If the rotary vane vacuum pump is stopped, the oil hole is connected with the pump chamber or the exhaust valve, shaft seal, pump cover plane, intake pipe, gas ballast valve are not tightly sealed. Due to the existence of liquid level difference and gravity, and the pressure difference between the oil tank and the pump cavity when the pump cavity is in vacuum state, the vacuum pump oil will return to the pump cavity. When the oil volume is large enough, the oil will return to the air inlet pipe, causing the next start When the resistance is large, the vane and rotor force is large, the exhaust valve is stressed, and it is difficult to start, which affects the service life of components and reduces the reliability of rotary vane vacuum pump. Therefore, we should try to prevent oil return after stopping the pump. The principle is to cut off the oil circuit when the rotary vane vacuum pump is stopped, eliminate the negative pressure in the pump chamber, reduce the liquid level difference and reduce the amount of returned oil.

The specific measures are as follows:

1. Separate the oil near the exhaust valve from the rest, and the oil level is only slightly higher than the partition wall.

2. Move the oil tank and exhaust valve to the side to reduce the oil level and oil quantity.

3. The plane of the valve seat should be flat, and the valve plate should be elastic.

4. The static sealing parts of shaft seal shall be reliable and timely replaced.

5. Add a pipe into the oil hole to make the oil level only slightly higher than the oil inlet.

6. A check valve mechanism is set to automatically close the oil inlet hole when the pump is stopped.

7. The oil pump and auxiliary mechanism are set to cut off the oil circuit when the pump is stopped.

8. The rotary vane vacuum pump port is equipped with a charging valve.

9. Fill the inlet container.