What Is the Function of a Vacuum Pump?

A vacuum pump is a mechanical device that extracts gas from a liquid. The pump’s performance is dependent on the molecular weight of the gas. Smaller molecules leak more easily and can be absorbed by certain materials. A molecular pump is less effective than a classical vacuum pump at pumping gases with low molecular weights, such as air. Air is primarily composed of nitrogen, but chambers may still contain residual atmospheric gases. A palladium-lined vessel can cause a special outgassing problem.

Function of a Vacuum Pump

Oil lubrication

The most important consideration when selecting the correct lubricant for your vacuum pump is the oil’s viscosity. Too thin an oil will not form a proper lubrication seal, resulting in leakage and flow reversal. In addition, the proper lubricant will prevent metal-to-metal contact, which can cause premature failure and excessive wear. Therefore, a proper oil lubrication package is important for maximizing the life of your pump and maintaining high performance.

Different vacuum pump for sale in NYC react to different types of lubricants. Some react poorly to hydrocarbon-based lubricants, resulting in reduced performance and increased energy consumption. Low-quality oils may also cause damage to your pump, resulting in a costly mistake. When choosing oil lubrication for your vacuum pump, you should use a quality fluid designed specifically for the pump’s application.

Compression ratio

The Compression ratio of a vacuum pump refers to the amount of gas a pump can compress. It is measured from a blank-flanged inlet port to the outlet port. If the pump is working with constant atmospheric pressure, the ratio must be smaller than one. In the illustration below, the dead space is calculated as one-tenth the volume of the liquid. Hence, the compression ratio is 100 – 90 = 10 mL.

Hence, a high compression ratio vacuum pump should be chosen. It can be a very time-consuming process involving various product comparisons. Trade-offs between performance and economy are frequently used to make decisions. For example, the rotary backing pump may obtain a low hydrogen partial pressure. Another form of a high-compression vacuum pump is the rotating backing pump. It can achieve ultimate pressures of 10 to 11 mbar.

Pump performance curves

A pump’s performance can be determined by studying its pump performance curves. The PD curve shows the capacity of a pump in gallons or liters per minute at a given RPM. It also indicates the pressure in the pipeline upstream and downstream of the pump. The PD curve is also known as the pressure-flow curve.

A pump’s efficiency is measured in percentages. The efficiency curves are usually U-shaped and parallel to the head-flow impeller diameter curves. The greatest efficiency level is around 80%. A pump performance test is used to identify the optimal efficiency point. It can also include data on the total power consumption, efficiency ratio, and the required net positive suction head. If you consider a new pump, it is a good idea to consult a pump performance curve.


When selecting a vacuum pump, it is important to consider its main purpose. In some cases, you may be holding pressure for process reasons and need a high gas load capability pump. Other times, you will be using a vacuum system for hazardous materials removal. Regardless of the purpose, you should consider the features and applications of a vacuum pump to make the best choice.

Industrial and scientific processes use vacuum pumps. They are used for vacuum tubes, CRTs, electric lamps, semiconductor processing, and other mechanical devices. For example, vacuum pumps support hydraulic components in the automotive industry, including brakes. They are also used in airplanes for gyroscope control. In addition, a vacuum pump can be used in many other industries, from wood processing to medicine.

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