Refrigeration and Air Conditioning Equipment Cooling Episode 1 docx

SUBCOURSE EDITION OD1750 A REFRIGERATION AND AIR CONDITIONING IV (EQUIPMENT COOLING) [...]...Figure 12 Typical D/X equipment cooling system maximum water temperature and the quantity of water which is available to the unit Now that you have selected the proper equipment, let's discuss the installation of equipment or other applications requiring a +25°F to +50°F suction temperature 3 A medium temperature unit ( -10 ° F to +25° F.) should not be selected or equipment cooling applications... dioxide (40 p.s.i.g.) and check all the joints with a soap solution Release the pressure and repair any leaks that may have been found After the leaks have been repaired, charge the system with the recommended refrigerant to 10 p.s.i.g Add enough dry nitrogen or carbon dioxide to build the pressure to 15 0 p.s.i.g and leak test with a halide leak detector Purge the system and repair all leaky joints... Normally, this is 12 0 to 14 0 p.s.i.g for R -12 and 200 to 230 for R-22 4 Servicing and Troubleshooting 1 We have covered several service techniques in the previous section that relate to installation, including leak testing, dehydrating, and charging into the low side as a gas and into the high side with liquid We shall now go further into servicing as it relates to disassembly, inspection, and reassembly... position and wired as shown in the wiring diagram (fig 13 ) 12 Liquid line sight glass The liquid line sight glass is installed between the dehydrator and expansion valve You should locate the sight glass so that it is convenient to place a light behind the glass when you are observing the liquid for a proper charge 13 Water regulating valves Install the water regulating valve with the capillary down and. .. indicator and be sure the wick is clean Oil or dirt on the wick causes erroneous readings 20 To prevent loss of oil from the vacuum pump and contamination of the indicator, you must install shutoff valves in the suction line at the vacuum pump and the vacuum indicator When shutting off the pump, close the indicator valve and pump valve, and then turn off the pump Now we are ready to dehydrate the system 21. .. the compressor suction and discharge valves and connect your gauge and manifold to the appropriate compressor gauge connections The next step is to connect a refrigerant drum to the middle manifold hose Open the drum valve and purge the hoses, gauges, and manifold Then tighten all the hose connection Turn the suction shutoff valves a couple of turns from the backseat position and open the drum valve... charge Leave all the service valves on the condensing unit closed until the piping and accessories have been dehydrated Do not install a strainer-dehydrator until the piping is complete and the system is ready for evacuation Figure 14 Vibration isolation type hanger 10 Use a square ratchet or box-end wrench (1/ 4inch) to open and close the valve Do not use pliers or an adjustable wrench since they are likely... Figure 13 shows a typical wiring diagram for a semihermetic condensing unit 6 A table of wire size requirements is provided with the manufacturer's installation handbook For instance a 220-volt three-phase condensing unit requiring 8 amperes at full load must be wired with number 8 wire if the length the run is 300 feet However, number 14 wire can be used if the run is limited to 10 feet 7 Piping and. .. decrease the amount of water the pump must handle and to hasten dehydration When the pressure drops to a value corresponding to the vapor pressure of the water in the indicator, the temperature will start to drop 22 In the example illustrated in figure 18 , the ambient temperature and the temperature of the water in the indicator is 60° F Starting at 60° F., and 0 time, the temperature of the indicator... Looking back at figure 17 , you will find that a 35° F reading corresponds to a pressure of 0.204 inch Hg absolute This procedure may take several hours, and many times it is advantageous to run the vacuum pump all night After evacuation, turn off the indicator valve (if open) and the pump suction shutoff valve, and break the vacuum with the recommended refrigerant Disconnect the pump and vacuum indicator . EDITION OD1750 A REFRIGERATION AND AIR CONDITIONING IV (EQUIPMENT COOLING)