The physical adsorption or absorption of gas by common surface or porous materials can be used to obtain high vacuum. Adsorption or absorption technology can be used at any pressure, but due to practical limitations, it is only developed as a special application in vacuum technology.
In order to eliminate the possibility of hydrocarbon pollution caused by oil sealed mechanical pumps, adsorption pumps are often used for crude pumping in ultra-high vacuum system, and are often used with dry (oil-free) mechanical pumps. Two or three adsorption pumps can be used in turn according to the pumping procedure, which can discharge a large amount of air from the vacuum vessel. By switching to ion getter pumping, a sufficiently low pressure can be obtained without overloading it.
High vacuum can be obtained by adsorption, which can be achieved by desorbing the adsorbed gas material through heating, then returning to room temperature, or cooling to low temperature.
Commercial adsorption pumps are usually designed to obtain a pre vacuum. However, high vacuum can also be obtained by multistage pumping with similar basic structure, but a high inlet flow guide is required.
Hermetically sealed devices are usually vented and sealed at elevated temperatures. During the cooling period, the number of adsorption sites is large enough to provide a significant pressure reduction of air extraction, thus reducing the pressure by one or more orders of magnitude. Numerous examples show that when there is a large temperature change, there must be adsorption effect in the high real air. For example, when the heating element of the high vacuum furnace is still hot, isolate the vacuum guard from the pump and cut off the power supply. As long as the vacuum furnace is well sealed and the residual gas can be fully absorbed, the high vacuum of the vacuum furnace will be maintained overnight.
VACUUM FURNACE
industrial vacuum pumps,vacuum furnaces
Heat treatment equipment
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