PURPOSE OF BACK PRESSURE VALVE/HOW DIFFERENT ROOM TEMPERATURES ARE MAINTAINED IN REFRIGERATION SYSTEM?
Back pressure valves are maintaining the different room temperatures in refrigeration system.This valve is fitted at the outlet of higher temperature rooms like veg room.
There are two main reason to fit the back pressure valves,
1. Veg room is maintained at a temperature of +4 -5 degress while fish room is at about -12 to -15 degrees and the flow and amount of refrigerant at fish room and meat room is greater as compared to that of veg room. hence if back pressure valve is not fitted then refrigerants will come at the outlet of all the three rooms then the refrigerant will tend to flow towards veg room. To avoid it, a back pressure valve is fitted.
2. It serve to limit the pressure drop across the expansion valve by giving a set minimum pressure in the evaporator coil. This in turn limits the temperature of the refrigerant thereby preventing delicate foodstuffs such as vegetables from being damaged by having air at very low temperatures blown over them. Ultimately they may also be set to provide a safety limit to the room temperature by restricting the pressure to give a corresponding minimum saturation temperature of 0oC.
In simple words you can say that refrigerant will flow out only if the pressure inside the veg room outlet will be greater than the outlet from the main line.So back pressure valve increase the back pressure in veg, room line which increase the saturation temperature
If you know more or have doubts please comment below
Back pressure valves are maintaining the different room temperatures in refrigeration system.This valve is fitted at the outlet of higher temperature rooms like veg room.
There are two main reason to fit the back pressure valves,
1. Veg room is maintained at a temperature of +4 -5 degress while fish room is at about -12 to -15 degrees and the flow and amount of refrigerant at fish room and meat room is greater as compared to that of veg room. hence if back pressure valve is not fitted then refrigerants will come at the outlet of all the three rooms then the refrigerant will tend to flow towards veg room. To avoid it, a back pressure valve is fitted.
2. It serve to limit the pressure drop across the expansion valve by giving a set minimum pressure in the evaporator coil. This in turn limits the temperature of the refrigerant thereby preventing delicate foodstuffs such as vegetables from being damaged by having air at very low temperatures blown over them. Ultimately they may also be set to provide a safety limit to the room temperature by restricting the pressure to give a corresponding minimum saturation temperature of 0oC.
In simple words you can say that refrigerant will flow out only if the pressure inside the veg room outlet will be greater than the outlet from the main line.So back pressure valve increase the back pressure in veg, room line which increase the saturation temperature
If you know more or have doubts please comment below
lower the press higher is the evaporation.......if press control vlv not given after veg ref room,evaporation is so high that sudden loss in temp will rottt the veg.....so by fitting back press vlv press is increased so evaporation will be small and temp wiill be kept in control
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