Office chairs or desk chairs in use today feature height adjustment with a gas cylinder, sometimes referred to as a pneumatic lift. I have also heard some people call it a hydraulic shaft or even a plunger piston. The most common name in the industry refers to it as a gas cylinder.
I am often asked by people which office chair gas cylinder replacement is right for their office chair. To answer that question, we must first determine if the office chair manufacturer used a standard cylinder. Unfortunately, the markings you see on the gas cylinder that you currently have do not list the exact specifications.
You can easily determine which gas cylinder is right as a replacement without having to disassemble the chair or remove the gas cylinder.
A standard office chair gas cylinder basically has two parts. The top part is called a gas spring and has a diameter of 28 mm or 1.1 inches. The gas spring is what holds the pressurized nitrogen gas and some oil for lubrication. The top end of the gas spring holds the actuator or the button that, once pressed, lowers or raises the chair. This is the end of the gas spring that goes into the hole in the mechanism that's attached under the seat of the office chair. The top end portion of the gas spring is slightly tapered. The industry standard taper is 17-4 .
The other end of the gas spring has a piston that actually moves in and out of the gas cylinder and, in the process, lowers and raises the office chair.
The second part of the gas cylinder is the column. The column is approximately 2 inches in diameter, and that’s the end that goes into the five-legged base where the casters are. You will notice that most columns protrude from under the base.
Office chair gas cylinders are identified by the stroke. The stroke can best be explained by the travel of the seat from the lowest setting to the highest setting. So a 4-inch stroke gas cylinder means that your seat is going to travel or be raised 4 inches from the lowest setting to the highest setting. On our website, the part number is GC-4.
The easiest way to determine the stroke of your office chair gas cylinder is to take some measurements. You can take these measurements without removing the gas cylinder from the chair.
First, lower your office chair all the way down and move it next to a wall or a door. Using the arm or top of back as a template, place a mark on the wall or door. Then raise your office chair all the way up and make a second mark from the same exact spot as the first mark. Measure the distance between the 2 marks. The measurement is the travel of the seat, which is also the stroke.
The second consideration when choosing an office chair gas cylinder is to look under the chair base and measure how much the column is protruding from under the base.
Once you have taken these measurements, it will be easy for you to find the right gas cylinder for your office chair at our website, as we list all these measurements for the various gas cylinders that we offer.
Now that you have determined the proper replacement gas cylinder for your office chair, we will now discuss how to remove the old gas cylinder and install the new replacement gas cylinder for your office chair.
You will need some tools, starting with a hammer, flat head screw driver, WD-40, or liquid wrench.
Rotate the office chair so that the top of the back and front of the seat are resting on the floor. Positioning the office chair this way makes removing the gas cylinder easier.
Hold one of the base legs in one hand and apply pressure upwards as if you are lifting the office chair. With the hammer, strike the bottom of the office chair gas cylinder column that typically protrudes from the underside of the office chair base. Do not strike the center of the column where the retaining clip is located. Strike the rim area and rotate where you are striking. Continue striking in this manner until the office chair base pulls off.
There are instances when this method may not work. In that case, use the flat screwdriver and remove the clip and flat washer from the bottom of the gas cylinder column. Lift the office chair base and the attached gas cylinder column out.
Turn the office chair base with the attached gas cylinder column upside down and strike the gas cylinder column rim area until it pops out, freeing the base.
Remove the seat plate from under the seat. Place it flat on the floor. Spray some WD-40 around the space where the gas cylinder snaps into the hole. With the hammer, tap gently on the sides of the gas cylinder to help the WD-40 penetrate. Wait a couple of hours. Lift the gas cylinder with the seat plate still attached a couple of inches off the floor with one hand and strike the seat plate with the hammer as close to the old gas cylinder as possible, rotating where you are striking. It should come out.
Installing the new office chair gas cylinder replacement is a whole lot easier than removing the old gas cylinder. While your office chair is still in the upside down position described above, insert the gas spring end of the new gas cylinder into the hole in the mechanism. Slightly push down to set it firmly inside mechanism. Set the base onto the column end of the gas cylinder and press firmly down .Turn office chair upright and your done with assembly. Before sitting on the chair, use your knee to press onto the seat to further set the parts together. Now you can sit and raise and lower the office chair.