1. Composition and Classification of Vacuum Units
The vacuum unit is generally composed of the following components: various vacuum pumps, vacuum measuring devices, vacuum valves, vacuum pipes and some other components such as blowers, vacuum joints, gas storage tanks, bellows, dust collectors and vacuum relays.
According to the working pressure of the unit, there are rough vacuum units (>1330Pa), low vacuum units (1330~0.13Pa), high vacuum units (0.13~1.3x10-6Pa), ultra high vacuum units (1.3x10-6) ~1.3×10-11 Pa) and very high vacuum unit (<1.2×10-11 Pa).
2. Low Vacuum Unit
The main features of the low vacuum unit are high working pressure and large displacement, but the pumping speed is lower than that of the high vacuum unit. It is mostly used for rough pumping of vacuum chamber and some vacuum units that need high working pressure such as vacuum discharge units, vacuum impregnation units, vacuum filter units, vacuum degassing units, vacuum drying units and so on. The main pumps of the low vacuum unit are commonly reciprocating vacuum pumps, oil seal vacuum pumps, water jet pumps, water vapor jet pumps, water ring pumps, oil vapor jet pumps, molecular sieve adsorption pumps and Roots pumps. When using a low-vacuum unit, it is also necessary to configure components such as a dust collector and a dry filter according to the process requirements of the degree of cleanliness and humidity of the gas to be pumped.
3. High Vacuum Unit
3.1 Choose the main pump. The main pump can be diffusion pump, molecular pump, sputter ion pump, titanium pump, cryogenic pump and so on.
3.2 Choose the backing pump and the gas storage pipe (shockproof, shorten the working cycle, prevent a large amount of venting in the vacuum chamber, and stabilize the outlet pressure of the diffusion pump)
4. Ultra-High Vacuum Unit
The ultimate vacuum of the main pump is high, the leakage rate is low, and it is resistant to baking at 200-450°C.
4.1 Diffusion pump unit: reduce backflow and control pollution.
4.2 Molecular pump unit: The compression ratio to hydrogen is small, and the residual gas is mainly hydrogen.
4.3 Sputter ion pump unit: Usually used in combination with a titanium pump.
4.4 Cryogenic pump unit: no pollution.