The free training provided by the HVAC school podcast is made possible because of the generous support from our sponsors, testo rector, seal and carrier, something that's been emerging lately it's in the unified mechanical code and then a lot of local municipalities are starting to enforce. This is the idea of tamper, resistant, refrigerant caps, and this is to prevent the theft and abuse of inhalants, primarily the abuse young people using refrigerants as a means to get a quick and easy hai. And so it's a serious thing and it's something that is emerging. You're gon na start to see codes and local municipalities enforcing this.

So what I would suggest is go ahead and start to get some no vent caps from rector seal on your truck now, both on your installation, crews and on your service fans. If you have to put on new caps anyway, maybe start using no vent instead of the typical caps that you've been using. A lot of guys will point out. Well, I don't want to have to keep that tool on my truck or you're gon na have to keep the tool on your truck anyway, because if your competitors use the no vent caps, then you're gon na need to have the tool anyway, and rector seal makes A nice little keychain key that you can put right on your right on your keyring and that way you've got it, and so once you start to use them, whenever you have cases where you've got caps that don't have seals, you can offer them to your customer.

As an upgrade, you can install them and then it reduces the theft and the risk that a an adolescent, especially it's mostly young kids, are gon na abuse, the refrigerant as an inhalant. So that is the rector seal, no vent caps. You can find out more by going to rector seal comm when we exhume lock the ten-second flame free refrigerant, fitting from parker reduced labor cost by sixty percent with no brazing no flame had no fire spotter discover how suma can help you be more efficient and productive Visit zoom la comm for more information, and now your host, the guy, who checks the air filter of every single hotel room right when he walks in, but still can't change his own filter. When he's supposed to Brian or hey thanks for joining me, i'm brian with the hvac school podcast, this is the podcast that helps you.

Remember all the things that you might have forgotten about hvac our or maybe helps you remember things that you forgot to know in the first place today on the podcast, i'm gon na do kind of a basics podcast. I did one of these recently. You know with matter, but today i want to do the gas laws and i'm gon na try to make these as applicable as possible because, generally speaking, they're pretty self-evident. But there is some important things about them that you want to get as a technician, because as a technician, if you don't know the gas laws, you can start to believe that the impossible is possible.

My instructor at AC school, when i was learning all this stuff, he used to call it PF m, which stands for pure f word magic, and he was used that to explain away things that didn't make any sense, or at least didn't make any sense in the Eyes of a student that didn't understand the laws of nature, and so the gas laws are fallen to the laws of nature category and so, let's just go through them kind of, as they're generally taught from the most simple to the most complex. So the first one - and in fact it was discovered earliest because it is the most simple: it's called Boyle's law and Robert Boyle. He was an Irish guy and he discovered this in the 1600s. All that it essentially states is that there's a direct relationship, a proportional relationship between absolute pressure and volume, when we say absolute pressure is first thing we have to establish is that when we are measuring pressures, we're generally measuring them in gauge pressures, so we measure psig And PSI G just means that the gauge is already compensated for the atmospheric pressure.

The problem there is is that, of course, atmospheric pressure is not constant. If you live at sea level, then it's fairly constant, but it's not absolutely constant, even depending on things like barometric pressure, the atmospheric pressure, that's around, you is affected by your altitude and then also by the weather by the barometric pressure. So, whenever we're doing anything with the gas laws, you're always gon na need to convert to absolute pressure. So when you see people will they get questions wrong on quizzes that relates to compression ratios or anything related to the gas laws? They usually get it wrong because they forget that you have to convert everything over to psi: a naught psi G and in general, when you're doing this.

All that you're doing is you're just taking the original pressure, the original PSIG and you're just adding 14.7, which is the typical. It's actually not quite fourteen point seven, but it's we're not gon na go any more detail than that. But you add fourteen point: seven to it to compensate for the pressure of the atmosphere. So if you think of the let's say you have a glass vessel or a of a tank, and it's got 30 psi on inside that tank.

We're measuring 30 psi on a gauge and that gauge is already compensated for the atmospheric pressure in actuality. It's not 30 psi, it's actually, 44.7 by the time you add in the 14.7 to create the absolute pressure. So that's the first thing: all these gas laws relate to absolute pressure. So all that Boyle's law states is that the volume of a gas varies inversely with the absolute pressure provided.

The temperature remains constant, which means that if you don't have a change in temperature, then the more absolute pressure you put on something the more the volume drops when you decrease the pressure to something the volume that occupies increases. When you take a particular substance, a particular gas and you make it occupy a smaller volume, then you increase the pressure and if you take a particular gas and you make it occupy a larger volume, you decrease the pressure, it's all fairly obvious. But the fact is is that you can do the math and you can calculate that, and so the math is very simple: it's p1 times, v1 equals p2 times v2 and the two in the 1 just mean the original versus the new. So what that really means is the original pressure times.

The original volume equals the new pressure times, the new volume. So it's a super simple algebraic equation to solve for either side of that, and I'm not going to teach you algebra here, but you just isolate one of the values and then you multiply and divide - and you come up with the answer. If there's a change in any of the values, that's all there is to that and that's what Boyle's law says. So Boyle's law is just telling you volume and pressure they're directly related to one another, and you can mathematically look at a particular body of gas and by changing its volume you change is pressure by changing its pressure.

You change its volume, the two are interrelated, so the next one is Charles law, and this one came around in the 1800s so again, 200 years to come up with this new law, which is basically the same thing. But now, instead of pressure, we're talking in terms of volume and temperature and all it states is, is that at a constant pressure, the volume of a gas varies directly as to the absolute temperature and at a constant volume. The pressure of a gas varies with the absolute temperature, and so all that's telling you is that volume and temperature are interrelated if pressure stays the same now. Here's where it gets tricky, because we know that in a contained, cylinder or inside of a compressor or whatever not all things do stay the same, because when you take a vapor and you compress it yes, it is true that it heats up, and that does happen Because you're decreasing the volume, but you also know that you increase the pressure, and so that's where we get to the next law, but right now, charles law, which is the second one.

So Boyle's comes first 1600s. Charles laws next came in the 1800s, and all it's essentially telling you is that volume and temperature are interrelated and all that it says it is V 1 divided by T 1. So that's the original volume and the original temperature are equal to V 2 volume divided by T 2 temperature, so original volume original temperature are equal to new volume divided by new temperature. That's all that sang is just telling you that there's a relationship between those two testo celebrating 60 years of high quality instrumentation with their best-in-class fall combustion.

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A percent off then, just save your receipt that you get from true tech tools go to HVAC our school comm, four slash, fall, promo and fill out the form, and you will get either a free 770 3 meter or a 745 non-contact voltage sensor from test OU T'Est OU 60 years of excellence, perfect for testing perfect for service. The next one is the general law of a perfect gas and all that the general law of a perfect gas does. Is it just basically combines Boyle's and Charles laws essentially saying that the pressure volume and temperature are all interrelated, and so that's p1? So the original pressure times v1 the original volume divided by t1. The original temperature are equal to p2 times v2 divided by t2, and again I could do an entire podcast teaching.

You algebra, but all you do. Is you just isolate a number of those values and then get them on one side of the equation so they're by themselves, and then you solve for them? That's essentially how algebra works, and so using that you can see that pressure volume temperature are all interrelated and you can calculate what a change in volume is going to do. What a change in temperature is going to do and what a change in pressure is going to do, based on the initial pressure temperature and volume. Now what is this matter? This comes up multiple, multiple times this matters when you're doing a standing pressure test on a system.

If you pressurize a system of nitrogen and the temperatures change, your pressure will also change, which means that if you take some nitrogen and you put it in a system when it's cool in the morning and then you come back later in the afternoon, you're gon na Notice that your pressures go up if the system hasn't leaked and if you put it in the middle of the heat in the afternoon - and you come back in the evening and it cools down you're going to know such your pressures have dropped and that's just because The general law of a perfect gas states that p1 times v1 divided by t1, is equal to p2 times v2 divided by t2, which just means that they all interrelate with each other. So if you change any one of those in the two equations, so if p1 is equal to p2, v1 is equal to v2 and t1 is equal to t2. Well then, they're going to be the same: there's no change, but in this calculation, what we're saying is that the temperature part, which is the divisor the part on the bottom, that changes over time. So if you had a temperature, that was one thing so say: 70 degrees and you had a volume that was set.

So whatever the internal volume of that system is - and you have a pressure that you set and then that t2 changes well then that also changes the p2, because the v2, the volume stays the same, so the volume doesn't change. There's no way volume can change inside that system. That means that if the temperature changes then the pressure changes, I know I'm beating a dead horse here, but there's some of you who will argue because the argument is well. Nitrogen is an inert gas or argon, or carbon dioxide or everthere inert gases, and so why would they change with temperature all gases change with temperature? That's why it's a gas law and not against suggestion it's the general law of a perfect gas.

Now there are some that react, so there's actually chemical reactions, and so that will affect some of this. We are talking about a nonreactive gas here, meaning that there's not an actual molecular chemical interaction going on between different gases or between different substances, and that's really. All that means with nitrogen is that nitrogen is very unlikely to react with other things with oil or chemicals or whatever to have pressure changes, and so some people will ask why not use refrigerant vapor, and the answer is well because the EPA doesn't allow for that. That's why, back in the day, there were some people who would accidentally get some refrigerant liquid, mixed and well now, when you get liquid mixed into the equation.

Well, that does change because now you're dealing with full change of state, but if you're strictly talking a gas, the truth is that it doesn't really matter as long as it's not gon na have a chemical reaction with anything in the system or it's not going to Cause any damage, then any gas would do. We use nitrogen because it's readily available. The air is mostly made of nitrogen, it's largely unreactive with other compounds and chemicals and it's cheap and it's not illegal to discharge to the atmosphere, because what the air is made of. So that's what we use nitrogen, not because it doesn't change pressure with temperature, because it does change pressure with temperature, so in the 1800's.

So this is dalton's law, which is the final gas law that we often refer to. So we went from the beginning. We did Boyle's law, which is the earliest one 1600s, then Charlotte, which is just that pressure and volume are related. Charles law, volume and temperature are directly mathematically, related general law of a perfect gas.

All three of them are mathematically related and then dalton's law. He discovered that the total pressure of a confined mixture of gases is the sum of the pressures of each of the gases in the mixture, because there's this kind of misunderstanding, sometimes where we think that things somehow just mix with each other and they're just like. So you take nitrogen and you put it together with oxygen or you put nitrogen together with argon or something in a vessel, and that those two things are just going to somehow mix together and know. If you have 30 psi of nitrogen in a one cubic foot container and you have 30 psi of oxygen in the container of the same size and you combine them together into that container, then your pressure is going to be the sum of the two.

So if you have two with 30 psi, you put them into the same sized container, they're going to be 60 psi. All it's saying is is that the total pressures of a combined mixture of gases is the sum that means that the total pressure is equal to the different constituent parts and so with something like a mixed refrigerant that we see nowadays. You'll see this in some cases where the pressures are affected by the percentage of the mix, so an example would be 407 C versus 407, a a refrigerant they're, the same constituent parts, the same refrigerant mix but they're in different quantities. So it's the same three refrigerants that make up both of the 407 refrigerants, but the mixture of the two dictates the pressure that's exerted and that's just because the Daltons law, the law of partial pressures, applies to that.

So it's fairly simple stuff, fairly straightforward basic gas laws, but some people get confused and they'll think and that this applies to liquid and vapor mixes and it doesn't obviously when you have a tank of refrigerant sitting there that has liquid and vapor in it. Well, it's going to go to the saturated pressure and then anytime, you add more refrigerant to it. It's going to increase the level of the liquid in that tank and so the law of gases. It's not null but you're, not dealing with a gas you're dealing with a matter, that's in its saturated state, where there's a mixture of liquid and vapor in the same place at the same time, and so that's why, when you have liquid, you could add more refrigerant To a particular tank say a tank that was 30 percent full, you could add more refrigerant to it, so there's still an inner relationship there because, as you add refrigerant, you'll see the temperature go up and the pressure is affected by the temperature and all those interrelationships Still apply, but this whole idea of the amount of matter that's in this tank does change just the percentage of liquid to vapor mix and it's not a direct pressure volume.

Temperature relationship like it was when you're dealing with just the gas laws. So hopefully that makes sense again, so these apply to gases, if there's no other takeaway, and that I want you to have here. It's that anything you put into a system to pressure test. It will be affected by temperature.

If the volume is constant, the pressure will change based on temperature, doesn't matter what you use, whether it's nitrogen or refrigerant, vapor or argon, or whatever you use it's going to still play nice by the gas laws. So thanks for listening to this, this is the HVAC school podcast, a member of the blue-collar roots, collective of podcasts, which you can find all of them by going to blue-collar roots comm, and we actually a player right on the home page all of the podcasts in One little streams, if you want to kind of scroll through and listen to all the different episodes that right there and we also have all the separate shows if you go up to the podcast tab. The main thing that I'm going to request from you is that you subscribe to podcasts that you're interested in as opposed to just going and finding them each time, because it really helps us rank with the different players if you subscribe. So the best players are, if you have an Android device, use the Google Play Store or the stitcher app.

Is anyone called podcast addicts that you can use on Android devices and if you have Apple, then just use the podcast app right on your phone? I want to take a quick second and just thank carrier and carriers been with me since I started my business back in 2005 and really my relationship with carrier predates that. The main reason why I wanted to sell carrier when I started my own business is that I had such a good relationship with their training staff. There's a guy by the name of Ray Johnson and I used to go to his classes and Ray was just a no-nonsense, blue-collar guy and he would just tell it like. It was, and really smart taught me a lot about air conditioning.

And I liked that about carriers that they gather a big corporation, sure they're a big business, but they seem to always care about their research, development and technical side of their products. It shouldn't they advertise everybody advertises that mean them heck. This is sort of an advertisement. I guess, but it's an advertisement that comes from a caring for the core functionality of the product, and I've always appreciated that about carrier.

Everybody has bumps along the road. Everybody has things that every business has things that don't go perfectly from time to time, but I'm still glad that I'm a carrier dealer I'm proud to be a carrier dealer we're doing really well selling carrier equipment this year and and I'm really proud of how they Handle the green speed recall, you know they actually voluntarily came out and said: hey look, nothing's happened yet, but we've noticed some things. So let's recall these boards and replace them, and I thought that was pretty good. It was a seamless process, they treated me.

Well, they always have treated me well, even when I was a nobody, even when I think my first year in business, I sold something like I don't know, fifty thousand dollars worth of units you know which is well below what you should sell in order to do. Carrier equipment, but they worked with me and and I'm thankful to them for that, and I'm thankful that they're partnering with HVAC school to once again just invest in training of technicians. The same thing that brought me to carrier in the first place and made me choose to use them, is the same reason why they are partnering with us on hvac school, and I certainly appreciate it. You know a lot of people have said a lot of nice things about me lately and it's getting to be a little too much, but it just was reminded that a plateau is the highest form of flattery.

We'll talk next time on HVAC school thanks for listening to the HVAC school podcast, you can find more great HVAC our education material and subscribe to our short daily tech tips by going to HVAC our school comm. If you enjoy the podcast, would you mind hopping on iTunes or the podcast app and leave us a review? We would really appreciate it. See you next week on the HVAC school podcast.