The basic criteria for choosing an air compressor are economy, reliability and safety.

First, the level of exhaust pressure and the amount of exhaust should be considered. The discharge pressure of general-purpose aerodynamic compressors is 0.7MPa, and the old standard is 0.8MPa. At present, there is an air compressor with an exhaust pressure of 0.5MPa, which is unreasonable from the point of view of use, because the pressure margin is too small for pneumatic tools, and it cannot be used if the gas transmission distance is slightly longer. In addition, from the design point of view, this kind of compressor is designed for one-stage compression, and the pressure ratio is too large, which is easy to cause the exhaust gas temperature to be too high, resulting in carbon deposition in the cylinder, resulting in accidents. If the compressor used by the user is larger than 0.8MPa, it is generally specially manufactured, and the method of forced pressurization cannot be adopted to avoid accidents.
The air volume is one of the main parameters of the air compressor. The air volume of the air compressor should be matched with the required air volume, and a 10% margin should be reserved. If the air consumption is large and the air compressor discharge volume is small, once the pneumatic tool is started, the exhaust pressure of the air compressor will be greatly reduced, and the pneumatic tool cannot be driven. Of course, it is also wrong to blindly pursue large displacement, because the larger the displacement, the larger the motor equipped with the compressor, which is not only expensive, but also wastes the purchase capital, and also wastes electricity and energy when using it.
In addition, the peak consumption, the usual consumption and the trough consumption should also be considered when selecting the exhaust volume. If the trough consumption is large, but the usual consumption and peak consumption are not large, the usual method abroad is to connect air compressors with smaller displacement to obtain a larger displacement, and start up one by one as the gas consumption increases, so that Not only is it good for the grid, but it also saves energy.

The second is to consider the occasion and conditions of gas use. If the gas site is small (marine, vehicle), the vertical type should be selected; if there is a long-distance change (over 500 meters) in the gas site, the mobile type should be considered; if the power supply cannot be used, the diesel engine-driven type should be selected. ; If there is no running water in the use occasion, you must choose the air-cooled type.
In the two cooling methods of air cooling and water cooling, users often have a wrong understanding, thinking that water cooling is good, but it is not. Air-cooled compressors account for more than 90% of domestic and foreign small compressors. This is because air-cooling is simple and convenient in design, and no water source is required for use.
The fatal shortcomings of water-cooled compressors are four: there must be a complete upper and lower water system, and the investment is large; the life of the water-cooled cooler is short; it is easy to freeze the cylinder in the northern winter; a lot of water will be wasted in normal operation.

The third is to consider the quality of compressed air. Generally, the compressed air produced by the air compressor contains a certain amount of lubricating oil and a certain amount of water. In some occasions, oil and water are prohibited. At this time, not only should the compressor be selected, but also auxiliary devices should be added if necessary.
Solution: First, choose a non-lubricated compressor. This compressor cylinder is basically free of oil, and its piston rings and packing are generally polytetrafluoroethylene. But this kind of machine also has shortcomings, such as poor lubrication and high failure rate; PTFE is also a harmful substance, which cannot be used in the food and pharmaceutical industries; non-lubricated compressors can only deliver gas without oil, but not without water. The second and commonly used method is to add a primary or secondary purification device or dryer to the air compressor (whatever it is). This device can make the compressor air contain neither oil nor water, so that the oil-water content in the compressed air is below 5ppm, which can meet the process requirements.

The fourth is to consider the safety of compressor operation. An air compressor is a machine that works under pressure. It is accompanied by temperature rise and pressure during operation. The safety of its operation should be given the first place. The state implements a standardized "two certificates" system for the production of compressors, namely the compressor production license and the pressure vessel production license (gas storage tank). Therefore, when purchasing compressor products, it is necessary to strictly review the "two certificates". Usually, the product quality assurance system of certified manufacturers is perfect, and there will be no major quality problems. Even if there are some problems, the manufacturer will be responsible for the three guarantees.