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Author Topic: Metering Devices  (Read 93 times)

Offline Icehouse

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    • hvacbob
Metering Devices
« on: July 31, 2012, 07:13:07 PM »
In Refrigeration as well as Air Conditioning the refrigerant is feed to the evaporator by the "Metering Device" be it Capillary Tube, Expansion Valve, or Fixed Orifice Tube.
The expansion valve is adjusted by Super Heat measurement using  a pressure gauge and a digital thermometer.
 Start the refrigeration system and run it for at least 10 minutes to  establish steady-state temperatures. Connect the refrigerant manifold gauges to  the suction service valve between the  evaporator and the compressor. Connect the pipe clamp thermocouple to the  suction line near the suction service valve. Connect the thermocouple to a  digital thermometer.Measure the suction line pressure using the refrigerant pressure gauge.  Record this pressure and the suction line temperature from the thermometer. Use  the refrigerant temperature/pressure chart to convert the pressure gauge reading  to evaporator saturation temperature.Subtract the evaporator saturation temperature from the thermocouple  temperature. This difference is the system superheat. This shows the temperature rise  above the bubble point temperature of the system. Review the operating  specifications for your system to determine the proper superheat. Inadequate  superheat can cause liquid refrigerant to return to the compressor, resulting in  compressor damage. Incorrect superheat can also indicate improper refrigerant  charge, thermal expansion device problems, a clogged filter-drier or a dirty  condenser coil.
 
« Last Edit: July 31, 2012, 07:15:10 PM by Icehouse »
NATE, NCCER, PHCC,HVAC Certified Instructor
Member RSES, US Army Refrigeration Specialist(Retired), Former Refrigeration Teacher NYC Board of Ed.
a tragedy has happen to me : http://web.me.com/zenzoidman/Bobice/

Offline Icehouse

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  • Member Since: Oct 2008
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    • hvacbob
Re: Metering Devices
« Reply #1 on: July 31, 2012, 07:22:23 PM »
How to Adjust Super Heat on Air Conditioning R-22 With TXV

InstructionsTurn on your air conditioning system using the control box. Allow the system  to run for at least 30 minutes before moving on to the superheating  process.Locate your AC pump. It is generally located outside of the home. Inspect the pump closely. Notice that there are two refrigerant hoses connected  to the pump. The liquid line hose is smaller and attached near the bottom. The  vapor line hose is larger and connected to the top.Connect the blue hose of the compound pressure gauge to the valve on the  vapor line hose. Connect the red hose to the valve on the liquid line hose. Open the valve on the blue hose. Monitor the blue pressure gauge to get your  systemís saturated temperature reading. Write down this temperature reading on a  sheet of paper.Inspect the liquid line hose for an attached metallic tube. This is the  thermostatic expansion valve, or TXV. Apply a thermometer to the sensing bulb of the TXV. Record the temperature  from the sensing bulb on the sheet of paper along with the saturated  temperature. Subtract the saturated temperature from the temperature given from  the sensing bulb. The difference is the superheat measurement.Compare the superheat temperature to the recommended temperature of your  system. For most systems, this measurement should be approximately 10  degrees.Adjust the superheat temperature of your system by turning the adjusting knob  on the TXV. Turn the adjusting knob towards the closed position to increase the  superheat temperature. Turn the adjusting knob towards the open position to  decrease the superheat temperature
NATE, NCCER, PHCC,HVAC Certified Instructor
Member RSES, US Army Refrigeration Specialist(Retired), Former Refrigeration Teacher NYC Board of Ed.
a tragedy has happen to me : http://web.me.com/zenzoidman/Bobice/

Offline niobrara

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Re: Metering Devices
« Reply #2 on: July 31, 2012, 10:48:21 PM »
About time you started to share the knowledge again . Glad to see you posting again. Good information.Thank you.

Offline Icehouse

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  • Member Since: Oct 2008
  • Posts: 569
    • hvacbob
Re: Metering Devices
« Reply #3 on: August 04, 2012, 02:10:14 PM »
About time you started to share the knowledge again . Glad to see you posting again. Good information.Thank you.
Sorry Ex wife had a servre stroke
NATE, NCCER, PHCC,HVAC Certified Instructor
Member RSES, US Army Refrigeration Specialist(Retired), Former Refrigeration Teacher NYC Board of Ed.
a tragedy has happen to me : http://web.me.com/zenzoidman/Bobice/

Offline niobrara

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  • Member Since: Sep 2009
  • Posts: 1228
Re: Metering Devices
« Reply #4 on: August 04, 2012, 03:12:05 PM »
Sorry hope all goes well on recovery

 

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