mixed refrigerants

[jcool808]

Anyone ever had a system with mixed refrigerants? How did you come to that conclusion. What symptoms would one come across? Any cooling still available? What would the pressures look like. :)

[taz24]

Anyone ever had a system with mixed refrigerants? How did you come to that conclusion. What symptoms would one come across? Any cooling still available? What would the pressures look like. :)


I had a single condensing unit working 3 twelve foot dairy cases. 1 case had a R12 TEV, 1 case had a R22 TEV and the last had a R502 Tev. It had run like that for years and as the valves had failed they had been replaced for incorrect ones and charged with all the above refrigerants. I found it because the sytem played up in warm weather and would not condense correctly. I could not belive that the valves were what they were and I had to check, double check and tripple check to satisfy myself.

taz.

[NH3LVR]

I once put some R-22 in a R-12 system. Head pressure went up as did the amperage draw.
The head and suction pressure will rise as general rule.
I will note however that it was not uncommon to put a small amount of R-22 in a R-12 system to facilitate oil return at one time.
It will cool as long as the head pressures stay within normal limits, however you have changed the temperature pressure relationship of the refrigerant.

[monkey spanners]

My old boss once charged a system without vacuuming out the Nitrogen he had put in to test for leaks, and left it running like that......

[philfridge]

By mistake have charged a R22 system fridge with R409A which is a drop in gas for R12 and it worked fine.:p This happens a lot I bet and you cant really tell whether gas is mixed but best to check compressor data plate and t.e.v to confirm correct refrigerant before running out to van and grabbing some gas ;)

[pauldoubledee]

I found a cake fridge that was not condensing correctly and when I fitted gauges to the system and the needle on the low side was bouncing! After recovering the contaminated refrigerant and recharging with the correct refrigerant it was fine.[/font]

[old gas bottle]

depends on the system type and what mix etc, things like frosting back on the suction line,running continious,not holding temperature, compressors overheating,triping overloads,lots of differant symtems this is only a few,if in doubt pull it out;)

[Chunk]

I`ve put a whole bottle (60kg) of something into a pack that was running on r12,it lasted 7 hours and smashed all 6 compressors.

We sent a sample bottle back to ici where the bottle came from.They didnt tell us the outcome,but told us to send them the bill,no more questions asked.It took a week or so to clean the system,but it was never the same after that.

These days,we just get water or contaminated oil in the bottles.Happy days.

[monkey spanners]

I've had water in a new bottle of R134a once, i was vapour charging and as the bottle had cooled i picked it up to give it a shake in the time honoured fashion and was surprised to hear something rattling around in the bottle that wasn't there earlier.
Once the bottle was empty i put it on the vans engine to warm it up (this was in winter on a farm) and drained about a cup full of black water out of the bottle.
System ran ok after this, good job i was tryng to earn some overtime and vapour charging and not boiling liqiud off in the gauge line as normal:D

When i've had systems mixed or wrong refrigerants in, its been on systems i'm very familiar with and you get a gut feeling that something isn't right. The reported fault may be slow to cool or running too long, etc and after checking all the mechanical components are working fine you are left with the refrigerant.
You could pump the system down let the temperature settle and then compare the temperature and pressure you have with what it should be on your sliderule.

Jon

[Brian_UK]

I've had an R22 A/C system that had been topped up with R410a by a.n. other.

It ran, but oh boy the pressures were up a bit on what was expected.

It didn't like to run for too long when the sun came out either ...

[sawtell]

If you suspect you have a combination of refigerants within the system,
e.g. higher than normal operating high and/or low side pressures,
excess current draw,
not able to maintain a constant evaporator pressure,
lack of performance on high ambient days etc.
Shut the system down ,fit you guages and take the standing pressures, take the ambient temperature and check your P/T chart for the refrigerant at that ambient and compare your readings. If you have a low ambient temperature you may have to warm the system up or pick a higher ambient day as a few refigerants at low ambint are too close together to get a good seperation reading.

[chillin out]

I have put R404 in a R12 case.
R404 in a R407c a/c unit.
R22 in a R407c a/c unit.
R407 in a R22 a/c unit.
R22 in a R404 pack.
R404 in a R22 pack.

And just about any other combination you can think of.

And they are still running today.

Also had a large container of oil that unbeknown to us, somebody had urinated in and then another person put it all into a LT pack.
Engineers spent a full 90 hours solid (took it in shifts) to clean the system.
Happy days indeed.

Chillin:):)

[hendry]

Hi jcool808,
early days, it is common to have 2 refrigerant in the same system.
i learn from these guys that they do it for a purpose.

but, having understand the chemical properties of each refrigerant, i would advise avoiding it as much as possible.

1] each refrigerant responds differently to lube oil and temperature;
2] i remember the terminology, "temperature glide" would explain the difficult tasks encountered in commissioning the system later;
3] chemical behaviour of both lube oil and refirgerant at high temperature may cause complication in various parts of the system esp. when impurities exist in every equipment and devices.

my personal conclusion is "check the type of refrigerant in the system otherwise remove it & charge in those with your full knowledge".

hope that helps.

Hendry, on wesak day holiday.

[fridgey]

Anyone ever had a system with mixed refrigerants? How did you come to that conclusion. What symptoms would one come across? Any cooling still available? What would the pressures look like. :)

A system with mixed refrigerant has always been referred to as a 'shady' down here. I've seen it done numerous times, some of the time the systems seem to work other times not. The tell tail signs are ussually abnormal operation of the system. Operating pressure are wrong, won't condense on hot days, evaprators freezing up, high superheat or low superheat. Lots of symptons. You know something is not right. Best solution depending on how large system is, is the reclaim, evacuate and recharge.

I remember working on an old temprite plant in a pub still on R12. Some cowboy had topped up the system with god knows what a couple of days earlier and left it leaking. Know all the beer was freezing. Because the temprites rely on regulation of evap pressure to maintain temp. Now the settings were all wrong with no way to reference a pressure/temp relationship. The only option was to reclaim and recharge and retrofit R134a.

Then again in cascade refigeration it is quite common to see mixed refrigerant specified but always in calculated amounts.

In short it is best practice not to mix refrigerants unless specified.

[nadeem]

My window Ac's fins were damaged and condensation was not perfect and head pressure was high with less cooling. I mixed R12 and into R22 and found better colling with normal head pressure.

[mazbut]

someone here ever tried 75 % R22 mixed with 25 % R12 in a freezing plant?

[Chunk]

someone here ever tried 75 % R22 mixed with 25 % R12 in a freezing plant?

Have done once a long time ago,had a supermarket pack with 300 kgs of r22 in it,and we were having severe oil return problems with oil logging in the freezer evaporators.My supervisor at the time said to put a 60 kg bottle of r12 in.

It didnt cause any problems but it didnt help the oil return either.

[icecube51]

when the mixture is incorrect than the needle of the manifold is unstabel, the mixture can be of two refregirants, or water.

the one ho will invent a tool to recognise the refrigarant will gain the jackpot.

because nobody ever nows if it is the correct refrigerant.

had a to do a repair ones one a dual home airco ,and the inside units where R407c and the outside R410a.
i had to admit , but wich one.

if there was a tool, we could take a sample,and admit the correct one.

Ice

[mazbut]

Ice
Lovely fact !

[nike123]

Is this of some help?
http://www.yellowjacket.com/HVACRProducts.asp?t=HVACR&l=7&c=66&p=225

[icecube51]

NO,:o
what about all the other gasses???:eek:
R407c, 410a, 504,600, and so on:confused:

this is checking only 3 nown kinds.

if you are on a china plant,who has the paper stickers on the site,its no longer readeble and the manifold tells you it needs a few grm of cooland.
whitch one its needs??? there's the tool needed for, you dont mess up a good working plant,just because you dont now on which refrig its works and add the wrong one.

Ice

[taz24]

NO,:o
what about all the other gasses???:eek:
R407c, 410a, 504,600, and so on:confused:

this is checking only 3 nown kinds.

if you are on a china plant,who has the paper stickers on the site,its no longer readeble and the manifold tells you it needs a few grm of cooland.
whitch one its needs??? there's the tool needed for, you dont mess up a good working plant,just because you dont now on which refrig its works and add the wrong one.

Ice


That is the problem with new refrigerants.
The choice is vast there are about 30 usable refrigerants for each of the old R12, R22 and R502 refrigerants.
You can do a standing pressure test but all that will tell you is what similar type of refrigerant group you are working with, not the individual refrigerant.

taz.

[nike123]

NO,:o
what about all the other gasses???:eek:
R407c, 410a, 504,600, and so on:confused:

this is checking only 3 nown kinds.

if you are on a china plant,who has the paper stickers on the site,its no longer readeble and the manifold tells you it needs a few grm of cooland.
whitch one its needs??? there's the tool needed for, you dont mess up a good working plant,just because you dont now on which refrig its works and add the wrong one.

Ice

I am not familiar with this product but I think that this mean that it could analyze lot of refrigerants:


Analytical software identifies all EPA S.N.A.P. approved blends, as well as illegal replacements and blends including propane and butane
http://www.epa.gov/ozone/snap/refrigerants/reflist_20071004.pdf