pulling a vacuum

[tisme]

I would not charge without using a micron gauge first.
I used to build chillers and you could pull the gauges down to full vacuum even with a small leak in the system but the micron gauges would show it up very clearly. i use this example because on older systems you could have mosture in the system but on a brand new chiller it should be dry.
On the other side i have seen loads of people charge vehicle a/c systems without even pulling a vacuum and it still appeared to work to the customer, not d.i.y.ers either.

[gsxr]

When pulling a vacuum do you use your standard charging hoses or do you use flexible steel vacuum lines? I been reading on how rubber hoses are permeable and not good for vacuum

[fcs]

Mark could you repost the picture its gone (broken link)

Also I use the Yellowjacket Core removel tool. what to you find to be the best out there.

thanks

[ryand]

I tell the guys that question me about my micron gauge that you will never understand how important it is until you use one. For years, I didn't know any better and just watched my gauges like I had seen everyone else doing, until I had some extra money in my pocket one day and seen a shiny new micron gauge right there in the display case. I bought it and tried it out the next day. I couldn't get that thing to pull down at all, but yet, my gauge was dead on 30 inches of vacuum. I worked and worked to get my gauges and hoses leaktight and then realized my pump wasn't working correctly. I sent it in for repairs and things went much better after that, but I often wondered how long I had been hooking it up and doing nothing. That was probably 12 or so years ago and I have used a micron gauge since. Just two weeks ago, I had a system that wouldn't pull below 100,000 on my micron gauge. I kept at it until I found a tiny leak in the unit that I would have never even known was there without the micron gauge.

Bobby

what sucks for home owners is barely any installers use one so from day one the systems going down hill

[ryand]

I have always used a micron gauge but just recently bought a Y.J. two valve manifold with the 3/8th to 1/4 hoses and schrader core removers and it is one of the best investments i have made! not only did it pump down fast i pulled a residential 4 ton system down to 140 microns and held it at 168. I dont know about you guys but i have never gotten lower than 400 microns. the Y.J. part number for the kit is 93865 and its worth its weight in gold

[neophytes serendipity]

I have also had difficulty getting and maintaining 500 microns and below.

That started to change once I ditched the standard 3/8 charging/vacuum hose for one of those Goodyear Galaxy barrier hoses.

I also noticed a change when I switched to Refco charging hoses with the quick connects on them. The new Refco manifold may have helped, too.

I suspect that the only way to go is the stainless hoses.... or, all barrier style hoses.

Then I tried the triple evacuation method. There was plenty of time to let 10 psig of nitrogen sit in the system for 20 minutes a cycle, and that really helped to bring the micron levels down quickly.

*That* did the trick.

After actually doing it and watching the micron gauge, I don't believe there is a way to achieve and maintain low micron levels unless the triple evacuation method is used.

On the opposite end of the spectrum, I am aware of several big name outfits that don't even use a vacuum pump. Purge and go- only 2 hours per install...

[MechAcc]

To purge aircraft liquid oxygen systems we would run nitrogen through a 120 vac operated heater. One of those being used to sweep a wet system could have possibilities.

[MechAcc]

Found a photo of one of those purge kits at Carelton Technologies. The lox fill nozzle would have to be removed and a 5/16ths to 1/4 inch adapter fitting and hose would have to be installed but this could have possibilities on extremely wet systems.

[icchvac]

A micron gauge is one of the tools that I don't get unless I buy it. And since all my work is done for my employer (the state) there's really no incentive for me to buy one myself. Maybe I can talk the boss into buying one the next time he gets on a tool kick. I also need a digital scale, I'm stuck with the "shake the jug" method for now.

Since I don't have a micron gauge I normally try to pull down to 29 and if I'm in a hurry it's 29 and no vapor coming out of the pump. If I have some time to spare I'll pull on it overnight, shut it off in the morning, and see if it holds at least 27/28 for two hours. If so, then it's fill 'er up time.


Anybody like to donate to higher education? We "do it for the kids" is the party line around here.

[allstar08]

I am very familiar with the shake the jug charging method, as well as the touch and feel micron gauge.

I started using a micron gauge and a digital scale when I went into commercial. I do a residential job every once in a while, and I like using the scale and the gauge, it takes the guess work out. I just bought the YJ digital micron gauge, I had the supco before and lost it, because it is too small. I was told that the YJ is the best out right now.

[acemechanical]

Confession: I was a "beer can cold" guy for many many years.Never used a micron gauge.We got into the higher eff. units a few years ago, and with the TXV's it was impossible to get the charge right.So I bought the gauge and swear by the thing now.the question i have is: How long on average does it take you guys to pull 500microns on lets say a new install 3.5ton split with 50ft of refer(7/8-3/8) just the coil and refer of course without opening the system up yet?????Iv'e had it take several hrs, and question the vac. pump I use.Its an old Robinair 6cfm VacuMaster pump.When I isolate the pump and hoses all is tight and good.I also will do the triple purge with Nitro. and that seems to help the larger systems pull down faster.Are the "new and improved" pumps any faster/better?
Don't mean to hijack this thread, it just seemed like it was going in the same direction..

[allstar08]

That sounds about right. Some take longer then others. Change the oil in you vac after each use and thet will help.

[MechAcc]

On vacuuming the insulating space on cryogenic tanks we always left the gas ballast valve cracked open until the micron gage started going down. It helps to clear moisture vapors out the exhaust.

[Refer-Madness]

I always use a micron gauge.


.

[ryand]

Confession: I was a "beer can cold" guy for many many years.Never used a micron gauge.We got into the higher eff. units a few years ago, and with the TXV's it was impossible to get the charge right.So I bought the gauge and swear by the thing now.the question i have is: How long on average does it take you guys to pull 500microns on lets say a new install 3.5ton split with 50ft of refer(7/8-3/8) just the coil and refer of course without opening the system up yet?????Iv'e had it take several hrs, and question the vac. pump I use.Its an old Robinair 6cfm VacuMaster pump.When I isolate the pump and hoses all is tight and good.I also will do the triple purge with Nitro. and that seems to help the larger systems pull down faster.Are the "new and improved" pumps any faster/better?
Don't mean to hijack this thread, it just seemed like it was going in the same direction..

use schrader core removers and hook your hoses up there it will go much quicker

[gsxr]

use schrader core removers and hook your hoses up there it will go much quicker

regular gauge hoses or special vacuum hoses?

[boat racer]

I use a micron gage, core removers and the heavy black 3/8 hoses ... makes a 3 cfm pump think its a 5 or 6 .... makes a 7 think its a 10


using regular service charging 1/4 hoses and hose end valve depressors isn't really evacuating, esp if you are using hoses longer than 3 ft; 5 ft or longer hoses is like evacuating thru a cap tube or like trying to drive a railroad spike with a carpet tack hammer

Without a micron gage there is no way to truly asses the performance of your vacuum pump or test the leak seal of your hoses and their gaskets

[ryand]

regular gauge hoses or special vacuum hoses?

I use the superevac 2 valve manifold with 3/8 vacuum hoses and i **** you not it takes about 5 to 8 minutes to hold under 500 microns it makes a world of difference. you can buy the whole superevac system for around 230 bucks that includes to gauge manifold, two 3/8 hoses, and two schrader core removers. there is also one that comes with a micron gauge if you dont already have one obviously it will cost more. the yellow jacket upc # is 93865

[acemechanical]

Nice, thanks for the input.I'll look into the YJ setup.Dumb question but I don't get the valve core romoval deal and hooking up your guages to it?
I have a valve core removal tool but just not getting the picture I guess.I
always remove the cores and nitro charge the thing then pull vac. 3x.Then charge to positive psi, pull the hoses and insert the cores b4 the gas runs out.Then pull a final vac. down to 500 or so.Good bad?Comments.?
Thanks guys.

[BigJon3475]

Nice, thanks for the input.I'll look into the YJ setup.Dumb question but I don't get the valve core romoval deal and hooking up your guages to it?
I have a valve core removal tool but just not getting the picture I guess.I
always remove the cores and nitro charge the thing then pull vac. 3x.Then charge to positive psi, pull the hoses and insert the cores b4 the gas runs out.Then pull a final vac. down to 500 or so.Good bad?Comments.?
Thanks guys.

The valve core removal tool has a side port on it so you can remove the core, pull your vac and then reinsert the core. It aids in pulling a vac because it removes the restriction (core)