Atlas Copco Oil Stop Valve Kit Replacement – 2901074500

Atlas Copco 2901074500 – Oil Stop Valve Kit

The Atlas Copco 2901074500 (2901-0745-00) Oil Stop Valve Kit is a service and maintenance kit used in compatible oil-injected rotary screw compressors. Its primary function is to control the flow of compressor oil and prevent oil from returning from the oil separator system into the compressor air end when the compressor is stopped or unloaded.

Working Process:

During normal compressor operation, the compressor air end requires a continuous supply of oil for lubrication, cooling, and sealing of the screw rotors. The oil circulates through the compressor’s oil circuit and is separated from the compressed air in the separator system.

The oil stop valve forms an important part of this oil-circulation circuit. When the compressor is operating, the pressure generated by the compressor opens the oil-stop valve against its spring force. This allows the required compressor oil to circulate toward the air end.

As the compressor runs under load, the oil continues to flow through the lubrication and cooling circuit. The oil absorbs heat generated during compression and returns through the appropriate oil circuit for continued circulation.

When the compressor unloads or stops, the operating pressure changes. The spring inside the oil-stop valve forces the valve toward its closed position.

The valve closes the oil passage and prevents oil from flowing backward or draining from the oil separator and associated oil circuit into the compressor air end.

This function is particularly important during shutdown because excessive oil migration into the air end can cause oil flooding, difficult starting, increased oil consumption, or other operating problems.

The 2901074500 kit also incorporates a check valve, which assists in controlling the direction of flow and preventing unwanted reverse flow within the circuit.

Atlas Copco’s official catalog identifies 2901074500 as “KIT VALVE OIL STOP FOR OIL INJECTED SCREW COMPRESSOR.” The official listing gives a weight of 208 g.

The official component list includes:

• Spring – 1 pc
• O-ring 44.2 × 3 – 1 pc
• Seal washer M32 – 2 pcs
• O-rings – multiple pieces
• Check valve – 1 pc
• Washer M16 – 1 pc
• Oil-stop valve spring – 1 pc
• O-ring 59.5 × 3 – 1 pc
• Oil-stop valve – 1 pc
• Washer M10 – 1 pc
• O-ring 32.2 × 3 – 1 pc
• Dowty seal washers – supplied in the kit

These components restore the valve’s sealing, spring force, movement, and flow-control characteristics during servicing.

The oil-stop valve controls the oil passage. The springs provide the closing force when compressor operating pressure decreases. The check valve helps maintain one-way flow, while the O-rings and sealing washers prevent oil or pressure leakage around the valve assembly.

During continuous operation, these components are exposed to hot compressor oil, pressure fluctuations, vibration, temperature changes, and repeated opening and closing cycles. Over time, seals can harden or deteriorate, springs can lose their required force, and valve components can become contaminated or worn.

A defective oil-stop valve may remain partially open after compressor shutdown. This can allow oil to migrate into the compressor air end, potentially causing excessive oil carryover, oil flooding, difficult restarting, increased oil consumption, or abnormal compressor operation.

If the valve remains closed or becomes restricted during operation, the required oil flow to the air end may be reduced. Insufficient oil circulation can negatively affect lubrication, cooling, and sealing of the screw element.

During maintenance, the compressor must be stopped, electrically isolated, completely depressurized, and allowed to cool before the oil-stop valve assembly is serviced.

The valve, check valve, springs, O-rings, sealing washers, and mating surfaces should be inspected for wear, contamination, corrosion, deformation, and leakage.

All worn sealing and internal components should be replaced using the 2901074500 Oil Stop Valve Kit. O-rings and sealing washers must be installed correctly without twisting, cutting, or damaging the sealing surfaces.

The springs and valve components must be installed in their correct positions and orientations according to the applicable Atlas Copco service procedure.

After reassembly, the compressor should be checked for oil and air leakage. It should then be operated through its start-up, loading, unloading, and shutdown sequences.

During testing, the oil-stop valve should open correctly during compressor operation and close effectively when operating pressure falls during unloading or shutdown.

Correct operation ensures proper oil circulation while preventing unwanted oil migration when the compressor is not operating.

Using the Atlas Copco 2901074500 Oil Stop Valve Kit during maintenance helps restore oil-flow control, prevent reverse oil migration, maintain proper compressor lubrication and cooling, reduce oil carryover, and support reliable compressor operation.

Part Number: 2901074500
Alternative Number: 2901-0745-00 / 2901 0745 00
Brand: Atlas Copco
Part Description: Kit Valve Oil Stop
Official Description: Oil Stop Valve Kit for Oil-Injected Screw Compressor
Component Type: Oil-stop/check-valve service kit
Application: Oil-injected rotary screw compressors
Official Listed Weight: 208 g
Primary Function: Controls oil circulation and prevents unwanted oil return during shutdown
Secondary Function: Provides check/non-return flow control
Main Components: Oil-stop valve, check valve, springs, O-rings, washers, and sealing washers
Operating Function: Allows oil circulation during operation and restricts reverse oil flow during unloading/shutdown
Main Benefits: Proper lubrication, improved cooling, reduced oil migration, reduced oil carryover, reliable starting, 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.