BFP Efficiency Calculator
Measure the real-world efficiency of a boiler feed pump from field data: flow, differential pressure and shaft power.
Inputs
Discharge − suction pressure at the pump flanges.
Water at 220°F ≈ 0.95; ambient water = 1.00.
Results
Formula
η_pump = (Q × H × SG / 3960) / Brake HP, where Brake HP = Motor kW × η_motor / 0.7457.
Worked example
A BFP moving 100 GPM at 200 psi ΔP with 220°F water (SG 0.95) drawing 30 kW at a 92% motor: TDH ≈ 486 ft, hydraulic HP ≈ 11.7, shaft HP ≈ 37, efficiency ≈ 32% — a strong sign of wear or oversizing.
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Frequently asked questions
What is a typical BFP efficiency?
New multistage BFPs run 65–75%. Field values of 50–60% are common after a few years. Below 45% usually justifies overhaul.
Why is my efficiency so low?
Most likely causes: worn wear rings, operating far from BEP (throttled discharge), or oversizing at design.
Should I use nameplate motor efficiency?
No — use the operating-point value. Motors run inefficiently below 50% load.
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