Mercaptan level to get negative on Doctor Test

[stevethermo]

Does anyone have an idea of how low the mercaptan level needs to be to get a negative (sweet) on the ASTM D-4952 Doctor Test? Some fuel specs state 20 ppm S as mercaptan or to pass a Doctor Test. My expectation is that the Doctor Test is more stringent. (In this case I am assuming there is no H2S.) I know there is probably no absolute answer, but if you have a range, that would be helpful.
Thanks,
SteveThermo

 

[25362]

Why not use method D 3227-04a/IP 342 ?

 

[dcasto]

ASTM and GPA have searched for alternate method for testing for sulphur species other than the Dr. Test. There is no clear correlation for the amount (ppm) of the differnt species that can be found. I have not seen a range either.

25362 suggests an alternate, but that will not work because of section 1.5 of the ASTM D227-04a states, 1.5 This test method shall not be used when the sample is a referee sample or when QA/QC protocols specify the test method as written. Instances in which they can be used may be instances of routine refinery control samples.

Most commercial contracts specify the Dr. Test or an absolute ppm you quoted above.

I think you might get some more answers if you contacted the Gas Processors Association, the web site has the names of the chairmen that represent the industry on testing, Technical section B is the one you should talk to.

 

[mbeychok]

.
The suggestion by dcasto that you contact the Gas Processors Association is a good one ... if you can get an answer from them.

I think it might be much easier to get an answer from Universal Oil Products who probably know more about mercaptan removal than anyone else on the planet. Try contacting them at

http://www.UOP.com

... or better yet through their local representative in your area.

Milton Beychok
(Visit me at www.air-dispersion.com)
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