WELCH vacuum pumpWidely used in vacuum drying, distillation, electron microscope pumping and other scenarios, its fault manifestations are diverse (such as decreased pumping rate and abnormal noise), and accurate identification of specific problems is necessary for rapid repair. The following are common fault phenomena and corresponding judgment methods.
Fault 1: Insufficient pumping rate (vacuum degree does not meet the requirements)
Phenomenon: When the pump is running, the vacuum gauge shows a pressure higher than expected (if -0.09MPa is required, the actual pressure is only -0.07MPa).
Judgment: First, check if the air inlet is blocked (clean the dust or sample residue in the pipeline with a vacuum cleaner), and confirm that there is no leakage in the pipeline (apply soapy water to the connection, and the bubbling area is the leakage point). If the intake is normal, it may be due to pump oil contamination (the color of the oil turns black or there is sediment, reducing lubrication and sealing performance), and it is necessary to replace it with the same type of pump oil (usually high vacuum pump oil, viscosity grade meets the requirements of the pump). For rotary vane pumps, check whether the rotary vane is worn (disassemble the pump body and observe whether there are scratches on the surface of the rotary vane. Wear can cause an increase in the gap between the rotary vane and the cylinder body, and an increase in air leakage).
Fault 2: Abnormal noise (sharp or roaring sound)
Phenomenon: The pump produces abnormal harsh sounds during operation (normal is a smooth running sound).
Judgment: The sharp sound may be due to friction between the rotor and the cylinder body (eccentricity of the rotor or jamming of the rotary vane pump). Disassemble the pump body and check the position of the rotor (whether it deviates from the center, adjust the fixing screws with a wrench); The roaring sound may be due to bearing damage (worn bearings supporting the rotor). Rotate the pump shaft by hand (after power failure). If you feel stuck or shaking, replace the bearings of the same model. In addition, foreign objects entering the pump chamber (such as metal particles) can also cause abnormal noise and require disassembly and cleaning.
Fault 3: Overheating of pump body (shell temperature>60 ℃)
Phenomenon: After running for a period of time, the surface of the pump body becomes hot (normal temperature<50 ℃).
Judgment: First, check if the pump oil level is insufficient (the oil level is below the lower scale line, causing poor lubrication and frictional heat generation), and add the same type of pump oil to the appropriate position. If the oil level is normal, it may be due to a blockage in the exhaust port (the gas discharged by the vacuum pump cannot be discharged in time and flows back to the pump chamber). Check the exhaust filter (whether it is blocked by oil or impurities), clean or replace the filter. For pumps that run continuously for a long time (more than 8 hours), it is necessary to check the cooling fan (whether it is rotating normally, and if it stops, it needs to be repaired or replaced).
Fault 4: Oil leakage (pump oil seeps out from the seal)
Phenomenon: Oil droplets are falling from the surface of the pump body or exhaust port.
Judgment: Check whether the oil seal (the rubber part that seals the pump shaft and pump body) is aging (hardening or cracking after long-term use), and replace it with the same type of oil seal. If the exhaust port leaks oil, it may be due to a damaged exhaust valve (unable to close properly, causing pump oil to be discharged with gas). Disassemble the exhaust valve component (usually a metal or plastic valve plate), check if the valve plate is deformed or damaged, and replace it.
Fault 5: Unable to start (motor does not turn or stops immediately after starting)
Phenomenon: When the start button is pressed, the motor does not respond or automatically stops after running for a few seconds.
Judgment: First, check whether the power supply is normal (whether the plug is plugged in properly, whether the socket has power, test with a test pen), and confirm whether the motor winding is short circuited (measure the motor resistance value with a multimeter, if it is infinite, it means the winding is open and needs to be returned to the factory for repair). If the power supply and motor are normal, it may be due to overload in the pump chamber. Clean the air inlet and release excess pump oil (control the oil level at the center line of the oil gauge).
By observing the fault phenomenon and combining targeted inspections, it is possible to quickly locate itWELCH vacuum pumpTake timely maintenance or replacement measures to address specific issues and ensure the vacuum environment requirements for experiments or production. In daily use, regularly replacing pump oil (every 3-6 months) and checking seals (every six months) can reduce the probability of failure.