RA Pressure Temperature Chart. PRESSURE-TEMPERATURE CHART .. Refrigerants 22, a, A, and values are based on °F liquid temperature and the stated evaporator. PRESSURE-TEMPERATURE CHART .. Refrigerants 22, a, A, and values are based on °F liquid temperature and the stated.
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Refrigerant temperature is the design suction temperature when the compressor is on. Remember—too close a differential may maintain close temperature control, but cause short cycling, greatly shortening equipment life. Variations in systems will probably require small corrections of the 404w.
Figure 1 shows the usual starting set points to set up a LPC for various applications.
This type of control is most popular in small-refrigerated boxes such as beer coolers. To control box temperature with a low-pressure control, the system must use a thermostatic expansion valve, non-bleed type. Even low temperature freezers using R or RA should not be ot lower than 0 psi cut-out. The same is not true for a standard temperature control. The settings in Figure 1 are only a beginning reference.
The final chaft differential has to be a compromise. The differential is the difference between the cut-in and the cut-out pressures.
Refrigerant Pressure – Temperature Chart
Request Our Free Catalog. The TD of the evaporator coil. By cycling tp compressor in response to the suction low side pressure, box temperature can be controlled.
Set the cut-in at 18 psi. Figure 3 is a guide for setting the LPC for outdoor units. What all this means is that one picks cut-in and cut-out settings that should result in good temperature control, monitors the system, and then fine-tunes each specific job to achieve the desired results. Below that, flooded condenser valve systems should be used. Testing Wireless Solutions Testing wireless transmitters link.
chsrt This will be the cut-in setting. As an example for a beer cooler: Fine-tuning the differential setting should produce the desired results. An LP fan cycling control senses discharge head pressure and closes on rise of pressure.
Refrigerant Pressure – Temperature Chart
The LPC cut-in setting should be selected first. Unless gauges are installed at the outlet of the evaporator and at the LPC connection to the chagt, not practicalthis D P can be estimated. TD is the temperature difference between the box temperature and the refrigerant temperature in the evaporator.
A wide differential will give longer running time, but may cause wide temperature swings. The TD of the evaporator coil 3. Allow 2 – 3 psi for suction line D P. For condensing units outdoors, either the coldest unit operating temperature or the coldest ambient temperature selects the cut-in setting, whichever is the lowest temperature. There are some advantages to this type of system. Avoid cut-out settings that result in a vacuum.
It is a good starting point.
Two settings need to be made on the LPC: As box temperature decreases, the evaporator temperature decreases, and a lower suction pressure results. The control opens on cchart fall in head pressure and shuts off the condenser fan, or fans. Note that when the solenoid valve is closed off the refrigerant is essentially trapped between the solenoid valve and the discharge valves of the compressor.
To set the differential, and consequently the cut-out setting, four factors need to be determined: 404aa 8 is a chart for condensers with multiple fans. This D P between the evaporator and the LPC connection charh result in an increase in the differential setting.
For instance, a condenser with nine fans would have each fan cycling control turn three fans on and off at the same time.
Figure 5 and Figure 6 show two of the more common wiring diagrams for pump-down systems. Set the cut-in at 31 psi. Very large condensers having four or more fans, usually have the fan cycling controls control two or more fans at a time. Depending on how well the system balance was made, that is, matching the evaporator to the compressor capacity at the selected suction temperature, the compressor run time will be chhart enough to give 404s efficiency and not short cycle.
Since we know chaet cut-in we want, this is easily determined. The differential chosen will determine the compressor on time. The cut-out setting should be a reasonable amount of PSI lower than the cut-in, but not so low that the compressor will have difficulty reaching the cut-out setting. When the thermostat opens the circuit to the solenoid valve, the valve closes and the compressor pumps the refrigerant from the evaporator and suction line into the receiver cbart condenser, reducing the refrigerant pressure to the cut-out setting of the LPC and stops the compressor.
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