Pneumatic and Hydraulic Office Chair Cylinders

The height adjustable office chairs generally have a cylinder. Do you know what type of cylinders of the office chair you are sitting on? 

Nowadays there are two types of office chair cylinders: Pneumatic and Hydraulic. But most office chairs are installed with pneumatic cylinders. Some people call it gas cylinders, gas lifts. 

These two cylinders work in the same way, but their structure and infill stuff is different.

Let’s look at them one by one.

The Pneumatic Cylinders

Pneumatic cylinders work similarly as the pump for bicycle tire. When pressing the pump, the air is compressed into the inner tube and then discharged through the nozzle of the pump, entering to the outer cylinder tube.


The pressure level inside the pneumatic cylinders is very high. The cylinder cavities are filled with pressurized nitrogen instead of a simple air chamber. And these nitrogen is completely sealed, where the high pressure of these cylinders is stuck. You can know the structure of  the cylinders from the “gas cylinder installation” .


However, there is a way to release some of this pressure. The red button in below picture is the moving part of the cylinder which is locked in place by a gas spring. After unlocking, the high pressure will push the gas spring upwards. The chair is raised.


Whenever you raise your office chair, this is what happens behind the scenes. So how does your office chair sink?

If you unlock the spring and sit on the chair, it will drop back down. Nitrogen cannot be compared with your weight. It must accept the spring to return to the chamber and lower the seat of the chair.

You may be thinking, after adjusting the right height, how can I lock it? It is not the top or bottom, it is midway. It’s really easy. Whenever the activation button is not pressed, the spring locks in place. No pressure or weight can change it. 

Moreover the safety of office chair gas lift is mentioned by people some time.

The Hydraulic Cylinders

Hydraulic cylinders works the same as Pneumatic ones .But they have two chambers, Besides, they are filled with liquid, not nitrogen. 

One chamber is filled with high-pressure in-compressible oil. The other includes an expandable piston. The two chambers are connected at the bottom. However, a valve is designed to prevent high-pressure oil from entering the piston chamber.

If you raise the adjustment lever, the valve will open. And it will allow fluid to enter the piston chamber. The pressure of the incoming fluid forces the piston upward. Because it is in-compressible oil, it is powerful enough to lift the weight of the piston, which makes the seat of the chair raise. Like pneumatic cylinders. When you pull the lever, the hydraulic chairs don’t automatically lower. You need to increase the weight. You can sit on the chair and pull the lever. When doing this, you will force the piston down. This will also force the oil through the valve and into its chamber.



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