OAR Box 1313 

Preppedby LaTeiaShed 

Document Number: 

57) ll-B-31 

Docket Number: 

A-88-02 

Printed 6/12/2008 9:03:29 AM Sheet 57 of 99 

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A-88-02 

/ ^ \ UNITED STATES ENVIRONMENTAL f Andy Smith (MD-13) 

| kMK. 1 Office of Air Quality Planning a..« . 

\lSZ*J Research Triangle Park, North Carolina 27711 

DEC 1 7 1987 

7;' : . \r., , \ 0 ,'.- -'•'• 

MEMORANDUM ' n XL— 

\ „.Z.-- • """"*" 

SUBJECT: Screening Method Results from Roll Technology 

Corporation 

FROM: Frank R. Clay yy^LL 

Emission Measurement Branch 

TO: Chromium Electroplaters General File 

The screening method samples taken at Roll Technology 

Corporation (formerly Carolina Platers) are the best in the 

series to be performed by the Emission Measurement Branch. 

Sample results are all the same order of magnitude and there 

appears to be a modicum of consistency to the data. While the 

degree of accuracy of the method is not what is desired, there 

are steps that can be taken to improve accuracy, and the effort 

is, at least, encouraging. 

It appears that several of the earlier problems with the 

method have been solved. The waiting period between sample 

collection and sample results has been eliminated by performing 

sample analysis on site. It also appears that problems due to 

poor sample recovery technique have been eliminated as well. The 

major problem that remains is that of sample volume. 

An effort was made prior to the test at Roll Technology to 

insure accurate sample volumes. Before the test, all Thomas® 

pumps were run for one hour while being connected to a wet test 

meter. The sampling apparatus (cassette filter or Teflon® 

tubing) was also connected to the pump. Wet test meter volumes 

were determined and corrected for temperature and pressure to 

ascertain the standard cubic feet per hour sampling rate. The 

rotameter adjustment knobs were then fixed into position by using 

silicone rubber cement. The sample volumes determined in the 

laboratory were used for field calculations of chromium 

concentrations from screening method runs. Upon return from the 

field, the pumps were run again in the laboratory to see if the 

sample volumes were unchanged. Unfortunately, they were not, and 

the true volumes sampled in the field remain unknown. 

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Although the true volumes sampled in the field remain 

unknown, some of the pumps were relatively close when a 

comparison was made between the initial volume and the post test 

volume. The closest inlet number was 2% high, and the closest 

outlet number was 3% low. (This comparison uses the initial 

numbers as the standard or numerator.) The largest variation for 

the inlet pumps was 53% low while the greatest variation at the 

outlet was 47% low. 

Three of the eight pumps used for the screening samples were 

fairly close in pretest and post-test volumes. One was at the 

inlet and two were at the outlet. If it is possible to consider 

data from these three pumps as good (which it probably is not), 

then comparing these numbers with the Method 13-B values may give 

some indication as to how accurate the screening method is. 

The accuracy range of the inlet pump varied from 84% below 

the Method 13-B number to 395% above the 13-B number. The 

average of the positive and negative percent values is 73.7. The 

absolute average is 112.8. Either way, the values are something 

greater than the desired accuracy of ±50%. 

At the outlet, two of the pumps had volumes after the test 

that were close to the original volumes determined prior to the 

test. Emission numbers determined from these pumps varied from 

•31.0% to +121% for one of the pumps and 5.7% to 119.2% for the 

other pump. The average absolute values for these two pumps were 

54.9 and 54% respectively, and the average of the values was 42.5 

and 54% respectively. 

During the last run of the test, two spare pumps were 

operated at the outlet in addition to the four regular pumps. 

The spare pumps were run for 292 minutes (4 hrs 52 minutes). 

These pumps did not incorporate surge tanks or rotameters as used 

on the regular screening trains, but simply ran at maximum 

capacity during the run. Tapered tubes were used for sample 

extraction, and while the spare pumps were similar in size, one 

pump sampled a volume about ten times that of the other. 

Without a surge tank on the inlet side of the pump, the net 

effect of the pump is to extract a sample, but in the process, 

the pump pulses and puffs in the inlet direction. This may make 

it difficult to determine the direction of flow of the pump and 

is probably the reason that one of two pumps that sampled at 

maximum volume had the flow direction marked backwards. As a 

result of this mismarking of the pump, the pump was hooked up . 

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backwards. Thus, ambient air was being pumped into the outlet 

stack instead of being extracted from it. Nevertheless, the 

sample collected from this train was within 75% of the real 

concentration determined from the 13-B train and was low by only 

25%. The other pump, through extracting a smaller sample, 

sampled in the right direction and was only 2% greater than the 

real (13-B) number. 

Data from the two unrestricted pumps were based on a sample 

rate determined in the lab from 15 minutes of pump operation. 

During the test, these two pumps ran for over four hours, so a 

15-minute run may not have given an accurate sampling volume. 

The variation, however, would not have been sufficient to change 

the data significantly. Thus, the pump that blew ambient air 

into the stack provided some of the most accurate data of all. 

From the above discussion of- the two pumps, it is possible 

to conclude that it is more accurate to extract a sample from the 

stack rather than to blow ambient air into it if the 

determination of chrome 6 concentrations is the goal. This is 

just another way in which science works for you here at the 

United States Environmental Protection Agency. 

If the percent error of the screening run concentrations is 

averaged, it is possible to see how close the screening method 

comes overall to the concentration determined from the 

Method 13-B trains. The average and absolute average have been 

determined for each location using the two sets of Thomas ® pump 

volumetric flow rates determined in the lab both before and after 

the test. 

At the inlet, the average error of the screening method 

during the test when compared to the 13-B concentrations was 

+59.6%. The value of the absolute average was +93%. After the 

test (and using post-test sampling volumes) the average error at 

the inlet was 143% and the value of the absolute average was 

172.5%. 

At the outlet, the averages looked much better. The average 

error of the screening method during the test, when compared with 

the 13-B concentrations, was +40.3%. The value of the absolute 

average was 49.2%. After the test (and using post-test sampling 

volumes) the average error at the outlet was 32.4% while the 

value of the absolute average was 43.9%. 
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The range of the numbers varied quite a bit. For the inlet 

location during the test, percents varied from a high of +404% to. 

a low of -87.1%. Using the volumes determined after the test, 

inlet values varied from a high of 787.4% to a low of 83.9%. 

At the outlet, the range was smaller. During the test, the 

percents varied from a high of 125.4% to a low of -30.8%. Using 

sample volumes determined in the lab after the test, values 

ranged from a high of +121% to a low of -40.7%. 

Clearly, the inlet numbers are less accurate than the outlet 

numbers. Normally, this would not be expected since inlet 

concentrations are higher than the outlet and a larger sample is 

usually more accurate. There may be many reasons for this 

anomaly. The inlet location was very poor and did not meet the 

criteria of Reference Method I. It is also possible that the 

point of average velocity was not sampled. The outlet, on the 

other hand, was an ideal location with a better velocity profile. 

At the outlet, even a point that was not of average velocity 

would probably give good results. 

For the next phase of this project, some procedural changes 

will be made. First, no sample will be taken without determining 

that the sample point represents a point of average velocity. 

Second, only samples using tapered tubing will be collected and 

tubing holders will be modified to insure that the tubing faces 

directly into the stack flows. Third, only hypodermic needles 

encased in epoxy will be used as flow regulating devices. Needle 

gauge will be chosen based on velocities determined on the 

pretest survey visit. Fourth, pump volumes will be determined in 

the lab before and after the test with each pump in its sampling 

configuration. Fifth, the same sample recovery procedures that 

were used in Greenville, SC, will be used again. 

For the next test, only tapered tubing will be used to 

collect the samples. This is not because the tapered tubing is 

better for collecting a sample than the cassette filter, but it 

is easier to use. On the upcoming test, the goal will be to 

achieve reproducibility first and accuracy second. Using all 

tapered tubing samples will also give a better statistical 

number. 

Hypodermic needles give accurate and reproducible volumes in 

the lab - even when used with our worn out pumps. It is possible 

to select one of three needle gauges to sample within ± 30% 

isokinetic of the range of flow encountered in chromium plating 

operations (The gauge size assumes a 1/8" diameter tapered tube). 

A cassette filter will be used as a protective device for the 

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hypodermic needle, and gauge size for the next test will be 

determined when the test site is selected and the pretest survey 

has been completed. Prior to the test, Thomas® pumps will be 

checked for sample volumes in the test apparatus configuration, 

and during the 13-B test runs at the facility, an attempt will be 

made to get 8 one hour samples at both the inlet and outlet 

locations. This will provide a total of 24 samples at each 

location. Upon return to the lab, Thomas® pumps will again be 

checked for sample volume. 

If the upcoming test work is successful, there are some 

questions that still remain. How specifically, will the 

screening method be used? Will there be a specification as to 

tank loading and amperes that must be met before the screening 

method can be used, and lastly, if the technique is successful, 

how much additional testing will be needed to show that the 

method is accurate? 

cc: John Brown (MD-19) 

Bill DeWees (Entropy) 

Bill Grimley (MD-19) 

Gail Lacy (MD-13) 

Robin Segall (Entropy) 

Randy Straight. (MRI) 

Al Vervaert (MD-13) 

Andy Smith (MD^13) 

\b