Atlas Copco Check Valve Kit Replacement – 2906040400

The Atlas Copco 2906040400 is a Check Valve Kit used for servicing the check-valve assembly in applicable ZT110–145 compressors. The check valve controls the direction of airflow within the compressor system and prevents reverse flow when operating conditions change.

The check valve is important during loading, unloading and shutdown because it helps prevent compressed air from flowing backward into upstream compressor components.

Working Process

1. Compression – The compressor generates compressed air.
2. Forward Flow – Compressed air travels through the designated discharge path.
3. Check-Valve Opening – When upstream pressure is higher than downstream pressure, the valve opens and allows forward airflow.
4. Pressure Equalization – The valve remains open while the required pressure difference exists.
5. Flow Reversal Attempt – When downstream pressure becomes higher, the valve moves toward the closed position.
6. Backflow Prevention – The closed valve prevents compressed air from returning toward the compressor.
7. Compressor Protection – Preventing reverse flow helps protect internal compressor components.
8. Continuous Operation – The valve automatically responds to pressure differences during compressor operation.

Main Functions

• Controls one-way compressed-air flow.
• Prevents reverse airflow.
• Helps protect compressor components during unloading and shutdown.
• Supports stable compressor pressure.
• Helps maintain correct system operation.
• Restores check-valve performance during maintenance.
• Helps reduce leakage through a worn valve assembly.

Typical Failure Conditions

The check valve can develop problems because of:

• Normal mechanical wear.
• Damaged valve components.
• Contamination.
• Corrosion.
• Worn sealing surfaces.
• Weak or damaged internal components.
• Incorrect installation.
• Excessive operating cycles.

A faulty check valve may cause:

• Reverse airflow.
• Pressure loss.
• Compressor unloading problems.
• Abnormal pressure fluctuations.
• Increased energy consumption.
• Longer compressor running time.
• Abnormal noise.
• Difficulty maintaining system pressure.

Maintenance Procedure

Before servicing the check valve:

1. Shut down the compressor according to the applicable Atlas Copco service procedure.
2. Isolate the electrical supply.
3. Fully depressurize the compressor.
4. Allow hot components to cool.
5. Remove the check-valve assembly.
6. Inspect the valve and sealing surfaces.
7. Remove worn components.
8. Clean the valve housing and mating surfaces.
9. Install the replacement components supplied with 2906040400.
10. Check that the valve moves freely in the correct direction.
11. Ensure all sealing components are correctly seated.
12. Reassemble according to the applicable Atlas Copco procedure.
13. Restart the compressor.
14. Check forward airflow.
15. Check for reverse flow or abnormal pressure behavior.
16. Inspect for leakage and abnormal noise.

Service Benefits

Using the 2906040400 Check Valve Kit during appropriate maintenance helps:

• Restore one-way airflow control.
• Prevent reverse compressed-air flow.
• Improve pressure stability.
• Protect the compressor during unloading/shutdown.
• Reduce leakage.
• Improve compressor reliability.
• Reduce maintenance-related downtime.

Technical Summary

Atlas Copco parts references consistently identify 2906040400 / 2906-0404-00 as a Check Valve Kit, while application-specific listings identify it for ZT110–145.

Recommended catalog title: Atlas Copco 2906040400 – ZT110–145 Check Valve Kit, 2906-0404-00.

Compatibility note: Confirm the compressor model and serial number before ordering because check-valve configurations can vary between compressor versions.