@solcrestinc: Parallel pumps — will it work? Yes. Three things need to happen: 1. Same pump. One discharge pipe means one pressure. The weaker pump can't beat it, so its check valve never opens — motor running, nothing delivered, water heating inside until the seal fails. 2. Resize the suction pipe. It was sized for one pump. Two pumps pulling through it means higher velocity, higher friction, lower NPSH available — cavitation, and everyone blames the pump. 3. One check valve per pump. Not one on the header. Otherwise the idle pump backspins on reverse flow, and starting it that way takes out the coupling and shaft. Even with all three right, there's still the balancing — equal pipe lengths and fittings to each pump, header sizing, suction spacing, matched start/stop control. That's a design job. Is anyone running shared headers? Yes — it's standard. Packaged booster sets ship that way from the factory. Chilled water and condenser water plants. Fire pump rooms. Refinery and power plant cooling water. Boiler feed, transfer, sewage lift stations. The codes assume it: Hydraulic Institute covers parallel operation directly, API 610 / ISO 13709 requires a continuously rising curve to shutoff for stable parallel operation, NFPA 20 includes provisions for multiple pump units in parallel. So why can they do it? Because they can measure it. Test bench with calibrated flow meters on every branch. Pressure transmitters. They run the set and see the actual split — 52/48 — then correct it. Thermal imaging for the pump running hot. Vibration analysis for the one off its curve. Balancing valves with test ports so a commissioning engineer can trim each branch until they match. Manifold built on a jig, not fabricated on site. Pumps supplied as a matched set from the same production run. On site, you have one pressure gauge. You can't see how the flow is splitting. You won't know anything is wrong until a seal fails eight months later — and you'll blame the seal. So if you're doing this yourself, take the simpler route: line up a separate pipe for each pump — own suction, own discharge, nothing to balance. Or run it as a simple duplex — one pump working, one on standby, alternating. Never both at once. The difference isn't whether parallel works. It's whether you can measure it. Ref: ANSI/HI 1.3 & 9.6 series, API 610 / ISO 13709, NFPA 20. Cite your edition. Centrifugal pumps only. #pumps #centrifugalpump #API610 #NFPA20 #cavitation

Engr. Bhadz of SolCrest Inc.

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Tuesday 25 August 2026 09:06:37 GMT