Atlas Copco Oil Stop Valve Replacement – 2901201200

Atlas Copco 2901201200 – OSV/CV Kit C146

The Atlas Copco 2901201200 (2901-2012-00) OSV/CV Kit C146 is a service and replacement kit used in compatible Atlas Copco oil-injected screw compressor systems. The assembly combines an Oil Stop Valve (OSV) and Check Valve (CV) to control oil flow and prevent unwanted reverse flow within the compressor oil circuit.

Working Process:

During normal compressor operation, the screw air end requires a continuous supply of compressor oil for lubrication, cooling, sealing, and reliable compression. The oil circulates through the compressor oil circuit under controlled pressure.

The Oil Stop Valve controls the oil passage toward the compressor air end. When the compressor is running, the operating pressure acts on the valve mechanism and moves it to the open/operating position. This allows the required quantity of oil to circulate through the air end.

The circulating oil lubricates the rotating screw components, removes heat produced during compression, and assists in sealing the internal clearances between the screw rotors.

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

When the compressor unloads or stops, the pressure conditions in the oil circuit change. The spring-assisted Oil Stop Valve moves toward its closed position.

The valve restricts the oil passage and helps prevent excessive oil from draining or migrating into the compressor air end while the compressor is stopped.

At the same time, the Check Valve prevents unwanted reverse flow through the circuit. This maintains the correct oil-flow direction and helps protect the compressor from reverse oil migration.

This function is important during shutdown because uncontrolled oil migration can cause excessive oil accumulation in the air end, difficult starting, increased oil consumption, oil carryover, or abnormal compressor operation.

Parts references identify 2901201200 as “OSV/CV KIT C146” and as an Oil Stop Valve and Check Valve Kit. One parts listing specifies the kit as OSV/CV Kit C146 with a listed weight of approximately 590 g.

The assembly consists of valve, spring, piston, and sealing components that work together to provide pressure-operated valve movement, one-way flow control, and reliable sealing.

The Oil Stop Valve performs the oil-shutoff function, while the Check Valve prevents reverse flow. Springs provide the required return and closing forces, and sealing components prevent oil or pressure leakage around the assembly.

During continuous compressor operation, the OSV/CV assembly is exposed to hot compressor oil, pressure fluctuations, vibration, temperature variations, and repeated loading/unloading cycles.

Over time, the valve mechanism can become worn or contaminated, springs can lose their required force, and sealing components can deteriorate.

A defective Oil Stop Valve may fail to close correctly after compressor shutdown. This can allow oil to migrate into the air end and may result in excessive oil accumulation, increased oil consumption, oil carryover, difficult starting, or abnormal compressor operation.

A defective Check Valve may allow reverse oil flow through the circuit. This can disturb the intended flow direction and cause unwanted oil or pressure migration.

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

Maintenance Procedure:

Before servicing the OSV/CV assembly, the compressor must be stopped, electrically isolated, completely depressurized, and allowed to cool.

The existing valve assembly should be removed according to the applicable Atlas Copco service procedure. The Oil Stop Valve, Check Valve, piston, springs, sealing components, and mating surfaces should be inspected for wear, contamination, corrosion, deformation, and leakage.

Worn components should be replaced using the 2901201200 OSV/CV Kit C146.

All sealing components must be installed carefully without twisting, cutting, or damaging their sealing surfaces. The Oil Stop Valve, Check Valve, springs, and piston must be installed in the correct positions and orientations.

After reassembly, the compressor should be checked for oil and air leakage.

The compressor should then be operated through its start-up, loaded, unloaded, and shutdown sequences.

During testing, the Oil Stop Valve should allow the required oil circulation during normal operation and close correctly when the compressor unloads or stops. The Check Valve should prevent unwanted reverse flow.

Correct operation of the OSV/CV assembly maintains proper oil circulation during compressor operation while minimizing oil migration and reverse flow during unloading and shutdown.

Using the Atlas Copco 2901201200 OSV/CV Kit C146 during scheduled maintenance helps restore oil-flow control, reverse-flow protection, reliable sealing, proper shutdown behavior, and dependable compressor performance.

Part Number: 2901201200
Alternative Number: 2901-2012-00 / 2901 2012 00
Brand: Atlas Copco
Part Description: OSV/CV Kit C146
Official/Parts Description: Oil Stop Valve and Check Valve Kit
Component Type: Oil Stop Valve + Check Valve service kit
Application: Compatible Atlas Copco oil-injected screw compressors
Kit Designation: C146
Reported Kit Weight: Approximately 590 g
Primary Function: Controls oil flow and prevents unwanted reverse flow
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, reliable sealing, improved shutdown performance, and dependable compressor operation.

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