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What problems should we pay attention to when setting up the pressure switch? How to set the pressure for empty and heavy cars?
- Oct 19, 2018 -

Common problems in operation and maintenance of Air Compressors:


28.What problems should we pay attention to when setting up the pressure switch? How to set the pressure for empty and heavy cars?


There are two adjusting screws on the pressure switch. One is the pressure adjusting screw, which is used to adjust the starting pressure of empty car. The counterclockwise direction is to increase the empty car pressure. The other is to adjust the pressure difference, that is, the pressure of heavy trucks, and the increase of pressure difference in counterclockwise direction.

 

Reasonable empty and heavy truck pressure can improve the working efficiency of air compressor, reduce the running time of air compressor, and prolong the service life of air compressor. Attention should be paid to the following problems when setting up the pressure switch:

 

(1) Pressure setting of empty and heavy trucks of pressure switches is based on the upper and lower pressure limits of the air compressor control cabinet, and the setting of the upper and lower pressure limits of the air compressor control cabinet is based on the air equipment.

 

(2) the empty car pressure setting is lower than the air compressor rated pressure, generally lower than the rated pressure 0.02MPa.

 

(3) Because of the difference of the upper limit pressure between the empty car pressure and the air compressor control cabinet, there must be a certain difference between the empty car pressure and the upper limit pressure of the air compressor control cabinet. This difference is due to the pressure drop of the air dryer, air filter and other equipment. Generally, when the compressed air flow is stable, it passes through the filter and the dryer. The maximum pressure drop is set at 0.05 MPa, so the upper limit pressure of the space-time press control cabinet is set at 0.75 MPa, then the pressure switch empty car pressure should be set below 0.7 MPa.

 

(4) The greatest pressure difference of 0.1lMPa can be produced by the oil separator. If the empty car pressure is set equal to the rated pressure of the air compressor, the maximum actual working pressure of the air compressor may have exceeded the rated pressure, thus causing the motor overcurrent of the air compressor. If the air compressor motor capacity does not have an overload allowance of 10%, the air pressure opportunity will stop due to overcurrent. In this case, the air compressor empty car pressure should be lower than the rated pressure, the specific value can be determined according to the site equipment.

 

(5) Once the air compressor has been empty for too long and stopped, when the system pressure is below the lower limit, the control cabinet can not start the machine, and the pressure switch of the machine to start the machine.

 

(6) It is better to have a difference of more than 0.15MPa between the empty car pressure and the heavy car pressure of the pressure switch in order to facilitate the operation accuracy of the pressure switch.

 

(7) The pressure setting value of the pressure switch should be higher than the lower limit of the combined control cabinet pressure, and the pressure drop of the air dryer, air filter and other equipment should be considered. If the lower limit of the combined control cabinet pressure is 0.55 MPa, the setting value of the heavy vehicle pressure should be greater than 0.60 MPa.

 

(8) The pressure setting of empty and heavy trucks of pressure switches is based on the principle of not causing frequent start-up and stop of single compressor, that is, when the system pressure is high, empty truck signals are first sent out by the pressure switches, and when the pressure continues to rise, stop signals are sent out by the control cabinet; otherwise, when the system pressure is low, heavy truck signals are first sent out by the pressure switches, and pressure signals are sent out by the pressure switches.The control cabinet will also send out the start signal when it continues to decrease.

 

(9) When several air compressors are connected in parallel, the pressure of empty and heavy trucks of the pressure switches can not be set to a constant value of increasing or decreasing step by step. If set in this way, it will cause a machine to start or close frequently and reduce the service life of the machine. We should strive to set the same value so as to facilitate the normal switching and running timing of the main cabinet of the control cabinet.