagmometer

Alta Plating and Anodizing Sacramento, CA 2/2/2004 Decorative 1 1.45E-04 2.10E-05 972 28 39.60 Stalagmometer

Alta Plating and Anodizing Sacramento, CA 2/3/2004 Decorative 2 2.89E-04 4.12E-05 958 28 40.00 Stalagmometer

Alta Plating and Anodizing Sacramento, CA 2/4/2004 Decorative 3 1.49E-04 2.18E-05 982 28 39.90 Stalagmometer

Automatic Die Casting, BID St. Clair Shores, MI 4/25/1988 Decorative 1 1.90E-03 5.97E-04 2,340 31 40.00 Stalagmometer

Automatic Die Casting, BID St. Clair Shores, MI 4/26/1988 Decorative 2 1.20E-03 3.76E-04 2,270 31 38.00 Stalagmometer

Automatic Die Casting, BID St. Clair Shores, MI 4/26/1988 Decorative 3 3.40E-03 1.04E-03 2,240 31 38.00 Stalagmometer

Automatic Die Casting St. Clair Shores, MI 4/18/1988 Decorative 1 8.58E-01 2.73E-01 2,355 31 66.00 Stalagmometer

Automatic Die Casting St. Clair Shores, MI 4/19/1988 Decorative 2 9.21E-01 2.97E-01 2,387 31 72.00 Stalagmometer

Automatic Die Casting St. Clair Shores, MI 4/19/1988 Decorative 3 9.94E-01 3.15E-01 2,345 31 74.00 Stalagmometer

Automatic Die Casting St. Clair Shores, MI 4/25/1988 Decorative 1 1.80E-03 5.69E-04 2,335 31 40.00 Stalagmometer

Automatic Die Casting St. Clair Shores, MI 4/26/1988 Decorative 2 1.20E-03 3.69E-04 2,271 31 38.00 Stalagmometer

Automatic Die Casting St. Clair Shores, MI 4/26/1988 Decorative 3 3.30E-03 1.00E-03 2,244 31 38.00 Stalagmometer

Clovis Specialty Fresno, CA 10/19/2004 Decorative 1 6.49E-03 9.46E-04 945 27 44.10 Stalagmometer

Clovis Specialty Fresno, CA 10/20/2004 Decorative 2 3.59E-03 5.15E-04 931 27 41.60 Stalagmometer

Clovis Specialty Fresno, CA 10/21/2004 Decorative 3 6.53E-03 9.29E-04 922 27 42.20 Stalagmometer

Clovis Specialty Fresno, CA 5/24/2005 Decorative 1 6.79E-03 9.12E-04 871 27 36.60 Stalagmometer

Clovis Specialty Fresno, CA 5/25/2005 Decorative 2 5.21E-03 6.65E-04 828 27 32.70 Stalagmometer

Clovis Specialty Fresno, CA 5/25/2005 Decorative 3 6.64E-03 8.57E-04 836 27 22.10 Stalagmometer

Clovis Specialty Fresno, CA 6/29/2005 Decorative 1 1.30E-02 1.92E-03 955 27 31.50 Stalagmometer

Clovis Specialty Fresno, CA 6/30/2005 Decorative 2 5.26E-03 6.80E-04 837 27 31.50 Stalagmometer

Clovis Specialty Fresno, CA 6/30/2005 Decorative 3 1.01E-02 1.35E-03 864 27 31.50 Stalagmometer

Excello Los Angeles, CA 3/5/2003 Decorative 1 4.80E-04 1.42E-04 1,064 15 32.65 Stalagmometer

Excello Los Angeles, CA 3/6/2003 Decorative 2 7.30E-04 2.17E-04 1,068 15 33.10 Stalagmometer

Excello Los Angeles, CA 3/7/2003 Decorative 3 3.52E-04 1.04E-04 1,064 15 33.95 Stalagmometer

Excello Los Angeles, CA 3/5/2003 Decorative 1 4.80E-04 1.42E-04 1,064 15 23.75 Tensiometer

Excello Los Angeles, CA 3/6/2003 Decorative 2 7.30E-04 2.17E-04 1,068 15 23.65 Tensiometer

Excello Los Angeles, CA 3/7/2003 Decorative 3 3.52E-04 1.04E-04 1,064 15 24.20 Tensiometer

Genes Los Angeles, CA 12/12/2003 Decorative 1 2.39E-03 2.73E-04 411 15 24.50 Stalagmometer

Genes Los Angeles, CA 12/16/2003 Decorative 2 3.57E-03 4.26E-04 429 15 19.90 Stalagmometer

Genes Los Angeles, CA 12/16/2003 Decorative 3 4.64E-03 4.99E-04 393 15 20.50 Stalagmometer

Genes Los Angeles, CA 12/12/2003 Decorative 1 2.39E-03 2.73E-04 411 15 20.00 Tensiometer

Genes Los Angeles, CA 12/16/2003 Decorative 2 3.57E-03 4.26E-04 429 15 18.00 Tensiometer

Genes Los Angeles, CA 12/16/2003 Decorative 3 4.64E-03 4.99E-04 393 15 18.50 Tensiometer

Genes Los Angeles, CA 12/18/2003 Decorative 1 5.01E-03 6.01E-04 437 15 30.70 Stalagmometer

Genes Los Angeles, CA 12/18/2003 Decorative 2 4.41E-03 5.09E-04 416 15 28.70 Stalagmometer
7

Company Location Test Date

Type of 

Electroplating Run

Cr Emission 

Conc., 

mg/dscm

Normalized

Cr Emission 

Conc., 

mg/dscm

Flowrate,

DSCFM

Tank 

Surface 

Area, 

ft2

Surface 

Tension, 

dynes/cm Instrument

Genes Los Angeles, CA 12/23/2003 Decorative 3 2.43E-03 2.79E-04 417 15 26.60 Stalagmometer

Genes Los Angeles, CA 12/18/2003 Decorative 1 5.01E-03 6.01E-04 437 15 22.20 Tensiometer

Genes Los Angeles, CA 12/18/2003 Decorative 2 4.41E-03 5.09E-04 416 15 22.10 Tensiometer

Genes Los Angeles, CA 12/23/2003 Decorative 3 2.43E-03 2.79E-04 417 15 21.30 Tensiometer

Genes Los Angeles, CA 12/30/2003 Decorative 1 3.82E-03 4.37E-04 424 15 45.30 Stalagmometer

Genes Los Angeles, CA 12/31/2003 Decorative 2 5.39E-03 6.68E-04 456 15 39.30 Stalagmometer

Genes Los Angeles, CA 1/2/2004 Decorative 3 7.50E-03 9.18E-04 454 15 38.50 Stalagmometer

Genes Los Angeles, CA 12/30/2003 Decorative 1 3.82E-03 4.37E-04 424 15 28.00 Tensiometer

Genes Los Angeles, CA 12/31/2003 Decorative 2 5.39E-03 6.68E-04 456 15 26.50 Tensiometer

Genes Los Angeles, CA 1/2/2004 Decorative 3 7.50E-03 9.18E-04 454 15 25.70 Tensiometer

Genes Los Angeles, CA 1/7/2004 Decorative 1 4.85E-03 5.54E-04 416 15 30.50 Stalagmometer

Genes Los Angeles, CA 1/7/2004 Decorative 2 5.15E-03 5.80E-04 407 15 29.50 Stalagmometer

Genes Los Angeles, CA 1/8/2004 Decorative 3 7.71E-03 8.91E-04 423 15 30.00 Stalagmometer

Genes Los Angeles, CA 1/7/2004 Decorative 1 4.85E-03 5.54E-04 416 15 24.10 Tensiometer

Genes Los Angeles, CA 1/7/2004 Decorative 2 5.15E-03 5.80E-04 407 15 23.50 Tensiometer

Genes Los Angeles, CA 1/8/2004 Decorative 3 7.71E-03 8.91E-04 423 15 21.90 Tensiometer

Genes Los Angeles, CA 1/14/2004 Decorative 1 2.42E-03 2.94E-04 437 15 23.10 Stalagmometer

Genes Los Angeles, CA 1/14/2004 Decorative 2 3.03E-03 3.34E-04 391 15 22.80 Stalagmometer

Genes Los Angeles, CA 1/15/2004 Decorative 3 2.02E-03 2.43E-04 438 15 24.90 Stalagmometer

Genes Los Angeles, CA 1/14/2004 Decorative 1 2.42E-03 2.94E-04 437 15 21.30 Tensiometer

Genes Los Angeles, CA 1/14/2004 Decorative 2 3.03E-03 3.34E-04 391 15 20.90 Tensiometer

Genes Los Angeles, CA 1/15/2004 Decorative 3 2.02E-03 2.43E-04 438 15 20.10 Tensiometer

Genes Los Angeles, CA 1/21/2004 Decorative 1 1.90E-03 2.27E-04 437 15 46.30 Stalagmometer

Genes Los Angeles, CA 1/21/2004 Decorative 2 2.00E-03 2.40E-04 434 15 45.60 Stalagmometer

Genes Los Angeles, CA 1/22/2004 Decorative 3 3.17E-03 3.67E-04 430 15 51.90 Stalagmometer

Genes Los Angeles, CA 1/21/2004 Decorative 1 1.90E-03 2.27E-04 437 15 27.30 Tensiometer

Genes Los Angeles, CA 1/21/2004 Decorative 2 2.00E-03 2.40E-04 434 15 24.20 Tensiometer

Genes Los Angeles, CA 1/22/2004 Decorative 3 3.17E-03 3.67E-04 430 15 28.80 Tensiometer

Genes Los Angeles, CA 1/28/2004 Decorative 1 1.46E-03 1.68E-04 422 15 41.80 Stalagmometer

Genes Los Angeles, CA 1/28/2004 Decorative 2 1.46E-03 1.75E-04 437 15 40.40 Stalagmometer

Genes Los Angeles, CA 1/29/2004 Decorative 3 3.53E-03 4.30E-04 451 15 39.70 Stalagmometer

Genes Los Angeles, CA 1/28/2004 Decorative 1 1.46E-03 1.68E-04 422 15 24.80 Tensiometer

Genes Los Angeles, CA 1/28/2004 Decorative 2 1.46E-03 1.75E-04 437 15 25.30 Tensiometer

Genes Los Angeles, CA 1/29/2004 Decorative 3 3.53E-03 4.30E-04 451 15 25.60 Tensiometer

Genes Los Angeles, CA 2/4/2004 Decorative 1 2.27E-03 2.79E-04 455 15 31.20 Stalagmometer

Genes Los Angeles, CA 2/4/2004 Decorative 2 2.34E-03 2.56E-04 400 15 31.50 Stalagmometer

Genes Los Angeles, CA 2/5/2004 Decorative 3 3.18E-03 3.69E-04 429 15 29.40 Stalagmometer

Genes Los Angeles, CA 2/4/2004 Decorative 1 2.27E-03 2.79E-04 455 15 23.00 Tensiometer

Genes Los Angeles, CA 2/4/2004 Decorative 2 2.34E-03 2.56E-04 400 15 23.90 Tensiometer
8

Company Location Test Date

Type of 

Electroplating Run

Cr Emission 

Conc., 

mg/dscm

Normalized

Cr Emission 

Conc., 

mg/dscm

Flowrate,

DSCFM

Tank 

Surface 

Area, 

ft2

Surface 

Tension, 

dynes/cm Instrument

Genes Los Angeles, CA 2/5/2004 Decorative 3 3.18E-03 3.69E-04 429 15 22.50 Tensiometer

Genes Los Angeles, CA 6/11/1990 Decorative 1 1.68E-01 9.82E-02 2,105 15 70.00 Stalagmometer

Genes Los Angeles, CA 6/11/1990 Decorative 2 2.65E-01 1.54E-01 2,087 15 70.00 Stalagmometer

Genes Los Angeles, CA 6/11-12/1990 Decorative 3 2.34E-01 1.34E-01 2,066 15 70.00 Stalagmometer

Genes Los Angeles, CA 6/11-12/1990 Decorative 4 8.81E-01 5.15E-01 2,106 15 70.00 Stalagmometer

Genes Los Angeles, CA 6/12/1990 Decorative 5 6.79E-01 3.92E-01 2,080 15 70.00 Stalagmometer

Genes Los Angeles, CA 6/12/1990 Decorative 6 1.83E-01 9.54E-02 1,881 15 70.00 Stalagmometer

Genes Los Angeles, CA 6/14/1990 Decorative 1 2.78E-03 1.69E-03 2,180 15 32.75 Stalagmometer

Genes Los Angeles, CA 6/14/1990 Decorative 2 1.82E-03 1.13E-03 2,248 15 33.25 Stalagmometer

Genes Los Angeles, CA 6/15/1990 Decorative 3 2.35E-03 1.45E-03 2,220 15 35.60 Stalagmometer

Genes Los Angeles, CA 6/15/1990 Decorative 4 3.08E-03 1.91E-03 2,239 15 33.70 Stalagmometer

Genes Los Angeles, CA 6/18/1990 Decorative 5 2.32E-03 1.46E-03 2,265 15 33.70 Stalagmometer

Genes Los Angeles, CA 6/18/1990 Decorative 6 1.38E-03 8.66E-04 2,258 15 33.93 Stalagmometer

Sherm's Sacramento, CA 3/9/2004 Decorative 1 2.07E-03 2.89E-04 904 27 35.75 Stalagmometer

Sherm's Sacramento, CA 3/10/2004 Decorative 2 2.10E-03 3.51E-04 1,030 27 36.70 Stalagmometer

Sherm's Sacramento, CA 3/11/2004 Decorative 3 2.83E-03 3.95E-04 943 27 37.85 Stalagmometer

Valley Commerce, CA 2/2/2000 Decorative 1 5.06E+00 1.04E+00 3,050 60 78.00 Stalagmometer

Valley Commerce, CA 2/2/2000 Decorative 2 4.13E+00 8.62E-01 3,060 60 78.00 Stalagmometer

Valley Commerce, CA 2/2/2000 Decorative 3 4.47E+00 9.42E-01 3,060 60 78.00 Stalagmometer

Valley Commerce, CA 2/5/2000 Decorative 1 1.17E+01 2.40E+00 3,010 60 78.00 Stalagmometer

Valley Commerce, CA 2/5/2000 Decorative 2 1.11E+01 2.32E+00 3,060 60 78.00 Stalagmometer

Valley Commerce, CA 2/5/2000 Decorative 3 1.14E+01 2.36E+00 3,030 60 78.00 Stalagmometer

Valley Commerce, CA 2/11/2000 Decorative 1 1.45E-02 3.00E-03 3,080 60 38.00 Stalagmometer

Valley Commerce, CA 2/11/2000 Decorative 2 1.39E-02 2.88E-03 3,060 60 38.00 Stalagmometer

Valley Commerce, CA 2/11/2000 Decorative 3 1.32E-02 2.74E-03 3,060 60 38.00 Stalagmometer

Valley Commerce, CA 2/12/2000 Decorative 1 5.64E-03 1.13E-03 2,960 60 38.00 Stalagmometer

Valley Commerce, CA 2/12/2000 Decorative 2 4.50E-03 9.27E-04 3,030 60 38.00 Stalagmometer

Valley Commerce, CA 2/12/2000 Decorative 3 5.08E-03 1.05E-03 3,020 60 38.00 Stalagmometer

Van Nuy's Van Nuys, CA 4/9/2003 Decorative 1 1.49E-02 3.20E-03 728 14 55.35 Stalagmometer

Van Nuy's Van Nuys, CA 4/10/2003 Decorative 2 2.02E-02 4.44E-03 743 14 46.00 Stalagmometer

Van Nuy's Van Nuys, CA 4/11/2003 Decorative 3 1.64E-02 3.67E-03 756 14 42.40 Stalagmometer

Van Nuy's Van Nuys, CA 4/9/2003 Decorative 1 1.49E-02 3.20E-03 728 14 31.40 Tensiometer

Van Nuy's Van Nuys, CA 4/10/2003 Decorative 2 2.02E-02 4.44E-03 743 14 26.35 Tensiometer

Van Nuy's Van Nuys, CA 4/11/2003 Decorative 3 1.64E-02 3.67E-03 756 14 27.80 Tensiometer

Walker's Custom Chrome Shasta Lake, CA 2/15/2006 Decorative 1 5.43E-04 1.05E-04 899 19 35.10 Stalagmometer

Walker's Custom Chrome Shasta Lake, CA 2/16/2006 Decorative 2 7.71E-04 1.59E-04 958 19 35.40 Stalagmometer

Walker's Custom Chrome Shasta Lake, CA 2/17/2006 Decorative 3 7.01E-04 1.51E-04 1,000 19 35.40 Stalagmometer

CM Grinding, Inc. South Bend, IN 5/28/1997 Hard 1 9.69E-03 1.29E-03 130 6 49.90 Stalagmometer

CM Grinding, Inc. South Bend, IN 5/28/1997 Hard 2 8.58E-03 1.14E-03 130 6 49.90 Stalagmometer
9

Company Location Test Date

Type of 

Electroplating Run

Cr Emission 

Conc., 

mg/dscm

Normalized

Cr Emission 

Conc., 

mg/dscm

Flowrate,

DSCFM

Tank 

Surface 

Area, 

ft2

Surface 

Tension, 

dynes/cm Instrument

CM Grinding, Inc. South Bend, IN 5/29/1997 Hard 3 7.91E-03 1.10E-03 136 6 49.90 Stalagmometer

CM Grinding, Inc. South Bend, IN 5/27/1997 Hard 1 1.00E-02 5.35E-03 814 6 48.40 Stalagmometer

CM Grinding, Inc. South Bend, IN 5/28/1997 Hard 2 1.07E-02 5.65E-03 808 6 48.40 Stalagmometer

CM Grinding, Inc. South Bend, IN 5/28/1997 Hard 3 9.32E-03 4.94E-03 808 6 48.40 Stalagmometer

D & B Polishing Clinton Township, MI 6/25/2000 Hard 1 4.00E-04 2.19E-05 961 75 42.17 Stalagmometer

D & B Polishing Clinton Township, MI 6/25/2000 Hard 2 6.00E-04 3.38E-05 989 75 42.17 Stalagmometer

D & B Polishing Clinton Township, MI 6/25/2000 Hard 3 7.00E-04 3.92E-05 972 75 42.17 Stalagmometer

Diamond Hard Chrome Howell, MI 5/14/1996 Hard 1 8.55E-03 4.42E-03 16,710 135 38.09 Stalagmometer

Diamond Hard Chrome Howell, MI 5/14/1996 Hard 2 4.43E-03 2.43E-03 17,785 135 41.09 Stalagmometer

Diamond Hard Chrome Howell, MI 5/14/1996 Hard 3 5.70E-03 3.23E-03 18,371 135 43.75 Stalagmometer

Diamond Hard Chrome Howell, MI 5/14/1996 Hard 1 8.55E-03 4.42E-03 16,710 135 27.35 Tensiometer

Diamond Hard Chrome Howell, MI 5/14/1996 Hard 2 4.43E-03 2.43E-03 17,785 135 29.30 Tensiometer

Diamond Hard Chrome Howell, MI 5/14/1996 Hard 3 5.70E-03 3.23E-03 18,371 135 25.95 Tensiometer

Electronic Cr Santa Fe Springs, CA 7/1/1994 Hard 1 5.10E-03 3.08E-03 3,607 25 27.90 Stalagmometer

Electronic Cr Santa Fe Springs, CA 7/1/1994 Hard 2 2.10E-03 1.33E-03 3,763 25 27.70 Stalagmometer

Electronic Cr Santa Fe Springs, CA 7/1/1994 Hard 4 5.30E-03 3.19E-03 3,640 25 26.90 Stalagmometer

Electronic Cr Santa Fe Springs, CA 7/1/1994 Hard 5 3.60E-03 2.16E-03 3,550 25 25.80 Stalagmometer

Electronic Cr Santa Fe Springs, CA 7/1/1994 Hard 6 1.10E-02 6.73E-03 3,623 25 32.50 Stalagmometer

Hohman Plating Dayton, OH 9/16/1997 Hard 1 2.47E-01 7.79E-02 2,192 30 72.00 Tensiometer

Hohman Plating Dayton, OH 9/16/1997 Hard 2 3.03E-01 9.75E-02 2,214 30 72.00 Tensiometer

Hohman Plating Dayton, OH 9/16/1997 Hard 3 2.77E-01 8.79E-02 2,175 30 72.00 Tensiometer

Hohman Plating Dayton, OH 9/17/1997 Hard 4 3.85E-01 1.27E-01 2,288 30 72.00 Tensiometer

Hohman Plating Dayton, OH 9/17/1997 Hard 5 4.24E-01 1.39E-01 2,249 30 72.00 Tensiometer

Hohman Plating Dayton, OH 9/17/1997 Hard 6 3.91E-01 1.28E-01 2,238 30 72.50 Tensiometer

Hohman Plating Dayton, OH 9/30/1997 Hard 1 2.16E-03 6.85E-04 2,229 30 24.50 Tensiometer

Hohman Plating Dayton, OH 9/30/1997 Hard 2 2.13E-03 6.77E-04 2,218 30 24.50 Tensiometer

Hohman Plating Dayton, OH 9/30/1997 Hard 3 2.15E-03 6.82E-04 2,226 30 24.50 Tensiometer

Hohman Plating Dayton, OH 10/1/1997 Hard 4 9.96E-04 3.33E-04 2,414 30 24.50 Tensiometer

Hohman Plating Dayton, OH 10/1/1997 Hard 5 1.31E-03 4.43E-04 2,452 30 24.50 Tensiometer

Hohman Plating Dayton, OH 10/1/1997 Hard 6 1.31E-03 4.43E-04 2,437 30 24.50 Tensiometer

Hohman Plating Dayton, OH 10/14/1997 Hard 1 1.67E-03 5.58E-04 2,406 30 25.00 Tensiometer

Hohman Plating Dayton, OH 10/14/1997 Hard 2 2.16E-03 6.52E-04 2,171 30 25.00 Tensiometer

Hohman Plating Dayton, OH 10/14/1997 Hard 3 3.20E-03 1.03E-03 2,302 30 25.50 Tensiometer

Hohman Plating Dayton, OH 10/15/1997 Hard 4 1.65E-03 5.50E-04 2,456 30 25.50 Tensiometer

Hohman Plating Dayton, OH 10/15/1997 Hard 5 1.44E-03 4.43E-04 2,246 30 25.20 Tensiometer

Hohman Plating Dayton, OH 10/15/1997 Hard 6 1.91E-03 6.15E-04 2,326 30 25.00 Tensiometer

Hohman Plating Dayton, OH 10/28/1997 Hard 1 4.31E-03 1.32E-03 2,232 30 25.00 Tensiometer

Hohman Plating Dayton, OH 10/28/1997 Hard 2 4.67E-03 1.41E-03 2,201 30 25.00 Tensiometer

Hohman Plating Dayton, OH 10/28/1997 Hard 3 8.92E-03 2.69E-03 2,189 30 25.00 Tensiometer
10

Company Location Test Date

Type of 

Electroplating Run

Cr Emission 

Conc., 

mg/dscm

Normalized

Cr Emission 

Conc., 

mg/dscm

Flowrate,

DSCFM

Tank 

Surface 

Area, 

ft2

Surface 

Tension, 

dynes/cm Instrument

Hohman Plating Dayton, OH 10/28/1997 Hard 4 2.26E-03 6.90E-04 2,220 30 25.50 Tensiometer

Hohman Plating Dayton, OH 10/29/1997 Hard 1 2.65E-03 5.18E-04 1,429 30 25.00 Tensiometer

Hohman Plating Dayton, OH 10/29/1997 Hard 2 3.47E-03 6.83E-04 1,423 30 25.00 Tensiometer

Hohman Plating Dayton, OH 10/29/1997 Hard 3 2.60E-03 5.15E-04 1,423 30 25.00 Tensiometer

Hohman Plating Dayton, OH 10/30/1997 Hard 4 4.23E-03 8.55E-04 1,479 30 25.00 Tensiometer

Hohman Plating Dayton, OH 10/30/1997 Hard 5 2.55E-03 5.17E-04 1,467 30 25.00 Tensiometer

Hohman Plating Dayton, OH 10/30/1997 Hard 6 2.40E-03 4.87E-04 1,457 30 25.00 Tensiometer

Hohman Plating Dayton, OH 1/6/1998 Hard 1 6.98E-03 2.22E-03 2,269 30 29.00 Tensiometer

Hohman Plating Dayton, OH 1/6/1998 Hard 2 1.63E-03 5.52E-04 2,414 30 29.00 Tensiometer

Hohman Plating Dayton, OH 1/6/1998 Hard 3 8.72E-03 2.87E-03 2,333 30 29.00 Tensiometer

Hohman Plating Dayton, OH 1/7/1998 Hard 4 1.55E-03 5.42E-04 2,505 30 29.00 Tensiometer

Hohman Plating Dayton, OH 1/7/1998 Hard 5 1.91E-03 5.41E-04 2,032 30 29.00 Tensiometer

Hohman Plating Dayton, OH 1/7/1998 Hard 6 2.03E-03 5.64E-04 1,983 30 29.00 Tensiometer

Modern Hard Chrome, Tank 12 Warren, MI 7/30/1996 Hard 1 5.85E-01 1.75E-01 5,122 37 67.20 Tensiometer

Modern Hard Chrome, Tank 12 Warren, MI 7/30/1996 Hard 2 5.42E+00 1.64E+00 5,289 37 67.20 Tensiometer

Modern Hard Chrome, Tank 12 Warren, MI 7/30/1996 Hard 3 5.87E+00 1.81E+00 5,338 37 67.20 Tensiometer

Modern Hard Chrome, Tank 13 Warren, MI 8/5/1996 Hard 1 2.98E+00 7.06E-01 8,343 80 69.20 Tensiometer

Modern Hard Chrome, Tank 13 Warren, MI 8/6/1996 Hard 2 9.89E-01 2.32E-01 8,634 80 69.20 Tensiometer

Modern Hard Chrome, Tank 13 Warren, MI 8/6/1996 Hard 3 1.06E+00 2.55E-01 8,614 80 69.20 Tensiometer
11

Table 2. Upper Tolerance Limits for Chromium Concentration

as a Function of Surface Tension

Surface tension 

measurement device

Surface tension 

range, dynes/cm

Upper tolerance 

limit, mg/dscm

Stalagmometer

≤ 25 0.0018

≤ 27.5 0.0055

≤ 30 0.0050

≤ 32.5 0.0078

≤ 35 0.0065

≤ 37.5 0.0056

≤ 40 0.0055

>40 0.0065

Tensiometer

≤ 25 0.0037

≤ 27.5 0.0038

≤ 30 0.0045

≤ 32.5 0.0047
 

Appendix 

Scatter Plots of Emission Concentration Data
1-1

 

Exhibit 1. Scatter Plot of Corrected Chromium Concentrations for Decorative Electroplating and Surface Tension Measured by 

Stalagmometer.
1-2

Exhibit 2. Scatter Plot of Corrected Chromium Concentrations for Decorative Electroplating and Surface Tension Measured by 

Tensiometer.
1-3

Exhibit 3. Scatter Plot of Corrected Chromium Concentrations for Hard Electroplating and Surface Tension Measured by 

Stalagmometer.
1-4

Exhibit 4. Scatter Plot of Corrected Chromium Concentrations for Hard Electroplating and Surface Tension Measured by 

Tensiometer.
1-5

Exhibit 5. Scatter Plot of Corrected Chromium Concentrations for Decorative Electroplating and Surface Tension Measured by 

Stalagmometer, with Surface Tension < 60 dyn/cm.
1-6

Exhibit 6. Scatter Plot of Corrected Chromium Concentrations for Decorative and Hard Electroplating and Surface Tension 

Measured by Stalagmometer, with Surface Tension < 60 dyn/cm.
1-7

Exhibit 7. Scatter Plot of Corrected Chromium Concentrations for Decorative and Hard Electroplating and Surface Tension 

Measured by Tensiometer, with Surface Tension < 60 dyn/cm.