1. The operating pressure of the vacuum pump shall satisfy the requirements of the limit vacuum and operating pressure of the vacuum equipment. For example, vacuum coating requires a vacuum of 110-5 mm Hg, and the vacuum of the selected vacuum pump should be at least 510-6 mm Hg. Generally, the vacuum degree of the selected pump is half to one order of magnitude higher than that of the vacuum equipment.
2. Select the operating point of vacuum pump correctly. Each pump has a certain operating pressure scale, such as: the dispersive pump is 10-3-10-7 mmHg, in such a wide pressure scale, the pump speed changes with the pressure, its stable operating pressure scale is 510-4-510-6 mmHg. Therefore, the operating point of the pump should be selected within this scale, and it can not be allowed to operate for a long time under 10-8 mmHg. Another example is that the titanium pump can operate under 10-2 mmHg, but its operating pressure should be less than 110-5 mmHg.
3. Vacuum pumps should be able to discharge all the gases that occur in the technological process of vacuum equipment under their operating pressure.
4. Correct combination of vacuum pumps. Because the vacuum pump has selective pumping, so sometimes choose a pump can not satisfy the pumping request, several pumps need to be combined to complement each other to satisfy the pumping request. For example, titanium pump has a high pumping speed for hydrogen, but it can not pump helium, while tripolar sputtering ion pump (or bipolar asymmetric cathode sputtering ion pump) has a certain pumping speed for argon, the combination of the two will make the vacuum equipment get a better vacuum degree. In addition, some vacuum pumps can not work at atmospheric pressure, and need pre-vacuum; some vacuum pumps outlet pressure is lower than atmospheric pressure, the need for front-end pumps, so they need to be combined with the use of pumps.
5. Request of vacuum equipment for oil pollution. If the equipment strictly requests oil-free, we should choose all kinds of oil-free pumps, such as water ring pump, molecular sieve adsorption pump, sputtering ion pump, cryopump, etc. If the request is not strict, the oil pump can be selected, together with some anti-oil pollution methods, such as adding cold traps, baffles, oil traps, etc., can also reach the cleaning vacuum request.
6. Understand the composition of the extracted gas. The gas contains no condensable vapor, particulate dust and corrosiveness. When selecting a vacuum pump, it is necessary to know the gas composition, and select the appropriate pump for the pumped gas. If the gas contains vapor, particles, and corrosive gases, it should be considered to install auxiliary equipment in the intake pipeline of the pump, such as condenser, dust collector, etc.
7. How does the oil vapor from the vacuum pump affect the environment? If the environment is not allowed to be polluted, oil-free vacuum pumps can be selected and oil vapor may be discharged outdoors.
8. Whether the oscillation during the operation of vacuum pump has an impact on the technological process and environment. If the technical process is not allowed, non-oscillation pumps should be selected or anti-oscillation methods should be adopted.
9. Vacuum pump quotation, operation and maintenance costs.
The liquid ring vacuum pump revolves in the pump chamber by the bias impeller to make the volume of the chamber change periodically in order to realize the pumping vacuum pump. Its studio is composed of rotating liquid ring and impeller. Its structure and working principle are similar to that of liquid ring compressor. When working, the suction port is connected with the vacuum container. If the pump chamber is filled with water, the Liquid Ring Vacuum Pump is called Liquid Ring Vacuum Pump. It has the advantages of simple structure, easy manufacture, reliable operation, convenient use and durability. It can extract corrosive, dusty gas and gas-water mixture. The optimum temperature of the extracted gas is 0 ~ 40 C. Circulating water should not contain impurities. The pumping rate of the Liquid Ring Vacuum Pump ranges from 0.25 to 500 m (/ h) and the limit pressure is 8 x 10 (~2 x 10) for the unipolar pump and 2 x 10 (~1 x 10) for the two-stage pump. Liquid Ring Vacuum Pump is mainly used in vacuum distillation, vacuum drying and pumping.
The liquid ring vacuum pump can be divided into single stage and double stage, as well as the difference between single and double action. Single-stage and double-stage vacuum pumps refer to the series of their impellers; single/double action refers to the form of their impellers/shells; gas in the impeller of single-acting impeller vacuum pumps undergoes one inhalation/exhaust in one rotation cycle; gas in the impeller of double-acting vacuum pumps undergoes two inhalation and exhaust in one rotation cycle.
|Curve No.||Model||Max. suction capacity||Ultimate vacuum
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