Fault analysis and troubleshooting of insufficient flow of screw pump

Fault analysis and troubleshooting of insufficient flow of screw pump

(1) Fail to meet the specified requirements on the test bench (under the specified pressure, oil suction vacuum, conversion to the specified speed and viscosity).

1) The volumetric efficiency of the pump is too high in the design, so the pitch diameter of the pump needs to be redesigned to reduce the volumetric efficiency and pitch diameter. In the case of the determined structural size, the lead of the screw shall be changed appropriately to meet the specified requirements.

2) If the meshing clearance of the screw is too large, appropriately reduce the meshing clearance of the screw profile and change the number of sealing cavities. Properly reduce the clearance between center distance, inner and outer circle bottom diameter and screw bushing hole, and check whether the combination tolerance calculated meets the drawing requirements.

3) Pay attention to whether the viscosity of the conveying liquid changes and whether the oil temperature is too high. Regularly check the viscosity of the oil and replace the test oil if necessary. Properly reduce the oil temperature and keep the viscosity stable. When the volume of the oil tank is small, the cooling system should be added.

4) Pay attention to whether the hole diameter in the oil return system inside the screw, the clearance of the balance piston and the dimensional tolerance of the sliding bearing meet the specified requirements. Properly reduce the oil return hole diameter, properly reduce the clearance at the fitting and reduce the leakage.

5) Pay attention to whether the safety valve is sealed and whether the preload of the spring is well adjusted. The safety valve shall be subject to sealing test or closed temporarily. Measure the luminous characteristics of the safety valve spring.

(2) The flow at the user's site cannot meet the specified requirements

1) First, check whether the pressure gauge and vacuum gauge of the pump in the pipeline system meet the specified requirements. The discharge pressure gauge of the pump shall not exceed the specified value. When the value of the pressure gauge exceeds the specified value, the flow of the pump will decrease. Too large or too small vacuum gauge value of the pump will also reduce the flow of the pump, in which the filter may be blocked, the pipeline resistance is too large (the length of elbow and valve also affects the resistance), or the suction pipeline leaks.

2) Check the temperature of the liquid medium. If the temperature is too high, take cooling measures.

3) To measure whether the speed of the pump meets the requirements, you can also check whether the voltage is normal.

4) Check the service life of the pump, judge the wear of main parts, and repair or replace them in time. When the fit clearance between the outer circle of the driving screw and the pump body hole δ 1. When the wear increases, brush plating can be used to ensure that the fit gap between the outer circle of the driving screw and the pump body hole must be 0.03 ~ 0.05mm; When the matching clearance between the outer circle of the driven screw and the pump body hole δ 2. In case of poor processing or increased wear, as shown in figure y, brush plating shall be adopted to ensure that the fit gap between the outer circle of the driven screw and the pump body hole must be 0.03 ~ 0.05mm, or it shall be replaced; When the meshing clearance of the conjugate tooth profile meshing line between the driving screw boss and the driven screw groove increases due to poor processing or wear clearance, it will seriously affect the output flow. The method of lapping and running in of three screws is used to improve the screw tooth profile accuracy and ensure that the meshing opening dimension of three screws is within the specified tolerance range; When the meshing clearance between the top circle of the driving screw and the root circle of the driven screw, the outer circle of the driven screw and the meshing line of the root circle of the driving screw does not meet the requirements, brush plating can be used to ensure that the meshing opening dimension of the three screws is within the specified tolerance range.