Atlas Copco Minimum Pressure Valve (MPV) Kit Replacement – 2906009500

Atlas Copco 2906009500 – Minimum Pressure Valve (MPV) Kit

The Atlas Copco 2906009500 (2906-0095-00) Minimum Pressure Valve Kit is a service and repair kit designed for the minimum pressure valve assembly used in compatible Atlas Copco screw compressors. The kit is associated with GA90–315 compressor applications and is used to restore the valve’s sealing and pressure-control performance.

Working Process:

The Minimum Pressure Valve (MPV) is installed in the compressor’s compressed-air outlet circuit. Its main purpose is to maintain the required minimum internal pressure inside the compressor’s separator vessel and air circuit before allowing compressed air to flow freely toward the downstream system.

During compressor start-up, the MPV remains closed or partially restricted. This allows pressure to build inside the separator vessel.

Maintaining sufficient internal pressure is important in an oil-injected screw compressor because the pressure difference supports proper oil circulation through the lubrication, cooling and sealing circuits.

When the internal pressure reaches the valve’s specified opening pressure, the pressure acting on the valve mechanism overcomes its spring force. The MPV then opens and allows compressed air to flow toward the aftercooler and downstream air network.

During normal loaded operation, the valve remains sufficiently open to permit the required compressed-air flow while maintaining suitable internal pressure.

When the compressor unloads or stops, pressure conditions change and the valve moves toward its restricted or closed position. This helps limit reverse airflow from the downstream network toward the compressor.

The 2906009500 service kit is therefore used when the internal MPV components or sealing elements have become worn, damaged or unreliable.

Main Functions:

• Maintains minimum internal compressor pressure.
• Controls compressed-air discharge from the separator vessel.
• Supports correct oil circulation in oil-injected compressors.
• Helps prevent reverse airflow during unloading or shutdown.
• Maintains stable compressor operating conditions.
• Restores sealing and mechanical performance during MPV maintenance.

Component Function:

The service components in an MPV repair kit are used to restore the valve’s internal sealing and pressure-regulating mechanism.

The spring-loaded valve mechanism provides the controlled opening and closing action. Spring force keeps the valve restricted until the required minimum pressure is achieved.

Sealing components, such as O-rings and associated seals, prevent unwanted air leakage around the valve assembly.

The valve’s internal moving components respond to the pressure difference between the compressor’s internal circuit and downstream air system.

Operating Cycle:

1. Compressor Start-up: The MPV restricts the outlet flow.
2. Pressure Build-up: Internal separator pressure increases.
3. Minimum Pressure Reached: The pressure force overcomes the valve’s spring force.
4. Valve Opening: The MPV opens progressively.
5. Normal Operation: Compressed air flows toward the downstream system.
6. Unloading/Shutdown: Changing pressure conditions cause the valve to restrict flow and help prevent reverse airflow.

This sequence ensures that the compressor does not operate with insufficient internal pressure.

Possible Failure Conditions:

With prolonged operation, the valve mechanism and sealing components can experience wear, contamination, spring fatigue and deterioration.

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

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

If the MPV opens too early, the compressor may not build sufficient internal pressure during start-up. This can negatively affect oil circulation and compressor performance.

If the valve fails to open correctly, discharge airflow can become restricted and internal pressure may rise excessively.

If the valve fails to close correctly during unloading or shutdown, downstream pressure can flow back toward the compressor.

These conditions may result in unstable pressure, increased energy consumption, poor compressor performance, excessive internal temperature 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 MPV assembly should be inspected for:

• Valve contamination
• Worn internal components
• Damaged sealing elements
• Weak or damaged springs
• Air leakage
• Abnormal valve movement
• Damaged sealing surfaces

The existing worn components should be removed carefully without damaging the valve housing or mating surfaces.

The components supplied with the 2906009500 MPV Kit should be installed in their specified positions.

All sealing surfaces must be clean and free from dirt, old seal material and foreign particles.

O-rings and seals must be installed without twisting, cutting, overstretching or pinching.

The spring and valve mechanism must be positioned correctly so that the intended opening pressure is maintained.

After assembly, the valve should be checked for smooth movement and proper seating.

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

The technician should check internal pressure build-up, discharge flow, leakage and overall compressor behavior.

A correctly serviced MPV should maintain the required minimum internal pressure and allow controlled compressed-air discharge.

Using the Atlas Copco 2906009500 Minimum Pressure Valve Kit during the appropriate maintenance operation helps restore pressure regulation, valve sealing, controlled discharge and reliable compressor operation.

Part Number: 2906009500
Alternative Number: 2906-0095-00 / 2906 0095 00
Brand: Atlas Copco
Part Description: Minimum Pressure Valve Kit / MPV Kit
Application: Atlas Copco screw compressors
Known Application Reference: GA90–315
Component Type: Minimum pressure valve service/repair kit
Primary Function: Maintains minimum compressor internal pressure
Secondary Function: Controls compressed-air discharge and helps prevent reverse airflow
Operating Function: Restricts discharge during pressure build-up and opens after the required minimum pressure is achieved
Main Benefits: Stable internal pressure, reliable oil circulation, reduced leakage, controlled airflow and dependable compressor operation.

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