Problem
The site needed more stable RO feed pressure after membrane element life dropped below expected service intervals. Diagnosis pointed to pressure spikes from an oversized pump running far from BEP, a cavitation symptom at the feed inlet, and incorrect impeller clearance on an ageing unit.
Engineering review
FlowCore reviews membrane system pressure requirement, feed water TDS and chemistry, suction tank level and NPSH margin, SS304 or SS316 material selection, VFD control potential, CIP exposure, and operating hours before recommending a vertical multistage replacement.
- Feed pressure target — derived from membrane manufacturer's specification
- NPSH available — suction tank level, pipe length, and losses
- Stainless grade — SS304 for standard treated water, SS316 where chloride is present
- VFD control — justified when recovery rate varies across the operating day
- Impeller clearance and wear ring condition on the existing unit before replacement decision
Solution approach
A correctly sized vertical multistage pump in stainless steel, operating near BEP at the membrane's required feed pressure, with VFD control where the recovery rate varies and shaft alignment verified before first start.
What this project confirms
RO pump upgrades should be based on the membrane system's pressure requirement, not on matching the replaced motor size. Pressure stability protects both permeate quality and membrane service life.