Atlas Copco OSV/CV Kit C111 Replacement – 2901201800

Atlas Copco 2901201800 – OSV/CV Kit C111

The Atlas Copco 2901201800 (2901-2018-00) OSV/CV Kit C111 is a maintenance and replacement kit designed for compatible Atlas Copco oil-injected screw compressors. Its main purpose is to control compressor oil flow, prevent unwanted oil migration during shutdown, and maintain one-way flow through the associated compressor circuit.

Working Process:

During normal compressor operation, the screw air end requires a continuous supply of compressor oil for lubrication, cooling, sealing, and efficient compression. Oil circulates through the compressor oil circuit while compressed air is produced and delivered to the downstream system.

The Oil Stop Valve (OSV) controls the oil passage to the compressor air end. When the compressor is running, the pressure conditions in the circuit act on the valve and piston mechanism, allowing the required oil flow to pass through the assembly.

The circulating oil reaches the air end and performs three important functions: it lubricates moving components, removes heat generated during compression, and helps seal the clearances between the screw rotors.

The Check Valve (CV) provides one-way flow control. It allows flow in the intended direction and prevents reverse flow when the pressure differential changes.

When the compressor unloads or stops, the operating pressure inside the oil circuit decreases. The spring-loaded oil-stop mechanism moves toward its closed position.

The OSV then restricts the oil passage and prevents excessive oil from draining or migrating into the air end while the compressor is stopped.

At the same time, the check-valve function prevents unwanted reverse flow through the circuit. This helps maintain proper pressure and oil-flow conditions during unloading and shutdown.

This combined OSV/CV function is important because uncontrolled oil migration can lead to excessive oil accumulation in the air end, difficult starting, increased oil consumption, oil carryover, or abnormal compressor operation.

Atlas Copco’s official catalog identifies 2901201800 as “OSV/CV KIT C111 FOR OIL INJECTED SCREW COMPRESSORS.” The official listing gives a kit weight of 674 g.

The official component list includes:

• Spring – 1 pc
• O-ring 32.15 × 3.53 – 1 pc
• O-ring 85 × 3 – 1 pc
• O-rings – supplied in the kit
• Plug G 3/8 – 1 pc
• Plug – 1 pc
• O-ring – 1 pc
• Valve – 1 pc
• Instrument OSV/CV C111 – 1 pc
• Spring – 1 pc
• O-ring 59.5 × 3 – 2 pcs
• Valve Oil Stop – 1 pc
• O-ring 32.2 × 3 – 2 pcs
• Piston – 1 pc
• O-rings – 4 pcs
• Plug G1 FKM sealing – 1 pc
• Plug G 1/2 – 1 pc

These components work together to provide controlled oil flow, one-way flow protection, spring-assisted valve operation, piston movement, and reliable sealing.

The oil-stop valve controls oil supply and prevents unwanted oil migration when the compressor stops. The check valve prevents reverse flow. The piston responds to pressure changes and transfers the operating force to the valve mechanism.

The springs provide the required return and closing forces, while the O-rings and sealing components prevent oil and pressure leakage around the valve assembly.

During normal compressor operation, the assembly is exposed to hot compressor oil, pressure fluctuations, vibration, temperature changes, and repeated loading/unloading cycles. Over time, valve components, springs, and seals can become worn, contaminated, hardened, or damaged.

A faulty oil-stop valve may fail to close properly after shutdown. This can allow excessive oil to migrate into the compressor air end, potentially causing oil accumulation, difficult starting, increased oil consumption, or abnormal operation.

A faulty check valve may permit reverse flow through the circuit. This can disturb the intended oil-flow direction and cause pressure or oil migration problems.

If the valve becomes restricted or fails to open correctly during operation, oil circulation to the air end may be reduced. Insufficient oil flow can negatively affect lubrication, cooling, and sealing of the compressor element.

During maintenance, the compressor must be stopped, electrically isolated, completely depressurized, and allowed to cool before the OSV/CV assembly is serviced.

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

Worn components should be replaced using the 2901201800 OSV/CV Kit C111. O-rings must be installed carefully without twisting, cutting, or damaging the sealing surfaces. The valve, piston, springs, and plugs 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 complete start-up, loading, unloading, and shutdown sequence.

During testing, the OSV should permit the required oil circulation during compressor operation and close correctly during unloading or shutdown. The check valve should prevent unwanted reverse flow.

Correct operation of the 2901201800 OSV/CV assembly ensures proper oil circulation during compressor operation while reducing oil migration and reverse flow when the compressor is unloaded or stopped.

Using the Atlas Copco 2901201800 OSV/CV Kit C111 during scheduled maintenance helps restore oil-flow control, reliable valve sealing, reverse-flow protection, proper shutdown behavior, and dependable compressor performance.

Part Number: 2901201800
Alternative Number: 2901-2018-00 / 2901 2018 00
Brand: Atlas Copco
Part Description: OSV/CV Kit C111
Official Description: OSV/CV Kit C111 for Oil-Injected Screw Compressors
Component Type: Oil Stop Valve + Check Valve service kit
Application: Atlas Copco oil-injected screw compressors
Official Listed Weight: 674 g
Primary Function: Controls oil flow and prevents unwanted reverse flow
Secondary Function: Prevents excessive oil migration into the air end during shutdown
Main Components: Oil-stop valve, check valve, piston, springs, O-rings, plugs, instrument assembly, and sealing components
Operating Function: Allows controlled oil circulation during operation and restricts reverse oil flow during unloading/shutdown
Main Benefits: Proper lubrication, reduced oil migration, reverse-flow protection, improved shutdown performance, reliable sealing, 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.