First, we have to consider the exhaust pressure and the volume of the exhaust.
Based on the national regular, the exhaust pressure of general purpose atmosphere compressor is 0.7 MPa (7 atmospheric pressure) and the old regular is 0.8 MPa (8 atmospheric pressure). Because 
the design operating pressure of pneumatic tools and wind machinery is usually 0.4 Mpa, the working pressure of atmosphere compressor can fully meet up with the requirements. If the atmosphere compressor utilized by the user is larger than 0.8MPa, it should be specially manufactured. The technique of forced pressurization can’t be adopted in order to avoid accidents.
How big is the exhaust can be one of the primary parameters of the air compressor. Choosing the surroundings volume of the air compressor should match its own exhaust quantity and leave a 10% margin. If the air flow volume is large and the atmosphere compressor exhaust volume is small, when the pneumatic equipment start, the exhaust pressure of the atmosphere compressor will be greatly reduced, but the pneumatic tools can’t be driven. Of program, additionally it is wrong to pursue huge exhaust capacity blindly, since the bigger the exhaust capacity, the larger the electric motor allocated by the air compressor, not only the higher the purchase price, but also a waste of buying funds, and the use of electricity and energy will end up being wasted.
Consider the combination of gas areas and conditions.
If the utilization of air space is narrow, it should be vertical; if there is a long-distance modification in the use of air (more than 500 m), mobile type should be considered; if the usage of electricity can’t be utilized, Chain diesel engine generating type ought to be selected; if there is no circulating drinking water in the use of occasions, air-cooled type should be selected. In the air-cooled and water-cooled cooling settings, many users have an incorrect proven fact that water-cooled is good, but in fact it isn’t. The air-cooled type accounts for a lot more than 90% of the small compressors at home and abroad. That is since the air-cooled type is simple in design no water source is necessary in use. There are four fatal shortcomings of water-cooled compressor: it must have a complete higher and lower water system with large purchase; water-cooled cooler has brief life; it is easy to freeze the cylinder in winter in the north; it will waste a whole lot of water in normal operation.
After that consider the compressed air quality.
Generally, compressed air made by air compressor contains a certain quantity of lubricating oil and water. In some cases, it really is prohibited from oil and water. At the moment, attention should be paid not only to the selection of compressor, but also to the addition of auxiliary products when necessary.
Lastly, it is to expand the data of reference.
1. Balance: With the strong rise of China’s economy and the constant emancipation of the minds of all sorts of manufacturers, manufacturers from coast to coast are busy with production work. In the process of production, air compressors, which play an important role, are often completely loaded and operate all-weather. In the entire production of factories, atmosphere compressor gas production is unstable, which is a very troublesome thing, often will bring incalculable losses. Therefore, 
when we purchase air compressors, the initial criterion may be the stability of air compressors. At present, some high-end brands both in the home and overseas can meet this requirement. With the mature technology of variable frequency air compressor, it could be said to meet this requirement.
2. Gas creation: The second reason is gas production. Some enterprises have very good quality of gas. For example, in the pharmaceutical industry, basically the gas they need is oil-free. In this regard, it is still based on the enterprise’s own situation. If the business includes a high demand for this, then it’s been a long period to purchase more well-known devices. If the demand is not high, it depends upon other circumstances. As the future development trend of the air compressor industry, the adjustable frequency air compressor is still very excellent in gas production, since the variable frequency air flow compressor includes a prominent characteristic of monitoring gas creation, and at the same time the gas quality produced is very considerable.
3. Power consumption: This is a comparatively important place as well as the focus of debate, because air compressor, as a simple equipment, is generally operated all-weather, and surroundings compressor itself is a very power-consuming equipment, the general manufacturer of surroundings compressor power consumption accounts for 20-30% of the full total plant power usage. If effective control, the effect is very obvious. Many domestic enterprises are now pursuing the base price. In fact, the bottom price is quite one-sided. For general production enterprises, the price of air compressor only makes up about 5% of the total cost of air flow compressor, 9% of the maintenance and labor costs, and 86% of the total cost of electricity. Therefore, considering the last expenditure, the frequency conversion air compressor should be much lower compared to the ordinary air flow compressor. Frequency conversion air compressor is the first expense, but if you take the electricity price into account, you really can calculate a bill. Today, the general energy-saving amount of frequency converter surroundings compressor is very objective, and the domestic professional regularity converter air compressor, its power-saving rate is as high as 30%, usually within a 12 months can recover the difference. Therefore, when choosing air compressor, choosing an excellent variable frequency air flow compressor is really the best answer to the issue of power consumption.