Many users are confused when they choose air compressors. In fact, as long as they pay attention to some principles of air compressors, they can already select air compressors that are suitable for them, mainly including safety, operating environment, gas quality, exhaust pressure and displacement.

Sullair screw air compressor TH200-250 twin-screw

1. Operation safety of air compressor.

Air compressor is a kind of machine working under pressure, which is accompanied by temperature rise and pressure when working, and its operation safety should be put in the first place. The state implements a standardized "two license" system for the production of compressors, namely the compressor production license and the pressure vessel production license (gas tank). Therefore, the "two certificates" should be strictly examined when purchasing compressor products. Generally, the product quality assurance system of the certified manufacturer is perfect, and there will be no major quality problems. Even if there are some problems, the manufacturer will be responsible for three guarantees.

2. Consider the gas field conditions.

If the gas field is narrow (for ships and vehicles), it should be vertical; If the gas field has long distance change (more than 500 meters), mobile type shall be considered; If there is no power supply for the use occasion, the diesel engine driven type shall be selected; If there is no tap water for the use occasion, the air-cooled type must be selected.

In terms of air cooling and water cooling, users often have the wrong understanding that water cooling is good, but it is not. The air-cooled type of small compressors at home and abroad accounts for more than 90%. This is because the design of air-cooled is simple and convenient, and there is no need for water when using. The fatal disadvantages of water-cooled compressor are as follows: it must have a complete water supply and drainage system, with large investment; Short service life of water-cooled cooler; In northern winter, it is easy to freeze the cylinder; A lot of water will be wasted in normal operation.

3. Compressed air quality shall be considered.

Generally, the compressed air produced by the air compressor contains a certain amount of lubricating oil and water. In some cases, oil and water are prohibited. At this time, attention should be paid not only to the selection of the compressor, but also to the addition of auxiliary devices when necessary.

Solution: First, select a non lubricated compressor. The cylinder of the compressor is basically free of oil, and its piston ring and packing are generally polytetrafluoroethylene. But this kind of machine also has shortcomings, such as poor lubrication and high failure rate; Polytetrafluoroethylene is also a harmful substance, which cannot be used in food and pharmaceutical industries; The non lubricated compressor can only deliver gas without oil, not without water. The second and commonly used method is to add the air compressor (no matter which) to the first or second stage purification device or dryer. This device can make the compressor air free of oil and water, and make the oil and water content in the compressed air below 5ppm, which can meet the process requirements.

4. The high and low exhaust pressure and exhaust volume shall be considered.

The discharge pressure of compressor for general purpose air power is 0.7MPa, and the old standard is 0.8MPa. At present, there is an air compressor with an exhaust pressure of 0.5MPa in society, which is unreasonable from the perspective of use, because the pressure margin for pneumatic tools is too small, and it cannot be used if the gas transmission distance is a little far away. In addition, from the design point of view, this kind of compressor is designed for primary compression. Too large pressure ratio will easily lead to high exhaust temperature, which will lead to carbon deposition in the cylinder and accidents. If the compressor used by the user is greater than 0.8MPa, it should be specially manufactured. Forced pressurization is not allowed to avoid accidents.

The air displacement is one of the main parameters of the air compressor. The air displacement of the air compressor shall be matched with the required air displacement, with 10% allowance. If the air consumption is large and the air compressor discharge is small, once the pneumatic tool is started, the air compressor discharge pressure will be greatly reduced, and the pneumatic tool cannot be driven. Of course, it is wrong to blindly pursue large exhaust volume, because the larger the exhaust volume is, the larger the motor equipped with the compressor is, which is not only expensive, but also a waste of purchase funds, as well as electrical energy when using.