Screw pumps (progressive cavity pumps) are reliable, but issues can arise due to wear, improper operation, or fluid incompatibility. Below are common problems, causes, and solutions.
Insufficient suction pressure (clogged inlet, air leaks)
Worn stator or rotor (loss of sealing)
Wrong rotation direction (motor wired backward)
Fluid too viscous (exceeds pump capacity)
Cavitation (low NPSH – Net Positive Suction Head)
✔ Check and clean inlet filter/strainer.
✔ Inspect suction line for leaks (tighten connections).
✔ Verify motor rotation direction.
✔ Replace worn stator/rotor if clearance is excessive.
✔ Preheat viscous fluids or select a higher-capacity pump.
✔ Increase NPSH (lower pump speed or raise fluid level).
Misalignment (drive shaft, couplings)
Worn universal joint or bearings
Dry running (no fluid lubrication)
Cavitation (vapor bubbles collapsing)
Mechanical blockage (solid buildup)
✔ Check shaft alignment and adjust if needed.
✔ Replace worn U-joints or bearings.
✔ Ensure pump is primed before starting.
✔ Reduce pump speed or increase suction pressure.
✔ Inspect for solid debris in the pump.
Dry running (no fluid cooling/lubrication)
Excessive discharge pressure (system blockage)
Worn stator causing friction
High fluid temperature
✔ Always prime the pump before starting.
✔ Check discharge valve (ensure it’s not closed).
✔ Replace worn stator if overheated.
✔ Install a pressure relief valve if needed.
✔ Cool the fluid or use a heat-resistant stator.
Abrasive fluids (sand, particles)
Dry running (causes excessive friction)
Chemical incompatibility (stator material degradation)
High operating temperature
✔ Use a harder stator material (e.g., high-abrasion rubber).
✔ Avoid dry running (install run-dry protection).
✔ Verify chemical compatibility (switch to EPDM, PTFE, etc.).
✔ Monitor fluid temperature (use cooling jackets if needed).
Worn mechanical seal or packing
Misaligned shaft
Excessive pressure
Dry running damage
✔ Replace mechanical seal or packing gland.
✔ Realign pump and motor shaft.
✔ Install a pressure relief system.
✔ Ensure proper lubrication of seals.
✅ Inspect stator & rotor regularly for wear.
✅ Lubricate bearings & seals as per manufacturer guidelines.
✅ Monitor pressure & temperature to avoid overloading.
✅ Avoid dry running (use run-dry protection sensors).
✅ Check alignment after installation or maintenance.
If vibration persists after alignment checks.
If leakage continues after seal replacement.
If unusual noises indicate internal damage.
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