Office Chair Sinks When Sitting

The most common reason an office chair sinks when sitting is the aging or poor sealing of the gas lift, leading to the leakage of high-pressure nitrogen gas inside or the wear of the oil seal, which is a normal wear and tear phenomenon. Specifically, it manifests as the gas lift being unable to maintain the locking pressure and showing 'slow sinking' or 'weak rebound' under the pressure of the human body weight. Here are detailed analyses and handling suggestions:

Fault Diagnosis Methods

1. Listen to the sound and feel
   When lifting or sitting quietly, if you hear a distinct 'hissing' air leakage sound or a stuttering noise from metal friction, it may indicate that the gas lift's seal has failed or the internal structure is worn.

2. Observe the sinking pattern

   • Slow and continuous sinking: Slow leakage of high-pressure nitrogen gas inside the gas lift, which is a common fault.
   • Sudden and resistance-free drop: It may involve serious damage to the internal structure of the gas lift (such as piston breakage), and use should be stopped immediately.

3. Check mechanical connections
   Check whether the connections between the gas lift and the five-star base (pedestal) and the seat chassis are loose. Loose screws may cause the chair to be unstable, but usually do not trigger regular automatic sinking.

Distinguishing Normal Phenomena from Faults

• Slight cushioning sinking: When sitting down, the seat sinks 1-2 centimeters as a cushion and rebounds automatically after getting up. This is a normal phenomenon due to the piston's inability to be completely sealed and does not require repair.
• Fault manifestation: If the chair continues to sink slowly as soon as you sit down or directly drops to the lowest point and cannot be locked, it indicates a failure of the gas lift and requires repair or replacement.

Repair and Replacement Suggestions

1. Strictly prohibit self-disassembly
   The inside of the gas lift is under high pressure. Self-disassembly, drilling, or repair may lead to the risk of explosion and must be handled by professionals.

2. Contact the official after-sales service

   • If the chair is within the warranty period, mainstream brands usually provide a 3-5 year warranty for core components such as the gas lift and chassis, and you can enjoy free repair or replacement services.
   • If the warranty period has expired, you can inquire about official paid repairs or purchase original parts.

3. Replace the gas lift by yourself
   If the chair is out of warranty and the official repair cost is too high, you can replace the gas lift by yourself, but note the following:

   • The gas lift is a one-time sealed component and cannot be repaired, only replaced as a whole.
   • When replacing, choose a specification that matches the original chair (such as the stroke and load-bearing grade of the gas lift) to avoid safety hazards.