Fire Pump Suction Pipe Sizing Calculator

Size fire pump suction piping per NFPA 20 based on velocity limits, friction loss, and NPSHa requirements

Input Parameters

Results

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Minimum Pipe Diameter
in
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Selected Pipe Size
in
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Actual Velocity
ft/s
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Suction Friction Loss
psi
Note: NFPA 20 Section 4.18 requires suction piping to be at least one nominal size larger than the pump suction flange. Suction velocity should not exceed 15 ft/s. Low friction loss in suction piping is critical to maintain adequate NPSHa.

Reference

Fire Pump Suction Pipe Sizing (NFPA 20): Min dia from velocity: d = sqrt(0.4085 × Q / Vmax) NFPA 20 Sec 4.18: suction pipe >= 1 size larger than pump connection Max velocity: 15 ft/s (NFPA 20), 10 ft/s preferred Friction: p = 4.52 × Q^1.85 / (C^1.85 × d^4.87) Keep suction losses minimal for adequate NPSHa.