Tech Tips: Let’s Find Out about the Operation Principle of IVR(Internal Vacuum Relief)

Pd: Pressure of Discharge Gas
Pm: Pressure of Middle Chamber (Intermediate Pressure)
Ps: Pressure of Suction Gas

Intermediate pressure is built which pushes the piston.
When the refrigerant is not suctioned or insufficient, the force of the spring becomes stronger than the intermediate pressure and the piston moves to the left.
The path opens and the high pressure gas is released to the low pressure side.

When sufficient high pressure gas has been released the pressure of Pd and Ps becomes equal. The piston reverts to its original position and opens the intermediate pressure path.

The pressure is built through the open intermediate pressure path, blocking the high pressure path and going back to its normal operation.

1. Blockage of path/capillary.
2. Locking of service valve.
3. Shielding or freezing of evaporator due to fan fail.

Operates on phenomena causing the reduction of refrigerant flow and pressure.

The gas bypassed through IVR function, induces OLP operation and protects the compressor.

This protective device is for a scroll type that uses an axial sealing method as a tip seal structure. It is a recommended protective device to protect the compressor from abnormal high compression ratio operation such as vacuum operation. If there is a protective device in the system such as low pressure switch or TPS that can protect it, then IVR may not be attached.