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What Is The Difference Between A Vacuum Pump And An Air Compressor?
Jun 20, 2018

Vacuum technology and equipment network As the authoritative media communication platform in the vacuum industry, we provide an open technology exchange and communication platform for the vacuum industry with an open mind.

Recently, there is a micro message to ask about the difference between an air compressor and a vacuum pump. Recently, Xiao Bian has collated relevant materials and edited the following related contents in hopes of helping everyone.

Air compressor

1. The air compressor is the main body of the air source device. It is a device that converts the mechanical energy of the prime mover into gas pressure energy, and is an air pressure generating device for compressed air.

2. There are many kinds of air compressors. According to the working principle, they can be divided into volumetric compressors, centrifugal workers' compressors and piston compressors.

1) The working principle of the volumetric compressor is the volume of compressed gas, so that the density of gas molecules per unit volume increases to increase the pressure of the compressed air;

2) The working principle of the centrifugal compressor is to increase the movement speed of the gas molecules, so that the kinetic energy of the gas molecules is converted into the pressure energy of the gas, thereby increasing the pressure of the compressed air.

3) The working principle of the piston compressor is to directly compress the gas and discharge it when the gas reaches a certain pressure.

3. The commonly used air compressors are piston air compressors, screw air compressors, centrifugal compressors, and vane type air compressors and scroll air compressors.

Relevant sources said that the choice of air compressor is mainly based on the working pressure and flow rate of the pneumatic system. The working pressure of the gas source should be about 20% higher than the maximum working pressure in the pneumatic system, because the loss and local loss of the gas supply pipeline must be considered. If the working pressure requirement is low in some parts of the system, a pressure reducing valve can be used to supply air. The rated discharge pressure of the air compressor is divided into low pressure (0.7 to 1.0 MPa), medium pressure (1.0 to 10 MPa), high pressure (10 to 100 MPa), and ultra high pressure (100 MPa or more), which can be selected according to actual needs. The common pressure is generally 0.7~1.25MPa.

Vacuum pump

1, structure and principle

"Vacuum" refers to a gaseous space where the pressure is less than 101.3 kPa. Any device that can withdraw gas from the container and reduce the gas pressure can be called a vacuum pump. The commonly used vacuum pump in the inspection room is an oil seal mechanical vacuum pump. The vacuum degree is generally 101~1Pa. This type of pump has a steel cylindrical stator. The stator has an eccentric steel solid cylinder as the rotor. The diameter of the rotor is embedded with a spring-loaded slider. When the motor drives the rotor to rotate, the slider is in the cylinder. The chamber is operated so that the pump chamber is partitioned into two areas and its volume is periodically enlarged and reduced. After the gas container to be pumped is connected to the air inlet of the pump, when the space of the pump chamber increases, the gas to be pumped is sucked in. As the rotor rotates, the gas is compressed and discharged from the exhaust port. As the rotor continues to rotate, the suction, compression, and exhaust processes continue to repeat. The gas in the container is continuously reduced and the pressure is continuously reduced. The entire machine is immersed in a lubricating oil tank. The vapour pressure of the lubricating oil is very low. It acts as a lubricant, seal, and cold action.

2, use and precautions

1) The vacuum pump is mainly used in the inspection room in the following aspects:

A. Vacuum Drying The vacuum pump is connected to the drying oven. The sample can be removed from the sample at a lower temperature in a vacuum oven to remove water and difficult-to-volatile high-boiling impurities. In order to avoid decomposition of the sample at high temperatures.

B. Vacuum distillation, ie, vacuum distillation, can reduce the boiling point of the material and allow it to be distilled at a relatively low temperature. It is suitable for the distillation of organic materials that are easily decomposed at high temperatures.

C, vacuum filtration, special materials difficult to filter, vacuum filtration can speed up the filtration rate.

Others can also be used for tests that require vacuuming.

2) Use cautions:

A. Before starting the vacuum pump, check whether the liquid level of the oil in the pump is at the marking line of the oil hole. Too much oil will cause the gas to splash outward from the exhaust hole during operation. If the oil is not enough, the pump body cannot be completely submerged and the seal and lubrication cannot be achieved. The vacuum pump body is damaged.

B. The vacuum pump is driven by the motor and should be used so that the voltage of the power supply matches the voltage required by the motor. For a three-phase motor, remove the belt before power transmission and check whether the motor rotation direction matches, and do not make the motor reverse, causing the pump oil to spray. After checking, connect the belt again.

C. The vacuum pump must not directly pump condensable vapors. D. When the vacuum pump is running, pay attention to the temperature of the motor. Do not exceed the specified temperature. There should be no friction and metal crashes. If there is any abnormality, it should be shut down for professional service.

E. Before stopping the pump, the air inlet of the pump should be ventilated to the atmosphere before the power is cut off to prevent the back pressure of the pump oil from entering the suction system. For this purpose, it is advisable to connect a three-way piston at the air inlet. Before shutting down, the three-way piston should be in a position to keep the system in a vacuum and to open the pump to the atmosphere.

F. The vacuum pump should periodically clean the fine mesh at the air inlet so that small solid particles do not fall into the pump and damage the pump body. Lingge air compressor Tip: After the vacuum pump is used for six months or one year, oil must be changed.

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