Hello, yes, this is the HVAC school podcast. This is a short episode. This short episode is about P OE and mineral oil, and yes, I am driving into work this morning. You may hear a little sleep still in my voice, but never fear.

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My friend all right. So here we go p OE in mineral oil. What's the difference in? Why should you care now? First thing that I have to note here is that for those of us who are nerds in the business, that's something that we've spent a lot of time. Thinking about is POA versus mineral oil, but you'd be surprised how many technicians and installers are out there today, who really don't even know that there is a difference.

They just think of reversion oil as being one thing, and obviously there are other types of refrigerant oils. Other than POA in mineral, but I'm just going to focus on those two, because those are the most common ones that we see, and so let's first talk about mineral oil and what its advantages are. One of the advantages of mineral oil is that it's very stable mineral oil does have. There is some affinity for moisture, for example, if you think of vacuum pump oil vacuum pump, oil is heavily refined mineral oil and we know that vacuum pump.

Oil does have a hygroscopic property, which means that it does have a property to absorb moisture but regular, refrigerant oil that we have in a typical old-school, a/c system, saying r22, our 12 system. While it can absorb some moisture, it doesn't have near the hygroscopic city. I don't know if that's word, the hygroscopic properties them water, absorbing properties of pol, also mineral oil. Just again, like I mentioned it's very stable, it just is oil.

So what it is it absorbs from moisture it gets cloudy, but it doesn't change what it is. It's just mineral oil doesn't cause as many problems in the system other than mineral oil does have this nasty property of not being very well carried by the refrigerant now, with old r22, our twelve older refrigerants, they would carry the mineral oil through the system by maintaining Proper refrigerant velocity, so you would, when you were designing the piping say on a refrigeration unit or on an air conditioner. You had to think a lot about making sure that you maintained your refrigerant velocity and so pipe size was a really important consideration and refrigerant line pitch was an important consideration and trapping things like that. Those are all important when you have mineral oil, because mineral oil, while it's a good oil and it's very stable - it's not carried through the system quite as easily as pou oil.

Another thing is: is that mineral oil doesn't act as a solvent in the way that pol does you'd have older systems, and you would braise without flowing nitrogen, and you would notice if you cut those lines open years later, that a lot of them would still have That carbon on the inside of the lines that accumulated when they were originally braised and so mineral oil is not really a solvent. It's just some oil. It just travels through the system. It's an oil, then we come up with pou oil, and the first thing we got to know about pol is that, of course, what is POA stand for stands for polyester.

It's an ester oil which I don't really know what that means. Frankly, I'm not a chemist, but I do know what it does and why it matters, and the reason why we had to start using p OE is that the newer refrigerants of the four series refrigerants, especially so, are 410 a and our 407 see anything. It starts with a four which a lot of our modern blends have that they just didn't. Carry the mineral oil.

The way that the old single component refrigerants did like our 22 and our 12 and so you'd run into these problems for the oil would just kind of sit in the evaporator coil or it wouldn't return back to the compressor. Because the goal of oil is to keep it in the compressor, that's where we want it. We wanted it in the compressor, but coming out of the compressor. You have really high refrigerant velocities and so that compressor over time will lose some of its oil it'll just blow out some of its oil, let alone, if you have a flood back or flooded start condition, and then you'll really start to lose a lot of oil.

As head oil foams and gets blown out of the compressor, so you have these circumstances where your oil gets out of the compressor and if your refrigerant doesn't carry it back, if it doesn't have the properties necessary to help move that oil back to the system. Well then, it gets stuck in all kinds of places to get stuck in it. Evaporator coil gets stuck in low points, causes all sorts of trouble and eventually it can cause some real. The capacity problems and even issues with your readings you'll start to have restrictions because you have a protocol and a meeting.

Your device gets full of oil. It's a major problem and you can't use mineral oil with the 4 series refrigerants. For that reason, again, that's refrigerants like for 10a, so they had to come up with a new oil and they came up with this polyol ester oil, the POA oil and the pou oil has a really great property, which is that it is carried with the refrigerant And some people get the idea that pol is only good with the 4 series. Reversion MP OEO fine with our 22 as well.

In fact, you'll see. Sometimes, if you replace a compressor that the new compressor may come with pou oil and that's something you need to know because you're gon na have to think about that. If you had mineral oil in the system before you're gon na want to know that the new compressor potentially could come with pou oil, even if it's a are 22 compressor. So pou oil is a really good oil from the standpoint of being carried through the system.

In fact, you'll notice that there's not nearly so many requirements for traps or pitching or a lot of that stuff that we used to have to think a lot about. When we had mineral oil. We don't have to think as much about when you have pol, because pol is carried with the refrigerant and the term that's used for carrying the oil with the refrigerant is called miscibility. I think that's how you say it actually, not sure I read that word all the time, but I don't say it out loud now that I say it: I'm not sure that that's the right way of saying it, but miscibility is the oil miscible and the refrigerant Meaning it doesn't mix as it carried along with the for jpoa, is very missable in most of our modern refrigerants.

It's carried along very well, and so that's a good thing. The bad thing with P OE is that P. Oe is very reactive, and it also acts more so as a solvent than mineral oil did, which means that you could have an old system that previously had mineral oil in it. And then you put P o EO Ella in it and that pou L scrubs the walls of that copper and picks up all that carbon and throws it into your expansion valve and into your line, dryers and all that sort of stuff.

So it causes some trouble from the solvency standpoint, the fact that it can scrub stuff off the walls of the inside of your system, and it also creates a little bit of trouble from the standpoint of moisture absorption. So if you had an old system, let's say that you converted to pou oil or change refrigerants and went to pol or maybe an old line set, that you put a new piece of equipment on and that part of the equipment is wet. It has some moisture and moisture bonded to the walls and moisture trapped in the oil and moisture here and moisture there and moisture everywhere well pol. It's gon na react with that moisture and it's gon na actually change its properties.

So, unlike mineral oil or mineral oil will become cloudy and maybe a little globby with some water, but at the end of the day, even when it mixes with water, it's still going to be mineral. Oil POA actually changes its properties and becomes acidic. This has been well discussed and documented, and just from personal experience, I can tell you that I had many cases and the previous company that I used to work for where they would start up units wet. So the start up technician wouldn't pull a proper vacuum that maybe the Installer ran the line set, jammed it through a water-filled chase, with the end zone capped or with plastic caps on the ends that were breached, and you had significant water in the system and they Would start these things with pou oil, and these things would blow the compressor black oil everywhere within a matter of a couple days.

I've seen it on several occasions. Now, that's an extreme circumstance. We don't see that all the time, but to a smaller extent, even any amount of water, any amount of moisture and or I should say any significant amount of moisture - that's left in the system. A drop of water can greatly reduce the life of a system that contains pol again.

Many of you know this, but some of you may not. The other thing to think about is - and I know we're generally - not a additives or those sorts of things, but you do need to know like, for example, if you're using an acid, scavenger or acid inhibited product of some sort, acid neutralizing product that different products. Some of them work with pou oil and some of them work with mineral oil. So that's another thing to think about with POA and mineral now.

Another thing that comes up a lot is when people make refrigerant retrofit, so they go from our 22 to another option. Whether it's 407 C or 438, a or whatever it is a lot of people are concerned about well, what's gon na happen. If I put that new refrigerant in with the older mineral oil - and the answer is, is that it's not good? It's not a good thing to put four series refrigerants in with a mineral oil system, but a lot of people swear by adding in a little bit of pol and that that will help carry the mineral oil around the system. Early on when POA oa first came out, there was all these I'll call urban legends that if you mix mineral oil and pol that somehow would react and would cause all this trouble.

And what we found is is that's not really the case. You don't want mineral oil in with pol, because the mineral oil is just gon na get stuck places. It's gon na get stuck in the evaporator, coil and low points, and it's gon na cause issues with heat transfer and issues with restrictions. But it's not so much that mixing the pol and the mineral oil causes some sort of like terrible reaction or something I'm in fact, like I said, some people are actually adding small amounts of pou when they make retrofits and I've even seen some documentation from some Manufacturers, refrigerant manufacturers, it seems to say that's: okay, but all this sort of dances in a gray area.

I'm not gon na talk a lot about this, but I tend to be one that I just prefer to use the refrigerant that's design for the piece of equipment until the time comes to change the equipment to different equipment. Now, obviously, if you're working in the world of refrigeration, where you have to retrofit a whole parallel rack or something you're, not gon na replace the whole rack, that would be ridiculous. So retrofits and those sorts of applications make a lot more sense, but also in large rack, grocery store refrigeration. They also tend to take a lot more care when they make those conversions to remove the old oil and put in new oil and make sure to replace the line dryer so on and so forth.

The different factors that can come in when you make that transition from POA and again there are other types of oils as well. When I got a gum up the works here, this podcast just keep it simple. So that's it. Mineral oil is a good oil.

It just tends to get stuck places and you got to think a lot more about velocity and oil return and the type of refrigerant that it works with VOE oil is a great oil, but it acts as a solvent. It tends to grab contaminants and plug stuff up, and it also is very hygroscopic, which means that it really likes to grab moisture and that can change it to an acid which can cause all sorts of damage, which is why and modern air conditioning. We talked so much more about flowing nitrogen while brazing and pulling really deep vacuums, because it does matter more than it used to it always mattered, but it matters more than it used to now that we have pol. So when an old-timer tells you they've been doing 30 years and it never made a difference with them well, they worked in a time before there was a lot of pol.

So now the world has changed. I hope that helps we'll talk to you next time. On the HVAC school podcast.