01

Loss of prime or no delivery

Common causes include an empty tank, closed isolation valve, blocked strainer, air leak, gas-locked liquid end, excessive suction lift, vapour formation or check valves held open by deposits. Confirm chemical availability and suction conditions before dismantling the drive.

  • Verify tank level and valve positions
  • Inspect suction line for air ingress
  • Vent trapped gas using the approved procedure
  • Clean or replace fouled check valves
  • Check that fluid temperature is below problematic vapour conditions

02

Low or unstable capacity

Erratic flow may result from suction starvation, worn valves, insufficient differential pressure, pulsation interaction, incorrect calibration or operation below the useful adjustment range. Compare actual calibrated output at stable conditions against the expected setting.

  • Calibrate against time and volume
  • Check back-pressure stability
  • Inspect valve orientation and wear
  • Confirm stroke and speed control signals
  • Review suction acceleration losses

03

Leakage and repeated seal failure

Leakage can indicate incompatible materials, excessive pressure, worn packing, damaged diaphragm, incorrect assembly or piping loads. Replacing the same component without correcting the initiating cause usually leads to repeat failure.

  • Isolate and depressurise safely
  • Identify whether leakage is process or hydraulic fluid
  • Verify relief-valve operation
  • Check alignment and nozzle loads
  • Confirm parts and tightening procedure

04

Noise, vibration or overheating

Investigate cavitation, loose mounting, coupling alignment, bearing condition, incorrect lubricant, excessive discharge pressure and drive overload. Stop the equipment if continued operation could damage the pump or create a chemical-release risk.

  • Compare motor current with nameplate and baseline
  • Check foundation and fasteners
  • Listen for check-valve and cavitation symptoms
  • Inspect lubricant level and condition
  • Verify pressure against design limits

Frequently asked questions

Why does a dosing pump lose prime repeatedly?

Frequent causes include suction air leaks, gas-forming chemicals, excessive lift, vapour formation, blocked suction components or check-valve contamination.

Should the relief valve discharge back to the suction line?

The return destination must be engineered for the chemical and system. Returning directly to a restricted suction line can create additional problems; use the approved design and safe destination.