What is the Cylinder Under the Office Chair

Regarding ergonomic office chairs, which are designed to enhance comfort, reduce strain, and improve posture, the cylinder must be mentioned. It is a gas lift mechanism that allows workers to adjust the height, especially when used in combination with a standing desk. This article delves into the function of the cylinder under the office chair, explaining how it works and why it matters for overall ergonomics. Not only that, Sunaofe will bring you to explore the standard height among different users.

Cylinder Introduction

Chair cylinder is under the cushion, as a pneumatic or gas lift. By using compressed gas sealed inside the cylinder, this component enables effortless height adjustment with a simple pull of a lever. Their material is high-strength steel to handle constant pressure and daily use.

A well-built cylinder is engineered to support a significant weight from 120 kg to 250 kg. Extending to Sunaofe chairs, their Morph Collection weight capacity is 300 lbs, around 136 kg, as the ideal office chair for heavy person.

Cylinder Components

1. Gas Chamber (Pressure Tube): This is the inner cylinder that holds the pressurized nitrogen gas.
2. Piston and Rod: The piston is a disc that moves up and down inside the gas chamber. It is attached to a rod that connects to the chair's seat.
3. The Valve: Located at the very top of the cylinder, this is the "gatekeeper." It is usually a small pin that, when pressed by the chair's lever, allows gas to move between different sides of the piston.
4. Bypass Channel: A small opening or path that allows gas to flow from one side of the piston to the other when the valve is open.

How Does the Cylinder Work?

The pneumatic lift uses a gas spring mechanism, using high-pressure nitrogen gas instead of metal coils. The system transforms the potential energy stored in the compressed gas into kinetic energy to lift the chair's seat against gravity. Therefore, it provides a "cushioned" feel when you sit down.

Regarding the mechanism of action, the movement of the chair depends on whether the valve is open and whether there is weight (force) on the seat.

Raising the Chair (Need to stand up and pull the lever)

• The lever pushes the valve pin down.
• This opens a passage, allowing the high-pressure gas to flow to the bottom of the piston.
• The pressure of the gas exerts an upward force (F = P x A) on the piston. (P is Pressure / A is Area)
• Since your weight is removed, the gas pressure easily overcomes the weight of the chair seat, pushing the rod upward.

Lowering the Chair (Requires sitting down and pulling the lever)

• The valve opens again.
• Your body weight provides a downward force that is greater than the upward force of the gas.
• This forces the gas back through the bypass channel into the upper chamber as the piston is pushed down.
• When you release the lever, the valve closes, "locking" the gas in place and holding the chair at that specific height.
  

Why the Cylinder Matters When Choosing an Ergonomic Chair

Regarding an ergonomic chair, the cylinder is arguably the most critical component for long-term comfort. If the cylinder fails, the chair loses its ability to hold your specific ergonomic "sweet spot," leading to poor posture and back strain.

Durability: The "Class" System

Cylinders are categorized into Classes (1 through 4) based on the thickness of their steel walls and the quality of their internal seals. This directly impacts how long the chair will last before it starts "sinking."

• Class 1-2: These gas cylinders are used on budget chairs, with a 2-year lifespan.
• Class 3: This cylinder type is standard office use, reliable for average weights. Its lifespan is more than 5 years.
• Class 4: Premium ergonomic chairs can find a Class 4 cylinder. Like Steelcase Gesture.

Tip: Look for TÜV or BIFMA certifications on the cylinder housing, which has undergone rigorous testing for thousands of cycles.

Load-Bearing Capacity

The cylinder is the primary load-bearing component. Choosing one that doesn't match the user's weight can lead to "sudden sinking" or structural failure.

• Standard Capacity: Class 3 cylinders typically support up to 250–330 lbs (113–150 kg). Sunaofe's office chair is, and has a 5-year warranty.
  
• Heavy-Duty Capacity: Class 4 cylinders are often rated for 350–500 lbs (158–226 kg) and utilize heat-treated steel for extra strength.
  

Height Range: The "Stroke" Length

The "stroke" is the vertical distance the cylinder can travel. This is critical because if your feet aren't flat on the floor, your circulation and posture suffer.

• Standard Stroke (4" to 5"): Ideal for most users (5'4" to 6'1").
  
• Short Stroke: Designed for petite users to ensure the seat goes low enough for feet to rest flat.
  
• Long Stroke: Used for "drafting stools" or very tall users to prevent their knees from being higher than their hips.

Cylinder Maintenance

To keep an ergonomic chair like the Sunaofe Morph functioning at its peak, the cylinder requires minimal but specific care. Because these systems are pressurized and sealed, you cannot "refill" them; however, you can significantly extend their lifespan through proper maintenance.

Common Issues with Cylinders

Issues 1. Over years of use, the rubber O-rings (seals) inside the cylinder can dry out or develop microscopic tears. This allows the high-pressure nitrogen gas to slowly leak into the outer chamber.

Issues 2. The chair may "jerk" when adjusting height, or it may become completely stuck at one height. Don't doubt, it is a mechanical binding. The target part is the piston rod.

Maintain Cylinders Correctly

1. Periodically wipe the silver piston rod with a clean, lint-free cloth.
2. Apply a small amount of silicone-based lubricant or white lithium grease to the rod if the movement feels "stiff." Avoid WD-40 for long-term lubrication.
3. Respecting weight limits. A strict ban on exceeding the rated capacity.

Conclusion

A pneumatic cylinder is far more than just a metal pole; it is the fundamental engine of your chair's ergonomics. By managing high-pressure nitrogen and precise piston movements, the cylinder ensures your seat remains at the exact height needed to protect your posture.

Of course, while choosing an ergonomic chair, cylinder is only one factor considered. If you want to understand more factors you need to consider, please browse our article "Good Office Chair Guidelines."