Greg: 

If when you do the initial velocity traverses you confirm that the flows have that range and that this is not due to 

process variations, you can select the points to be tested and then select the fewest nozzles that can be used to 

meet the isokinetic and point by point requirements. Since this is a constant volume test method, the sample 

volumes are governed by the dwell time at each point. Changing nozzles will be a pain and result in somewhat 

longer sampling times to allow the cyclones to cool so you can change the nozzle and then warm back up to 

resume the sampling. This was in an earlier version of OTM 27 but was pulled because we were informed that 

this was not a common occurrence. Since you are the third person that has identified the issue, we may want to

put it back in the method. 

_________________________________

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 

Ron: 

I put in old data from a particulate tests done a few years ago. The cut 

point is 2.22. The flows range from .2 - 1.9. traverses from the two 

ports show this very mixed flow. I don't know if it is still this way. 

With these numbers I can't get both delta p's to fall in. If the flow is 

still running this way , I think I have a problem. 

-----Original Message----- 

From: Myers.Ron@epamail.epa.gov [mailto:Myers.Ron@epamail.epa.gov] 

Sent: Wednesday, July 29, 2009 12:03 PM 

To: Rock, Gregory J (GE Infra, Energy) 

Cc: Dewees.Jason@epamail.epa.gov; Westlin.Peter@epamail.epa.gov; 

Parker.Barrett@epa.gov; Eddinger.Jim@epamail.epa.gov; 

Maxwell.Bill@epamail.epa.gov; Shrager.Brian@epamail.epa.gov; 

Segall.Robin@epamail.epa.gov 

Subject: Re: Pm 2.5 constraints 

Greg: 

Without more information I'm not sure that I can give you a definitive 

answer. If as you indicate that the gas stream is not amenable to 

satisfactory testing with OTM 27 because of flow characteristics, I 

would this that it is very strange. If the problem is one of very high 

stratification in flow, then you would need to address the 

stratification problem for any testing that you may conduct. If the 

From: "Rock, Gregory J (GE Infra, Energy)" <gregory.rock@ge.com>

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

Date: 07/29/2009 01:13 PM

Subject: RE: Pm 2.5 constraints

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problem is that this is a batch process and the flows are highly 

variable but can be accommodated with Method 5 sampling, then you would 

need to document fully the flow conditions and cite that as the reason 

that OTM 27 can not be performed. Other issues that I could think of 

are as follows: 

Acceptability of cut points:

Figure 9 of the method, shows that acceptable cut points are achievable 

with gas temperatures from 50F to 700F (the upper end of which the 

method indicates there are galling problems with normal stainless 

steel). If the gas temperature is in excess of about 500F then you 

should document that fact and perform EPA Method 5 rather than OTM 27. 

Isokinetic sampling: 

Once the cut point is selected the issue becomes on of the selection of 

a nozzle that achieves near isokinetic sampling. Using Figure 9 of the 

method indicates that the maximum sampling rate is associated with the 

highest temperatures. A central sampling rate of 0.8 acfm would be 

associated with a cut point of 2.75 with 500F gas temperature and 2.25 

with 44F gas temperature. This is probably the upper range of the 

method. At these higher temperatures and therefore flow, there are 

nozzles that are satisfactory from delta P's of 0.13 to 5.49 (see the 

below table). One might be able to extend this range somewhat by 

sampling a little below isokinetic at the lower velocity's and a little 

above isokinetic at higher velocity's. Another way of reaching lower 

velocity's is to use a larger diameter nozzle (which we do not currently 

have in the method). 

(Embedded image moved to file: pic31316.jpg) 

That was the high end of the temperature and velocity spectrum. At 

lower temperatures one needs to use a lower sample velocity to achieve 

the desired cut point. At temperatures of 50F to 100F (probably much 

lower than the sources you are testing), nozzles than can go as low as a 

delta P of 0.05 and as high at 2.15. Again, the isokinetic requirements 

of the method are 80 to 120% and these delta P's could be stretched a 

little. 

(Embedded image moved to file: pic20671.jpg) 

If this does not address your situation, let me know more details about 

the source. 

_________________________________ 

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 

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 |Peter Westlin/RTP/USEPA/US 

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Greg: 

I am copying Ron Myers on your question as he is much better informed on 

the method than I. I am sure that he will respond, soon. 

Peter 

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Mr. Westlin: 

We will be doing the 114 Pre MACT info testing next week. I am going 

through some old data and it does not look like the cut point, min and 

max delta p's will fit. If we can't get this to work, do we perform 

m5/otm-28? 

Field Engineer 6 

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