How often should the gas cylinder on a drafting chair be replaced?

A Class 4 gas cylinder on a commercial drafting chair should last 5–8 years of daily use before the seal begins to fail (evidenced by the seat slowly sinking during use). Replacement cylinders are typically available for commercial chair brands and cost $20–$60. The replacement process takes 5–10 minutes with a pipe wrench. At OfficeFurniture2go.com, we carry replacement cylinders for the chair brands we stock — call 1-800-460-0858 for parts sourcing help.