PSA Oxygen Filling System: Determining Cylinder Fullness

While molecular sieve pressure swing adsorption (PSA) oxygen generators can meet the oxygen needs of small and medium-sized users, bottled oxygen is more suitable for intermittent or highly fluctuating oxygen demands. Combining these two approaches has led to the development of PSA oxygen filling systems. This equipment can simultaneously address the needs of on-site oxygen generation and oxygen cylinder filling. However, in practical operation, it is impossible to visually determine whether an oxygen cylinder is full. The following methods can be used:

I. Pressure Value

1. Principle

• During oxygen cylinder filling, pressure inside the cylinder gradually increases as oxygen is continuously injected. When the cylinder is full, the pressure stabilizes at a specific value. A pressure sensor can monitor real-time pressure changes.

• An empty cylinder initially exhibits pressure close to normal atmospheric pressure.

2. Operation Method

• After connecting the cylinder to the filling system, check the initial pressure before starting. If the initial pressure is near atmospheric pressure, the cylinder is empty or contains minimal residual gas.

• During filling, when the pressure rises to the preset full-pressure value (determined by cylinder specifications and requirements) and remains stable for a period (e.g., 1-2 minutes), and the flow meter shows no significant gas flow, the cylinder is full. For example, if the target pressure is 15MPa, reaching and maintaining this pressure with zero flow indicates full capacity.

II. Flow Meter Monitoring

1. Principle

A flow meter measures oxygen inflow. As the cylinder fills, internal space decreases, increasing resistance to gas flow. When nearly full, flow rate slows significantly or approaches zero.

2. Operation Method

Observe the flow meter during filling. Initially, it will show a high flow rate (e.g., 10 m³/min). As the cylinder fills, the reading gradually drops. When flow falls below 0.1 m³/min and pressure stabilizes at the target value, the cylinder is full.

Post-Filling Procedures

Once confirmed full: 

• Close the oxygen supply valve to stop gas inflow.

• Carefully disconnect the cylinder from the system.

• Store the cylinder in a ventilated area away from fire sources per safety regulations.

• Ensure secure packaging meeting transport standards if shipping.