The Importance of Decay Testing in a Vacuum

Decay testing is plays a critical role in a successful evacuation to assure that the system is dry and tight. This is especially important for heat pumps where the outdoor coil can operate far below freezing.

[@TheGhettoLobster]

I find it ironic that they had such high standards in the day where almost every old tech I've spoken to just used liquid purges and equipment lasted 40 years

[@annaplojharova1400]

There are two "tiny" difference: First the freon used in the past was rather immune towards even significant contamination. The drawback of the modern fill gasses, that do not destroy our atmosphere once they leak, is they (and the lubricants compatible with them) are unfortunately very sensitive, so do need careful cleanup and evacuation of the system. And the second difference is, we weren't using refrigeration systems in such wide range of operating conditions as come with the heatpump/AC unit as we are today.

[@HVACRTECH-83]

​@annaplojharova1400 ever hear of a walk in or a walk in freezer? They been around just as long as anything else. Mineral oil, as in older 22 systems was less sensitive to moisture but only to a degree, still needed to evac and any good tech always did,even back in the day. Poe oil has about zero tolerance for moisture. Compressor and moving components may only last a year if moisture is present if your lucky. Anyone in the trade should no why so I won't go into that here unless someone is interested. Either way, a older 22 system most certainly needs to be evacuated still

[@annaplojharova1400]

@@HVACRTECH-83 Well I did not want to say the R22 or so tolerate really every abuse, I just want to point out the modern ones requiring way stricter care to not blow up within a year, is not the machines alone being made worse, but because there is quite a difference what sloppyness R22 unit working at fixed temperatures allows you to get away with, but the modern fill materials moreover when operating over wide temperature range (here I'm refering to things like getting the charge exact,...) won't... I never said it was ever any good idea to do a sloppy work with any system...

[@hvacslayer2929]

Lol or it was put the gauges on run it in a vacuum without some type of micron gauge, let’s grab lunch come back and charge.

[@measureQuick]

Your also talking 1959, most of those techs are dead if they they were in their 30s then.

[@SqueakyHinge]

Great video. Thanks.

[@blh3741]

thanks for the refresher coarse!

[@hvacslayer2929]

Jim got a question for you. Pulling down that low on the compressor side would the low microns cause oil viscosity change or cause effects to the oil?

[@HVACRTECH-83]

The only effect would be a positive one, viscosity won't change but the lowest microns you can achieve, the more refrigerant and or moisture will boil out of the oil, that's the hardest place to dehydrate and heat is your friend in achieving a dry system, run your fans, circulate water if a chiller or water source, warm your compressor shell, should be standard practice but...

[@hvacslayer2929]

@@HVACRTECH-83 after some reading and research, oil has a very low micron level/boiling point in which we would never achieve with our pumps. If I get into a bind with not getting to my micron level I’ll triple evac to help move moisture, but on used systems with refrigerant already mixed it starts getting tough trying to that very low micron level due to boiling out refrigerant from the oil. I care about removing moisture and any other contamination if I can get the system to 500 with a passing decay than we are rocking. Techs face that difficult decision in the middle of the summer with crying customers who don’t care about a proper evacuation on a very tight time frame with other calls piling up. We all stride to be perfect but in the real situations we have to use a wider practical approach here.

[@vincentgelles3805]

I run into this problem very often. I change a lot of reversing valves, a few condenser coils, and a ton of compressors. I find that even on the compressor replacements if the system has an accumulator there is still trapped refrigerant and it makes achieving a 100 micron vacuum impossible in a reasonable amount of time. Especially when I have someone rushing me to get to the next service call. I have the tru blu hoses and the BluVac pro but the only way to get trapped refrigerant out is with a heat source and lots of time on vacuum, like 24 hours or sometimes more. In those cases, I just use a triple evac and install a larger drier. Haven’t seen any issues so far. I forgot to mention all of the systems are heat pumps, residential and light commercial. In my part of the country Eastern North Carolina, 99 percent of the systems I work on are heat pumps

[@vincentgelles3805]

On all my new installs and equipment change outs, I’m pulling down to 100 microns or less every time. I got one with a new lineset down to 43 microns once but I often get down to 70 or 80 microns. Service work is a different ballgame all together though. I never achieve levels that low if the system is off gassing trapped refrigerant

[@measureQuick]

@@vincentgelles3805 Achieving a very low vacuum on 410a systems (POE oil systems) is almost impossible if it was not evacuated right they first time and or of air is introduced into the system during service. The oil bonds with the moisture and it can only be removed with a dryer. If the evacuation stalls, and the gauge does not indicate a leak, then a reasonable target is below 1000 microns and let the dryer handle the residual moisture. I would recommend however that you also use a moisture indicator after the filter dryer to assure that the dryer has not used all of it capacity.

[@DANIEL-fl7ix]

Would like some comments about vacuum in absorption chillers and vacuum test, providing that in those cases we have water as refrigerant. Thank you.

[@measureQuick]

That is not an area of my expertise. I have only helped repipe a few of those. I never serviced one.

[@fernandobenitez4311]

Nice video, I thought I was doing great vacuum down to 300 microns and decay no higher than 500 😢

[@HVACRTECH-83]

You are, especially if you are seeing that on an existing system you're in good shape,

[@BillyN31]

@@HVACRTECH-83definitely! New installs are easier to vac. No oils and condensers to pull down.

[@RATCHETMAN1001]

im using u guys techniques on the automotive side now. i have to vacuum sometimes 24 hrs but can get under 500 and times to 200 with at most 200 rise on 10 to 15min decay. just tickled. shitless

[@HVACRTECH-83]

Around 180 or so is as low as ive ever been able to get to, even on a brand new system. As far as im concerned thats very much good enough for anything ive ever worked on. Not many techs can afford true blue hoses. I use the appion large hoses which give great results but the question is, if even those cant achieve what we are "supposed" to be achieving then why doesnt the industry make and supply only 3/4 id vacuum purposed hoses like tru blue? 10 years ago as far as i ever knew a 3/8 yellow jacket hose was the largest hose available to us and before those we all used 1/4" hoses with our manifolds and obviously struggled to even get to 500 on many systems. I wonder what hoses they were using in the testing you showed from back in the day, and why it wasnt till less than 10 years ago that us techs have heard of anything larger than a 3/8 hose. At least in my area thats how it is. And why doesnt major manufacturers like yellow jacket, jb, ect that have made the majority of vac pumps in the field to this day, make hoses that can achieve these micron levels?

[@hvacslayer2929]

I could be wrong I believe they used braided copper lines or copper lines for fast and deep vacuums. T Lech KZbinr used copper for deep vacuuming it was what his father thought aeons ago.

[@measureQuick]

All I can surmise is that we have forgotten everything that we have learned and let the marketing department run engineering. This was all common knowledge in 1959. It was science forgotten. Technicians simply were not taught correctly. The math and the science are not new. What is crazy is if you go into the refrigerator manufacturing industry large hoses and deep evacuation as low as 30 microns are common. They use vacuum rigs with hoses that are 3/4” and bigger with dedicated vacuum rigs. The cost of a TruBlue hose is only a small amount more then Appion and considering the performance and the cost of labor after only a few uses a lot less expensive.

[@blh3741]

IMO, it is also what the business owners wants, a faster turn around. Old employer wanted vacuums done in minutes and "500micron was too low and took to long..." @@measureQuick

[@RATCHETMAN1001]

@@hvacslayer2929 tom is my hero

[@mr.invisible3770]

I’ve spent so much money on micron gauges - Appion, fieldpiece, suppco, each like $400 a pop. the only gauge that still works right is my cheap CPS gauge. I’m not waisting another dollar on an expensive ass micron gauge just to have it not work after a couple weeks.

[@Gcanno]

Blu vac small usb stick worked very well for me, the older Fieldpiece one was awful ,I'm close to the fieldpiece office and they gave me replacement which i still didn't like . Got the newer one but haven't used it yet . I do like Fieldpiece and there customer service is second to none . Try contacting them even if its out if warranty .

[@infinitivesolutions786]

I've had a BlueVac Professional for roughly 5 years. It has always worked great just like day 1. I also have an Appion on another truck and it is still working great. That one is going on 3 years... perhaps is operator error?

[@hvacslayer2929]

Fieldpiece MG44 is 230$. Bluvac+ micro is 220 and does the app. What are you complaining about ? Bluvac gauges can be recalibrated by you. I still have my micro before the app was ever out 6 years ago still works and because I clean it properly and calibrate it. To further calibration I test it against other gauges I own several bluvac’s.

[@steveH384]

this sounds like you are doing something wrong bro i have used several models of micron gauge and not experienced similar problem

[@CoolChris2023]

Use an additional vacuum rated core control tool or vacuum rated core removal tool for the ability to isolate the gauge before introducing refrigerant into the system as to prevent exposing the micron gauge to positive pressure and refrigerant oil. Periodically clean your micron gauges with 91% isopropyl alcohol and then pull a vacuum on the gauges to dry them out on the work bench. Little maintenance goes a long way.

[@jaymz0074]

So is Evac 100 and Decay 200 what we should be doing now? Not Evac 500 decay 1000?

[@hvacslayer2929]

More important for heat pump systems.

[@HVACRTECH-83]

Some walk in freezers usually call for very low sub 200's do to the obvious reasons. Def don't want even a tiny amount of moisture in a freezer circuit. For comfort cooling it's still 500 or under and 1000 after decay is too high, I always try to stay under 600 on a used system, under 500 on new, usually on a new install you can get decay to stay under 250 though. Someone may disagree of course and that's inevitable but you'll have no issues when following these rules

[@jaymz0074]

@@HVACRTECH-83 thank you

[@hvacslayer2929]

@@HVACRTECH-83 Akhvac has a video of him with Jim doing a vacuum on a huge chiller system, the equipment vacuum requirement was 1500.

[@measureQuick]

@@hvacslayer2929 That is a rarity, also because a low pressure chiller does not see the low temperatures that would allow freezing and or the high temperatures that promote acid and sludge production. With low pressure machines the evacuation is more about controlling the head pressure.