### Environmental Condition Testing of 31 Sampled Measurement Technology Laboratories 46.2

- mm PTFE (Teflon®) Filters

Environmental Condition Test

Client: Tennessee Department of Environment and Conservation

Leidos/ TDEC Purchase Order No.: P010157692

RTI Project No.: 0212441.001.022

Draft Date: May 20, 2014

Final Date: July 18, 2014

By

Paige Presler

- Jur RTI International 1
3040 Cornwallis Road Research Triangle Park, NC 27709

- 2194

919

- 541

- 6813

Submitted To

Robert Brawner Technical Services Program Air Pollution Control Division
15 th Floor William R. Snodgrass Tennessee Tower

312 Rosa L. Parks Avenue Nashville, TN 37243

1 RTI International is a trade name of Research Triangle Institute.1



### INTRODUCTION

RTI was instructed to perform Environmental Condition testing of Measurement Technology Laboratories (MTL) 46.2

- mm PTFE (Teflon ® ) filters . Thirty

- one sampled filters were provided for the test by the Tennessee State Laboratory . The 31 filters provided for the test ing were received by RTI on April 17, 2014

. RTI suggested a statistically valid number of filters was 30

- 50 filters based on the statistical power analysis for the number of samples needed to be 95% certain a difference between the tw o populations of weighings actually existed (i.e., two different environmental conditions). For reference, the EPA acceptance criteria according to standard moisture pickup test descriptions outlined in 40 CFR Part 50, Appendix L, and enclosed with the fil ters, a filter ’ s weight is not to increase by more than 10 μ g after 24

- hour exposure to air of 40% relative humidity, relative to its weight after 24

- hour exposure to air of 35% relative humidity. Th e sample size was also based on this EPA a cceptance crite ria that the average at the two weights can differ by up 10 ug and still be deemed ‘passing’ the moisture pickup acceptance test. TDEC chose to evaluate both relative humidity and temperature by varying the environmental conditions to 25% RH and 45% RH as well as 18 ° C and 25 ° C.



### GRAVIMETRIC ANALYSES

The microanalytical balance used for the moisture pickup test was a Mettler Toledo Model XP6 with a readability of 0.1 μ g and a repeatability of 0.25 μ g. This balance is installed in the MTL
AH

- 225 Precision Weighing System shown in Exhibit 1. All weighings for the Environmental Condition Tests were completed by the MTL AH

- 225 robotic autohandler.

Exhibit 1. MTL AH

- 225 Precision Weighing System for Roboti c Gravimetry Analysis

MTL’s AH225 series is a n automated filter processing system that vastly increases our throughput

capabilities while providing greater precision and lower detection limits

.

1. Filters were equilibrated and weighed in a controlled

- environment weighing chamber (seen in Exhibit 2) whose ambient temperature and relative humidity are controlled and monitored by a dedicated conditioning, humidification, and dehumidification system.2 Exhibit 2

. Environmentally Controlled Weighing Chambers

RTI chamber systems provide optimal conditions and high quality data collection

for the gravimetric analysis of filter samples.

Filters were placed in the weighing chamber on April 23, 2014

, and allowed to equilibrate in the weighing environment at 3 6 % relative humidity and 2 2 ° C for 24 hours. Pre

- test weighing at
these conditions was performed on April 24, 2014 . The chamber ’ s temperature controls were
then reset for 18 ° C . The filters were allowed to equilibrate in the weighing environment at 18 ° C temperature and 36% relative humidity for 24 hours, and then were reweighed on April 25,
2014

. At that time, t he chamber ’ s temperature controls were reset for 25 ° C, and the filte rs were allowed to equilibrate in the weighing environment at 25 ° C temperature and 36% relative humidity for 24 hours . They were reweighed on April 27, 2014

. The post test was completed in a weighing environment of 22 ° C temperature and 36% relative humidit y on April 29, 2014

. Relative humidity and temperature data were collected for the 24 hours prior to each weigh session using both the probe data logger in the MTL AH

- 225 and a temperature and humidity data logger for the chamber that was placed on top of the autohandler (seen in Exhibit 3) . Data logger output s w ere exported into Excel ® spreadsheet format for calculation of means and standard deviations and for inclusion in this report. The data are provided in Attachment 2

.3 Exhibit 3

. Location of the Environmental Condition

Sensors

Multiple environmental data loggers were used to provide a
clear illustration of the conditions in the chamber at the MTL
AH

- 225

.

In between the two weekend tests, the f ilters were placed in the holding silo of the MTL AH

- 225 and kept in the weighing chamber at 3 6 % relative humidity and 2 2 ° C for 24 hours. Pre

- test weighing for the % relative humidity testing was performed at these conditions on May 8, 2014

. The chamber ’ s relative humidity controls were then reset for 25 % relative humidity. The filters were allowed to equilibrate in the weighing environment at 25 % relative humidity and 2 2 ° C for 24 hours, and then were reweighed on May 9, 2014

. At that time, the chamber ’ s relative humidity controls were reset for 45% , and the filters were allowed to equilibrate in the weighing environment at 22 °C temperature and 45 % relative humidity for 24 hours. They were reweighed

on May 10, 2014 . The post test was completed in a weighin g environment of 22°C temperature and 36% relative humidity on May 12 , 2014. Relative humidity and temperature data were collected for the 24 hours prior to each weigh session using both the probe data logger in the MTL AH

- 225 and a temperature and humidit y data logger for the chamber that was placed on top of the autohandler (seen in Figure 2). Data logger outputs were exported into Excel ® spreadsheet format for calculation of means and standard deviations and for inclusion in this report. The data are pro vided in Attachment 3

.

Two NIST

- traceable reference weights bracketing the weight of the MTL 46.2 mm PTFE filter ( 1 00

- mg and 4 00

- mg) were weighed after balance start

- up and calibration and then again after every tenth filter to monitor balance fluctuation in each weigh session. In addition, all filters w ere reweighed to monitor filter stability during each weigh session.4



### RESULTS OF ANALYSES

Weights for the 31 filters for the temperature and relative humidity tests are presented in the attached Table 1 and 2, respectively. The internal duplicate QC data are presented with the weighing data in Tables 1 and 2 of Attachment 1. Relative Mass Diffe rence is presented in Tables 1b and 2b for the temperature and relative humidity, respectively. Internal Environmental Chamber Condition QC data are presented in Tables 3 and 4. The QC data includes readings from the AH probe sensor. The chamber data logge r data is reported for comparison Attachments 2 and 3. During the Moisture Pickup Acceptance Tests in previous years, RTI noticed that the MTL filters had a tendency to have greater static effects than filters previously tested for the program. The MTL AH

- 225 robotic autohandler is equipped with multiple static protections to minimize the effects of static for these Environmental Condition tests. RTI invested in the MTL autohandler Faraday pan to substantially reduce the effect of static charge on the mass measurement result. The MTL AH

- 225 is also equipped with multiple Polonium strips in the balance weighing chamber.



### DISCUSSION

Attachment 1 Tables 1 a and 2 a report the filter weighings for each test. Attachment 1 Tables 1b and 2b show the mean difference s in filter weights recorded for the 31 test filters at the varying temperature and humidity settings. There were no net mass differences outside the +/

- 30 μg acceptance for Field Blank weight changes and a limited number of net mass differences outside of the +/

- 15 μg acceptance for duplicate weights shown in Exhibit 4

.

Exhibit 4. Number of Filters with Relative Mass Differences Outside Field Blank and Duplicate Specifications for (a) Temperature and (b) Relative Humidity

4a. Corresponds to Mass Difference Attachment 1,Table 1b Relative Mass Difference ‘Pre

- Test'

-

18°C 18°C

- 25°C ‘Pre

- Test'

- 25°C ‘Pre

- Test'

-

'Post

- Test'

> +30 ug 0 0 0 0

<
- 30 ug 0 0 0 0 > +15 ug 1 0 1 3

<
- 15 ug 0 0 0 0

4b. Corresponds to Mass Difference Attachment 1, Table 2b Relative Mass Difference 'Pre

- Test'

-

25% 25%

- 45% 'Pre

- Test'

- 45% 'Pre

- Test'

-

'Post

- Test'

> +30 ug 1 0 1 1

<
- 30 ug 0 0 0 0 > +15 ug 1 0 1 1

<
- 15 ug 0 0 0 0 Relative Mass Difference compared to Acceptance for FRM Field Blanks and Duplicates.5

All r eplicate weighings of the reference weights and duplicate weighings of the MTL filters were within the acceptance ranges set forth in the U.S. EPA Quality Assurance Handbook, Volume II, Part II, Section 2.12 (Guidance Document 2.12)

. The attached data suggest that the sample size chosen for the study is sufficient for the purposes of this s tudy. Filter number 14334066 was a designated Laboratory Blank initiated at the time of the first weigh session and weighed at least one time during each consecutive weigh session. There was variation in the temperature and humidity readings between MTL AH

- 225 data logger probe and the chamber data loggers as seen in Attachments 2 and 3. Both data loggers are within their annual calibration completed by a NIST traceable calibration service. The set points for the relative humidity and temperature were taxin g to the RTI chamber. Differences in air flow around the MTL AH

- 225 could also have attributed to the slight difference in the readings. Exhibit 3 provides an image of where the data logger and sensor probe were located during the testing. Attachments 2 an d 3 show the variation in the data collected from both instruments. The conditions were stable in all tests and are believed to be representative of the chosen relative humidity and temperatures.6

Attachment Table 1a7

Attachment 1 Table 1b8

Attachment 1 Table 2a9

Attachment 1 Table 2 b10

Attachment 1 Table 311

Attachment 1 Table 412

Attachment 213

Attachment 3