Office Chair Sinking Issue

The sinking of an office chair may be a normal phenomenon or a fault, which needs to be judged and handled according to the specific situation.

Normal Phenomenon

When sitting down, the chair sinks slightly by 1-2 centimeters and rebounds on its own after standing up. This is a normal physical phenomenon for pneumatic lift chairs. The piston inside the gas spring cannot be completely sealed, leaving a small space for gas compression, which causes slight sinking.

Fault Conditions and Causes

If the chair drops directly to the bottom as soon as you sit down, cannot be locked during its travel, or experiences slow and continuous sinking, it indicates a fault with the chair. Common causes are as follows:

• Faulty gas spring: The sealing ring ages, leading to the leakage of high-pressure nitrogen and insufficient support force; or a low-quality gas spring is used, such as one with a thin tube wall, substandard material, or insufficient purity of the internal gas (nitrogen purity below 90%).
• Failed adjustment lever: The seal of the black tray (throttle) that controls the lifting fails, preventing it from locking the height.
• Loose connections: The connecting screws between the base, gas rod, and seat are loose.

Inspection and Repair Methods

• Inspection:
  • Safety check: Turn the chair over and place it on an open and flat surface for inspection.
  • Check screws: Tighten all visible screws, especially those at the connections between the base and gas rod, and between the gas rod and seat.
  • Press test: Press down hard on the seat. If there is little or no resistance and you hear a hissing sound of air leakage, it indicates that the gas spring has failed.
  • Observe sinking pattern: Sit on the chair. If it sinks slowly and uniformly or drops rapidly to the lowest point, it indicates that the sealing ring of the gas spring has aged or there is gas leakage.
  • Preliminary check for oil stains: Tilt or invert the chair and check for black or transparent oil stains seeping out at the connections between the gas spring and the seat, and between the gas spring and the five-star base. If so, the sealing system is damaged.
• Repair:
  • Simple repair: For slow air leakage caused by poor sealing at the top of the oil cylinder, add one or two drops of engine oil around the vent button or sealing ring to increase the sealing property, but this is only a temporary measure.
  • Use hose clamps: Follow the steps, including removing the plastic skirt, wrapping the hose clamp, improving the grip, tightening the clamp, and testing and adjusting.
  • Use PVC pipes: Measure the diameter and length of the cylinder, purchase suitable PVC pipes, cut them, and push them onto the cylinder for fixation.
  • Replace the gas spring: If the above methods are ineffective, or if the gas rod has cracks, obvious rust, or deformation on its surface, stop using it immediately and replace the gas spring or the entire chair. When replacing, separate the gas spring from the five-star base and the seat according to the steps.