Screw Air Compressor Valves

An air compressor is a device that makes use of air or pressurized gas to convert electric or chemical energy into potential energy. One of its many types is a Screw Air Compressor which uses a rotary-type positive-displacement mechanism. This screw air compressor is made up of multiple valves which are discussed extensively below:

The main function of the intake valve is to control the amount of air that is sucked in by the screw air compressor. When the intake valve is wide open, air will enter inside the compressor,  the pressure of the air inside will begin to rise. When the air pressure has risen to the required pressure value, the intake valve almost completely closes to prevent any more air from entering the compressor. The intake valve is never completely closed and a little hole is always open. This little hole allows oil to keep flowing in so that the compressor stays lubricated and cooled.

The function of a check valve is to allow only one-sided flow. What this means is that the air approaching it from one direction will be allowed to flow through it but if the air is approached to it from an opposite side, it will not be allowed to flow through. This is extremely important to have in the compressor since different parts inside may need to be depressurized. Placing check valves in the right spots can thus be used to maintain different pressures inside the compressors.

The function of a minimum pressure valve is essentially just to make sure the air inside is at or above a certain pressure value. This pressure value is dictated by the oil circulation requirements. For the rotary screws to remain cooled and lubricated, the oil needs to be circulated inside. This oil does not spread below the minimum pressure value thus, this valve is essential to have.

The function of the oil stop valve is similar to a check valve except that it allows the one-sided flow of oil only. The oil approaching the valve from one direction will be allowed to pass through it but the same oil approaching it from the opposite side will not be allowed to pass through it. This is important to have since usually when the compressor is stopped, the oil tends to flow back to the inlet filter so having the oil stop valve prevents that from happening.

As the name suggests, the function of the temperature control valve is to regulate a certain temperature inside the compressor. The temperature control valve is essential to have in a screw air compressor since its absence leads to numerous problems such as oil metamorphism which, in turn, can cause wear and tear in the compressor. Not having this valve also shortens the lifespan of various parts.

The safety valve is a simple yet crucial part of any screw air compressor. Its function is to control and restrict unwanted pressure buildup in the compressor. It makes sure that the pressure inside does not exceed the maximum allowable working pressure (MAWP). The compressor parts can be badly damaged or, in a worse case, can even explode in the absence of a safety valve.

The main function of the solenoid valve is to prevent the compressor from staying pressurized for a long time in order to avoid receiving any damage. What happens is that when the system is operating and the motor is running the compressor, power is provided to the solenoid valve and it is kept at a specified pressure. When the tank is filled and the compressor is to be shut down, the motor stops but the pressurized air remains in the compressor. The solenoid valve then comes into play and de-energizes and exhausts air away from the compressor.

The function of a vent valve is to finish the job of the solenoid valve. The solenoid valve releases pressure from the main rotors but the air is still within the compressor. The vent valve releases that air from within the compressor to the atmosphere. In the absence of a vent valve, the trapped air remains in the air compressor and it adds load to the start circuit.

The compressed air by the rotors is often stored in a tank. In that tank, a capacity regulating valve is used to control the pressure of that tank. This essentially means that this valve can open or close to either restrict or release the pressure according to the requirements of the output pressure required.

The function of an inverse proportion valve is to ensure automatic regulation of air input according to the air output. Its main working principle revolves around the fact that the higher the exhaust pressure of the system, the lower is the control pressure. The control pressure is related directly to the degree by which the inlet is opened so essentially, the higher the exhaust pressure is, the less air is allowed by the intake valve(and vice versa).

When the intake takes in atmospheric air, it includes water vapour. The water vapour is compressed along with the air and can cool down to form water droplets. These droplets can cause serious damage to the compressor parts such as rust, corrosion, etc. To avoid any such damage, a drain valve is used. The function of the drain valve is to simply filter the water out of the air and is then drained out of the whole system.

The function of the bypass valve is to control the temperature of the oil and prevent it from going too low or too high. The valve comes along the oil system. When the oil temperature is below its set point, the bypass valve shuts off the supply to the oil cooler and the oil cooler is bypassed. If the oil temperature exceeds the set value, the valve starts opening the supply from the cooler.