Atlas Copco MPV/Thermostatic Valve Kit 8000H Tropical Replacement – 2901354500

Atlas Copco 2901354500 – MPV/Thermostatic Valve Kit 8000H Tropical

The Atlas Copco 2901354500 (2901-3545-00) is an MPV/Thermostatic Valve Kit designed for compatible oil-injected screw compressors. It combines service components for the Minimum Pressure Valve (MPV) and the thermostatic valve, allowing both pressure regulation and compressor oil-temperature control to be restored during scheduled maintenance.

Atlas Copco officially describes the product as “MPV/THERM.VALVE KIT 8000H TROP” and lists the kit weight as 260 g. The kit is designed for an 8,000-hour maintenance interval and the “TROP” designation indicates the tropical-service version.

Working Process:

The kit services two important compressor-control functions:

1. Minimum Pressure Valve (MPV)

The MPV is located in the compressed-air outlet circuit of an oil-injected screw compressor.

During compressor start-up, the MPV restricts the outlet flow so that pressure can build inside the air/oil separator vessel.

Maintaining sufficient internal pressure is important for proper oil separation, oil circulation, cooling and sealing.

When the internal pressure reaches the required minimum level, pressure acting on the valve overcomes the closing spring force. The MPV then opens and allows compressed air to flow toward the aftercooler and downstream air network.

During normal operation, the MPV allows the required airflow while maintaining suitable internal pressure.

During unloading or shutdown, changing pressure conditions cause the valve to restrict the outlet and help prevent reverse airflow from the compressed-air network toward the compressor.

2. Thermostatic Valve

The thermostatic valve controls the temperature of the compressor oil.

When the compressor starts and the oil is relatively cold, the thermostatic valve restricts the flow through the oil cooler. This allows the oil to reach the required operating temperature more quickly.

As oil temperature increases, the thermostatic valve progressively opens the path toward the oil cooler.

Hot oil is then directed through the cooler, where heat is transferred away from the oil before it returns to the compressor lubrication circuit.

This process maintains the oil within the appropriate operating-temperature range.

Proper oil temperature is important because oil in an oil-injected screw compressor performs several functions, including lubrication, cooling, sealing and noise reduction.

The combination of the MPV and thermostatic valve therefore helps maintain both correct compressor pressure and correct oil temperature.

Official Kit Components:

Atlas Copco’s official component listing includes:

• Piston – 1 pc
• Thermostatic Valve 75°C – 1 pc
• Tube Grease – 1 pc
• O-ring – 1 pc
• Compression Spring – 1 pc
• Compression Spring – 1 pc
• O-ring 26.7 × 1.78 – 1 pc
• O-ring 34 × 1.5 – 1 pc
• Assembly Valve – 1 pc
• O-ring 35.1 × 1.6 – 1 pc
• MPV/Thermostatic Valve Kit Assembly Instructions – 1 pc

The 75°C thermostatic valve responds to oil temperature and regulates the oil flow through the cooler circuit.

The piston and assembly valve form part of the MPV mechanism and control compressed-air flow according to the pressure conditions inside the compressor.

The compression springs provide the required mechanical forces for valve operation.

The O-rings maintain leak-tight sealing between the valve components and their mating surfaces.

The supplied grease is used during assembly where specified by the service instructions.

Operating Sequence:

1. Compressor Start-up: The MPV restricts air discharge while pressure builds.
2. Pressure Build-up: Internal separator pressure increases.
3. MPV Opening: Once minimum pressure is achieved, the MPV opens.
4. Oil Temperature Control: Cold oil is initially restricted from passing fully through the oil cooler.
5. Oil Heating: Compressor operation raises oil temperature.
6. Thermostatic Regulation: At approximately 75°C, the thermostatic valve regulates oil flow toward the cooler.
7. Oil Cooling: Hot oil passes through the oil cooler and releases heat.
8. Temperature Stabilization: Cooled oil returns to the compressor and the cycle continues.

This coordinated operation helps maintain stable compressor pressure and suitable oil temperature during changing load conditions.

Possible Failure Conditions:

With prolonged operation, springs may lose their original force, O-rings may harden or crack, and valve components may become contaminated or worn.

If the MPV develops a sealing problem, compressed air can leak through the valve assembly.

If the MPV opens too early, the compressor may not build sufficient internal pressure.

If the MPV remains excessively closed, compressed-air discharge may become restricted and internal pressure may rise abnormally.

If the thermostatic valve becomes stuck closed, oil may not receive sufficient cooling and the compressor oil temperature can increase excessively.

If the thermostatic valve remains open when the oil is cold, oil may be cooled too early, potentially delaying the achievement of the desired operating temperature.

Incorrect oil temperature can negatively affect lubrication, cooling and compressor efficiency.

Typical symptoms may include:

• Abnormal oil temperature
• High compressor discharge temperature
• Incorrect pressure build-up
• Air leakage
• Increased energy consumption
• Unstable compressor operation
• Poor oil circulation
• Excessive thermal loading

Maintenance Procedure:

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

The assembly should be inspected for:

• Damaged O-rings
• Weak or damaged springs
• Contaminated valve components
• Worn piston
• Thermostatic valve malfunction
• Air or oil leakage
• Damaged sealing surfaces

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

The 2901354500 service kit should be installed according to the applicable Atlas Copco service instructions.

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

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

The springs must be positioned correctly.

The 75°C thermostatic valve must be installed in its correct orientation.

The piston and MPV assembly valve must move freely without binding.

After assembly, the compressor should be restarted and monitored during start-up, loading and unloading.

The technician should verify:

• Correct pressure build-up
• Correct MPV operation
• Absence of air/oil leakage
• Correct oil-temperature behavior
• Proper oil-cooler operation
• Stable compressor discharge temperature

A correctly serviced assembly maintains the required minimum internal pressure while regulating compressor oil temperature according to operating conditions.

Using the Atlas Copco 2901354500 MPV/Thermostatic Valve Kit during the appropriate 8,000-hour maintenance operation helps restore pressure regulation, oil-temperature control, sealing performance and reliable compressor operation, particularly in demanding tropical environments.

Part Number: 2901354500
Alternative Number: 2901-3545-00 / 2901 3545 00
Brand: Atlas Copco
Part Description: MPV/Thermostatic Valve Kit
Official Description: MPV/THERM.VALVE KIT 8000H TROP
Application: Oil-injected screw compressors
Service Interval: 8,000 operating hours
Service Version: Tropical (TROP)
Thermostatic Valve Rating: 75°C
Component Type: Minimum Pressure Valve + Thermostatic Valve service kit
Official Listed Weight: 260 g
Main Components: Piston, 75°C thermostatic valve, springs, O-rings, assembly valve, grease and instructions
Primary Function: Maintains minimum compressor pressure and regulates oil temperature
Secondary Function: Supports proper oil cooling, lubrication and compressed-air discharge control
Operating Function: MPV controls pressure/discharge while the thermostatic valve regulates oil flow according to temperature
Main Benefits: Stable internal pressure, controlled oil temperature, improved lubrication and cooling, reduced leakage and dependable compressor performance.

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