Oil Type Rotary Vane Vacuum Pump Maintenance Tips

Oil Type Rotary Vane Vacuum Pump Overview

Oil sealed rotary vane vacuum pump is a very mature and reliable vacuum pump, usually also called oil pump, mechanical pump, rotary vane pump, etc. It is cheap and has good vacuum, and is widely used in heat treatment, vacuum coating, mass spectrometry, sample pretreatment, freezing drying, glove boxes, leak detection and other applications that are less sensitive to oil vapors. They are also often used as backing pumps for molecular pumps.

 

Single Stage Vacuum Pump or Double Stage Vacuum Pump

The oil-type rotary vane pump is divided into single-stage and double-stage. The double-stage rotary vane pump compresses the gas twice, which effectively reduces the backflow, so the vacuum degree is better, but the condensable gas is also easier to be condensed in the pump. It is very important to choose a suitable vacuum pump according to the actual application.

 

Correct Use of Gas Ballast Valve

Some processes generate a lot of water vapor, such as vacuum drying, vacuum freeze drying, etc., and the inner wall of the vacuum chamber will also absorb moisture (especially in wet seasons), which will vaporize under vacuum to form a large amount of water steam. After the water vapor is compressed in the vacuum pump, it will condense into liquid water and accumulate in the pump, causing problems such as oil emulsification, shaft seal oil leakage, internal rust, increased noise, and poor ultimate vacuum.

Gas ballast valve is required to avoid condensation of water vapor. The gas ballast valve plays the role of aerating air into the vacuum pump. When the gas ballast valve is opened, the external dry gas is sucked to dilute the water vapor in the pump, so as to avoid the condensation of water vapor. For applications with high water vapor content, it is recommended to keep the gas ballast on. For applications requiring ultimate vacuum or low water vapor content, user can let the pump continue to run with gas ballast valve for about 1 hour when drainage is required, and then close the gas ballast valve again. For applications with a large amount of dust, a dust filter must be installed. Otherwise, a large amount of dust will enter the pump cavity, which will cause serious wear of the pump cavity and make the whole pump lose its maintenance value.

 

Do Not Work Under High Pressure For Long Time

Many rough vacuum pumps, including oil rotary vane vacuum pumps, can be started directly from atmospheric pressure, but it does not mean that they can work under atmospheric pressure or poor vacuum for a long time. When the rotary vane vacuum pump works under a relatively poor vacuum degree for a long time, a large amount of lubricating oil will be ejected from the exhaust port in the form of oil mist or even oil droplets, resulting in pump oil loss. In addition, when the vacuum degree is relatively poor, the vacuum pump will have relatively severe heat.

 

Try To Avoid Low Temperature Start

Oil rotary vane vacuum pumps generally require the ambient temperature to be above 5 degrees Celsius. When the temperature is too low, the viscosity of the lubricating oil will drop and even sand will form. At this time, power-on startup will cause serious failures such as motor burnout, coupling damage and even rotor twisting.

 

Regular Maintenance

The pump oil of the oil rotary vane pump plays the role of lubrication, sealing and cooling. The dust in the process gas and the metal debris worn off during the operation of the pump will enter the pump oil, and the condensable steam that is not successfully discharged will also be condensed. After mixing in the pump oil, to a certain extent, the pump oil will be discolored, emulsified, and the lubricating performance will decline, so the pump oil needs to be replaced regularly. Some rotary vane pumps are equipped with special oil filters. When changing the oil, change the oil filter too. The frequency of replacing the pump oil depends on the actual process and the type of pump oil. Generally, it is recommended to replace it every six months to one year.

 

If There Is Any Abnormality, Check and Repair In Time

The rotary vane vacuum pump needs to be inspected and repaired in time to avoid more serious damage when the rotary vane vacuum pump is used for about 5 years, or when the pump has abnormal noise during operation, the pump temperature is too high, and the shaft seal oil leaks.

 

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