Selection of water ring vacuum pumps

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I. Determination of pump type The type of pump is primarily determined by the volume of air required for operation, the level of vacuum, or the exhaust pressure. 　　When the pump is in operation, two aspects need to be taken into consideration: 1. It is advisable to operate it within the high-efficiency range, that is, in the area of critical vacuum or critical exhaust pressure. 2 Operation near the maximum vacuum level or maximum exhaust pressure should be avoided. Operating within this range is not only extremely inefficient, but also results in unstable operation, prone to vibrations and noise. For vacuum pumps with a high degree of vacuum that operate in this range, cavitation often occurs as well; obvious signs of this phenomenon are noise and vibration inside the pump. Cavitation can cause damage to components such as the pump body and impeller, resulting in the pump being unable to function. 　　Based on the above principles, when the vacuum level or gas pressure required by the pump is not high, a single-stage pump should be preferred. If the vacuum level or exhaust pressure is high, a single-stage pump often fails to meet the requirements. Alternatively, if it is necessary for the pump to handle a large volume of gas at high vacuum levels, that is, if a relatively flat performance curve at high vacuum levels is required, a two-stage pump can be used. If a vacuum level of above –710 mmHg is required, a water ring-atmospheric pump or a water ring-Rotary vane vacuum unit can be used as the vacuum pumping device. 　　If it is to be used only as a vacuum pump, a single-acting pump is a better choice. Due to their simple structure, single-acting pumps are easy to manufacture and maintain, and they exhibit good cavitation resistance under high vacuum conditions. If it is to be used solely as a compressor for large air volumes, then a double-acting pump is more suitable. Because double-acting pumps have a large air volume, small size, and light weight, the radial forces can be automatically balanced, the shaft is less prone to fatigue fracture, and thus the pump has a longer service life. II. Selection of a vacuum pump based on the required gas volume Code Main features Ultimate vacuum level (mmHg) Operating vacuum level (mmHg) Pumping speed range (m³/min) Seal type SK Domestically designed single-stage water ring vacuum pump; it features a simple structure and is easy to maintain. The current mainstream low-vacuum water-ring vacuum pumps in China. -700-300~-6500.15~120: Gaskets, mechanical seals. It is a two-stage water ring vacuum pump designed in China; it is equivalent to two SK water ring pumps connected in series. Compared with single-stage water ring pumps, it features a higher vacuum level as well as a greater pumping speed at high vacuum conditions. Currently, the mainstream water ring vacuum pumps in China. -735-300~-700; 1.5~30: Packing and mechanical seals. The 2BV series utilizes Siemens’ advanced technology. It features a coaxial configuration of the motor and pump, compact structure, high efficiency, high vacuum level, and stable performance. It will gradually replace the SK and 2SK series water ring vacuum pumps with pumping speeds ranging from 0.4 to 6 m³/min. -735-300~-7000.45~8.33 Mechanical seal 2BE1 utilizes Siemens’ advanced technology; it features high efficiency, high vacuum levels, and stable performance, and will gradually replace the SK and 2SK series of water ring vacuum pumps with a pumping speed of 6~120 m3/min. -735 -640-300~-700 -300~-6005~400: Gaskets, mechanical seals. Based on Soviet technology from the 1950s; low efficiency and high energy consumption. They were phased out in the early 1980s and are mainly used by existing customers. -640~-700-300~-650, 1.5~27 packing rings; based on Soviet technology from the 1950s, these units have low efficiency and high energy consumption; they were phased out in the early 1980s. They were mainly used for pumping water, and have now been replaced by SK series water ring pumps. -600-300~-5500.33~0.66: The packing 2SY is mainly used in water ring compressors, with a maximum discharge pressure of 0.6 MPa. 6~30: The mechanical seal 2YK has a structure similar to that of the 2SK series; it can use the medium being pumped as the working fluid, and its ultimate vacuum level varies depending on the saturated vapor pressure of that medium. The ultimate vacuum value in the table refers to that when the working medium is transformer oil. -755-300~-7201.5~30 Mechanical seal