Paul: 

If I said that it would be appropriate to eliminate the PM10 cyclone when the duct diameter is less than 18 inches, 

then that was not exactly correct. Both OTM Method 27 and the proposed Method 201A state that the method 

can be use for testing for PM10 only, PM2.5 only or for the combination of PM10 and PM2.5. Here is a link to the 

proposed method ( http://www.epa.gov/ttn/emc/proposed/m-201Ar1.pdf ) and OTM27 

( http://www.epa.gov/ttn/emc/prelim/otm27.pdf ). 

The methods now only have the combined cyclone area to calculate the blockage and does not address the use 

on only the PM10 head or only the PM2.5 head. In the method we state that the combined area of both the PM10 

and PM2.5 heads is 20.5 square inches. The method indicates that the maximum 6% blockage is exceeded 

when the stack duct is about 18 inches We are measuring a few cyclones to get a more definitive information for

the blockage of the various components and will revise the method accordingly. So, if you are required to test for 

only PM2.5, then the method allows for the use of only the PM2.5 cyclone and by my estimates the minimum duct 

diameter will drop to about 12 inches. This is based upon my estimate that the PM2.5 cyclone has a total 

blockage of about 12 square inches when fully inserted and about 6 square inches on average. 

If there is a requirement to test for PM10, and the duct is less than 18 inches in diameter, then the combined 

PM10 and PM2.5 cyclones are more than 6% of the duct area (the combined cyclones block about 20.5 square 

inches when fully inserted and average about 12 square inches). The 12 square inches of average blockage will 

cause excessive disruption of the flow characteristics in the duct. In that case, to decrease the blockage, one 

would have to reduce the blockage. One way to do that if there is a requirement to test for PM10 and PM2.5 

would be to sample for PM10 and PM2.5 separately. The PM10 sampling head would be the most problematic 

since it is the larger of the two. We are re assessing the duct sizes that comprise the 6% blockage and the lowest 

duct size may not be reduced much but may drop to something around 14 or 15 inches for the PM10 head only.

Rather than you informing the state of the details or using the proceedings (which will not have any detail) have 

the State look on the EMC guidelines documents web page ( http://www.epa.gov/ttn/emc/guidlnd.html ) and 

specifically look in the documents related to Boiler and Process Heater Testing. While the guidelines documents 

may not address all of your questions, one will address the situation of sampling in small ducts using only the 

PM2.5 cyclone head. When I have more definitive measurements and we post an update for the Boiler and 

Process Heater Testing the updated size information will be one of the questions that will be addressed. 

My presentation did not have the above information in it, but if you would like my presentation, let me know and I'll 

e-mail you a copy. 

_________________________________

Ron Myers 

U.S. Environmental Protection Agency 

Office of Air Quality Planning and Standards 

Sector Policy and Programs Division 

Monitoring Policy Group, D243-05 

RTP NC 27711 

Tel. 919.541.5407 

Fax 919.541.1039 

E-mail myers.ron@epa.gov 

From: "Paul Taylor" <rtaylor@barr.com>

To: Ron Myers/RTP/USEPA/US@EPA

Date: 06/26/2009 12:57 PM

Subject: AWMA ACE 2009 Panel Discussion

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Mr Myers: 

 

Would it be possible to obtain the printed material associated with the panel discussion on "PM2.5 NSR 

Implementation Issues" that you participated in on 6/18/09? 

 

Of particular interest is your comment that, when testing stacks smaller than 18 inches in diameter, it would be 

appropriate to eliminate the larger PM10 cyclone at the head of the in-stack sampling train. 

 

We are planning to test for PM2.5 on some stacks with diameters between 12 and 18 inches using the proposed 

Method 201A (previously OTM 27). The state agency has approved the use of the method (modified to exclude 

the PM10 cyclone) but has expressed an interest in seeing any discussion by USEPA of this variation of the 

method. 

 

I've been unable to find any reference to the session (EP-1h) on line (http://www.conferencearchives.com/awma/) 

and, although we are ordering the conference proceedings on CD-ROM, we would like to pass on the information 

to the state agency as soon as possible. 

 

Thanks in advance for any help you can provide. 

 

Paul Taylor, Ph.D. 

Air Quality Engineer 

 

Barr Engineering Company 

4700 West 77th Street 

Minneapolis, MN 55435-4803 

Tel: 952-832-2671 (direct) 

Fax: 952-832-2601 

e-mail: ptaylor@barr.com 

 

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