From: <Myers.Ron@epamail.epa.gov>

To: jimn@esclabs.com CC: Segall.Robin@epamail.epa.gov; Parker.Barrett@epamail .epa.gov; Westlin.Peter@epamail.epa.gov; Joe.Fanjoy@erg.com; Dan ny.Greene@erg.com; . . . Date: 7/8/2009 7:21 PM Subject: Re: CPM method question

Jim: First an appology for a somewhat late response or an appology for a second response should I have already responded to this que stion.

The purpose of the divided box with somewhat different temperature requirements is to minimize the potential to form sulfate artifact in the first two impingers and to maximize the collecteion of water vapor for calculating the moisture content of the sampled ga s.

If you do not mind the increased potential to form sulf ate artifact in the first two impingers, you can put the first two imp ingers in the same box or part of the box for the impingers that are inte nded to collect water vapor passing through the first two impingers an d the back up filter. The temperature at the exit of the back up f ilter will be much lower than 85F and satisfy the requirements of the meth od.

In the stakeholder process to develop the method, there w ere two considerations for selecting the temperature level. Th e first consideration was the desire to minimize sulfate artifactformation. Environment Canada provided information that the solu bility of SO2 in water was greater at lower temperatures. Decreasing th e solubility of SO2 reduces the quantity of SO2 that can oxidize to SO3 where it can not be removed with the nitrogen purge. The second conside ration was the desire to establish a collection temperature that is con sistent and is representative of ambient temperature. In the use of another sampling method that is based upon the dilution of the sampled gas with filtered and conditioned ambient air during a hot humid day, w e were only able to reduce the filtration temperature to 85F. This is a t emperature that is reasonable as an ambient temperature level and is ne ar the standard temperature and within the normal 25F range for mai ntaining temperature for stack sampling. Also, this somewhat elevated temperatu re addresses concerns that the promulgated Method 202 condenses organi c and inorganic vapors greater than would be consistent with ambient tem peratures of about 35 to 40F. The dilution in ambient air would further reduce the solid concentrations of these compounds. The combination of the lower temperature and the lack of dilution would tend to pr ovide a high bias to the particulate matter collected. This information is documented in the running commentary on the method development thatis in the docket and on the FAQ page for Method 202 ( http://www.epa.gov/ttn/emc/methods/method202.html#af).

Let me know if you have additional questions.

_________________________________ Ron Myers U.S. Environmental Protection Agency Office of Air Quality Planning and Standards Sector Policy and Programs Division Monitoring Policy Group, D243-05RTP NC 27711

Tel. 919.541.5407 Fax 919.541.1039 E-mail myers.ron@epa.gov

-----"Jim Narens" <jimn@esclabs.com> wrote: -----

To: Ron Myers/RTP/USEPA/US@EPA From: "Jim Narens" <jimn@esclabs.com> Date: 07/07/2009 04:36PM Subject: CPM method question

Ron,

I was hoping you could clear some confusion I have with t his method. Looking over this method, it seems to be vague about the specifics of the temperature of the external filter and how it is achieved.

I know that it is stated in Section 8.5.1 to “maintai n the CPM filter ≤ 30oC(≤ 85oF) during sample collection”. Figure 1 in Section 18 it is clearly shown to be two sections in the co ld box portion of the train.

Why is this?

The iced portion of the box (back half), used to drop out any remaining moisture, will be below 68 oF. Does this not satisfy thecondition of being ≤ 30oC (≤ 85oF)? Could we not simp ly use a non-divided box and circulate the ice water through our condenser t o achieve a filter temperature of ≤ 30oC (≤ 85oF)? The entire premise of the method deals with this condensation temperature of 85oF. Any gas passing through the train less than 68 oF will more th an satisfy this condition. Again, why have two separate temperature re quirements when 68 oF is obviously ≤ 30oC (≤ 85oF)?

Thank you for any insight you can provide.

Jim

James A. Narens, III jimn@esclabs.com E nvironmental S ervices C ompany , Inc. 13715 W. Markham Little Rock , Arkansas 72211 ph. # 501-221-2565 ext. 122 fax # 501-221-1341 www.esclabs.com