Select country
Contact us

Screw Pump Fault Diagnosis

Here is a guide given on Screw pump fault Diagnosis: 

Problem

Possible Cause

Remedy

Low Capacity or loss of flow

System restriction

Check system including all vales on suction and   discharge. Check fluid levels in tank, and that any non-return valves are   functioning as intended

Pump Priming

Ensure all air has been vented from pump and that

Low Pump Speed

Check motor speed, and ensure motor is not overloaded.   If belt driven ensure belt is taught, without slippage. If operated via VFD   ensure pump is operating at correct speed on panel.

Reverse Rotation

Check motor direction of rotation is in line with arrow   on nameplate and motor

Blockage

Check suction and discharge pipes. Remove blockage

Screws Worn

Replace screws. Ensure idler and driving screws are   replaced as set and not individually

Liquid Change

Check viscosity of a fluid is as per pump design. Check   if fuel has been switched to one of low lubricity such as Low Sulphur Fuel   Oil (LSFO)

Bypass Valve Operation

Check bypass valve operating pressure, check spring and   maintenance history as may require replacing

NPSH not met

Insufficient suction pressure. Reduce pump speed,   increase the level in the suction tank, check fluid viscosity, check the temperature of fluid that is not close to vapor pressure, deepen suction pipe.

Loss of Suction

System Blockage

Check suction pipework for blockage, check valves are operational in both suction and discharge.

Air Ingress

Check pipework connections for wear and air ingress.

Viscosity too High

Check viscosity is in line with pump design. Increase motor size, increase pump size, heat fluid, reduce pump speed.

Suction Strainer Blocked

Check inlet filter and clean or replace

Reverse Rotation

 

Check the motor direction of rotation is in line with arrow   on nameplate and motor

Low Discharge Pressure

NPSH not met

 

Insufficient suction pressure. Reduce pump speed,   increase level in the suction tank, check fluid viscosity, check the temperature of fluid is not close to vapor pressure, deepen suction pipe.

 

Air Ingress

 

Check pipework connections for wear and air ingress

Screws Worn

 

Replace screws. Ensure idler and driving screws are   replaced as set and not individually

 

System Blockage

 

Check suction pipework for blockage, check valves are operational in both suction and discharge.

 

Suction Strainer Blocked

 

Check inlet filter and clean or replace

 

Bypass Valve Operation

 

Check bypass valve operating pressure, check spring and   maintenance history as may require replacing

 

Noise or Vibration

Misalignment

Check coupling alignment

Pump loose on base plate

Check pump fixings

System Blockage

 

Check suction pipework for blockage, check valves are operational in both suction and discharge.

 

Air Ingress

 

Check pipework connections for wear and air ingress

Suction Strainer Blocked

 

Check inlet filter and clean or replace

Relief Valve

The relief valve is opening and closing rapidly. Check   relief valve set pressure and increase

Pump parts contact

Check pump bearings, shaft wear, casing condition and   seal. Replace as required

Solid ingress

Check screws for solid ingress or particles located   within pump above a specified size

Excessive Pump Wear

Fluid

Check fluid for particles, check inlet filter, check the history of fluid, if LSFO checks for low lubricity.

Water

Some Screw pumps are not designed for water or glycols of specific concentrations. Speak with a technical sales engineer to check   pump selection and chemical compatibility

Misalignment

 

Check coupling alignment

 

NPSH not met

 

Insufficient suction pressure. Reduce pump speed,   increase the level in the suction tank, check fluid viscosity, check the temperature of the fluid is not close to vapor pressure, deepen suction pipe.

High Absorbed Power

Fluid Viscosity

Check viscosity is in line with pump design. Increase motor size, increase pump size, heat fluid, reduce pump speed.

Suction Strainer Blocked

 

Check inlet filter and clean or replace

Pump parts contact

 

Check pump bearings, shaft wear, casing condition and seal. Replace as required

Pump Speed

Check pump speed is in line with the design

Air Ingress

 

Check pipework connections for wear and air ingress

 

Positive Displacement Pump Repair

As the leading European supplier of positive displacement pumps we are experts in their repair

read more about positive displacement pump repair

Pump Repair

AxFlow are one of the UK's leading pump repairs and offer local support across the country from our 5 regional bases.

read more about pump repair & maintenance
PD Pumps Team
AxFlow stores encrypted data. They won't be distributed. Website Policy