Can a split-case fire pump be used with a suction that is below negative 1.5 psi of pressure (below 1.0m)?
Would this be acceptable under NFPA 20?
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10/23/2020 10:06:15 am
Can you provide additional info on the conditions? Is the supply city-fed or a water tank. Is the basis of the question from a design or NFPA 25 inspection?
10/23/2020 10:06:51 am
NFPA 20 permits up to -3 psi at the pump suction flange when pulling water from a storage tank that has its outlet at or above the pump suction elevation. Other than that, I believe 0 psi or greater is required at the suction flange when pulling from a water supply.
10/23/2020 10:25:32 am
Simple answer - Do not use a split case fire pump in that application. NFPA may permit it - but the mfg or the water supplier may not.
10/23/2020 11:20:53 am
It depends on many conditions and if the AHJ allows you to do so.
10/23/2020 01:56:19 pm
If you are taking the suction from storage tank, then it's allowed as per NFPA 20. Section 184.108.40.206 otherwise not less than o psi. This means NPSHa can be lower when using tank.
10/25/2020 11:34:22 am
NFPA20 permits 0,2bar negative pressure at %150 flow when pump room floor and atmospheric water storage tank bottom is at same level.
10/31/2020 05:52:54 am
"This means that any NFPA20 fire pump must have NPSH required value at %150 flow lesser than 0,8 bar approximately."
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