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Thread: R404a charging

  1. #1
    Join Date
    Jul 2004
    Posts
    18
    I need to charge from scratch a low temp unit (Copeland M4FL0040IAA201) with R404a. The system is under vacuum and ready for charging. I have never charged a blend before but understand that it must be done as a liquid. Could someone please walk me through this? Do I add the liquid through the high side valve? When do I start up? After start up, how do I add more liquid safely?

    Obviously, I am not an expert. This unit is on a scientific instrument, which I use daily in my work. I have replaced the compressors on several other similar units in the past but they were R12 and R502, which didn't require liquid charging (or at least I didn't do it that way).

    Thanks in advance for your help.

  2. #2
    Join Date
    Feb 2004
    Location
    Maine
    Posts
    483
    First of all I assume you are EPA certified? If not don't touch it, if so liquid charging is easy. Being a "blend" your bottle of 404a has a dip tube in it to allow liquid charging with the bottle in the upright possition. You can buy a device that hooks up to your manifolds low side hose. This device allows you to remove the refrigerant from the tank in its liquid state, it then flashes it off into a vapor before it enters the low side port on the unit. Or you can just "throttle" the flow while charging liquid into the low side. Liquid charging into the low side can damage or destroy the compessor if done to fast and the compressor takes a slug of liquid. The expansion device that turns the liquid to vapor is the best and safest bet. They are pretty inexpensive and will get lots of use as most newer refrigerants on the market are blends. You shouldn't leave a system under vacuum for a long period of time, if there are any leaks you will get non condensibles and or moisture in the system, its best to add like 10 psi of dry nitrogen as a holding charge, then re evacuate to 500 microns or less just prior to charging. Being an HFC blend you have POE oil in that compressor and POE oil absorbs moisture very easily. Be sure to change liquid line drier if equiped or add one if it's not. Hope this helps.


  3. #3
    Join Date
    Jul 2004
    Posts
    18

    r404a

    thanks for the advice.

    Could you tell me the name of the "expansion device" for adding the refrigerant through the low side valve? I am looking at a United Refrigeration Catalog and can't seem to locate what you are talking about.

    By the way, the R404a can does not have dip tube as far as I can tell. It simply says that it should be turned upside down when charging.

    Again, thank you for helping me.



  4. #4

    Talking

    Dr.Frankenstein, if it is such a high tech, scientific instrument, why not call someone to fix it?
    Hey cockroach, don't bug me! ©

    www.AskTheDiceman.com

    www.TheColdConspiracy.com

    www.Pennwood-HVAC.Com

    Bring Em Home....

  5. #5
    Join Date
    Nov 2003
    Posts
    501
    Whoa...I'm going to appologize if it's explained farther down becaue I didn't read the whole thing. 404a does NOT have a dip tube. You MUST turn the bottle upside down to charge as a liquid. If you keep it upright, you will charge as a gas and change the properties of the refrigerant, opening up a whole new can of worms for yourself.

  6. #6
    Join Date
    Jul 2004
    Posts
    18

    answer to the question

    I enjoy learning about new things and fixing stuff myself, at work and at home. Also, we have a very limited budget.

    There is no dip tube on the 404a from Atochem.

  7. #7
    Join Date
    Jul 2000
    Location
    Guayaquil EC
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    10,483
    The dip tube thing caused a bunch of confusion out here in the field for sure. DuPont provided a dip tube on all of the blends way back at the beginning while the other manufacturers didn't. DuPont changed to drums without diptubes a long time ago to get in step with all the rest.

    If you have an old tank, just be sure to read the info on it so you'll know which end is up.

  8. #8
    Join Date
    Jan 2004
    Posts
    526
    Originally posted by Diceman
    Dr.Frankenstein, if it is such a high tech, scientific instrument, why not call someone to fix it?
    thats what i was thinking, if its in a lab and is important

    it keeps a specific temp you awt to call out a pro why chance

    it.

  9. #9
    Join Date
    Nov 2003
    Location
    Wisconsin
    Posts
    458
    Dip tube. No dip tube. Arrows on the jug or arrows rubbed off. When you purge your hoses, you'll know when you have liquid.

  10. #10
    Join Date
    Feb 2004
    Location
    Maine
    Posts
    483
    Sorry for the confusion on the dip tube. I bought quite a few cans of different SUVA blends back when they had dip tubes on them. I haven't made any refrigerant purchases for quite a while. If you need to turn the can upside down there will be arrows that show which way for liquid. The name of the device that flashes off the liquid is Insta-Charge. They have them at Johnstone supply.

  11. #11
    Join Date
    Jul 2004
    Posts
    18

    another stupid question...

    It is with great trepidation that I ask another stupid question but I seem to be creating entertainment for the pros so here goes...

    To bring you up to date, the system was evacuated, filled with dry nitrogen at 150 psi, leak tested, then evacuated again. R404a was added as a liquid using a scale. I could not find the charging amount stamped on the compressor or on the internet so I tried 2.5 lbs. I started up the unit. I slowly brought the temperature down to 5F in steps of 5 degrees. At each point along the way, the unit cycled off, as it should. I need to get to a temperature of about -35F.

    The problem: The pressures seem much too low: At the 5F cabinet temperature and an ambient temperature of 70F, the Lo side=1-2 psi and the Hi side=175 psi. Also, there is no liquid refrigerant in the sight glass and the compressor is warmer than what I think it should be.

    I think I need more refrigerant?

  12. #12

    Re: another stupid question...

    Originally posted by dmh

    I think I need more refrigerant?
    I think ya need a serviceman..........but add some juice, see what goes, whaddya got to lose at this point anyway.
    Hey cockroach, don't bug me! ©

    www.AskTheDiceman.com

    www.TheColdConspiracy.com

    www.Pennwood-HVAC.Com

    Bring Em Home....

  13. #13
    Join Date
    Feb 2004
    Location
    Maine
    Posts
    483
    Oh man you were doing so good until you tried to charge it. I take it you don't have a good strap on thermometer to check super heat and subcooling? I'm with Dice on this one, call a service man in before you overcharge it and kill it for good.

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