What does a discharge bypass valve do?
On refrigeration systems, discharge bypass valves are used to prevent the suction pressure from going below the minimum value recommended by the compressor manufacturer.
How do you adjust a discharge bypass valve?
By turning the adjustment stem counterclockwise one complete turn, the pressure setting will decrease approximately 4 psig. Using an adjustable wrench, remove the cap that covers the adjustment stem of the valve. Make sure to adjust in small increments allowing the system to stabilize between adjustments.
What controls the discharge bypass valve?
This is done by a modulating control valve — commonly called a Discharge Bypass Valve (DBV). This valve, which opens on a decrease in suction pressure, can be set to automat- ically maintain a desired minimum evaporating pres- sure regardless of the decrease in evaporator load.
Why would hot gas bypass be utilized in a system?
Hot gas bypass can stabilize the system balance point by diverting hot, high-pressure refrigerant vapor from the discharge line directly to the low- pressure side of the system. This tactic reliable operation by introducing problems stemming from insufficient oil return and refrigerant logging in the HGBP line.
What is a false load?
By adding hot gas from the discharge line into the evaporator, we can increase the evaporator pressure and temperature. Because this load is not put there by heat from the return air, the load is referred to as false.
Is hot gas bypass same as hot gas reheat?
Advances in HVAC controls and technology in HVAC systems over the years has made hot gas reheat very popular. HOT GAS BYPASS provides an artificial load on the evaporator by introducing a portion of high pressure, high temperature gas to the evaporator/suction side of the system.
What is the effect of hot gas bypass method as a capacity control on compressor?
Using a hot gas bypass valve can also prevent short cycling of a compressor and prevent evaporator freezing in low load conditions. As a space or process temperature reaches set point, hot gas can be added to the evaporator to raise its temperature.
What is a quench valve?
The quench valve is a small valve that monitors the discharge temperature of the refrigerant leaving the compressor. the sensing bulb is secured to the discharge line at the compressor.
What is a Rawal valve?
Rawal Devices is the manufacturer of highly efficient and cost-effective solutions (including the APR Control (analog) and APR-E (digital) Valves) that solve temperature and humidity control problems in commercial, industrial and institutional building applications.