With the development of vacuum applications, the types of vacuum pumps have evolved into a wide range of pumping speeds ranging from a few tenths of a second to hundreds of thousands of liters per second, millions of liters; the ultimate pressure (ultimate vacuum) ranges from low vacuum to 10-12 Pa Above the ultrahigh vacuum range. Due to the wide range of working pressures involved in the vacuum application sector, it is not possible for any type of vacuum pump to be suitable for all working pressure ranges. Different types of vacuum pumps can only be selected for different types of working pressure depending on different working pressure ranges Vacuum pump Selection of vacuum pump, you need to note the following: 1, the working pressure of the vacuum pump vacuum equipment should meet the ultimate vacuum and pressure requirements. Such as: vacuum coating requires 1 × 10-5mmHg of vacuum, the vacuum of the vacuum pump used at least 5 × 10-6mmHg. Usually choose the degree of vacuum pump is higher than the degree of vacuum vacuum equipment to an order of magnitude. 2, the correct choice of vacuum pump working point. Each pump has a certain working pressure range, such as: Roots pump 10-1 ~ 10-4 mmHg, in such a wide range of pressure, pump pumping speed varies with pressure, and its stable working pressure range of 1 ~ 10-1 mmHg. Therefore, the pump operating point should be selected within this range. 3, the vacuum pump in its work pressure, should be able to drain away all the gas generated in the process of vacuum equipment. 4, the correct combination of vacuum pump. Due to the vacuum pump selective suction, therefore, sometimes the choice of a pump can not meet the pumping requirements, the need for several pumps combined to complement each other to meet the pumping requirements; some vacuum pumps can not work at atmospheric pressure, the need for pre-vacuum; Of the vacuum pump outlet pressure below atmospheric pressure, the need for pre-stage pump, it is necessary to use the pump combination, that is, vacuum unit. 5, vacuum equipment, oil pollution requirements. If the equipment is strictly required oil-free, should choose a variety of oil-free pumps, such as: water ring pump, molecular sieve adsorption pump, sputtering ion pump, cryogenic pump. If the requirements are not strict, you can choose a pump, plus some anti-oil pollution measures, such as adding cold trap, baffle, oil well, etc., but also to achieve clean vacuum requirements. 6, to understand the composition of the gas being drawn, the gas containing non-condensable vapor, whether the particles of dust, whether or not corrosive. When choosing a vacuum pump, you need to know the gas composition and select the appropriate pump for the purged gas. If the gas contains vapors, particles, and corrosive gases, consideration should be given to installing auxiliary equipment such as condensers, dust catchers, etc. on the pump inlet piping. 7, the vacuum pump out of the oil vapor on the environment how the impact. If the environment does not allow contamination, you can choose oil-free vacuum pump, or the oil vapor to the outside. 8, the vibration generated by the vacuum pump on the process and the environment have no effect. If the process is not allowed, should choose no vibration pump or take anti-vibration measures. 9, the price of the vacuum pump, operation and maintenance costs. Select the most cost-effective and can meet the technical requirements of the vacuum pump model.
