<P> Refrigerant may also explain flash - gas occurrence . When a system lacks refrigerant, or has a leakage, it may exhibit flash - gas as the volume in the piping exceeds the capacity of the refrigerant to fill it as liquid . This may force the refrigerant into a phase change . On the other hand, lack of refrigerant can sometimes also produce the opposite effect: an overall increase on the subcooling (and superheating) which will depend on the size and design of the system and its piping . If the system's refrigerant is degenerate, flash - gas may also be produced, as physical properties of the fluid change . This happens because the piping is designed for a specific refrigerant mixture that allows liquid in the liquid line, given certain thermodynamic conditions . If the refrigerant mixture changes its composition considerably, the original designs will not be adequate . Degenerated refrigerant produced by leakage, chemical decomposition or loading with gas when using a glided refrigerant; will most likely make the system perform very poorly, alter oil's circulation or composition, and may eventually render gear inoperative . </P> <P> It is also common to find that refrigerant begins to evaporate immediately after the expansion valve, before arriving to the evaporator . This may also be considered as flash - gas but normally doesn't produce complications in the refrigeration cycle . Many refrigeration systems have the expansion valve set up inside the room being cooled, consequently generating productive refrigeration if absorbing heat from the room, to produce this kind of flash - gas between the expansion and the evaporator . Besides, the expansion valve deregulates its operation if the fluid arriving to it is boiling . In this case, the boiling occurs after the expansion . </P> <P> Flash - gas may be detected in the system by the observation of bubbles or gas presence in the liquid line, or the foamy aspect of the fluid . Depending on the location of the glass: this may also indicate an overwhelmed condenser, and the nonobservance of these at the glass isn't definite of the nonoccurrence of flash - gas in the liquid line . </P> <P> Considering the saturation table for the refrigerant, if it is possible to confirm that a certain amount of condenser subcooling is being produced, and the glass still exhibits gas in the liquid line, one may identify this with flash - gas being produced between the condenser and the glass . The flash - gas phenomena may create a deceiving temperature drop on the liquid line that can be misinterpreted as subcooling . This is due to the fact that the refrigerant may use part of the heat obtained from lowering its temperature, to finish vaporizing itself to be able to occupy the volume of the pipes at those pressures . </P>

How can flash gas in the liquid line be identified