Pressure Relief Valve Required for Fire Pumps?

10/26/2018

When are pressure relief valves required for fire pumps, and what is their intended purpose? There's a wide variety of pump arrangements and many don't include pressure relief valves.

Posted anonymously by a member for discussion. Discuss this here.

3 Comments

MHK

10/29/2018 02:48:52 am

I think that one of the cases where a pressure relief valve is required is a fire pump system with a diesel engine driven fire pump. If a total of 121% of the diesel pump shutoff pressure plus maximum static pressure exceeds the system rating pressure, a pressure relief valve shall be provided.

WESLEY

10/29/2018 06:29:30 am

Agree with MHK from NFPA 20 (2013 Edition 4.18.1.2).

NFPA 20 also requires a pressure relief valve on electric variable speed limiting controllers when the churn pressure is higher than the rating of the system components (NFPA 20 2013 4.18.1.3).

Also addressed for Jockey Pumps where a centrifugal or turbine type is used and the shutoff pressure is higher than the rating of the system components (NFPA 20 2013 4.25.4.1).

We try to avoid exceeding 175 psi in a system to begin with but will use high-pressure pipe and components for portions that are exceeded. NFPA 20 (A.4.7.7) hasn't allowed the use of pressure relief valves to reduce pressure since 2003 for normal operation, but does permit pressure reducing valves (A.4.7.7.2).

10/30/2018 03:29:03 pm

Good topic, I was confused because I was blurring pressure relief and pressure reducing. Seams clear now.

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