First, consider the level of exhaust pressure and the amount of exhaust. The general-purpose aerodynamic compressor discharge pressure is 0.7 MPa, and the old standard is 0.8 MPa. At present, there is an air compressor with an exhaust pressure of 0.5 MPa, which is unreasonable from the angle of use, because the pressure margin is too small for the pneumatic tool, and the gas transmission distance is slightly far away and cannot be used. In addition, from the design point of view, this type of compressor is designed to be one-stage compression, and the pressure ratio is too large, which may cause the exhaust gas temperature to be too high, causing the cylinder to deposit carbon and causing an accident. If the compressor used by the user is larger than 0.8 MPa, it is generally manufactured in a special way, and it is not possible to adopt a forced pressurization method to avoid an accident. The displacement is one of the main parameters of the air compressor. The air volume of the air compressor should be matched with the required displacement and leave a margin of 10%. If the air volume is large and the air compressor has a small exhaust volume, when the pneumatic tool is started, the air compressor exhaust pressure will be greatly reduced, and the air moving tool cannot be driven. Of course, blindly pursuing large displacements is also wrong, because the larger the displacement, the larger the motor of the compressor, not only high, but also wastes the purchase of funds, which also wastes power energy when used. In addition, peak and normal usage and low volume should be considered when selecting the displacement. If the amount of low trough is large, and the usual dosage and peak usage are not large, the usual method in foreign countries is to obtain a larger displacement in parallel with an air compressor with a smaller displacement, and turn on one by one as the amount of gas is increased. Not only is it good for the grid, but it also saves energy.
Second, it is necessary to consider the use of gas conditions and conditions. If the gas field is small (for marine or vehicle use), the vertical type should be selected; if there is a long-distance change (more than 500 meters) in the case of gas, the mobile type should be considered; if the use cannot be supplied, the diesel-driven type should be selected. If there is no tap water in the use, you must choose air-cooled. In the air cooling and water cooling cooling methods, users often have a wrong understanding, and think that the water is cold, but it is not. China's small external compressors account for more than 90% of the air-cooled type, because it is designed to be air-cooled and easy to use, without the need for water. The fatal shortcomings of water-cooled compressors are four: there must be a complete water supply system, and the investment is large; the water-cooled cooler has a short life; in the north, it is easy to freeze the cylinder; in normal operation, a large amount of water is wasted.
Third, it is necessary to consider the quality of compressed air. Generally, the compressed air produced by the screw air compressor contains a certain amount of lubricating oil, and has a certain amount of water. In some occasions, oil is forbidden and water is forbidden. At this time, not only the selection of the compressor should be noted. If necessary, add attachments. Solution: First, choose a non-lubricated compressor. The compressor cylinder is substantially free of oil and its piston rings and packing are typically polytetrafluoroethylene. However, this kind of machine also has shortcomings, poor lubrication and high failure rate; PTFE is also a harmful substance, which cannot be used in the food and pharmaceutical industries; the non-lubricated compressor can only make the gas without oil and cannot be water-free. The second and common method is to add an air compressor (regardless of it) to a primary or secondary purification unit or dryer. This device allows the compressor air to be both oil-free and water-free, allowing the oil-containing water in the compressed air to be below 5 ppm to meet process requirements. Fourth, it is necessary to consider the safety of compressor operation. The air compressor is a pressurized machine with temperature rise and pressure, and the safety of its operation should be first. The state implements a standardized two-certificate system for the production of compressors, namely the compressor production license and the pressure vessel production license (gas storage tank). Therefore, when selecting a compressor product, it is necessary to strictly examine the two certificates. Usually, the product quality assurance system of the certified manufacturer is perfect, and there will be no big quality problems. Even if there are some problems, the manufacturer will be responsible for the three bags.
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