View Full Version : R404a mineral oil ?

26-07-2002, 12:20 PM
Does anybody know or had experience of minereral oil or alkaline benzine/mineral oil in a R404a system. I would imagine becuse they do not mix the oil would end up in the evaporator and would cause premature compressor breakdown and lack of evaporator performance. But do they cause any chemical breakdown ? If anyone has any ideas or experence with this thier input would be appreciatted.

27-07-2002, 04:00 PM
Early on we know we had units running with a fairly rich mineral oil/polyolester mix after retrofitting. I think I saw as high as 25%.

We failed to see any lubrication related failures or chemical breakdown, although we decreased the mineral oil with oil changes just to be safe.

I would expect the only problem you would see with mineral oil and 404A would be poor oil return.

28-07-2002, 01:38 PM
There have been some appliance makers who
(for repairs) have successfully used a super
thin alkylbenzene oil (which is just synthetic or
highly refined mineral oil - stable unlike
Esters) and R134a in fridges... but evap
is uphill and oil drains/dragged back.

No chemical problem with HFCs like 404A or
134a and mineral oil, just the oil return

I don't like the long term instability of
PAG/POE oils nor their moisture grabbing/
acid forming abilities. When R22 is unavailable,
I would put R-290 (propane) in my heatpump
before letting somebody put in a refrigerant
which needed POE/Esters..

Also, If I ended up with a system which used
R404A, R410A (Puron), or R407C and Ester oil,
I would take out that sewage and replace it
with mineral oil, and put the refrigerant
back in, and add 10% propane or propylene
to make it work with mineral oil. This would
probably not pass an ASHRAE/UL spec for
"A1/A1" and may have some regions of weak
flamability during a leakdown, but it is sure
a lot safer than pure propane ,etc..

28-07-2002, 06:18 PM
:) Hi, ghg
Sounds like history repeating it'self. When R502 was used on mineral oil in flooded systems, or for that matter DX with large pipe runs, up tp 10% R12 was added to aid oil return.
Regards. Andy.:)

Preston Roy Powell
22-09-2002, 05:40 PM
R-404A must have 90% poe oil, OR ALk benzene oil. That is want copeland says in their copeland engineering book that I have. If you dont get all the old oil out your going to have problem with refrigeration and compressor failure...

preston roy powell

Steve Niles
23-09-2002, 03:25 PM
You asked a specific question that begs further attention. You asked if POE use with other refrigerants could cause breakdown of the oil.

The oil and refrigerant manufacturers say no. The problem is this, POE loves moisture. If you create acid, by any means, burn out, electrical burn, leak that draws in moisture under a low side vac., etc., once the moisture and acid is in the latent oil trapped in the system, it is a perpetual source for recontamination. The oil trapped in the evap or anyother component, cannot get back to a point that it can be extracted. Once contaminated with acid, it continues to contaminate any future oil and refrigerant that is put in the system. So in answer to your question, no the other oils are not harmful to POE in their pure state, but once contaminated and latent in the system, they can continue to be a pain.

What to do?
Find a way to locate and remove the unwanted oil. Trap and tap the evaporator and drain it. Put trap and drain points in you systems low points and clear them periodically until all you get out of them is pure POE.

Although I am not a stong proponent of adding anything to system, I know that there are some additives that you can get from your local chemical supplier that neutralizes acid.

There are also products on the market now that flush the system legally and safely. In the "good old days" we used to flush systems with R11 after a burn out to clean it up. This pushed the contaminated oils and build up either out of the system or at least to the closest restriction where they could be extracted. We can't use R11 anymore, but there are similar cleaning products now available from your local wholesaler.

Add refrigeration filters and driers. Check and change them regularly until you have a clean system. Too ofter these are added and never checked again.

The best prevention is good original conversion. Take the time when first converting the system to cut it open, flush it out, check and trap low velocity points in the system, and in general, start out with a clean system. I often get complaints that the first costs of conversion are too expensive if we do all of these things. I'm not sure that they are after you factor in multiple lost compressors, call backs, multiple oil changes, filter/drier changes, and when everything is done, you still have a contaminated system.

Hope this helps.

23-12-2002, 09:56 PM
I have had of several reliable service reps around the country switching the POE with Alkaline-Benzine as a test, but the time in system is low and I would not recommend it for a customers system. Try it in-house first.

I have never heard of any failure mode associated with Alkaline-Benzine and R404a because of chemical interactions.

Also, be careful of any "off the shelf" additives mixed with POE for clean up of moisture or burn-out. I had to work with two different companies that use "burn out" cleaners with POE systems, trying to clean up after the oil overheated due to a lack of maintenance. In both cases, each had repeat oil failure within two weeks. I always prefer changing the oil, drier and metering device as a clean up.

I have never heard anyone at Copeland recommend a flush or drying agent with POE. The additives they use, in my opinion, are too unstable.

The senor chemist at Copeland told me they use virgin POE to flush after burnouts because of its acidic or "detergent" nature. This is why not using a nitrogen flush when welding is such a problem.

Anyway, I chasing rabbits again. Just try the Alkaline-Benzine before you expose a customer.

24-12-2002, 02:16 AM
I do not ues R-404 but Im thinking that you must use 99% poly oil I have know a few techs that use a 50- 50 mix they say the comprssor is still runing after 6yrs. bettere lucky they good I guse.