Atlas Copco Inlet Valve Kit Replacement – 2901200652

The 2901200652 Inlet Valve Kit is used to service the compressor’s air-inlet/unloading valve assembly. The valve controls the amount of atmospheric air entering the screw compressor and helps the compressor transition between loaded and unloaded operation.

During loaded operation, the inlet valve opens to allow air into the screw element. When the required system pressure is reached, the control system causes the inlet valve to close or restrict the intake, reducing compression demand and helping the compressor operate efficiently.

Working Process

1. Air Intake – Atmospheric air approaches the compressor inlet.
2. Loading Command – When air demand exists, the inlet valve opens.
3. Air Entry – Air enters the screw compressor element.
4. Compression – The screw rotors compress the incoming air.
5. Pressure Build-Up – System pressure increases toward the required set point.
6. Unloading Command – When demand decreases, the control system commands the inlet valve to unload.
7. Inlet Restriction – The valve closes/restricts the air intake.
8. Reduced Compression – Less air is compressed, reducing unnecessary energy consumption.
9. Reloading – When system pressure falls, the inlet valve opens again.
10. Continuous Control – The cycle repeats automatically according to air demand.

Main Functions

• Controls compressor air intake.
• Supports loading and unloading.
• Helps regulate system pressure.
• Reduces unnecessary compression during unloading.
• Helps improve compressor energy efficiency.
• Maintains stable compressor operation.
• Provides replacement components for worn inlet-valve parts.

Components Associated With the Kit

A parts breakdown for 2901 2006 52 identifies components including a relief valve, regulation valve, plain washers, nut, O-ring, screws, fittings, hose/tube, damper, nozzle and hose clamps.

Possible Failure Symptoms

A worn or damaged inlet valve can cause:

• Compressor not loading.
• Compressor not unloading.
• Continuous loading.
• Slow pressure build-up.
• Unstable operating pressure.
• Excessive energy consumption.
• Air leakage.
• Difficult starting.
• Abnormal valve noise.
• Compressor alarms or shutdown.

Maintenance Procedure

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 the compressor to cool.
5. Isolate the control-air circuit where applicable.
6. Remove the inlet-valve assembly.
7. Inspect the valve, regulation components and sealing surfaces.
8. Remove worn components.
9. Clean the mating surfaces.
10. Install the replacement components from 2901200652.
11. Replace the O-rings and sealing components correctly.
12. Reconnect hoses, tubes and fittings.
13. Check that the inlet mechanism moves freely.
14. Restart the compressor.
15. Test loading and unloading.
16. Check for air leakage.
17. Verify stable pressure operation.

Technical Summary

Recommended catalog title:
Atlas Copco 2901200652 – Inlet Valve Kit / C80 Inlet Valve Assembly for Oil-Injected Screw Compressors, 2901-2006-52.

Compatibility note: Atlas Copco recommends confirming the exact part using the machine serial number and Spare Parts Book, because the applicable configuration can vary by compressor model and version.

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