As a commonly used fluid transfer equipment, screw pumps play an important role in industrial production. However, in the process of use, screw pumps will also appear some common problems. These problems and their solutions are described in detail below.
Pump does not discharge liquid
Reason analysis: suction pipeline blockage: there may be foreign objects, sediments, etc. in the pipeline, blocking the suction channel, resulting in the liquid can not enter the pump. Suction height is too high: If the suction height exceeds the permissible suction height of the pump, it will result in the situation that the liquid cannot be sucked. There is air in the pump: before starting the pump or during operation, air may have entered the pump, affecting the suction of liquid. Wrong direction of rotation: the direction of rotation of the motor is not consistent with the specified direction of the pump, resulting in the pump not working properly. Damaged stator: The stator is the key component of the screw pump, if the stator is worn, ruptured or deformed, it will affect the sealing and conveying capacity of the pump.
Solution: Clean the suction line: Check the suction line and remove the blockage. You can use compressed air blowing, disassemble the pipeline for cleaning and other methods. Reduce the suction height: Re-adjust the installation position of the pump and reduce the suction height so that it is within the permissible range. Exclude the air inside the pump: Before starting the pump, open the bleeder valve of the pump to discharge the air inside the pump. During operation, if air is found inside the pump, it can also be discharged through the bleeder valve. Adjust the motor rotation direction: Check the wiring of the motor to ensure that the motor rotation direction is the same as the specified direction of the pump. Replace the stator: If the stator is damaged, it should be replaced with a new one in time. When replacing the stator, pay attention to selecting the appropriate model and material to ensure that it matches the other parts of the pump.
Insufficient flow
Cause analysis: Air leakage in suction line: Poor sealing in the suction line will cause air to enter the line and reduce the suction capacity of the pump, thus reducing the flow rate. Stator wear: the stator will gradually wear out during long-term use, resulting in reduced sealing of the pump and reduced flow. Low rotational speed: the rotational speed of the motor is lower than the rated speed of the pump, which will reduce the flow of the pump. Discharge pipeline resistance is too large: the valve opening in the discharge pipeline is small, the pipeline is blocked or too long, etc., will increase the resistance of the discharge pipeline, so that the pump flow is reduced. Liquid viscosity changes: If the viscosity of the transported liquid changes, beyond the scope of application of the pump, it will also affect the flow of the pump.
Solution: Check the suction line sealing: Check each connection part of the suction line to ensure good sealing. If the seal is found to be not tight, the seal should be repaired or replaced in time. Replace the stator: When the stator is worn out seriously, it should be replaced with a new one in time to restore the sealing and conveying capacity of the pump. Increase the speed: check whether the speed of the motor is normal or not, if the speed is too low, you can adjust the frequency of the motor or replace it with a suitable motor to increase the speed of the pump. Reduce the resistance of discharge pipeline: check whether the valve opening in the discharge pipeline is appropriate, clear the blockage in the pipeline, shorten the length of the pipeline or increase the diameter of the pipeline to reduce the resistance of the discharge pipeline. Adjust the viscosity of the liquid: If the viscosity of the transported liquid varies greatly, you can consider replacing the pump suitable for the viscosity, or take heating, dilution and other methods to reduce the viscosity of the liquid.
Unstable pressure
Cause analysis: Air in suction line: Air in the suction line will lead to unstable suction of the pump, thus making the pressure fluctuate. Uneven stator wear: Uneven stator wear will affect the sealing and conveying capacity of the pump, resulting in unstable pressure. Clogging in the discharge pipeline: Clogging in the discharge pipeline will increase the discharge pressure of the pump, and when the clogging is flushed away, the pressure will suddenly drop again, resulting in unstable pressure. Unstable motor speed: unstable motor speed will affect the flow and pressure of the pump, resulting in pressure fluctuations. Inappropriate opening of the pump’s inlet and outlet valves: the valve opening is too small will limit the flow of the pump, so that the pressure rises; the valve opening is too large will make the pump flow too much, the pressure decreases.
Solution: Exclude the air in the suction line: open the bleeder valve of the pump and discharge the air in the suction line. At the same time, check the sealing of the suction line to ensure that no air enters. Replace the stator: If the stator is worn unevenly, consider replacing it with a new one to ensure the pump’s sealing and delivery capacity. Clear the discharge line: Inspect the discharge line and remove any blockages. Ensure that the discharge line is clear and unobstructed. Stabilise the motor speed: check whether the speed regulator of the motor is normal to ensure that the speed of the motor is stable. If the motor is faulty, it should be repaired or replaced in time. Adjust the opening of the import and export valves: according to the flow rate and pressure requirements of the pump, reasonably adjust the opening of the import and export valves. Generally speaking, the valve opening should be moderate, both to ensure the normal work of the pump, but also to avoid pressure fluctuations.
Pump body heating
Reason analysis: Pump flow is too large: when the flow of the pump exceeds its rated flow, it will increase the power of the pump, which will lead to the heating of the pump body. Stator and rotor friction: If the gap between the stator and rotor is too small or improperly installed, it will lead to friction between the two, which will cause the pump body to heat up. Poor lubrication: If the bearings, seals and other parts of the pump lack sufficient lubrication, it will increase the friction and cause the pump body to heat up. High conveying temperature: If the temperature of the conveyed liquid is too high, it will make the pump body heat up through heat conduction.
Solution: Reduce the flow rate: Adjust the opening of the pump inlet and outlet valves to reduce the flow rate of the pump and make it work within the rated range. Adjust the gap between stator and rotor: check whether the gap between stator and rotor is suitable, if the gap is too small, the gap can be increased by adjusting the position of the stator or replacing the stator with a suitable one. At the same time, make sure the stator and rotor are installed correctly to avoid friction. Strengthen lubrication: Check the lubrication of the pump regularly, add or replace the appropriate lubricant to ensure that the bearings, seals and other parts have good lubrication. Reduce the temperature of the liquid: If the temperature of the conveyed liquid is too high, cooling measures can be taken, such as adding coolant to the liquid, setting cooling devices around the pump, etc., to reduce the temperature of the liquid.
Excessive noise
Reason analysis : The installation of the pump is not firm: If the installation foundation of the pump is not firm or the foot bolt is loose, it will make the pump vibrate and make noise during the operation. Stator and rotor friction: The friction between stator and rotor will produce noise. Damaged bearings: bearings may be damaged during long-term use, resulting in unstable pump operation and noise. Air in the suction line: Air in the suction line will make the pump suction unstable and generate noise. Failure of motor: Failure of motor, such as bearing wear, short circuit of winding, etc., will also produce noise.
Solution: Reinforce the installation of the pump: check whether the installation foundation of the pump is firm and whether the ground bolts are loose. If there is any problem, reinforcement and adjustment should be carried out in time. Adjust the gap between the stator and rotor: check whether the gap between the stator and rotor is appropriate, if the gap is too small, the gap can be increased by adjusting the position of the stator or replacing the stator with a suitable one. At the same time, make sure the stator and rotor are installed correctly to avoid friction. Replacement of bearings: If the bearings are damaged, they should be replaced with new ones in time. When replacing the bearings, choose the right type and quality to ensure that they can meet the operating requirements of the pump. Remove the air in the suction line: Open the bleeder valve of the pump to discharge the air in the suction line. At the same time, check the sealing condition of the suction line to ensure that no air enters. Repair the motor: If the motor is faulty, it should be repaired or replaced in time. When repairing the motor, choose a professional repairer to ensure the quality of repair.
Seal leakage
Cause analysis: Damaged seals: Seals will gradually wear out, deteriorate or be damaged during long-term use, resulting in seal leakage. Improper installation: Incorrect installation of seals, such as uneven sealing surface, too tight or too loose installation, etc., will affect the sealing effect, resulting in leakage. The working pressure of the pump is too high: if the working pressure of the pump exceeds the capacity of the seals, it will make the seals fail and produce leakage. The transported liquid is corrosive: If the transported liquid is corrosive, it will cause corrosion to the seals and lead to leakage.
Solution: Replace the seals: when the seals are damaged, they should be replaced with new seals in time. When replacing the seals, choose the right type and material to ensure that they can meet the working requirements of the pump. Install the seals correctly: Install the seals in strict accordance with the installation instructions to ensure that the sealing surface is flat and the installation force is moderate. Reduce the working pressure of the pump: If the working pressure of the pump is too high, you can adjust the opening of the inlet and outlet valves and reduce the speed of the motor to reduce the working pressure of the pump. Select corrosion-resistant seals: If the transported liquid is corrosive, you can select corrosion-resistant seals, such as fluorine rubber seals, PTFE seals, etc..
Screw pump jamming
Reason analysis: foreign objects enter into the pump: in the process of conveying liquid, there may be foreign objects enter into the pump, such as iron, stone, etc., resulting in the screw and stator jammed. Stator and rotor fit too tight: If the clearance between the stator and rotor is too small, or the concentricity between the stator and rotor is not good during installation, it will make the fit between the two too tight, resulting in pump jamming. Poor lubrication of the pump: If the pump bearings, seals and other parts of the lack of adequate lubrication, will make the friction increase, resulting in pump jamming. Long shutdown without disc: If the pump is not disc after a long shutdown, the liquid between the stator and rotor will solidify, resulting in pump jamming.
Solution: Clean up the foreign matter in the pump: disassemble the pump body and take out the foreign matter. When installing the pump, a filter can be set in the suction line to prevent foreign matter from entering the pump. Adjust the gap between the stator and rotor: check whether the gap between the stator and rotor is suitable, if the gap is too small, the gap can be increased by adjusting the position of the stator or replacing the stator with a suitable one. At the same time, make sure the stator and rotor are installed correctly to ensure concentricity. Strengthen lubrication: Check the lubrication of the pump regularly, add or replace the appropriate lubricant to ensure that the bearings, seals and other parts have good lubrication. Regular disc: After the pump is shut down for a long time, it should be disced to make the liquid between the stator and rotor flow and prevent solidification.
In short, solving the common problems of screw pumps requires comprehensive consideration of a number of factors, including installation, commissioning, maintenance and other aspects. When using the screw pump, it should be operated in strict accordance with the operating procedures, and the pump should be inspected and maintained on a regular basis to find and solve problems in time to ensure the normal operation of the pump and improve the reliability and service life of the equipment.
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