Two-stage Air Compressor

Two-stage Air Compressor

Common Problems:

1. Malfunction Check Valve

Check valve act as a “One Direction Custom Gate” in between piston head and storage tank. High pressure can only go from piston to tank and not the other way round.

Piston air creates high pressure air, while tank store air. Check valve gate is closed at the beginning. Piston head creates high pressure fluid, gate open, air flow to tank, gate is closed and another cycle begins. The piston creates air bits by bits until the tank has enough air (indicated by tank pressure). The creates-air and receive-air process stop when tank pressure reached a desired pressure (12 bar)

When check valve failed to work, two conditions will happen.

a. When tank is at low pressure (4 bar)

Say if at time tank is at low pressure around 5 bar, and check valve does not work and the piston air and tank air can flow freely to each other. Piston will create air (let say created air is at 7 bar) and this air will keep flowing to tank. Everything seems fine at the moment.

b. When tank have enough air and now tank at high pressure (10 bar)

Since there’s no gate and air can flow freely, the higher pressure side (tank – 10 bar) will push fluid to the lower pressure side (piston 7 bar). Now the tank is high at pressure, so tank air will force itself to piston side. Piston would not slow down because the tank haven’t reach desired pressure at 12 bar). When strong air coming from tank side, just as someone find himself harder to walk against strong wind, he will walk with greater effort, the piston head is now ordering the motor to supply more power so piston can push harder.

As this continue to happen, motor will work at higher and higher amp, eventually overheat and stop working.

2. Improper pulley size

When user assemble the air compressor themselves, they might use an unsuitable pulley, usually a few sizes too big then the desired one.

Our piston head is operating at maximum 800RPM, while the electric motor is operating at 1450RPM. The pulley size must be chosen accordingly. This is not hard to calculate as pulley online calculator is available online.

The pulley of electric motor side if too big, will burden the piston; if too small, will be energy inefficient.

Before using the air compressor, foremen could measure the motor ampere at it is advised to not exceed 11AMP.

3. Pressure valve/ Limit Switch setting and pipe leakage

User can set pressure valve to operate at maximum working pressure. At the same time, user must check there’s no pipe leakage else it will affect compressor performance.

4. Malfunction Control Switch (Green and Red Button)

When pressure switch senses that the tank has enough air ( reach desired pressure), it will activate a spring and send data to control switch and tell it to stop. For whatever reason control switch is ordered to stop but does not stop, air compressor head will continue to operate. When it’s operating non-stop, electric motor will overheat and die off. The air compressor tank will not explode as long as the safety valve is releasing excess air from the tank.


  1. I have a question for you if you have a second. Are vertical tank air compressors better than horizontal tanks? I was told that the vertical tank compressors can handle higher PSI. That doesn’t seem right though… I really appreciate the help!

    1. Hi dear,

      Speaking for our own products, there is no difference in term of maximum pressure for both tank. Given the same capacity, both tanks can withstand same pressure. Vertical tank cannot handle higher PSI. The only plus for vertical tank is space saving.

      Horizontal usually have roller underneath and make itself portable at work.

      Air compressor tend to gather air droplets at bottom of the tank, especially we are in a tropical country. Often air compressor is placed on work site with uneven flooring. If both vertical and horizontal tank is placed on an even flooring, its easier to drain for vertical tank, because water inside the horizontal tank might tilt to somewhere far from the drainage port.

  2. Hi, thank you for such a brilliant post. I have been reading some blogs that gives me more knowledge about two stage air compressor; I must say this is one of the best among them. You have done a great research for I feel, thanks for sharing.

Leave a Reply

Your email address will not be published. Required fields are marked *