Across three seating lines, the part that generates the most avoidable warranty claims is small, cheap and hidden inside the column: the office-chair gas lift. It is the first thing a price-driven supplier quietly downgrades, because the buyer never sees it on a sample. So when we quote an office chair, the cylinder class is one of the first things we pin down.
What the class number means
Gas lifts are graded by tested load and durability. In round numbers, a Class 3 cylinder is rated for about 120 kg and suits task and study chairs used a few hours a day. A Class 4 is built for roughly 150 to 180 kg and for harder duty — call centres, shared desks, 24/7 stations and big-and-tall lines. The class is not only about maximum weight; the higher class also tolerates more up-down cycles before it starts sinking on its own. The genuine article carries a mark on the steel — typically a TUV or SGS reference plus the class — and you can ask for that photo before production. We would rather you check it than take our word.
The trade-off, stated plainly
Class 3 is fine, and we ship plenty of it. For a home-office chair used four hours a day, paying for Class 4 buys a number the user never reaches. But for a contract order going into an open-plan office where different people sit in the chair all day, we push you to Class 4 — and yes, it costs more per unit. The reason is warranty math, not comfort. The few dollars saved on Class 3 across a 40HQ come straight back as replacement cylinders, freight on spares and an unhappy reseller. We have watched that happen to buyers who switched suppliers on price alone, and it is not a saving.
How we set it on your order
Tell us where the chairs are going and how hard they will be used, and we map the class to the duty. If your market has a heavier average user, we default to Class 4 on the chairs that carry your brand and keep Class 3 for the budget line — you do not have to upgrade the whole catalogue. The tilt mechanism and the cylinder are built and tested to BIFMA-style cycle patterns; testing to BIFMA or EN can be arranged per order. A "Class 4" claim with no stamp and no test reference is just a word — ask any supplier, us included, for the cylinder mark before you confirm.
If you want a chair programme spec'd by duty level, our ODM/OEM team does this every week. Start a thread through our contact page or write to mail@qmyz.net. If you also run a comfort line, the same logic applies to the actuators on our massage and recliner seating.