Date: August 15, 2012

Subject: Comparison of Studies on Non-PFOS Fume Suppressant Performance

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: Richard Marinshaw

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

This memorandum summarizes and compares the results of two recent studies that 

investigated the performance of wetting agent fume suppressants (WAFS) that do not contain 

perfluorooctyl sulfonic acid (PFOS) in controlling emissions from chromium electroplating. 

Section I provides a description of the two studies; Section II compares the methods and results 

of the studies; and references are provided in Section III.

I. Overview of Studies

Two studies were conducted recently that evaluated the performance of non-PFOS 

WAFS in controlling emissions from chromium electroplating: a study conducted by the 

Institute für Galvano- und Oberflächentechnik Solingen GmbH & Co, hereafter referred to as the 

German Study; and a study conducted by Danish Ministry of the Environment, hereafter referred 

to as the Danish Study. Details on each of the studies are provided below.

German Study (IGOSG, 2012)

The purpose of this study was to investigate the performance of a non-PFOS product, 

which had not yet been commercialized, compared to a PFOS-based WAFS and to a non-PFOSbased WAFS product that is currently available in the market. Three phases of testing were 

performed. The first phase evaluated emissions from hard chromium electroplating for baseline 

conditions (no WAFS used), and each of the three WAFS products. In the second phase, 

emissions from decorative chromium electroplating were sampled for the baseline, commercial 

non-PFOS product, and the experimental product. The third phase of testing evaluated the defrothing effects of the experimental product on the commercialized non-PFOS product. Since 

this last phase had no bearing on the performance of PFOS or non-PFOS WAFS, it is not 

discussed further in this memorandum.

Bench-scale tests were performed using a 5-liter (L) glass beaker as the electroplating 

“tank” for each of the products tested. The volume of the electroplating solution was 4.5 L. 

Emissions were captured using a fabricated perforated piping system that surrounded each test 

vessel. Sampling was performed using DIN EN 13284, Stationary source emissions -

Determination of low range mass concentration of dust, and the samples were analyzed using 
2

DIN EN 15205 - Determination of hexavalent chromium in corrosion protection layers -

Qualitative analysis. For most of the testing, three test runs were performed, and the test runs 

varied from 33 to 50 minutes in duration. Regarding the surface tension of the plating solution, 

the report states that a tensiometer was used to develop a calibration curve that relates WAFS 

concentration to “bubble lifetime” and surface tension. However, it is unclear if surface tensions 

were measured during the testing. A separate document prepared by EMD presents the results of 

the study and indicates that surface tensions were about 30 dynes per centimeter (dynes/cm) 

during the testing (EMD, 2012), but the actual study report does not present surface tension data.

Based on the technical data sheet (Atotech, 2010) for the non-PFOS product used (Fumetrol 21)

and the reported concentration during test (2.0 to 2.5 milliliter per liter [ml/L]), the surface 

tension should have been about 35 to 47 dynes/cm for the non-PFOS fume suppressant test.

Table 1 summarizes the test results in units of milligrams per dry standard cubic meter 

(mg/dscm), as presented in the report. The conclusions of the study generally relate to the 

performance of the experimental product. However, the study also concludes that the PFOS and 

non-PFOS products both reduced emissions by more than 95 percent.

Table 1. Summary of Results for German Study as Reported

Test 

condition WAFS Product No. of test runs

Chromium emissions, mg/dscm

Minimum Maximum Average

Hard Cr 

electroplating

None (baseline) 9 0.280 0.529 0.378

Experimental non-PFOS 3 0.515 0.936 0.681

PFOS 2 0.006 0.007 0.006

Non-PFOS 3 0.017 0.043 0.027

Decorative Cr

electroplating

Experimental non-PFOS 9 0.537 1.077 0.837

Non-PFOS 3 0.004 0.021 0.012

The data indicate that the experimental non-PFOS product actually increased emissions 

of chromium. However, as this product is still under development and not commercially 

available, the results are not relevant to the performance of WAFS for controlling chromium 

electroplating emissions in the U.S. and are not discussed further in this memorandum. 

As reported, the results for the commercially available non-PFOS product appear to 

indicate that emissions would not meet the current emissions limits specified in the Chromium 

Electroplating NESHAP for large or new small hard chromium electroplating (0.015 mg/dscm), 

or for decorative chromium electroplating (0.01 mg/dscm). However, on closer examination, the 

data show that the ventilation rate for the test vessel was much lower than is recommended for a 

chromium electroplating tank in the U.S. Based on the reported flow rate (3 L/min) and the test 

vessel surface area (0.008 square meters), the ventilation rate was 1.2 cubic feet per minute per 

square foot of surface area (CFM/ft2

). The minimum recommended ventilation rate in the U.S. is 

250 CFM/ft2 (ACGIH, 1986), or approximately 200 times the ventilation used rate during the 

test. If the flow rate were normalized using the recommended ventilation rate, hard chromium 

electroplating emissions for the both the PFOS product (0.000033 mg/dscm) and the non-PFOS 

product (0.000137 mg/dscm) would be well below the NESHAP emission limits. For decorative 

chromium electroplating, emissions for the non-PFOS product (0.000063 mg/dscm) also would 

be well below the NESHAP limit. Although scaling flow rates and adjusting emissions 
3

concentrations by that large of a factor is questionable, the magnitude of the adjusted emissions 

concentrations also raises the question of whether the exhaust system was capturing all of the 

emissions. It should also be noted that the uncontrolled results, 0.0019 mg/dscm when scaled for

ventilation rate, are more than three orders of magnitude lower than typical uncontrolled 

emissions in the U.S., which are 3.1 mg/dscm based on AP-42 data (EPA, 1996).

In summary, the test conditions and results also call into question the representativeness 

of this study for full scale chromium electroplating operations and the appropriateness of the test 

results for comparing the performance of PFOS and non-PFOS WAFS. Specifically: 

• The purpose of the study, and thus the study design, was to examine the performance of 

an experimental product that is not commercially available;

• The test vessel, which had a volume of 4.5 L was at least two orders of magnitude 

smaller than the tanks commonly used in the electroplating industry;

• The exhaust system design, fabricated from piping placed around the outside of the 

vessel, does not resemble tank hoods and ductwork used in the industry;

• The ventilation rate was more than 200 times lower than what is recommended in the 

U.S.; and

• The analytical test method used was not developed for analyzing emission samples and, 

based on the method title, is a qualitative, rather than a quantitative method.

Danish Study (DME, 2011)

The purpose of this study was to compare the performance of PFOS-based WAFS to nonPFOS-based WAFS. Commercially available products were tested in a small hard chromium 

electroplating tank. The tests consisted of five test runs, each of which was 24 hours in duration. 

In addition, one uncontrolled 12-hour run was conducted to establish the baseline (i.e., without 

WAFS). The entire tank was fitted with a hood to capture all emissions from the process.

Emissions were sampled and analyzed using BS EN 14385:2004, Stationary source emissions. 

Determination of the total emission of As, Cd, Cr, Co, Cu, Mn, Ni, Pb, Sb, TI and V. 

It does not appear that surface tensions were measured during the testing. However, the 

study reports that WAFS were dosed at approximately 50 percent more than manufacturer’s 

specification. Based on the technical data sheet (Atotech, 2010) for the non-PFOS product used 

(Fumetrol 21) and the reported concentration during test (3.6+ ml/L), the surface tension should 

have been about 28 to 35 dynes/cm for the non-PFOS fume suppressant test.

Table 2 summarizes the emission test results in mg/dscm, as presented in the report. 

Table 2. Summary of Results for Danish Study as Reported

Test 

condition WAFS Product No. of test runs

Chromium emissions, mg/dscm

Minimum Maximum Average

Hard Cr 

electroplating

None (baseline) 1 12.0

PFOS 5 0.011 0.30 0.12

Non-PFOS 5 0.013 0.089 0.036
4

The results indicated that the non-PFOS product performed better than the PFOS product 

in reducing chromium emissions. However, the results, as reported, indicate that for neither test 

did emissions meet the NESHAP limit of 0.015 for large hard chromium electroplating tanks. 

As was the case for the German Study, it appears that the ventilation rates were lower than would 

be the design practice in the U.S. Based on the reported flow rate (180 cubic meters per hour) 

and the test tank surface area (0.22 square meters), the ventilation rate was 45 CFM/ft2. The 

minimum recommended ventilation rate in the U.S. (250 CFM/ft2) is approximately 5.6 times the 

ventilation rate used during the test. If the flow rate were normalized using the recommended 

minimum ventilation rate, emissions for the PFOS product are 0.022 mg/dscm, and, for the nonPFOS product are 0.0067 mg/dscm. However, it should noted that the recommended ventilation 

rate of 250 CFM/ft2 in the U.S. is what is required “to maintain minimum control velocities” 

across the tank surface area. Thus, tanks are typically designed for higher ventilation rates, 

thereby decreasing emissions concentration. Therefore, the calculated value of 0.0067 mg/dscm 

is considered a maximum value and actual tanks would have greater flow rate and lower 

emissions concentrations. Nevertheless, this result for the non-PFOS product is generally 

consistent with data on emissions from tanks controlled with PFOS-based WAFS in the U.S. 

The result for uncontrolled emissions (12 mg/dscm) also is consistent for uncontrolled hard 

chromium emissions in the U.S.

In summary, although the test tank was smaller than most electroplating tanks, the test 

design and conditions appear to be representative of hard chromium electroplating in the U.S. 

The exhaust system (completely hooded tank) and test method used indicate that the emissions 

concentrations were appropriately quantified. The ventilation rate was lower than would be 

required in the U.S., but not to the extent that would compromise the adjusted concentrations.

II. Comparison of Studies

Table 3 provides a side-by-side comparison of the two studies and the results for hard 

chromium electroplating emissions. In summary, the Danish Study appears to be much more 

representative of chromium electroplating operations and used a more appropriate test design and 

test methods, than the German Study.

III. References

1. Institute für Galvano- und Oberflächentechnik Solingen GmbH & Co. KG. Report on 

Findings, 20110508, English Edition, Solingen, Germany, July 14, 2012 (IGOSG, 2012).

2. EMD. Effect of Cr(VI) Emissions and Surface Tension of Non-PFOS Mist Suppressants in 

Hard and Decorative Chrome Plating. Merck KGaA, Darmstadt, Germany, 2012 

(EMD, 2012).

3. Atotech. Data Sheet, Fumetrol® 21 LF, Chromium Mist Suppressant, Version: 02. June 29, 

2010 (Atotech, 2010).

4. American Conference of Governmental Industrial Hygienists. Industrial Ventilation – A 

Manual of Recommended Practice, 19th Edition. Lansing, Michigan, 1986 (ACGIH, 1986).
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5. U.S. Environmental Protection Agency, Emission Factor Documentation for AP-42 Section 

12.20 Electroplating. July 1996 (EPA, 1996).

6. Danish Ministry of the Environment, Environmental Protection Agency. Substitution of 

PFOS for Use in non-Decorative Hard Chrome Plating. Denmark, 2011 (DME, 2011).
6

Table 3. Comparison of German and Danish Studies

Item German Study Danish Study Remarks

Process type Hard Cr Hard Cr For both studies, current density was 50 A/dm2

Plating Tank Volume, gallons 1.2 29 German Study was lab-scale; Danish Study was full scale 

Exhaust capture system Perforated pipe Full hooding German Study used a fabricated capture system consisting of 

perforated pipe surrounding the test vessel; Danish Study used 

fully hooded tank, thereby ensuring 100% capture

PFOS product HSO FL Fumetrol 140 PFOS product for German Study not typically used in U.S.

Non PFOS product Fumetrol 21 Fumetrol 21 Both studies used non-PFOS that is widely used in U.S.

Surface tension Not specified (a) Not specified (b) No surface tension measurements reported. See Notes (a) and 

(b) below for estimated surface tensions

Test Method EN 15205 (c) EN 14385 (d) Method used for German study was not meant for quantifying 

emissions and is a “qualitative” method; method used for 

Danish Study was developed for quantifying stack emissions

No. of test runs PFOS: 2

Non-PFOS: 3

PFOS: 5

Non-PFOS: 5

Danish Study included more test runs

Test run duration, hours 33 to 50 1,440 Test run durations for the German Study are less than what is 

commonly used in the U.S. and may not be adequate to 

properly quantify results; for the Danish Study, test runs were 

24 hours each, which should be more than adequate

Detection limit, ug/m3 Not specified 0.9 German Study did not specify detection limit

Average Cr concentration, adjusted for 

ventilation rate, mg/dscm

PFOS 0.000033 0.022 See Section I for discussion of representativeness of results for 

Non-PFOS 0.00014 0.0067 the two studies

(a) Study included calibration curves that relate fume suppressant concentration and bubble lifetime to surface tension, but it unclear how the calibration curves 

were used; report states that PFOS and non-PFOS chemical concentrations were in accordance to manufacturer’s specifications; based on Fumetrol 21 data sheet 

and reported concentration during test (2.0 to 2.5 ml/L), the surface tension should have been about 35 to 47 dynes/cm for the non-PFOS fume suppressant test.

(b) Report states that both PFOS and non-PFOS chemical concentrations were 50% more than manufacturer’s specification; based on Fumetrol 21 data sheet and 

reported concentration during test (3.6+ ml/L), the surface tension should have been about 28 to 35 dynes/cm for the non-PFOS fume suppressant test.

(c) DIN EN 15205, Determination of hexavalent chromium in corrosion protection layers - Qualitative analysis.

(d) BS EN 14385:2004, Stationary source emissions. Determination of the total emission of As, Cd, Cr, Co, Cu, Mn, Ni, Pb, Sb, TI and V.