Atlas Copco Check Valve Kit Replacement – 2906017700

The Atlas Copco 2906017700 Check Valve Kit is used to service the check-valve assembly in applicable ZR/ZT 75–90 and Z45–55 oil-free compressors. The check valve allows compressed air to flow in the required direction while preventing reverse airflow when pressure conditions change.

The valve automatically responds to the pressure difference across it. During normal operation, it opens to allow forward airflow. When downstream pressure becomes higher or the compressor unloads/stops, the valve closes to prevent compressed air from returning toward the compressor.

Working Process

1. Compression – The compressor generates compressed air.
2. Forward Airflow – Compressed air flows through the check valve toward the downstream system.
3. Valve Opening – Differential pressure moves the valve to the open position.
4. Normal Delivery – Air passes through with controlled flow restriction.
5. Unloading/Shutdown – Pressure conditions change when the compressor unloads or stops.
6. Valve Closing – The internal spring and pressure difference move the valve toward the closed position.
7. Backflow Prevention – The closed valve prevents compressed air from returning to the compressor.
8. Protection – Preventing reverse flow helps protect compressor components and supports stable operation.

Kit Components

Atlas Copco’s official listing identifies the following components in 2906017700:

Main Functions

• Controls one-way compressed-air flow.
• Prevents reverse airflow.
• Helps maintain system pressure.
• Supports correct compressor unloading.
• Protects the compressor against backflow.
• Maintains sealing around the check-valve assembly.
• Helps restore reliable valve operation during maintenance.

Possible Failure Symptoms

A worn or damaged check valve may result in:

• Reverse compressed-air flow.
• Pressure loss.
• Compressor unloading problems.
• Increased energy consumption.
• Pressure fluctuations.
• Abnormal valve noise.
• Air leakage.
• Difficulty maintaining system pressure.

Maintenance Procedure

1. Shut down the compressor according to the applicable Atlas Copco procedure.
2. Isolate the electrical supply.
3. Fully depressurize the compressor.
4. Allow the equipment to cool.
5. Remove the check-valve assembly.
6. Inspect the valve, spring, bushing and sealing surfaces.
7. Remove worn components.
8. Clean the mating surfaces.
9. Install the replacement components from 2906017700.
10. Ensure the O-rings are correctly seated and not twisted.
11. Install the spring, bushing and valve in the correct orientation.
12. Reassemble the check-valve assembly.
13. Restart the compressor.
14. Check forward airflow.
15. Verify that reverse flow does not occur.
16. Inspect for leakage and abnormal noise.

Service Benefits

Using the 2906017700 Check Valve Kit helps:

• Restore one-way airflow control.
• Prevent reverse compressed-air flow.
• Maintain stable pressure.
• Improve unloading performance.
• Reduce air leakage.
• Protect compressor components.
• Improve compressor reliability.

Technical Summary

Recommended catalog title: Atlas Copco 2906017700 – ZR/ZT 75–90 & Z45–55 Check Valve Kit, 2906-0177-00.

Atlas Copco’s official product listing confirms the part as the ZR/ZT75-90, Z45-55 CV Kit and specifies the kit weight and components.