Atlas Copco Minimum Pressure Valve / Service Kit Replacement – 2901000600

Atlas Copco 2901000600 – Minimum Pressure Valve / Service Kit

The Atlas Copco 2901000600 (2901-0006-00) is a service kit used in compatible oil-injected screw compressors, particularly associated with the GA11–GA22 range. The official Atlas Copco catalog describes it as a “Kit for Oil Injected Screw Compressor” and lists a weight of 150 g.

The kit is commonly referenced in the market as a Minimum Pressure Valve (MPV) repair/service kit. This valve is installed in the compressor’s compressed-air outlet circuit and helps maintain the minimum internal pressure required for correct compressor operation.

Working Process:

During normal operation of an oil-injected rotary screw compressor, compressed air mixed with compressor oil enters the air/oil separator vessel.

The separator removes most of the oil from the compressed-air stream. The compressor must maintain an appropriate internal pressure so that oil can circulate correctly through the lubrication, cooling and sealing circuits.

The Minimum Pressure Valve (MPV) helps maintain this required minimum pressure.

During compressor start-up, the MPV remains closed or sufficiently restricted. This allows pressure to build inside the separator and compressor circuit before large quantities of compressed air are discharged to the downstream system.

Once the internal pressure reaches the valve’s opening pressure, the MPV opens and allows compressed air to flow toward the aftercooler and downstream air network.

The valve therefore provides two important functions:

1. Maintains minimum internal pressure during start-up and low-pressure conditions.
2. Controls reverse flow so downstream pressure does not freely return toward the separator when compressor conditions change.

The 2901000600 service kit provides replacement components needed to restore the valve mechanism and sealing performance.

Atlas Copco’s official component list includes:

• Compression Spring – 1 pc
• O-ring 39.2 × 3 – 1 pc
• Kit IN.SH GA11-22 – 1 pc
• Tube Grease – 1 pc
• SC Lock Washer 10.2-22-2.7 FZB – 4 pcs
• O-ring 59.5 × 3 – 1 pc
• Compression Spring – 1 pc
• Circlip / Retaining Ring – 1 pc
• Piston Ring – 2 pcs

The springs provide the required closing force for the valve mechanism and help determine the pressure at which the valve changes position.

The piston and piston rings provide the moving sealing interface within the valve assembly. They allow pressure forces to act on the valve mechanism while maintaining controlled movement.

The O-rings provide airtight sealing between the valve components and housing. Proper sealing is essential because leakage can interfere with the pressure differential required for correct MPV operation.

The circlip/retaining ring mechanically secures the relevant internal component and prevents unwanted axial movement.

The lock washers help maintain secure fastening of the valve assembly during continuous compressor vibration.

The supplied grease is used where specified during assembly to facilitate correct installation and movement of applicable components.

Operating Cycle:

When the compressor starts, the MPV restricts the discharge path sufficiently for internal pressure to build.

As internal pressure reaches the required minimum level, pressure acting on the valve mechanism overcomes the spring force and the valve begins to open.

Compressed air can then flow toward the downstream system.

During normal loaded operation, the MPV remains sufficiently open to permit the required airflow while maintaining the appropriate internal pressure conditions.

When the compressor unloads or stops, pressure conditions change and the spring-loaded mechanism moves toward the closed/restricted position.

This helps prevent uncontrolled reverse airflow and protects the compressor’s internal pressure and oil-circulation conditions.

Failure Conditions:

With prolonged operation, springs can lose their original force, O-rings can harden or become damaged, piston rings can wear and internal surfaces can become contaminated.

A damaged O-ring can cause internal or external leakage.

A worn piston or piston ring can result in poor sealing and unstable valve operation.

A weakened or damaged spring can alter the valve’s opening pressure.

If the MPV opens too early, the compressor may fail to build the required internal pressure during start-up. This can negatively affect oil circulation and compressor operation.

If the MPV fails to open correctly, excessive internal pressure or restricted discharge flow may occur.

If the valve does not close properly after unloading or shutdown, downstream pressure may flow back toward the compressor.

These conditions can result in unstable pressure, increased energy consumption, poor compressor performance, oil-circuit problems or premature component wear.

Maintenance Procedure:

Before servicing the MPV, the compressor must be stopped, electrically isolated, completely depressurized and allowed to cool according to the applicable Atlas Copco safety procedure.

The valve assembly should be inspected for:

• Damaged or hardened O-rings
• Worn piston rings
• Weak or damaged springs
• Contamination
• Excessive piston movement
• Damaged retaining components
• Air leakage
• Abnormal valve movement

The old service components should be removed carefully without damaging the valve housing or sealing surfaces.

The components supplied in the 2901000600 kit should be installed in their specified positions.

All sealing surfaces must be clean before installation.

O-rings should be installed without twisting, cutting, overstretching or pinching.

Piston rings should be installed correctly and checked for free movement.

The springs must be positioned correctly so that the intended valve closing force is maintained.

The circlip and lock washers must be properly seated and secured.

Grease should be applied only where specified by the applicable Atlas Copco assembly procedure.

After assembly, the valve mechanism should move freely without sticking.

The compressor should then be restarted and monitored during start-up, loading, unloading and shutdown.

Internal pressure should build correctly before the valve permits unrestricted downstream airflow.

The system should be checked for air leakage and abnormal pressure behavior.

A correctly serviced MPV helps maintain stable compressor pressure, proper oil circulation and reliable loading/unloading operation.

Using the Atlas Copco 2901000600 service kit during the appropriate maintenance operation helps restore valve sealing, spring performance, piston movement and minimum-pressure control.

Part Number: 2901000600
Alternative Number: 2901-0006-00 / 2901 0006 00
Brand: Atlas Copco
Part Description: Kit for Oil-Injected Screw Compressor
Common Service Description: Minimum Pressure Valve / MPV Service Kit
Application: Oil-injected screw compressors; associated with GA11–GA22 applications
Component Type: Valve service/repair kit
Official Listed Weight: 150 g
Main Components: Compression springs, O-rings, piston rings, retaining ring, lock washers, grease and IN.SH GA11-22 kit
Primary Function: Maintains minimum internal compressor pressure
Secondary Function: Controls discharge and helps prevent reverse airflow
Operating Function: Restricts discharge during pressure build-up and opens after the required minimum pressure is reached
Main Benefits: Stable internal pressure, reliable oil circulation, improved valve sealing, controlled discharge flow and dependable compressor operation.

Disclaimer: All manufacturer names, trademarks, model numbers, and part numbers are used solely for identification and compatibility purposes. Our products are high-quality aftermarket replacement products and are not manufactured, sponsored, endorsed, or authorized by the original equipment manufacturer (OEM). All trademarks remain the property of their respective owners.