High-Side Vessels
This vessel located directly downstream of the condenser stores excess liquid refrigerant and holds the entire charge during a pump-down.
What is a liquid receiver?
This protective shell is piped in the suction line immediately upstream of the compressor to prevent liquid floodback.
What is a suction line accumulator?
This valve throttles closed when suction pressure rises to protect the compressor motor from overloading during high-load startups.
What is a Crankcase Pressure Regulator (CPR valve)?
The two visual indicators shown by a standard liquid-line sight glass installed before the metering device.
What are moisture presence (color change) and flash gas/bubbles (solid liquid column)?
An electromechanical valve that opens or closes refrigerant flow when its magnetic coil is energized.
What is a liquid line solenoid valve (LLSV)?
The manual shutoff valve positioned on the liquid receiver outlet that features front-seated, back-seated, and mid-seated positions.
What is a King valve?
The small calibrated opening at the bottom of an accumulator's internal U-tube that meters oil safely back to the compressor crankcase.
What is an oil return bleed hole (or aspirator orifice)?
This valve maintains a minimum pressure and saturation temperature inside a specific evaporator coil in a multi-evaporator system.
What is an Evaporator Pressure Regulator (EPR valve)?
The specific desiccant material used in filter-driers that is superior at capturing moisture but ineffective against inorganic acids.
What is molecular sieve?
The valve installed in the suction line of the coldest evaporator to stop warm vapor migration during the off-cycle.
What is a suction check valve?
This component installed between the compressor outlet and condenser inlet strips lubricant droplets from hot gas and returns them to the crankcase.
What is a discharge line oil separator?
This heat-transfer component solders the warm liquid line to the cold suction line to raise liquid subcooling and suction superheat.
What is a liquid-to-suction line heat exchanger?
The operational pressure that an EPR valve senses and responds to across its internal bellows.
What is inlet (evaporator) pressure?
The core material added to specialized cleanup filter-driers to adsorb hydrofluoric and hydrochloric acids.
What is activated alumina?
The control sequence where a thermostat de-energizes a solenoid valve, letting the compressor pump refrigerant into the receiver until a low-pressure switch cuts out.
What is an automatic pump-down cycle?
The internal mechanism inside an oil separator that rises as lubricant accumulates to open a needle return valve.
What is a float mechanism (or float valve)?
A severe, destructive compressor failure caused when pure liquid refrigerant enters the cylinder compression chamber.
What is liquid slugging?
The operational pressure that a CPR valve senses and responds to across its internal bellows.
What is outlet (crankcase/suction) pressure?
The maximum acceptable pressure drop across a liquid line filter-drier before it must be replaced.
What is 2 psig?
A method of low-ambient head pressure control that backs liquid refrigerant up into condenser tubing to reduce heat transfer area.
What is condenser flooding?
An operational condition where an oil separator shell feels cold to the touch, indicating this specific internal mechanical failure.
What is a stuck-open float valve (or continuous refrigerant blow-by)?
The thermodynamic value gained on the high side when a liquid-to-suction heat exchanger lowers liquid temperature before the TXV.
What is increased subcooling (or increased Net Refrigerating Effect / NRE)?
A defrost method or startup condition where a CPR valve is critically required to throttle high-density vapor surges.
What is post-defrost recovery (or hot gas defrost recovery)?
The primary reason a temporary suction line cleanup filter-drier must be removed after a burnout cleanup is completed.
What is to eliminate suction pressure drop (or prevent high compression ratios)?
In a parallel compressor supermarket rack, this component receives oil from the main discharge separator and distributes it to individual compressor sight-glass regulators.
What is an oil reservoir?