What should be paid attention to when selecting vacuum system for roots liquid ring pump vacuum unit

In addition to good mechanical properties and processing properties, roots liquid ring pump vacuum unit should also meet the requirements of other properties, such as easy degassing, low saturated vapor pressure, certain chemical stability, certain purity and cleanliness, appropriate radiation capacity, etc Therefore, the roots liquid ring pump vacuum unit has its particularity, and its cleaning requirements are very strict, so the pollution of parts should be removed or reduced The requirements for working environment of roots liquid ring pump vacuum unit are: all vacuum units in roots liquid ring pump are required to be free of accumulated pollution sources, dust, iron chips and rust on the surface The surface of the vacuum chamber shall be smooth, free from soft tissues, pores, internal welds and other defects affecting the vacuum In the unit, the moving parts in the vacuum chamber shall not be lubricated with engine oil, the diffusion pump oil and silicone oil with low saturated vapor pressure shall be used as lubricants, and the sealing parts of the flange and observation window shall be coated with high vacuum grease Generally, roots liquid ring pump vacuum unit should work in a clean air circulation environment with a temperature of 15-30 ℃ and a relative humidity of no more than 70% The temperature of cooling water inlet water should not be higher than 25 ℃ The function of roots liquid ring pump vacuum unit is to remove gas molecules from the vacuum chamber, reduce the gas pressure in the vacuum chamber, and make it reach the required vacuum degree In order to meet the requirements of process indexes, working efficiency and equipment working life of different products, different vacuum system configurations are required for different vacuum sections In order to meet the requirements of vacuum system configuration, the following points should be considered: 1 Check the type of gas to be pumped and the amount of air to be pumped to determine the type and amount of air to be pumped required by the process Because if the kind of pumped gas reacts with the liquid in the pump, the pump system will be polluted At the same time, it is necessary to determine the appropriate exhaust time and the amount of gas produced in the process of extraction 2 Vacuum degree determines the structure of the product There are gauge pressure and pressure readings Pressure indicates that the reading is a value, i.e the closer the reading is to '0', the higher the vacuum But on the other hand, the closer the gauge pressure is to 760mmh ɡ, the higher the vacuum degree is If the required pressure (limit vacuum) is close to '0', then only the roots liquid ring pump vacuum unit can meet this demand, but if the demand is close to 1bar (atmospheric pressure), then the fan or centrifugal fan can be selected to meet this demand 3 To determine the working vacuum range, first check and determine the vacuum degree required by each process Because each process has its suitable vacuum range, it must be carefully studied and determined IV vacuum volume inspection: determine the time required to reach the required vacuum degree, flow resistance and leakage of vacuum pipeline After the required vacuum degree is reached, the air extraction rate required to maintain vacuum under certain process requirements is considered V determine the limit vacuum degree: check the limit vacuum degree of the vacuum pump system on the basis of determining the vacuum degree required by the process, because the limit vacuum degree of the system determines the working vacuum degree of the system Generally speaking, the limiting vacuum degree of the system is 20% lower than the working vacuum degree of the system, and 50% lower than the limiting vacuum degree of the previous stage pump.