How to replace an office chair gas cylinder

Tools and safety

You need a pipe wrench or large adjustable wrench, a rubber mallet, a tape measure, and ideally a helper. Some people use penetrating spray on stubborn joints. Work on a clear floor with something soft underneath to protect the chair and floor.

Gas lifts contain gas under pressure. Never cut, drill, heat or open one, and do not stand on the chair. Dispose of the old cylinder through your council's recycling centre or the method the supplier recommends, rather than in household waste.

Note:Gas lift cylinders are pressurised. Do not cut, heat or open them, and wear eye protection when using a mallet.

Removing the old cylinder

The cylinder fits by a taper at each end: one into the seat mechanism, one into the centre of the base. Both lock with friction under your weight.

1. 1

   Lower the seat fully, then turn the chair upside down.

2. 2

   Pull the base off the bottom of the cylinder, or tap the base hub with the mallet around the cylinder to free it.

3. 3

   If the cylinder stays in the seat mechanism, grip the outer tube with the pipe wrench near the top and twist while pulling.

4. 4

   If it will not move, tap the side of the mechanism where the cylinder enters with the rubber mallet while twisting.

5. 5

   Some chairs need the seat removed from the mechanism first; follow your manual if it describes this.

6. 6

   Once free, check the taper holes in the mechanism and base for damage or debris.

Measuring and choosing a replacement

Most office chairs use a standard taper, so many replacement cylinders fit a wide range of chairs. Premium makers sometimes use their own parts, so for Herman Miller, Steelcase and similar chairs, check whether the maker sells a specific replacement.

Measure the old cylinder's overall length fully extended and fully compressed, from the top of the release pin to the bottom of the tube. The difference is the stroke, which sets the seat height range. Match the outer tube diameter too; 50 mm is common but not universal. If your chair sat too low or too high, a slightly shorter or longer cylinder can fix that.

Class 3 against class 4

Gas lifts are graded by class, with class 4 the heavier-duty grade. Class 4 cylinders have thicker walls and are generally recommended for heavier users and intensive use. Class 3 is common on lighter-duty chairs. If you are near the top of your chair's load rating, choose class 4. Several chairs in our guides list class 4 lifts, including ProtoArc, COLAMY, Corsair and Trust models, while the Efomao PU chairs list class 3. EN 16955 is the European standard for seating gas lifts.

Chairs with heavy-duty gas lifts →

Fitting the new cylinder

If the seat does not rise, check that the lever reaches the release pin. Some mechanisms have an adjustable contact that may need a slight tweak. Our office chair sinking guide covers lever problems.

1. 1

   Remove any protective cap from the release pin, but leave the pin itself alone.

2. 2

   Push the narrow bottom end of the cylinder firmly into the base hole.

3. 3

   Fit the plastic cover over the cylinder if your chair has one.

4. 4

   Turn the seat mechanism the right way up and lower it onto the cylinder top.

5. 5

   Sit down firmly to seat both tapers; the joints tighten under weight.

6. 6

   Test the lever: the seat should rise when you stand and stay put when released.

Frequently asked questions

Are office chair cylinders universal? Many use a standard taper and fit widely, but lengths, diameters and some premium chairs differ. Measure before ordering.

How long do office chair gas cylinders last? It varies with quality, use and user weight. Many last several years; heavy daily use wears seals faster.

Do I need class 4? It is the heavier-duty choice and a sensible default, especially for heavier users.

Can I replace a gaming chair cylinder? Yes, the process is the same. Check whether a longer cover needs removing first.