This episode of the HVAC school podcast is made possible by generous support from all of our sponsors, which include carrier makers of fine quality, air conditioners, heat pumps, all kinds of different stuff. You know that you know carrier carrier turn to the experts. Also, thank you to rector seal rector seal sent me recently. The new, clear, bodied safety switch model SS, one, I'm sure you've seen the SS one switch, but it also comes with a really neat little adapter that you can use to actually blow out the T.

If you use it in line, I'm grabbing it right now, you can actually insert it into the T and use it too. If you're you can use in the primary train, you can actually use it as a clean-out for the primary drain, either like a normal, clean out tee or you can use it and actually pressurize it with nitrogen and blow the drain out. That way, it's a pretty cool device and the clear body is actually really nice on it, because you can see if there's any water in it, no matter what the configuration is. This episode is also made possible by one of our original sponsors.

Testo big. Thank YOU to testo for partnering with hvac school and thank you to test o for being willing to work with measure quick, app. We're really excited to see that relationship gets started. Test o perfect for testing perfect for service.

This episode also sponsored by Parker zoom, lock, meet zoom on the 10 second flame free refrigerant, fitting from Parker reduced labor costs by sixty percent, with no brazing no flame, and no fire spotter discover how sue block can help you be more efficient and productive visit. Zoom want comm for more information. This is the man who had posters of Willis carrier and John Gorrie on his wall as a teenager, Brian or yes. That is true.

Actually it's not true. I've mentioned this before I didn't have those posters, but I would have those posters now. I could find a John Gorrie poster I'm a big fan of John Gorrie. For those of you who know the Thomas Edison Nikola Tesla battle, that's maybe kind of an obscure reference, but John Gorrie and Willis carrier both have some claim to creating air-conditioning, whereas John Gorrie really did create ice machine.

I mean that's kind of what he really created. His refrigeration night, let's sit - let's just let's just agree to disagree on this. Let's just agree that John Gorrie invented compression refrigeration and Willis carrier invented the concept of dehumidification or humidity control, but that's really what that's really what Willis carrier did more than anything else, but I'm not knocking the man. I'm a big Willis carrier fan big fan of Willi, but I'm also a fan of John Gorrie and he's a Florida boy.

So something to that all right today on the podcast we've got the Jim Bergman. Jim Bergman is back and Jim is talking more about evacuation. We talked about evacuation once, but this time we kind of do it soup to nuts last one was more of a 101 on this one. We go from top to bottom cover everything with evacuation.

So if you want to know the official Jim Bergman stance on evacuation, everybody's talking of a QA ssin right now, people big hoses people, that's what everybody's talking about. But this episode we kind of go through his soup to nuts, which i think is helpful. If you kind of want to know the entire rig, what's what's recommended, we talked about breaking the nitrogen, some things that a lot of people have asked me. So that's what this podcast is about.

If you get down with this podcast and you try some of these things and you want some feedback, you have some questions, you can always email me at Brian, be rya and at HVAC our school comm HVAC, our school comm or, if you haven't been to the Website then, I would suggest that you go to w-w-w-w-w-w-wait all kinds of resources there, including a lot of information on evacuation. So here we go. We got Jim Bergman talking about evacuation all right, so today I want to talk about advance evacuation. I've been saying: oh my lot, lately, oh man, actually it's like um.

Actually this I'm actually that when I was recording a mid role, one of the tooltips for test of the other day. I said actually like 17 times, and so I haven't note now on my computer. That says stop saying actually I'm supposed to be a professional of this. I thought it would be done with this by now.

Um, actually you're, not yeah. Thanks for the thanks for the vote of confidence there, Jim actually see I did it again. I do have two preteen daughters now, so maybe I'm just getting to be more like them, the more I go on it could be, or it just could be. You're hanging around me and you're like a little fan girl running around screaming all the time.

I don't know yeah it's true. So do you think that'll wear off anytime soon you have any advice. Any management maybe help that we're we're off. You know, as long as we keep talking about evacuation, I think it's just gon na it's gon na stay.

It's gon na stay up high up there yeah. That is a pretty stimulating conversation. Alright, so we're gon na do this quick, because we got a lot of ground to cover, so the most important thing thing number one thing you talk about more than anything else is that, in order to pull a deep vacuum quickly, you need to use two large Diameter hoses so half inch or 3/8. Something like that right, yeah, that's correct, because when you're evacuating the the lowest pressure that you can achieve is negative.

Fourteen point: six: nine, six right, we're limited in physics on the depth of vacuum. It can't get any deeper than removing all the atmosphere, which is negative. Fourteen point, six, nine six, so the only way to increase the speed is to increase the hose size, rent increase the volume of gases we remove. We got to have a larger hose to do it because the no the limiting factor of pressure.

So yes, now, I think, number two so first, the first thing is having large diameter hoses. Half inch of 3/8. Think number two is using two core remover tools and removing your Schrader cores before you connect your hoses in the first place. Right, yes, Schrader cores are a significant restriction.

The hoses are actually maybe five times more important than the just Ruben Schrader course. When the Schrader cores also provide very significant restriction, you want to pull those out of there and that'll that'll dramatically speed things up. What just happened there are you yawning? I did. I dad was forgetting us basic stuff.

I sleep again yeah. So as another aside, when you are recovering refrigerant, when removing refrigerant from a system, it's also good to remove your Schrader's during that situation as well, because the Schrader's act as like, almost like a metering device which impedes the flow of the refrigerant when you're recovering yeah. In general, it's good remove Schrader's and it's good to actually, if you're doing it as part of a service process, throw new ones in there charge a customer for new Schrader valves and put new ones in because they don't last forever either then put on some nice New brass cap, so that nice gaskets on there you can it's a nice, upsell or locking caps for those that live in neighborhoods, where people Huff refrigerant, because it not only saves refrigerant, it saves lives. I mean I live in the country and in the country.

It's just this is what we do for fun: hey your brother, pees and bottles. I check yeah. I check the refrigerant levels at the office yeah I'm trying to keep the bottle peeing thing under wraps. I don't.

I don't really want people to know about that. It changed me forever when I watched that video - I'm sorry yeah boy yeah, I don't know I I think I think it's my mother's fault something and she had heatstroke when my brother was in the womb, there's something wrong with that boy for sure. Okay, so after that, you want to make sure that you don't use a manifold when you're pulling the vacuum, because the manifold is a restriction, but it's also a potential leak point well and the other thing it does a manifold does. Is it doubles the length of your hose right? Because, if you think about you know, you got the yellow hose going to the red hose.

So if you've got a five-foot hose now, you got 10 foot 1/4 inch hose and when it comes to conductance speed, the length of the hose plays a big factor. So you want hoses that are as large and as short as possible to provide the minimum amount of friction. So the manifold is a huge source of leaks, because a lot of the packings are not engineered for vacuum. That is one thing: products like the the I manifold they actually are.

That is our vacuum rated manifold, that's a very good manifold, but you have multiple connection ports, the hoses and things like that. So if you can avoid using the manifold it's going to dramatically decrease your evacuation time, even manifolds are engineered for it. I wholeheartedly say: please never do that. The the only reason that the the manifold was ever equipped with a with a hose is because of the marketing department, because somebody said at one time boy if I could just not have to hook up all these hoses and do this faster.

You know by doing it this way, you know I'd, buy that manifold all day long well, the problem was: is that there's some disconnect between the guys and engineering that actually knew how to do an evacuation and the marketing department? That just thought it was a good idea to make it. You know, because somebody requested it that didn't understand what they were asking for, and that happens a lot in our industry and there's a lot of products out there. We see that or you look at it. You go what what in the heck were they thinking when they made this thing, and it just goes back to as an industry.

We've we've forgotten, sometimes the fundamentals, it happens, it happens in every industry and we're just we're victim of that too. If I let you go for more than about 30 seconds, you just start preaching. I do you just hop up on that pulpit and you just start pounding right. I've never been off the pulpit.

I just keep on the saying man and raise my hands from the back of the pews. It's try or actually, then, actually, I totally want to raise my hands and like say, Amen, and he just pick on me just beat me up. So you pointed out this short large diameter hoses and I bought a bunch of three-foot half-inch hoses and, in my opinion those are a little bit too short that was kind of a mistake. That's not a mistake, and it's just too short.

If you can't get him hooked up, I mean I mean they were really challenging, so I gave them to a bunch of different technicians and they're, just a little too short in general to connect. So I guess in cases where it is still a possibility, then it's a good thing to have them nice and short, like that, but they're a little tricky in some cases and in some cases just trying to make the 90 to get it around with how stiff A half-inch owes is, I'm not gon na suggest getting three foot hoses. I would suggest in most cases get to large diameter 6 foot hoses. Well, the only reason they're standard is because that's the length they make them and that's no joke I mean that's.

They come, you know API, probably the number one seller of vacuum, rated hoses in our industry, and they just happened to sell most of them as our six-footers. By default, they can custom, make yo hose any any length you want, and so a lot of guys to order customized links, but for the most part, that's why we see so many six-foot hoses is simply because that's what they make them well, they do make three-foot Hoses and they do make them and we tried them, and I wouldn't necessarily recommend them, although I will say if you do want a fast vacuum, we did use them the other day, two of them with a small 5 CFM robin air pump, and it it did A great job, so I'm not saying don't I'm not saying don't do it, but I wouldn't recommend it because they are a little tough to deal with yeah. That's what people don't realize is you're, probably getting a true 5 C if true 5 CFM out of that pump, you take that 5 CFM pump and you put quarter-inch hoses on it. Leave the Schrader's in there you're lucky if you're getting point 7 CFM, no matter how big the pump is, you could put a a 3 CFM pump, a 5 CFM pump, 15 CFM pump on that system and the most you're going to get out of it is 0.7 CFM with that rig attached to it, because the rig is the limiting factor, because no matter how big the pump is, it can't pull a deeper vacuum.

The negative fourteen point, seven or fourteen point: six: nine, six they're all limited by physics. So the rig the vacuum rig. What we attached to the pump is almost more important than the pump size itself all right. The next thing that you practice and I practice in our business is we use nylon and this isn't a need to thing, but nylock does help as an assembly lubricant when you connect things together and you connect all your rigs together and it also just helps make Sure everything is tight and well sealed, but I've seen a lot of guys over.

Do it recently, where they're, putting like a half a bottle on stuff, when really it just needs to be a small amount. I use night log but use it extremely sparingly like we're. Talking quarter of a drop of nylon, something night log is actually an assembly lubricant. So what it does is it keeps things from from galling or binding as you hook them up together.

It's it's just an oil. It's it's really, not a sealant. I don't think it ever dries for say they may advertise it as a sealant, but it's really it's a it's a high quality assembly lubricant and it makes sure when the gaskets seat that they're not binding up or anything and they're, not nothing's getting cut the the Challenge with nighlok, if you're gon na use nine log on things, I cannot stress enough, put plugs in your hoses and put caps on your stuff after done because night log, because it's an oil, it also tracks dirt and grime, and things like that and there's I Don't know of anything actually that that is a solvent for night log, so the only gon na do is wipe it off. If you don't put plugs in your hoses you're, not putting caps on your on your mail connections, they're gon na attract dirt, and then then you got a you know.

Then you've got other problems you got to deal with. You got to clean all that off off. There - and you know then then reapply it but night logs good, but very, very, very sparingly, especially keep it out of your vacuum gauge, because once you get nine log on the on the thermistor there's virtually no way of getting it off. Yeah I've experienced that same thing.

I've seen guys just use way too much and it gets all dirty and everything, but one thing that I do agree with you about just about putting caps on everything and keeping everything sealed up. But I have never done that with my hoses I mean I put them on the stops on the back of my manifold, but with vacuum hoses. I've just never done this, but one thing that I think would be a good idea, and I've experimented with this is actually connecting the two hoses together with just a male, the male fitting yep. That's perfect to you ever taken a hose out of the truck like out of the bag, and you smell the rubber smell of the hose.

You know you can smell. It smells like Robert smells, like you know, black, rubber or whatever or pencils you open to a bag of pencils, and you smell a smell the pencils or whatever everything has sort of a smell to it. Well, that's the smell is outgassing and outgassing. We're talking a refrigerant hose or an evacuation hose the hose has to out gas for several hours before you can achieve its ultimate vacuum level when you smell rubber on the hose.

What you're smelling is gases coming out of that hose and until you evacuate it long enough that the rubber is fully cured, the hose cannot achieve its ultimate vacuum level. Now that said, when you dry out a hose when you pull a deep deep vacuum and that hose becomes dry, rubber becomes very dry. Well, then, that rubber also becomes hydroscopic, because now, when you open that hose up the atmosphere, it's immediately gon na pull all that moisture you you just try to remove back into the hose till it gets an equal vapor pressure and equal. You know in equilibrium with them with a moisture, that's in the air and if you have any pol in there a film of oil in there, then there's a chemical attraction or the weather.

Poa is gon na bond to the water and that hose will become almost useless because it's very very hard to remove pou oil from from a or water from p OE. So it just becomes. You know this molecular bond and it's very very hard to break so. Keeping that hose free of oil at dedicated vacuum hoses number one dedicated vacuum hoses, don't don't use the same hose used for charging for evacuation with pol.

It's a that's a huge problem today, the the the hoses. If you have hoses evacuation hoses always on the Parkes, always tight on the Parkes, don't disconnect the hose from the manifold and leave them off there, because they will pull in moisture and you're going to introduce that moisture back into the system. Separate hoses for evacuation. Close the hoses off if you're done evacuating, to keep them from pulling in moisture from the atmosphere.

And if you keep that hose clean dry and tight, it's going to last much longer and it will also significantly decrease your evacuation times. Because once you get that sucker dried out, it's never it's! You don't have to go through that drying process again, each time you use it. I believe a peon is part of their hose testing. They still de gas all their hoses before they send them and say put them on a on a rig.

They run them, they pull them in a vacuum is part of the testing process. They do a long-term pull down on the hose and it does a degassing of the hose they bag it up. So it's not like they do put some plastic caps on there, they're, not sealed, but they do go through an initial degassing or initial curing of that rubber and then all you're removing autumn. At that point, when you get them in the fields to moisture, i always tell guys one thing that when you're looking at your hoses connect your your gauge directly to your vacuum pump with a little brass, coupler, just connect it directly to the vacuum: pump, pull vacuum, It'll, pull down like a good pump, will pull down below 10 microns and some will pull down two or three microns 50 microns is a minimum.

I like to see in a pump some people say 100. I don't like to see a pump pool in less than 50, but you pull down somewhere below 10 microns on a good on a good pump. Most JB pumps, yellowjacket pumps, hill, more pumps are all rated in that range now disconnect the vacuum gauge attach your hose to it and attach your vacuum gauge to into your hose and pull that vacuum again. And what you're going to see is the impact of the of that hose on the system you're not going to be able to pull down as deep, because the hose is degassing and the hose is also gas permeable.

Any hose, that's flexible, you know, copper line is less gas permeable than rubber hoses, let's say by a long shot, but even copper is gas. Permeable will not in a molecular level, even copper leaks for the most part. It's so tiny of a leak rate. It's insignificant for our industry over the last 100 years, let's say, but it is going to leak out over time, but that rubber hose is even more gas.

Permeable and you'll see that in your micron gauge, especially if you're using a really good vacuum gauge. That's got high resolution like the blue, vac gage. You know it'll show you that pretty quickly, then you get to understand a little bit more about how important keeping that dry are, and if you let that, run and run a run on that, just that vacuum hose as that hose the gases it'll pull down faster. The next time and faster the next time again till it reaches its ultimate pulled on rate and then all you're looking at is a gas permeability of the hose.

Then you take the hose out in the middle of a thunderstorm and you expose it to rain and weather and then you're just right back to square one again. Only if you have the hose open to the atmosphere, if you, if you don't, have those open atmosphere, the rains on the outside the hoses dry on the inside yeah, we - I was joking anyway. Well, I don't care, I'm not gon na. Let you be sarcastic during evacuation topics, it's the serious stuff.

I know this is serious stuff I mean this is like this is vacuum. This is evacuation. Sorry, I should have known better all right. Thank you, serious stuff here, actually um all right.

So what I would recommend is get a coupling: that's quarter, inch male flare to 3/8 male flare or something like that and just kind of connect, your hoses in a loop. So that way, they're connected end to an end. Something like that. You can do it that way or you can just buy a 3/8 by quarter coupling and just hook your hoses end-to-end and storming a truck hang them on a hook or something just so they're in a circle, but the 3/8 by quarter.

Coupling will work. Just fine throw it in your tool bag when you're not using it, and then you know you're good to go. If you don't want to leave, if you don't want to leave it attached to your vacuum tree, oh okay, I see I see what you're saying all right so just leave everything connected all yeah, either way just keep that just keeping plug just keep them so they're, Not exposed to atmosphere, that's all at the point is: is that your vacuum hoses? You want to keep them sealed up. You want to keep them from getting atmosphere and moisture inside the hoses, and I agree with that.

It's just something that I don't think that most technicians are practicing, so I guess it's an area for improvement, but all right. So the next thing I want to talk about is vacuum pump. Oil. Are you one of these who says that you need to change vacuum pump oil after every single evacuation? Is that what you practice? The answer is, it depends and no not after every single vacuum, but if every single vacuum I did was on a dirty contaminated system, then yes, if every single vacuum I did was on a cleaned new installation, then no right-it vac vacuum pump oil.

It removes it removes contaminants, you know that get pulled in in a vacuum it removed and contaminants, meaning more gas. Contaminants things that out gas in the oil than solids vacuum pumps. Don't pull solids back to the pump. You might get a little bit when it first starts because there's some what's called viscous flow, where you might pull back some oxides or things like that.

But for the most part vacuum pumps don't pull solids. It's like dropping a BB in the bottom of a coke bottle and trying to suck it out from the top right, no matter how hard you're sucking that coke bottle there's no flow through it. You just drop the pressure, there's no flow. It's the same thing happens in a vacuum: pump now they'll remove some of the contaminants they get entrained in the viscous flow and then they're pulling out moisture.

It's a big thing: the vacuum pump oil removes there is a gas ballast which will I'm sure we'll talk about in a minute. But the gas ballast helps remove some of the moisture from the vacuum pump, oil and, depending on the type of oil that you're using. Sometimes oils are either hydro, scopic or hydrophobic is two terms you might hear, which one readily absorbs moisture and one readily rejects moisture, but sometimes you get different oils that will well pull that moisture in and there's no way to get it out of there and other Times they can be easily released from the oil as it comes out. There's no one-size-fits-all for that answer.

Should you change it regularly yeah, I would say: if you're, not billing, the customer for the vacuum pump oil and changing it each time, then what are you doing? It's something you can do anyway. If I have somebody paying for the whale I'm gon na keep my pump oil as clean as possible and change it after every use. Maybe at most I might go three times. First, typical system evacuations, but I've got oil in the vacuum pumps at the office because I'm always evacuating clean tanks and things like that that item at that oil go for a year before I change it and that's not just me, I mean I can show you.

There's books on vacuum, science, Welsh vacuum pump. I'll, tell you exactly the same thing. You know six months to a year on on vacuum, pump oil, that's used in clean applications all right. So let's say somebody says: okay, ultimately the vacuum pump.

The point is, if you can pull the vacuum down to where you're supposed to you can blank it off and test it, and you pull down the 30 microns quickly. Is that an indication that the vacuum is working fine, regardless of the vacuum, pump oil? As long as you're, not seeing any sludge or the oil doesn't look creamy or anything like that, yes and no, I would always recommend that you pull a bit of oil from the bottom of your sump of your vacuum. Pump. You're gon na detect we're going to check your oil, put it in a clear container or white container or something on that white, because you can't see if it's milky or not, but put it in a clear container, pull if all a small sample out of the Bottom of the pump to see if the pumps oil is wet and dirty because oil floats on top of water right.

So if you have moisture will end up in the bottom of your pump and it ends up as a sludge and when you, when you start the pump up, it becomes a mullah fighter. It attaches to the oil. But over time, though, if the two will separate you get the water in the bottom and get the sludge in the bottom so trying to tell if the oil is dirty not to the site class, is it's not a real good way of doing it? Now, in the way a peon does it, and I saw like a nappy on salesmen today but good for you, a peon. You got something out of me for free, a peon, actually circulates the oil through there for the oil container, so you can see there's basically no oil left in the pump when you shut the pump off all the oil is back into the container, so you can Look at the at the appian pump oil and see whether or not it's clean or dirty.

That's a pretty cool feature of that pump. We're a regular pump. You know you just can't see it unless you, unless you pull a bottom sample on there. So I guess the key thing here is: don't discount the value of changing pump oil for the lubrication purposes of it and for not having those contaminants in it.

So it's actually the longevity and the operation of the pump itself, not just the hygroscopic properties of the oil. I guess is that good way of saying that a couple other things when you, when you store your pump cap, your pump, there's a a little red plug a rubber plug that you put into the back ear pump that you plug the vent with it's. Just a friction fit plug. Some of you guys will notice that there's a little cap that you can unscrew on the handle.

Don't ever put a cap on that cap? Okay, because if you forget to take it off, you boil your vacuum pump up because there's no there's no pressure relief on a vacuum pump exhaust and it will literally blow the housing into. If you put it. If you put a cap on that, but if you don't keep your pump, capped Richie sends little friction fit. Caps of the vent and JB puts a little rubber plug in the handle, and if you don't cap, the vacuum pump oil off.

Also, it's pulling in moisture it'll make the pump take a longer time to evacuate. This goes back to you know one of the things I almost religiously do. Every time I use a vacuum pump, is I disconnect my vacuum rig cap off the vacuum? Ports put my vacuum gauge on just the pump and check the ultimate pull down level the pump to make sure it goes down. In my case, I'd like to see below 10 microns below 25 is more than good for most of the things that we do, that some people tell you is high is 100, but at a hundred microns that pumps just not pulling well enough test the vacuum pump.

First and see how good the oil is make sure the pumps pulling and then I have to make sure the pumps pullin. Then you can determine if you need to change the oil or not pretty quickly, because if you have dirty vacuum pump oil, your pump won't pull down. There's no reason to let that vacuum pump run 45 minutes before you realize you're, not making good progress in your evacuation test the pump first, it's a lot cheaper and a lot faster. One other piece of advice: don't pour vacuum pump oil down rooftop drains or pour it on rooftops rubber roofs, vacuum pumps will eat the rubber roof and your boss will pay a whole boatload of money to get the rubber roof fixed and if you pour it down The drain your porn in and our sanitary systems and you're pouring it and our drinking water, because everything we flush gets recycled and we get to drink it a couple months later.

So don't do that either it's it's bad for the environment, bad for the roof. Take it to an oil recycling or take it back to your office if they have oil tanks and dump it in there, don't take a shortcut: don't keep the oil in your truck and gallons where it gets tipped over and eventually gets all over the floor either. That's not good either. They're tough drives me crazy, make sure you're managing that.

Well, because it is mineral oil, it's just like dumping automotive oil on the ground. It's not a good thing for the for anybody. Yeah quick tip here most auto parts stores will accept, used vacuum pump, oil and they're not going to complain about you. You know bringing that in they're, not gon na care that it's a mineral oil or if it's motor oil, yep yeah testo, celebrating 60 years of high quality instrumentation with their best-in-class fall combustion.

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Take the gauge off the pump honestly, if you want to leave a gauge on your vacuum pump, then buy a blue vac micro or buy an inexpensive vacuum gauge connected to your pump. But that is absolutely the worst place to do it to monitor the system of a Q. We said earlier in the podcast test. Your hoses you've got to see how much your hoses leaking how much it affects when you connect your hose to the system, how much it affects the ultimate vacuum level: you're going to see you're going to lose, maybe 10 to 100 microns, just through your hoses and Pumping capability don't be surprised because that's what's going to happen when we're connected right at the vacuum pump, the vacuum is deeper at the pump than it is at the system itself.

Think of a return in a room like a return. Grill right, a return, grill pulls from a local local area. You can't really pull air across the room from a return effectively, yet we can blow it across with a supply register, so the vacuum is strongest at the pump Inlet and the further away we get from the pump the weaker the vacuum gets, so the vacuum at The pump is not reflective of the vacuum at the system. If you got to the furthest point in the system, the vacuum would be at its weakest and when we isolate it with the core tools and we allow that vacuum equalized, then we can see what the true level of vacuum is on the system.

That's what those core tools are designed to do is to isolate the pump from the system and also the core tools are not gas, permeable or very minimal amount of permeability to the gaskets and things for our purposes. They don't leak like a hose leaks, so it allows us to get a very accurate reflection with the vacuum is in the system only isolating with the core tools and on the core tools the ideal place, I will say we have seen over and over and over Again on core tools that the Schrader does not fully open when you attach your brass non-permeable coupling for your vacuum gauge on there. So if you're, using a vacuum gauge that can handle higher pressures, just pull that Schrader core out altogether because it eliminates some nuisance problems. Be aware of that, when you see a vacuum gauge like fluctuating, like goes up 100 microns back down 100 microns up 100 microns down 100 microns up 100 microns down 100 microns up down up down up down up down and you're going what the heck's going on! It's not stuff boiling off out of your oil.

Your trader core is not open all the way and there's a thin film of oil around the Schrader core. That is, the oil is breaking open that because the viscosity of the oil, oil, sticky and every time, an oil bubbles through you see your vacuum change a little bit. It's just bubbling through the oil and that's what's causing your gauge to fluctuate so rapidly. Just to be clear, we're talking about the Schrader on the side of the valve core tool here, because we're removing the Schrader's that are actually in the system, the ones that are in the actual service valves those are taken out, but the one in the side port.

That's in there and when you attach the coupler that you attach your micron gauge to it may not be depressing pulley. Exactly some. Some guys will use a third core removal tool and they'll just attach it to that side port and then they can valve off their vacuum gauge when they go to charge the system up, so they don't damage the gauge. That's really important, like if you're using an old thermal thermal engineering vacuum gauge, because those are rated at about 50 pounds of pressure, a lot of vacuum, equipments, not rated for pressure at all.

Some things will take a hundred pounds. The blue vac. I actually hydrostatic test at that sensor and it failed at over 4,200 pounds of pressure. So it'll, hey, it'll, take 500 psi pretty easily.

Some vacuum gauges can handle pressure. Some cannot so. You just have to look at your vacuum gauge to determine what you have and you can either like. I said use the third core tool to isolate it.

If it's, if it can't handle any pressure at all, and it's not a bad thing to do anyway - I mean I even do it would do it on my blue VAX, but some guys don't want to spend an extra forty bucks for an extra core tool and That's that's their choice. Yep, that's a good thing to do and I'm sure it actually depends on the actual setup that you're using in some cases that little coupler might have a more aggressive depressor that might work fine, and it really just depends on the exact configuration you can even make A homemade piece with a Schrader on the end, there's a lot of different configurations. You can create for that type of coupler. We're gon na build an algorithm for that in the blue, vac professional gauge that will detect that exact problem, because I've seen it happen.

So many times we decided we just put an algorithm in when we get a few minutes to breathe. We get off the measure, quick topic and get on to some other things again, but it is a problem. You do run acrost all right, so we got vacuum. Pumps, oil, we got Schrader's all the way.

What's your next question in the last episode we didn't talk about decay, and decay is one of those topics that you've talked a lot about and we didn't really. We didn't cut touch on it much in the last podcast. So we know that the decay varies depending on the type of system, whether it's low temp or whatever. It is so.

We know that, but with the blue bat vac professional, you can actually set a decay target and so for a typical residential light, commercial application, something like that with the blue vac Pro or you can track it with your app and measure quick. What do you think? The average airconditioning decay rate. What should you set that up for when you're setting up that that app with blue vac, oh okay, I was gon na say you can prevent decay with fluoride toothpaste, but oh yeah, really all right well, yeah, my family's from West Virginia! So we give up on our teeth at like the age of 10, something like that. You know that that that the toothbrush was invented by a West Virginian yeah cuz.

Otherwise we called the teeth brush. That's correct! Okay! Thank you! I'm sorry West Virginia my feelings, man, but I'm picking on Brian, not all of West Virginia, so yeah all right, beautiful country up there. It is not a lot of teeth to go around, but a lot of cousins to marry better roads in Ohio by a long shot. So that's not hard, alright, so so back to the K.

Ultimately, the depth of vacuum that we try and achieve is based upon the the application. If the moisture is could freeze in the application so that when we get into like cascade systems, where we're going to negative 40 negative 80 negative 100, we have to have a much lower level of evacuation than we do in an air conditioning system. Because the dew point of the moisture in there is it's going to start to freeze out and cause other problems in the systems. So ultimately that's what drives that it's? How dry do we need that system? So we don't have issues with ice now, all that all that said on an air conditioning system.

If you look at carriers, installation manuals even for 410, a carrier will tell you that the maximum allowable decay is a thousand microns. So you pull down you hold below 500 microns for some period of time, typically hoping of 500 microns for ten minutes, you're gon na isolate your core tools and you're going to make sure that it holds below a thousand microns, that's the allowable. In practice, our industry does not want to see us go above 500 microns because we know that what's acceptable and what's good practice. Just like combustion analyzers, the maximum allowable Co is 400 ppm, but we like to see it below 100 ppm because we know that's totally achievable.

We know that vacuum levels below 500 microns are totally achievable if you're using a good rig. So typically, what I'll have guys do is pull down to 250 microns or below, isolate the system off and then watch the decay and make sure that it doesn't rise over 500 parts per million in a 10 minute period, the blue vac gauge again, oh, you just Said 500 parts per 500. Sorry, 500. Microns! Thank you.

I was just combustion. I talked about combustion. I went right that peak yeah yeah. You were just seeing if I was paying attention.

Yeah, yeah, so well, actually, moisture in a vacuum is measured in parts per million. So if we were measuring a moisture, a vacuum, we could do it that way, but that's a sidebar, because what we're looking at is moisture level. It's really cool. If you ever get a chance to take a tank and evacuate it down and isolate it and let it set you're gon na see this and it go up it'll curve and I'll tail off, and I have a pretty steep curve and tail off.

You know it'll rise quickly, almost go straight up, then I'll curve and then tail off on the on a vacuum. If you're, using like a gauge where you can draft the vacuum, take that same tank evacuated down, isolate it, let it set overnight, evacuate it again. The next day, look at the characteristic of the curve again and occur when you isolate it off, it will almost go dead flat when you isolate off the vacuum pump and that's because over time, the moisture that's molecularly bonded to the steel will dis attach from the Tank it'll get into the into the vapor of the tank and when you turn the vacuum pump on again you're pulling that moisture out and you're, not seeing the effect of the decay due to moisture bonded to the walls. So just because we can pull a vacuum.

Like super fast with a big hoses doesn't mean that we should not give it time to adequately dehydrate now. This is really only important if your piping is open to atmosphere, and you know we're not running nitrogen through it. We're not keeping the tubing dry because most tubing that we buy today it should be what's called refrigerant rated tubing and it should come with rubber plugs in and it should. You should get a hiss of nitrogen out when you open it up.

It's dehydrated from the factory, then you ain't, you know when you install that tubing you're running nitrogen through it when you're doing your brazing all that kind of stuff. Well, it's never going to get any many moisture on the walls of the tubing and you're going to get a very quick degassing and dehydration, the coils treated the same way when you're open up an evaporator coil, you get the hits of nitrogen on there. It's because it's been pre evacuated from the factory and then pressurized with nitrogen and it's it's clean, dry and tight. So again, when you isolate your pump off you're, not going to have this rapid rise and decay curve due to the moisture.

But typically, you know I'll set the targets personally me: 250 and 500 allowables 500 and a thousand. You know for some guys if they're using quarter-inch hoses to hit 500 microns might take him, you know, might take him an hour and a half two hours to do. Where you and I, with the hoses were using, we could pull that same system down in a minute and have it down below 500 and probably pull it 250 and maybe a minute and a half to two minutes on a on a 2 or 3 ton system. Using the right equipment definitely has some huge advantages to doing what we're prescribing here.

Interestingly enough, you have to be very careful when you're trying to determine the difference between decay and a leak in a vacuum. We found this out when I was building the app for the for the blue, back gauge and all vacuum gauges use a logarithmic type scale, which means you. You have a million points of data right, there, 760 thousand microns in atmospheric, so the vacuum gauge starts at. Let's say a million microns and then you're pulling all the way down to you know 50.

100 microns so think about this huge scale. Well, it's broken up into chunks, so it might be 750 thousand down to 50,000 at 50 thousand twenty-five thousand and then 25 thousand down to two thousand and two thousand down to thousand. And you know from a thousand down to five hundred and five hundred down to 50 and you know then 50 to one. So you got all these different scales and they aren't linear.

If you were to take in and look at it on a logarithmic graph, it would actually it's going to give you like some kind funky curve on there, because you're taking a whole bunch of different scales and condensing them, and it makes the vacuum look funny. So when you isolate it off, it's very hard to tell the difference between a leak and decay, and I actually I don't know if you remember or not, but actually wrote you an article for HVAC school, but you've put your name on that. Put my name at the bottom when we were first trying to figure this out now. It's do you know anything for me, Brian.

It is on there and actually we got some pictures of that. So what we ended up doing in in the blue vac apples. We actually made it walk. We took the logarithmic graph and when you do the decay test it, it makes it into a linear format.

So you can see the difference between the two. It's a really good article. If you got a few minutes ago to HVAC school and look up vacuum decay, maybe I don't know you can look it up and tell everybody at some point, but that was a an epiphany for me. I just never realized how much information was hidden in the logarithmic graph, so Jim is exactly right.

You can go to HVAC our school calm and just search vacuum and you'll find Jim's article and I'm absolutely sure you will find Jim a proper properly attributed in that article, so just search vacuum in there at the top of the gutter chol. You will find Jim Burton's name, I'm certain. If it isn't, then it will be by the time. This goes live because I can't be wrong about this sort of thing.

But the one thing I want to add here is that you're not going to under a typical circumstance, pull the system to 250 300 250. Have the system hold a vacuum of under 500 for 10 minutes and have a system that has a significant moisture issue or a leak in the system? That's just not going to happen under practical conditions, and so it's a good final test to do to ensure that you don't have leaks in the system and to ensure that the systems dry and tight so practically you're, you're correct from a practical standpoint. You're correct in in reality, you always have leaks. It's the rate of leakage that we're concerned with.

When you have mechanical fittings of any type, you can never with 100 % certainty get that system to where it is tight and will never leak. It's just what we're doing is reducing the leak rate when we have really good assemblies we're taking it to such a little late, great that it doesn't matter so you're, technically correctly, valid off the leak rate is so low. At that point, when it's down to 250 we're letting it rise to 500, if it doesn't go above five hundred and ten minutes, the leak rate is so low that it's insignificant, it's just technically, it is leaking and if you let it set for two or three Days or two or three weeks, you would see that your vacuum rose up over a thousand or 2,000 microns. At some point you know whatever it is.

It's gon na continue to decay, but it's just what we're looking at is leak rate. Don't ever think that you can get a system so tight that you're not going to have a leak? The only thing I could do that with it's like a ball, but a glass, a glass bulb. You might be able to get tight enough that you couldn't ever detect the leak rate on it, because you know when they heat the glass up and seal it off the vacuum screw and locked in there in class is not a gas permeable substance like rubber is, Or copper is or the mechanical fittings that we have all the packings and things that we have on valves and things like that mechanical flares. They all leak a small amount.

Now, if you're, using a good flare tool like that, the rigid spin flare and you're getting a really nice burnished face it's gon na leak less than if you're using you know some of the old-style flare tools we use that use the where they didn't deeper well And you had a lousy flare fitting the quality. Your flares can also dictate that, but all of them do leak at some small rate by rigid spin flare. He means the rector co prophit flaring tool. That's what I meant right.

Yeah, absolutely pro fits yeah, I'm sickened. I don't why I was taking rigid instead of rector seal and I actually I actually was just reading about that a couple weeks ago. So my my brain skipped a gear, but at least you know what the heck we're talking about all right. So the next question is about breaking with nitrogen, a lot of guys talk about a triple evac, but it's doing nitrogen sweeps at different stages in the vacuum.

So, under what circumstances do you advise that? Do you think it's a good idea? Some guys will say you absolutely have to do it. What are you, what is your stance on breaking with nitrogen sweeping nitrogen to the system? The only reason you want to do a triple evac today, you can do it. If you have moisture in the system, a triple evac may help with moving out some moisture because again Moisture will not bond the nitrogen. The nitrogen will not pick up the moisture to draw it like a sponge and you expel it out it just doesn't it doesn't happen that way? It's not like a hydroscopic sponge that goes through there.

What we do is call the nitrogen sweep. So, actually, one thing that we didn't talk about real, quick and before I say because it deals with nitrogen. I want to just sidebar this in there when, whenever you put nitrogen in a system, the very first thing you want to do is you want to enter inject the nitrogen into the let's say, the suction side of the system or the liquid side of the system. Whatever suits your fancy, probably put it in the in the liquid side of the system, so you're pushing it through the with a through the metering device and back out the other direction out the suction line.

You always want to purge it all the way through and you want to push the nitrogen, let's say from the liquid line through the metering device and then vent it out the suction line. So when you break the vacuum, take it just up to where it's a pound or two of pressure, then open up the core tool and push the nitrogen through the system and let it come out the other side. Now, there's a very good reason to to do that. Number one is called entrainment, so the moisture will be entrained with the nitrogen and it'll push that moisture out of the system.

Now: here's why you don't want to get done braising and then pressurize the system without doing a purge through. The reason is, is just like, if any of you guys have ever used an air compressor when you compress air and increase its density or compressed nitrogen increase. The density: what's the moisture, do in the air Brian answer? Is it condenses Jim it condenses to a liquid and typically in an air compressor? That's what we drain the air compressor out. We drain the moisture, that's condensed in the bottom of an air compressor.

Well, if we get moisture in a line and we can crease the pressure and we condense it and the moisture drops out wherever you know in the suction line and the compressor and the whatever, when that moisture drops out as a liquid, you cannot pull it out Of the system, except through evaporation, a vacuum gauge cannot suck the drop of water down the liquid line and out it's going. It can only reduce the pressure and, as the pressure is reduced, hopefully that moisture boils away and is carried away. But if it's in a cooler part of the system like we're talking, refrigeration, where you might have a two evaporators and the box is still at - let's say 40 degrees or zero degrees. When that moisture condenses out in the evaporator, it's going to just freeze to a little brick of ice, and then it's gon na have to be removed through sublimation, which is going to take forever.

You always want a nitrogen sweep and purge it through and then you'll be good. Now, here's the other thing, the nitrogen is the gas that your vacuum gauge is calibrated for anybody, that's using a thermistor style vacuum gauge, which would be JB test. Oh Robin air, thermal blue vac pick any manufacturer. You want, they use their mr.

vacuum gauges. There's nobody! That's using an absolute pressure sensor of any kind for measuring vacuums at the levels we do because they're just not accurate enough. There's some like test only uses a Pirani sensor. The thermistor gauge that's used in the blue vac is a very, very microscopic size, thermistor it's about the size of a hot wire and it's really really really tiny, and then you get other ones that are like the the thermal image in engineering.

They use a really thick heavy, robust thermistor, but there's different. You know: you'll see different sizes, they're misters, different applications, but they're all calibrated for the same thing, which is nitrogen or air. Okay. So here's a little science experiment, I'd like you to do next time.

You you get a second take a tank of 410, a r22 and just probably 410 a because r22 is so expensive. Put a small amount of refrigerant vapor in your sensor. Just you know, like you're, purging, a hose next time you purge your hose, so this can be a de minimis release. Purge that refrigerant gas into your vacuum.