About Air Intake Valves for Air Compressor

A general rule for screw air compressor intake valves is: The intake valve is loaded with power and unloaded with power loss.

Sometimes our equipment in the case of unloading, the current is slightly larger (22kW unloading current of 31A), preliminary suspicion that the intake valve is not closed tightly, because in the absence of gas, the machine unloaded, the pressure will slowly rise, and sometimes high-pressure alarm shutdown! Moreover, after stopping the machine, there is still some residual pressure inside the machine that cannot be unloaded (around 6kg), leading to overloading of the main unit when it is started up again.

Screw air compressor intake valve belongs to normally open intake valve, screw air compressor is not loaded when the solenoid valve is open, after the compressor is loaded solenoid valve is closed. When the solenoid valve is open, there will be a way to close the intake valve, but not completely shut down, but also to retain the inlet space to maintain the minimum pressure required for compressor lubrication, this pressure is generally in the 1.5bar; solenoid valve is closed, the compressor will enter the normal operating state, until the set operating pressure, which depends on the user.

The inlet valve has two ways of pipe, one way to empty, one way to bleed off the remaining air in the valve to ensure that the compressor is normally loaded. When unloading, the current is too high, which means that the tank pressure is high, and the intake valve opening tip is large, please adjust the air release screw to ensure that the tank pressure is not too high.

After the screw compressor stops, the tank pressure can usually be completely emptied in about 60 seconds, i.e. the pressure is 0. And there’s still 6 bar in the tank pressure, indicating a problem with the intake valve bleed line: It may be that the diameter of the pipeline is too thin; the combination of valve orifice is too small or whether debris clogging.

After unloading, the pressure will rise slightly back and forth, but this is only needed for balancing and for a short period of time. Will not rise to high pressure shutdown, high pressure shutdown should be the air compressor solenoid valve problem, please check whether it is intact, whether it can work properly. Regardless of the type of intake valve, the tank pressure should be maintained between 1.0 and 2.0 Bar during unloading, as too high a level is a waste of energy for the screw compressor.

Why won’t the intake valve open? What are the solutions?The air intake valve of the screw air compressor is the component that controls the air pressure in the storage tank. Commonly used air intake valves are rotating disc structure and reciprocating valve plate mechanism, which use disc or valve plate to open or close the air inlet to control the air flow into the head.

There are two types of control: One is a switch that closes the air inlet when the tank pressure reaches a high limit setting and reopens the air inlet when the pressure drops to a low limit setting. The other is, when the storage tank reaches a certain pressure, rotating discs under the control of the proportional valve micro-closed air inlet, when the storage tank pressure further increase, the air inlet is further narrowed, when the pressure of the storage tank is slightly reduced, the air inlet will be increased, so that the pressure is stabilized in a certain range. When the pressure has not reached the tolerance pressure, the intake valve disc is fully open, and the inlet port is fully open. Intake Valves for Air Compressor

Reasons and solutions for the intake valve of a PM VSD screw compressor  to close while it is running:

1. Excessive water in the control pipes and daily maintenance of the control pipes.

2. Intake valve work error; check the cylinder, valve sleeve and other parts, replace them if necessary.

3. Air intake valve stuck; check intake valve, sleeve, or shaft and replace them if necessary.

4. Intake valve spring broken; replace spring.

5. Solenoid valve  failure; repair or replace it as needed, should check the wiring before replacement.

6. Reciprocating valve damaged, repair or replace it.

7. Solenoid valve wire connector loose; check and tighten the wire terminal.

These can cause screw compressor inlet valve failure and should be handled with care during production operations. The intake valve is generally a normally closed valve to prevent a large amount of gas from entering the head during start-up and increasing the motor starting current.

The screw compressor intake valve has an intake bypass valve to prevent a high vacuum from forming in the head when the machine is started and unloaded, which can affect the atomization of the lubricant.