Fugitive emmission 1

[mrctchlr]

Hello to you all,

What is the most requested "performance class" (clients) for high performance butterfly valves?
Or, what should be the 'minimum' performance class a valve should satisfy?

Performance class defined by the combination of:
- tightness class
- endurance class
- temperature class

Ref: ISO 15848, TA-Luft, ANSI/ISA 93.00.01

Best regards,

MT

 

[NGiLuzzu]

Mticheler,
as far as I remember, TA Luft and the related VDI 2440 standard (see Thread408-93545 and Thread408-90905) do not provide for valve performance classes, but only distinguish between service temperatures lower and higher than +250°C.

Both ISO 15848-1 and ISO 15848-2 are drafts, still in "Inquiry Stage" (see [*])... and, as the relevant project started in 1997 or 1998, I don't think it will be actually finalized (target dates in 2005...!).

So it seems more appropriate to refer to Shell MESC SPE 77/312 specification (see Thread408-64093 and Thread408-83628) when talking about fugitive emissions performance classes; the latest edition should be dated June 18^th, 2004.

In any case, as a general rule-of-thumb, it can be said that:
- tightness class depends on the service fluid toxicity ("A" for carcinogen and very toxic fluids, "B" for other hydrocarbons...);
- temperature class depends on the valve materials selection and configuration;
- endurance class is usually agreed with the Customer based upon the type of actuation and the required cycle life (even if, in the latest editions of the mentioned document, the distinction became less and less important for production testing)...

Hope this helps, 'NGL


[*]=

http://www.iso.org/iso/en/stdsdevel...ilPage.TechnicalProgrammeSCDetail?COMMID=3813

P.S.: Many other threads have been written about Fugitive Emissions; in particular, take a look at:
- Thread408-93211 about the general issue, reference documents and testing;
- Thread408-48808 & Thread124-48813 about the relationship between helium concentration (ppm) and leak rate (mbar*l/s) .