the Workshop Compressor
  • Home
  • Air Compressor Info
    • Compressor Types
    • Compressor Parts
    • Compressed Air Uses
    • Systems and Components
    • Compressed Air Quality
  • Buying Guide
  • Calculators
    • Running Cost Calculator
    • Bar and Psi Calculator
  • Home
  • Air Compressor Info
    • Compressor Types
    • Compressor Parts
    • Compressed Air Uses
    • Systems and Components
    • Compressed Air Quality
  • Buying Guide
  • Calculators
    • Running Cost Calculator
    • Bar and Psi Calculator
the Workshop Compressor
  • Home
  • Air Compressor Info
    • Compressor Types
    • Compressor Parts
    • Compressed Air Uses
    • Systems and Components
    • Compressed Air Quality
  • Buying Guide
  • Calculators
    • Running Cost Calculator
    • Bar and Psi Calculator
  • Home
  • Air Compressor Info
    • Compressor Types
    • Compressor Parts
    • Compressed Air Uses
    • Systems and Components
    • Compressed Air Quality
  • Buying Guide
  • Calculators
    • Running Cost Calculator
    • Bar and Psi Calculator
Home » Compressed Air 101 » Air compressor parts: about the things you will find on your compressor. » Air compressor inlet valve

Air compressor 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.

There is another type of valve also called ‘unloader valve’, which is completely different and which can be found on small reciprocating piston compressors.

When the desired pressure is reached, the compressor will go in ‘unload’ mode: the unloader valve will almost completely close the air intake of the compressor. This way, no more are can be sucked in and compressed, so the compressor is basically just turning around, doing nothing.

At the same time, the pressure that is still inside compressor element is released through a small hole (you will hear a sssssshhh sound).

unloader valve of screw compressor  Unloader/inlet valve mounted
on top of compressor element (portable
compressor)

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/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.

Example of inlet/unloader valve… this one is from a 15 year old rotary screw compressor (Atlas Copco GA37)

inlet-valve-old-compressorInlet valve on old stationary rotary screw compressor.

Another example… this is the inlet valve of a brand new screw compressor (Atlas Copco GA30).

intake-valve-new-compressorBrand new inlet valve, with small control valve and solenoid on the right.

Compressed Air 101 Topics
  • Compressed Air 101
  • Compressor types: different ways to compress air
    • Rotary screw compressors
      • How oil-injected rotary screw air compressors work
      • How oil-free rotary screw air compressors work
      • Screw air compressor elements (air-ends)
    • The Reciprocating air compressor
      • Single stage reciprocating air compressors
      • Two stage reciprocating air compressors
    • The Scroll compressor: quiet and easy
    • Portable air compressor
      • Portable air compressor parts and maintenance
      • Portable air compressor operation
      • Best Portable air compressor
  • Air compressor parts: about the things you will find on your compressor.
    • Compressor Air filters
    • Air compressor oil filter
    • Air compressor oil
    • Air compressor pressure switch
      • How a compressor pressure switch works
      • Setting your air compressor pressure switch
      • Air pressure switch models and options
      • Buying a Compressor pressure switch
    • Air compressor unloader valve
    • Air compressor inlet valve
    • Air compressor check valve: what it does, why it’s there and how it works.
  • Air compressors are everywhere! Overview of top air compressor uses
    • Scuba diving and the scuba air compressor
    • Paintball compressor
    • Dental Compressor
    • 12 volt air compressor
  • Compressed air systems and Components
    • Compressed air filters
    • Inline compressed air filter
    • Compressed air piping
      • The best compressed air pipe for you
      • Compressed air pipe sizing
      • Compressed air pipe sizing calculation
    • How to select a compressed air dryer
      • Refrigerated compressed air dryer
      • What you should know about your desiccant compressed air dryer.
      • Compressed Air Dryer Manufacturers
  • Compressed air quality: how clean do you want your compressed air?
    • Clean compressed air
Subscribe

Subscribe To Our Newsletter

Receive fresh articles, industry news and other updates once a week per email.

You have Successfully Subscribed!

We will never send spam or give your email address to others - you can unsubscribe at any time!

Recent Articles
  • New: Compressed Air Calculators!
  • A little history

Let me help you with your workshop compressor setup :

  • Compressed Air 101
  • Buying Guides
  • More coming soon…
Scroll to top
Skip to content