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 a nd then select the fewest nozzles that can be used to meet the isokinetic and point by point requirements. S ince this is a constant volume test method, the sample volumes are governed by the dwell time at each point. C hanging 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 O TM 27 but was pulled because we were informed that this was not a common occurrence. Since you are the th ird 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 f ew years ago. The cut point is 2.22. The flows range from .2 - 1.9. trave rses 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 fa ll 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@epa mail.epa.gov; Parker.Barrett@epa.gov; Eddinger.Jim@epamail.epa.go v; 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 gi ve you a definitive answer. If as you indicate that the gas stream is not amenable to satisfactory testing with OTM 27 because of flow ch aracteristics, I would this that it is very strange. If the problem is one of very high stratification in flow, then you would need to addr ess 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 flo ws are highly

variable but can be accommodated with Method 5 samp ling, 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 tha t I could think of
are as follows:

Acceptability of cut points:

Figure 9 of the method, shows that acceptable cut p oints are achievable with gas temperatures from 50F to 700F (the upper e nd of which the method indicates there are galling problems with no rmal stainless steel). If the gas temperature is in excess of abo ut 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. U sing 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 t emperature and 2.25 with 44F gas temperature. This is probably the upp er range of the method. At these higher temperatures and therefore flow, there are nozzles that are satisfactory from delta P's of 0.1 3 to 5.49 (see the below table). One might be able to extend this ran ge somewhat by sampling a little below isokinetic at the lower vel ocity's and a little above isokinetic at higher velocity's. Another way of reaching lower velocity's is to use a larger diameter nozzle (whic h we do not currently have in the method).

(Embedded image moved to file: pic31316.jpg)

That was the high end of the temperature and veloci ty spectrum. At lower temperatures one needs to use a lower sample velocity to achieve the desired cut point. At temperatures of 50F to 1 00F (probably much lower than the sources you are testing), nozzles th an can go as low as a delta P of 0.05 and as high at 2.15. Again, the is okinetic requirements of the method are 80 to 120% and these delta P's co uld be stretched a little.

(Embedded image moved to file: pic20671.jpg)

If this does not address your situation, let me kno w 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 27 711 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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--------------------------------------------------- ----------------| |"Rock, Gregory J (GE Infra, Energy)" <gregory.roc k@ge.com> |

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--------------------------------------------------- ----------------| |Ron Myers/RTP/USEPA/US@EPA |

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Greg:

I am copying Ron Myers on your question as he is mu ch better informed on the method than I. I am sure that he will respond, soon.

Peter 

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--------------------------------------------------- ----------------| |Peter Westlin/RTP/USEPA/US@EPA |

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--------------------------------------------------- ----------------| |Pm 2.5 constraints |

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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 wor k, do we perform m5/otm-28?

Field Engineer 6 

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