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pressure bypass valve(BV)
pressure bypass valve(BV)

pressure bypass valve 1.automatic expansion valve under fixed pressure 2.maintain the fixed evaporation pressure

pressure bypass valve 


The BV Discharge-bypass valve is used in the refrigerating system, which is not equipped with unloading device for the system load adjustment.

l   The BV Discharge-bypass valve can be used as automatic expansion valve under fixed pressure to maintain the fixed evaporation pressure (temperature).

l   The BV Discharge-bypass valve is capable to maintain the minimum evaporating pressure.

l   SAE and ODF connecting .

l   Suitable for HFC and HCFC

l   Maximum working pressure: 30bar.

Technical data


Adjustable range

Nominal Liquid Capacity (kW)

Setting pressure

Connecting size




0~7 Bar























The BV-type Discharge- bypass valve can open or close automatically while outlet pressure varies to ensure the outlet pressure constant on the setting point regardless of the change of the inlet pressure (within a certain range). 

 BV used as expansion valve under the fixed pressure

If the inlet of the Model BV Discharge-bypass valve is connected to the condensing pressure and outlet to the inlet of evaporator, that is, the normal layout of thermal expansion valve. Under the condition, the BV valve is closed when system turning off due to higher evaporating pressure; and the BV will open automatically after compressor turning on due to evaporate pressure decreasing step by step. The refrigerant flows into the evaporator through the throttling hole of BV. After the evaporator absorbs heat, the increasing evaporating pressure makes the valve closed. Once again, operation of the compressor makes evaporating pressure decreased and the valve turns to open status. During the operation, the valve always keeps the dynamic balance, maintaining the evaporating pressure constant approximately at the setting point. The variation situation of the evaporating pressure has something to do with the volume of the valve, regardless of the influence of the condensing pressure (Or environment temperature) . 

BV used as throttling valve to regulate energy

The inlet of the BV Discharge-bypass valve is connected to the discharge pressure, and the outlet to the outlet or inlet of evaporator (Equivalent to extract pressure). Under this condition, the BV is closed when evaporator loading; Because of decreasing evaporate pressure with a period of operation of the compressor, that is, it requires less power of the compressor because the expansion valve throttle turns to smaller, the evaporating pressure also becomes lower. When lowering than the set value,BV is opened automatically. Parts of discharge gas of the compressor are by-passed to the inlet or outlet of evaporator.

BV functioned as regulate energy

In the process of loading and unloading described as above, in case that the compressor operates in the period when evaporator lowers the load, the evaporating pressure (less than 4bar) is increased to 4bar. The pressure drop decreasing between the discharge and suction reduce load of the compressor resulting in energy saving.

Suggestion of assembly

l   Bypass the hot gas to the inlet of the evaporator to increase temperature of the outlet of the evaporator, enhance supplying liquid volume and decrease temperature of the extract air.

l   Or add the injection valve to regulate the injection liquid to distribute parts of refrigerant entering into the suction tube to absorb heat from evaporator, thus reducing the temperature of the discharge gas

pressure bypass valve(BV)

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