A swivel chair that sinks by itself usually has a leaking gas lift (gas cylinder), but rule out the causes in order: sitting habits and load, a stuck lever pressing the valve button, a cylinder contaminated by oil or water, the wrong cylinder stroke, and a loose base taper. PRIMEAG recommends replacing only the cylinder if the base and seat are still good; chairs carry a 12-month warranty.
Set to the right height in the morning, sunk to the bottom by mid-shift: this is the most common fault in a batch of swivel chairs after a few months in a garment factory. Replace the gas lift without finding the real cause, and it fails again a few weeks later.
- Run 5 checks from easy to hard: sitting habits, lever, gas lift, cylinder stroke, base.
- A stuck lever keeps the valve open – fix it on the spot, no need to replace the cylinder yet.
- A leaking cylinder is replaced with the same type: low, medium or high.
- Wet areas need chairs without a gas cylinder: 4-leg stainless steel chairs or stainless steel stools with a threaded spindle.
1. Five causes, checked in order
Step 1 – Sitting habits and load
Dropping heavily onto the seat, standing on the chair to reach things, overloading: these shocks wear out the cylinder seals early. If the habits stay, a new cylinder will fail again.
Step 2 – Stuck lever pressing the valve button
A bent lever, or one snagged by thread, presses continuously on the valve button, so the chair sinks gradually while someone sits on it. Lift the lever gently: if the chair then holds its height, simply straighten the lever.
Step 3 – Leaking gas lift
If the lever moves freely but the chair still sinks, or will not rise, the cylinder has lost its gas. Common culprits: machine oil, fabric dust, cleaning chemicals and water spray when cleaning wet areas.
Step 4 – Cylinder stroke wrong for the table
A low cylinder at a high table: even fully extended it is too short, and users report it as a sinking chair.
Step 5 – Cracked base, loose taper
A cylinder loose in the taper hole makes the seat wobble and clunk, and feel as if it is sinking. Turn the chair over and check for cracks around the taper hole.
2. Replace the gas lift or the chair?
| Condition | Action |
|---|---|
| Bent lever, cylinder still holds gas | Straighten or clean the lever |
| Cylinder slowly sinks, base and seat still good | Replace with a cylinder of the same stroke |
| Cylinder not high enough for the table | Switch to a high cylinder, add a foot ring |
| Cracked base, deformed taper hole | Replace the base or the chair |
PRIMEAG chairs carry a 12-month warranty; when reporting a fault, include photos of the cylinder label and the underside of the chair.
3. Choosing a cylinder by table height
An easy rule of thumb: the seat sits about 27–30 cm below the table top. A low cylinder suits sitting tables of about 750 mm; sit-stand tables of 900–1,000 mm need a high cylinder plus a foot ring. How to measure tables: standing and sitting table heights based on anthropometry.
- Tables 850–900 mm, frequent turning: laboratory chair with small backrest.
- High seating, leaning forward: saddle chair with a high cylinder.
- Inspection counters 900–1,100 mm: bar stool with footrest.
- Sewing lines: choosing chairs for sewing operators who sit all shift.
4. Wet areas: choose chairs without a gas lift
The 4-leg stainless steel chair has no cylinder; choose one of the heights from 25 to 90 cm when ordering. If you need height adjustment, use the swivel stainless steel stool with threaded spindle: rotate the seat to raise or lower it, with no gas to leak. Both are made of stainless steel 201, produced in 7–10 days; wipe dry after washing, and ask us first for areas with chlorine. For short sitting near sinks: stool with FRP plastic seat and glides.
Where to start
- List the sinking chairs with their table heights and run the 5 checks in section 1.
- Group chairs with the same fault to order cylinders or switch chair types in one go.
- Send photos and quantities via the PRIMEAG consultation page; you get a quote within 30 minutes, with a recommended cylinder type.
Frequently asked questions
- Can a chair gas lift be recharged? — A gas lift is a sealed unit; once it leaks, replace it with a new one of the same stroke. What can usually be fixed on the spot is a bent or stuck lever.
- How do I know if my chair has a low, medium or high gas lift? — Measure the seat height at its lowest and highest positions and compare it with the table height; send the measurements with a photo of the cylinder label so PRIMEAG can check.
- Is a new chair that sinks after three months covered by warranty? — PRIMEAG chairs carry a 12-month warranty. Send photos of the cylinder, lever and base so our engineers can identify the fault before replacement.
Updated: 2026-10-28 — PRIMEAG engineering team
Email: info@primeag.vn · Phone/Zalo: +84 906 108 292
Written by the PRIMEAG engineering team
Updated: 2026-10-28