If a progressive cavity pump (PCP or single-screw pump) is not pumping properly, several issues could be causing the problem. Below are the most common reasons and troubleshooting steps:
Symptoms: Pump runs but delivers little or no fluid.
Possible Causes:
Suction line leaks (allowing air ingress).
Dry running (no fluid in the pump).
Inadequate submersion of suction pipe.
Solutions:
Check for leaks in suction piping & fittings.
Ensure the pump is properly primed before startup.
Increase fluid level in the supply tank.
Symptoms: Reduced flow, increased slippage, overheating.
Possible Causes:
Abrasive or corrosive fluids degrading the stator (elastomer liner).
Misalignment causing excessive wear.
Running dry (causing stator burnout).
Solutions:
Inspect stator for cracks, swelling, or loss of elasticity.
Check rotor for wear or corrosion.
Replace worn components with compatible materials.
Symptoms: Pump struggles, motor overloads, or flow stops suddenly.
Possible Causes:
Debris in suction line or pump cavity.
Solid buildup in discharge line.
Fluid viscosity too high for pump design.
Solutions:
Check suction strainer/filter for clogging.
Flush the pump and lines.
Verify fluid viscosity matches pump specifications.
Symptoms: Pump labors, motor trips, or flow drops.
Possible Causes:
Discharge valve closed or partially blocked.
System pressure exceeds pump rating.
Long discharge line with high friction loss.
Solutions:
Open/check discharge valve.
Verify system backpressure vs. pump capacity.
Install a pressure relief valve if needed.
Symptoms: Unusual noise, vibration, or shaft breakage.
Possible Causes:
Bearing failure (due to misalignment or lack of lubrication).
Coupling or universal joint damage.
Rotor-stator interference (jamming).
Solutions:
Inspect bearings, seals, and drive components.
Check alignment between pump and motor.
Ensure proper lubrication of mechanical parts.
Symptoms: Pump operates but produces no flow.
Possible Causes:
Motor wired incorrectly (running backward).
Solutions:
Check motor rotation (swap two phases if 3-phase).
Verify arrow direction on pump casing.
Symptoms: Stator degradation, swelling, or cracking.
Possible Causes:
Fluid temperature exceeds stator material limits.
Chemical incompatibility (e.g., oil swelling an NBR stator).
Solutions:
Confirm fluid compatibility with stator material (EPDM, NBR, etc.).
Check operating temperature vs. pump rating.
Check suction side: Prime, leaks, blockages.
Inspect stator/rotor: Wear, damage, fit.
Verify discharge side: Valve position, pressure.
Test motor & rotation: Correct direction, power supply.
Review fluid properties: Viscosity, abrasives, temperature.
If the problem persists after these checks, the pump may need professional servicing or component replacement. Let me know if you need help diagnosing a specific issue!
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