Atlas Copco Minimum Pressure Check Valve Kit Replacement – 2901099700

The Atlas Copco Minimum Pressure Check Valve Kit – 2901099700 is an important component used in rotary screw air compressors. Its main job is to maintain the correct internal pressure inside the compressor and prevent reverse airflow when the machine stops.

How the Minimum Pressure Check Valve Works

1. Compressor Start-Up Phase
When the compressor starts, air is compressed inside the air-oil separator tank. During this stage, the minimum pressure valve remains closed until the internal pressure reaches a preset value (usually around 4–5 bar).

This controlled pressure is necessary because:

It ensures proper oil circulation and lubrication
It helps efficient oil-air separation
It protects internal compressor components from damage

2. Pressure Build-Up
As compressed air pressure increases, the spring-loaded valve inside the kit begins to respond. Once the preset pressure is reached:

The valve gradually opens
Compressed air flows to the air system or receiver tank
Stable operating pressure is maintained

3. Normal Running Condition
During normal compressor operation, the valve:

Maintains minimum separator tank pressure
Reduces pressure fluctuations
Helps improve oil separation efficiency
Protects the separator element from excessive pressure difference

4. Compressor Shutdown
When the compressor stops:

The check valve/non-return function closes immediately
Prevents compressed air from flowing backward into the compressor
Keeps pressure in the air network or receiver tank stable
Main Components Inside the Kit

A typical minimum pressure check valve kit contains:

Valve housing
Spring
Piston or valve disc
O-rings and seals
Retaining components
Common Problems When the Valve Fails