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HP80 and MP39 replacements. We've used MP39 since the R-12 phaseout, same with HP80. Both work very well, with any oil in short coupled applications. 134A has been nothing but a nuisance with it's low capacity, and my habit has been to remove the 134A and replace it with MP39 when I do repairs on small equipment.
Just charge to full sight glass like normal and watch your superheat. I have personally converted a handful of r12 walk-ins to 134a. Pull down time from 70*F was marginally slower (at least in my head) but no problems maintaining. Your TXV will be slightly over sized with 134a so you may need to make a txv adjustment.
once again mp39/401a is the perfect drop in for r-12. kitten, pressures were 38/190 cooler temp was 38 degrees at completion! this post is just another thumbs up for this drop in refrigerant! No doubt, MP-39 is one of the best replacements for R-12 in medium temp applications.
This from ASHRE " MP39 has a slightly higher discharge temperature than R12, 409A has a significantly higher discharge temperature then R12 so caution must be used! [Edited by icehouse on 02-24-2005 at 04:14 PM] RAM Teaching Tomorrows Technicians Today. Reply.
Originally posted by rocket CFC & HCFC the oil issue should not determine your choice of gas example: MP39 & HotShot have almost exactly the same miscibility with mineral oil, so the one claiming "no oil change required" is pulling your chain. if you don't wish to change oil then don't with either, however you will have better results if you change the oil
I know all of the replacement refrigerants (R-409 / MP39 / MP66 / Hotshot) contain R-22, R-124, and some contain R-142, all HCFC refrigerants. This new DuPont MO49plus (R-437A) does not contain any HCFC refrigerants. Has any one tried this new refrigerant yet, and if so, how well does it work.
If you change the condensing unit go with 22 or med temp 404. If you use either 134 or 404 you'll need to blow the lines and evap out and flushing with RX11 would be even better. If you change a 22 unit would be the simplest way, you will need to change the TXV though. Reply. 08-26-2006, 07:08 AM #7.
Unfortunately, MP39 was used a lot as an R12 replacement. My experience is that it works about as good as any replacement. We used to use a lot of the HOT SHOT R12 replacement refrigerant and had good results with it. I don't remember what the actual number was of that stuff and it may be just as pricey as MP 39.
HP & MP points of clarity. Dupont developed these refrigerants in the early 90'S. MP39 & MP66. MP = medium pressure. 39 is the last two digits of the assigned research number. 66 is the last two digits of the assigned research number. HP63 & HP80 & HP81. HP = high pressure.
I have seen mp-39 in med temp systems quite frequently, and have used mp-39 as a retrofit on old r-12 reach ins, with out having to change the oil, with Great success. I've also used it in supermarket refrigeration, however have changed the oil to ab200. Must be a typo they mean poe. Using mo is a gamble.