HVAC 153 Nitrogen Pressure test with Analogue gauges

Pressure testing a system with nitrogen. part 1
We cover safety, tools, test pressures, analogue gauge limitations, procedures, ultrasonic detectors, and using bubbles.
Follow all manufactures instructions, Osha guidelines and laws.
Nitrogen is under high pressure of several thousand pounds.
We must use a regulator to reduce the pressure to a safe amount.
The regulator is made of brass so use an adjustable or open end wrench but never pliers.
During use and transportation place the tank where it will not fall as the regulator can easily break. Remove the separate flow regulator used during brazing. During transportation follow all DOT guidelines and regulations.
Wear safety glasses.
Check the data tag on the evaporator and the condenser to find the test pressures. To be safe use the lowest test pressure provided.
In this example the lowest number was 150 psig so that is what we used.
Have the manifold gauges set up like we discussed in previous videos with both sided closed.
Attach the yellow service hose to the nitrogen regulator.
Back out the regulator adjustment.
Open the nitrogen tank valve.
The dial closest to the tank reads the pressure in the tank, the other reads the pressure in the hose. Check your hose pressure rating and never exceed that number.
Turn the T handle dial to tighten or where it screws IN INTO the regulator to INcrease pressure. You can increase to the lowest test pressure OR above that point but never exceed the hose pressure rating
Open the high side manifold valve to allow nitrogen to flow into the unit. Watch the low side as it rises and stop at the lowest test pressure of the system. In this example we stopped at 150psig.
Listen for leaks.
Be sure to have the service valve caps on and secure. I recommend nylog. (no affiliation)
At this point you have 3 options for leak searching.
1 Leak detector bubbles and looking for the leak, this is best for isolated areas and brazed connections. it takes patience and visibly watch.
2 Ultrasonic leak detector that listens for a leak.
This is a great way of checking the whole system for leaks. For best results have oil inside the tubing or use a spray bottle and water on the outside to help the frequency of the nitrogen sound.
I will post links below.
3rd is time, temperature, and pressure but there are 3 problems.
1st the analogue (dial and needle) gauges make it difficult to see any change in pressure. Many analogue gauges use 5 psi for every mark and the pointer needle is already already the width of one mark. it is difficult to see the change unless its significant.
2nd it takes time to see the change. the longer you wait the better and more accurate the test will be. 15 minutes will only tell you if you have a very large leak, typically you need an hours and some manufactures have specified times even up to 24hrs.
3rd Nitrogen pressure changes with temperature as it follows the gas laws. As the temperature drops the pressure drops and as the temperature rises the pressure rises. There is a formula to account for this but we will discuss another method in the next video.
MORE!
My interview and demonstration with Matt form Accutrak ultrasonic leak detectors ( no affiliation)
• AHR2022 Matt with Accu...
Craig with ‪@acservicetechchannel‬ has the best videos especially with Ultrasonic, here are 2 great ones.
• Advantages of Ultrason...
and
• How to Find a Refriger...
This video is not sponsored and no paid endorsements.

[@LDriggs]

Thanks for a the little tid bits of information. Great to see you do this with old style gauge sets. Great Info & Video! Thx

[@SokachinEngineering]

The very best of them all. A natural born teacher. whether he is fast or not, he touches all there is to know

[@kevinpizzolato86]

Awesome teacher! Very simple, helpful, and direct. Big thank you!

[@love2hvac]

Glad it was helpful!

[@harlanhardy6126]

You have to be the most insightful and thorough hvac instructor on the web man.

[@love2hvac]

Thank you!

[@920HVAC]

I can’t thank you enough for that Ty! I’ve learned and continue to learn so much from you. Keep up the thorough lessons. Your a legend!

[@tommyteamer9037]

Amazing on how you get straight to the point where we can understand

[@samsmith854]

Love seeing new videos from you Ty.! Hope you have been doing great.!

[@love2hvac]

Thank you! I'm trying to balance work bills and videos.

[@osmansebsibe2824]

Kudos to your great videos! I strongly recommend everyone to watch your videos, they are helpful.

[@love2hvac]

Thank you

[@TCHAVEZGAMES]

Great informational video. Thank you.

[@acrepairnearme]

Great video! Thank you.🧲👍

[@shakilkassum4584]

Very good explanation.

[@kwiz8848]

Ive personally witnessed mixing nitrogen with refrigerant on a new split system install. I was left scratching my head. Pressures incorrect along with superheat and subcooling. Recovered refrigerant/nitrogen lol recharged with same weight r410a havent had an issue since. My advice give an extra turn on the service valves to ensure they are well seated. And i can find almost any leak with 100psig nitrogen 👍

[@william474]

Subscribed, fantastic video

[@charlieromeo7663]

Nice job, Ty. Thanks

[@Est-lj4tq]

Excellent video. I just slowed it down a bit when re-watching but that could be me

[@vernessalkic1065]

Great video!

[@love2hvac]

Thank you

[@al-ameenallu9927]

Waiting for more videos.....thanx ty

[@love2hvac]

more to come, just posted one Sunday and another will post Monday morning.

[@johnmccarthy1693]

As you said, using the right tool is important, It is also important to use the tool correctly. Please turn your adjustable wrench around for future videos.

[@love2hvac]

Great catch, thank you!

[@MegaJoselito01]

Awesome!!

[@iqbalchaudhary218]

Ty please start a Patreon so people who appreciate what you’re doing can support you. Thanks

[@love2hvac]

Working on it! Thank you!

[@ozziewelcome5612]

Good 👍

[@electrolatif]

Thank you sharing your knowledge ❤ What is the size for that nitrogen balloon?

[@stephwaylonwells3218]

👍

[@robtester3857]

Great video! thank you for the info! What would be your suggestion as far as PSI for a new Mini Split 28K condenser unit with 2 air handlers no more than 15 feet away from the condenser, 12k , 12k. Would you say 500psi thanks,

[@love2hvac]

On the tag of the unit, it should have a high side test pressure rating. Go with that and you will be good. I like to use the Measurequick app for pressure testing. It has a timer with a temperature compensation so it figures the temperature change with the pressure and time together for a pass fail.

[@Honestandtruth]

You are going to Kick WHO butt 😅😂❓❓

[@johndoe-wt4ui]

We do 450psi with lineset and both coils brazed together

[@love2hvac]

What test pressure is the equipment rated for?

[@playa1199able]

I have been using my fieldpiece digital sman gauges to do my nitrogen pressure test. I religiously test them at 200 psi hi & low. Hold them for about 10 min. I've had them drop to as much as 2.5 psi with a txv and always around 1-2 psi with a orfice. I use the blue bubble leak detector and I never ever find a leak. I know sometimes the system takes a few psi to settle out between hi and low side. Is this normal? My line sets are usually 15ft to 30ft max usually, these are all new build installs , so new copper condensor and coil.

[@love2hvac]

That's part 2 I'm uploading a video right now with the Sman digital. It should go live Sunday evening or Monday morning.

[@playa1199able]

@@love2hvac Got it, look forward to it.

[@prashantkrishna2743]

What is the formula to check the pressure wrt temperature and air pressure?

[@bobbyhodgesvlogish]

I been searching for this since i cant find it in the modern refrigeration book its driving me a little crazy

[@garza7676]

I hear a lot about using nitrogen for brazing but what about when you unsweat a line ?

[@love2hvac]

Beat practice to cut lines to prevent oil flash with unbrazing. However that's not always practical so yes I absolutely purge nitrogen when unsweating lines to help reduce oil ignition and oxidation.

[@abbe6305]

when i braze in a new compressor, scroll copeland, i need to have nitrogen, its it correct that i put nitro on low side and blow out on the high side? Becuse the compressor have a rewerse seal on high side in compressor and can damage the seal?. correct? so its ok to flow nitrogen in to the compressor while braze?

[@avsararas]

Just criuos why nitrogen is needed instead of regular air pressurizing, is air bad for the system just for testing before vacuum?

[@love2hvac]

Great question! Air has moisture in it. Moisture is the biggest enemy inside the refrigeration system as it turns to acid that eats the system from the inside out. Worse than air is pressurized air because it causes water vapor to condense into a liquid inside the lines. So we want to push the air out with nitrogen with a nitrogen purge, then we can pressurize with nitrogen.

[@nickrichards880]

Is that a 20 or 40 cubic feet cyclinder?

[@julianomartinez6080]

Question: is it right to use the refrigerant gas manifold intended for measuring R22, R410A and so on, to measure the Nitrogen pressure inside the system? Shouldn't you be using another Nitrogen manifold or, in case you don't have any, connect the hose out of the Nitrogen regulator straight to the system? Are the reads you get from the refrigerant manifold corrects when meassuring Nitrogen pressure?

[@love2hvac]

The manifold gauge sets just measure pressure. As long as what it's measuring is within its operational range it's good.A nitrogen tank has a regulator that reduces the nitrogen pressure to a level well within the range of the manifold gauge set.

[@julianomartinez6080]

​@@love2hvac Thank you very much for your reply. But I must say that I DO NOT AGREE with your argument. After all, each gas is a different chemical substance. Therefore, they have different physical and chemical properties. The gas can be more or less corrosive, can change its temperature when it comes into contact with the internal parts of the manometer, etc, etc. And that's the reason why you basically have a different gauge design for each specific gas. Different gases, different properties, different gauges with specific design based on that gas' specific properties. I guess the answer might be something like: "Nitrogen is an inert gas, so it won't really affect the functioning of the refrigerant gauge, and the reading you get will be pretty accurate after all."

[@love2hvac]

You are more than welcome to disagree. Disagreements and discussions are a great way for people to understand different points of view. I understand that laboratory equipment is calibrated precisely to a specific gas. In HVAC it's not that precious even 1 or 2 psi off, the saturated aka boiling temperature will be the same. For the longest time we had one gauge that was used for everything except ammonia. Then 410a came along that required higher pressure readings. So the gauges used for 410A could be used for the lower pressure R22 but the lower pressure R22 coils not be used for the higher pressure 410A. We use one set of gauges for multiple different refrigerants. The analogue is simply a bourdon tube. When pressure is applied the tube tries to straighten out and moves the gear set to the needle. Now we use transducers that convert to a digital signal. We use the same gauge set for hundreds of different refrigerants, even refregerant blends as long as it's in the operational range of the gauge set. The digital set can instantly be upgraded to a new refrigerant by downloading the PT chart. The only gauge set that's different is for CO2 systems or ammonia systems. I could not imagine having a different set of gauges for every refrigerant and every gas we use. It's just not practical, feasible or necessary. If your wanting a gauge set for each individual gas you would need to convince a manufacturer to make them, distribute and sell them. Then you would have to convince every tech to buy a new gauge set for every gas they are working with.

[@julianomartinez6080]

​@@love2hvac Thank you so much for your time and for such a detailed response. So to summarize your answer, what you're saying is that things seems to work after years of personal experience. Yet not a definitive answer to me, although I do believe what you explained. So if you'll be so kind, I have another question: based on that assertion that "gas is just gas and you can basically use any manifold for measuring pressure of any gas (except for those two you mentioned, CO2 and Ammonia), would you use your Nitrogen manifolds for measuring refrigerant gas pressure?

[@snoopdogie187]

@@julianomartinez6080 I just want to point something out. You are talking about measuring nitrogen pressures with a refrigerant manifold. Nitrogen being a noble element is about as nonreactive with anything else as you can get. The pressure reading may not be 100% accurate but it will also always measure the same with those gauges. Since you are also only looking for a change, it doesn't matter if the information isn't accurate, as long as it measures the same every time.

[@glennburton6655]

That looks like a 40 cf tank. Would a 20 cf tank provide enough gas to test an average system with about 25' of tubing?

[@sengle9831]

I used to see some tech charges a little freon and add nitrogen 150 PSI than use leak detector to find a leak? it works great.

[@love2hvac]

Yes the Trace gas method that video is coming soon with the pros and cons.

[@DavidGeorge-wp1kz]

Is there a certain type of nitrogen that you use for hvac

[@love2hvac]

Dry nitrogen. I'm not sure the grade

[@mark.r8900]

Can you please tell me what type of nitrogen should I use? Thanks

[@love2hvac]

Dry nitrogen

[@majkl8646]

I make a nitrogen test at morning outside temperature was 10°C and put inside new system 25barr, after few minutes pressure drops to 24.5 bar, so hmm okay maybe i make bad flare somewhere. I check all nuts with bubble test under that pressure and no leak or bubbles there. So i raised pressure to 25 bar again and then was no drop on gauges. Still 25 bar during 1 hour. 🤔

[@munawarsoomro8958]

Hello my esteemed teacher. Perfect timing. I am puzzled. I did nitrogen pressure test on system watched it for 15 20 minutes and no change using SM480 digital. But within 2 days 410A was gone. Yesterday after a lot of isolation and checking leaks found a leak in compressor discharge connect. Pressuring to 357 came down to 329.1 and stayed there while I know there is a leak and can feel air blowing. Totally puzzled and no confidence in leak checks Help sir please.

[@love2hvac]

15-20 minutes is not long enough. 357-329 is a big difference but the temperature change is essential to know. The next video will be perfect you you. It addresses exactly what your talking about. It should be available Monday or Tuesday

[@munawarsoomro8958]

@@love2hvac Thank you kind sir. You’re awesome.

[@eddier88r14]

Can you add refrigerant after you bleed out nitrogen??

[@love2hvac]

No, vacuum and vacuum decay test must be before charging

[@muhammadrizwanjan1984]

Sir I have a question, if a unit cooling 20000 ltr water 4c down in 1Hour. I want to know cooling capacity of that unit.

[@love2hvac]

93.02Kw / 317404btuh 80037.989 kilocalories

[@muhammadrizwanjan1984]

@@love2hvac THANKS Sir.

[@Elisummit845]

Woooooow am I seeing job link? 😉😂

[@love2hvac]

🤣 yea.. probably not. I'm not a big fan of the job link. The next video is with the HVAC school app and the one after that is with measurequick.

[@Elisummit845]

@@love2hvac no way I love my job link. I already have mine I think for 3 years they are awesome

[@love2hvac]

I do love the FP probes

[@YNG_PIG]

5:42 😅

[@nunyabusiness6746]

Why nitrogen, co2 is inert up to 3000 degrees Fahrenheit and since copper will melt under 2000 degrees I see no problem using it versus nitrogen during brazing, furthermore co2 is hydroscopic and has the ability to absorb residual moisture in a system and carry it out with it in the evacuation process, not to mention it’s vastly cheaper nitrogen. I personally have used co2 exclusively, and in nearly 50 years in the field I have had zero problems.

[@love2hvac]

I use to think that same thing until I went to work for Emerson. Turns out there are many grades CO2, most of them being wet depositing moisture in the lineset when pressurized. As you pressurize co2 it condenses some of the moisture out. To the POE oil. It also becomes chemically active when exposed to moisture and heat. Since most CO2 sold is wet or low grade CO2 it's an issue and varries by supplier. Then you spray nitrogen and get the ice crystals, many items that's the moisture. As you heat that lower grade carbon dioxide, the percentage of oxygen present would gradually increase. You end up with carbon monoxide and oxygen. The oxygen causes oxidation. You would need refregerant grade dried CO2 to prevent this Wich is not cost effective. When welders mix CO2 with argon or helium to keep it stable to prevent the oxydation. While it is still better than nothing it is not better than Nitrogen.

[@nunyabusiness6746]

I’m aware of the different grades of co2, I guess I forgot to mention I have always purchased my co2 from a local welding supply shop who has assured me of its quality and dryness. Actually I thought you might take issue with Co2’s global warming potential of 1. You may find the words of the ancient Greek philosopher Heraclitus interesting.

[@love2hvac]

@@nunyabusiness6746 The Only Thing That Is Constant Is Change

[@mp289634]

That’s too low of a pressure test. I don’t care what the test pressures says. We all know on a hot day the head pressure can be 400PSIG. I’ve seen braze joints that only leaked around 270PSI or higher. Also condenser is isolated. You should do a minimum of 250PSIG. You also should have purged your gauge set and lines before adding nitrogen.

[@love2hvac]

Did you know you can damage the fusite plug by going above the lowest test pressure. You can also push the nitrogen past the valve and mix with refregerant in a pump down. Every pice of equipment has the test pressures there for a reason. This example was an R22 unit, so that unit hitting 400 would be a big problem even on a hot day. This is a series and the least several video we already discussed purging and brazing with nitrogen. So there was no need to purge again. I'm open to a discussion about this but if you say "you should", then you should start with the instation manual that clearly stated what "should" be done. If you see the whole series I also discuss testing components are higher pressures when the rating allows.

[@muhammadmunir2187]

Can we check leak with Air pressure as an alternate of Nitrogen. Pumping air with compressor.

[@love2hvac]

Never use air! Air has moisture that mixes with oil and causes acids. Air has oxygen that mixes with oil that can cause combustion under pressure or oxidation in the system. Never use air under any circumstances.

[@bosserman1964]

Man you said alot about Nothing lol

[@love2hvac]

That's what I do