Unloading valve/inlet valve

The Air Compressor inlet valve regulates the capacity of your rotary screw compressor.

The air compressor unloader valve regulates the amount of air that is sucked in by your air compressor. By opening and closing the air intake, the capacity of a rotary screw compressor is regulated.

This valve is also commonly called an inlet valve,  intake valve, unloader and unload valve.

Air compressor inlet valve working principle:

Inlet valve ,also named intake valve,unloading valve and etc.It’s the breath part of air compressor,the gas go into the airend after inlet valve and gas is produced when compressed.It can control the air compressor loading and unloading and air pressure follow and etc function,it’s one of the main part of air compressor (air inlet control system).

Inlet valve consist of valve body,valve,piston,cylinder,spring,seal ring and etc,have control block and solenoid valve on the side of inlet valve,integrated regulation,unloading,silencer,decreased pressure and release and etc function.When the inlet valve unloading,a small part of gas will release through the holes in the valve to balance the intake volume of the inlet control valve hole and keep the oil separator tank pressure range between 0.2~0.3mpa which can maintain the air compressor lubricant cycle.The adjust system pressure sensor and solenoid automated control the inlet valve start or closed,the flexible of opening and closing action of the air intake control valve,is the most important for the reliability of the screw compressor.

What’s the common problem of inlet valve ?Normally is compressor not loading,inlet valve doesn’t closed.Inlet valve solenoid valve damage will cause loading issue,control valve block break down caused compressor oil leaking,if screw compressor over load,the air inlet vale will open before start-up.So the inlet valve should be repair or replace regularly to ensure in a good working conditions.While maintain the inlet valve,have to knock down the spare parts and check the friction surface of each part,especially the rubber seal ring surface,have to replace new one if have any damage or crack,all the parts should be clean and metal parts surface should be coated with lubricant.

Normally the instructions shows that have to replace air inlet valve kits after 8000Hrs.To save cost,some users don’t maintain accordingly until the inlet valve error,we suggest that should be do the maintenance in a reasonable period even though the compressor doesn’t have breakdown,as every compressor working environment is different.

The inlet valve mainly used for control loading and air pressure follow and etc,once the air into inlet valve to the airrend,gas is produced when compressed.The air compressor air (Nm/Min) depends on the air inlet valve,it’s relative with outlet.Once the air compressor start-up,the inlet valve is on closed to decreased the compressor main engine start load.In normal operation, according to the detected exhaust pressure and setting value, the regulating valve starts to make the inlet valve gradually closed or open with the pressure, making the outlet volume reduced in proportion, and control the air compressor to complete the load, unloading and other actions.

Note that there is always a small hole in the air compressor unloader valve, so it will never close 100%. This is to make sure there will be enough oil flowing for lubrication and cooling.

Most unloaders are of the Load or Unload type. Which means they are either completely open (compressor loaded) or completely closed (compressor unloaded). In unloaded state, when the unloader is closed, the unit will consume about 30% of it's nominal power.There is another type: CONTINUOUS or MODULATING. This way the compressor can work at any point between 0 and 100%. It is not often used in stationary compressors (it's not the most economical way of regulation). But it is often seen in portable diesel engine driven compressors.