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Relief valve with lift lever

Relief valve with lift lever

(OP)
we have two different relief valve models with the same SAP Number. The difference between the two is that the F2740UL-OL is basically obsolete and the predecessor of the Farris Model 27CA23120.
The F2740 series is .06 in^2 orifice while the 2700 series is a .068 in^2.
All other settings are the same and would respond the same in service according to a vendor.
The plant is using these for two service applications of Nitrogen and Compressed Air.
The big difference is that the F2740 series is equipped with a lift lever for the original service application for Compressed Air.
Is the F2740 series a good choice for nitrogen service with the lift lever?
Providing that these have the same SAP Number, these two different valves could be used in either service (Possible a safety issue).

What are your thoughts on this? What type of PSV (lift lever or no lift lever) should be used for Compressed Air Service?

RE: Relief valve with lift lever

ASME VIII Rules dictate a mandatory lever for steam, air and water (over 140'F/60'C) service, should the SRV be NB/UV code stamped. Nitrogen does not require a lever, but the SRV will work just as well. It then becomes a user preference. If you wish no N2 to escape to atmosphere, use a packed lever. For air service, specify an open lever if desired (not mandatory).

Per ISO, only the term Safety Valve is used regardless of application or design.

RE: Relief valve with lift lever

SrChemE,

The lifting lever is required by ASME VIII for air, so it can be periodically tested. However, ASME does have Code Case 2203, which allows the omission of the lifting device as long as:

- user has a documented procedure for the periodic removal of pressure relief valve for inspection and repair as necessary
- the omission is specified by the user
- the user shall obtain permission to omit the lifting device from the authority having jurisdiction over the installation of pressure vessels

I find it easier just to get the lever in most cases.

Does anyone know why ASME only requires one for air/steam/water over 140°F? Is it just because they're not generally hazardous if released to the atmosphere in a controlled manner? I assume they don't require one for nitrogen because of the asphyxiation hazard, since aside from that it's not too different from air?





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