Air Compressor Purchase Method

- Dec 07, 2020-

Air compressor purchase method


When preparing to purchase an air compressor, first determine the working pressure required by the air end, plus a margin of 1-2 bar, and then select the pressure of the air compressor. (The margin is based on the consideration from the installation location of the air compressor For the pressure loss of the pipeline distance to the actual gas end, the pressure margin should be appropriately considered between 1-2 bar according to the length of the distance). Of course, the size of the pipeline diameter and the number of turning points are also factors that affect the pressure loss. The larger the pipeline diameter and the fewer turning points, the smaller the pressure loss; on the contrary, the greater the pressure loss.


Therefore, when the distance between the air compressor and each gas end pipeline is too far, the diameter of the main pipeline should be appropriately enlarged. If the environmental conditions meet the installation requirements of the air compressor and the working conditions permit, it can be installed near the gas end.

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Selection of volume flow:


1. When selecting the volumetric flow rate of an air compressor, you should first understand the volumetric flow rate of all air-consuming equipment, and multiply the total flow rate by 1.2 (that is, enlarge the margin by 20%);

2. The new project can be selected according to the flow value provided by the design institute;   

3. Learn about the volumetric flow parameters of the gas-consuming equipment from the gas-consuming equipment supplier for selection;   

4. The reconstruction of the air compressor station can refer to the original parameter values and the actual gas usage for selection;


Appropriate selection is beneficial to both the user and the air compressor equipment. Excessive selection is wasteful, and too small selection may cause the air compressor to be in a long-term loading state or insufficient air or pressure cannot be applied.


The relationship between power, working pressure and volume flow


In the case of constant power, when the speed changes, the volumetric flow and working pressure also change accordingly; for example: a 22KW air compressor, the working pressure is determined to be 7bar at the time of manufacture, calculated according to the main compressor technical curve Speed, the displacement is 3.8 m3/min; when the working pressure is determined to be 8bar, the speed must be reduced (otherwise the drive motor will be overloaded), at this time, the displacement is 3.6 m3/min; because the speed is reduced, the displacement Qi also decreased accordingly, and so on.


The selection of power is to meet the working pressure and volume flow conditions, and the power supply capacity can meet the power of the matched drive motor.


Therefore, the steps for selecting an air compressor are: first determine the working pressure, then determine the corresponding volume flow, and finally the power supply capacity.