pulling a vacuum

**MechAcc** · 09-22-2007, 03:33 PM

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** · 09-25-2007, 04:18 PM

I always use a micron gauge.

.

**ryand** · 09-25-2007, 05:27 PM

Originally Posted by 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..

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

**gsxr** · 09-25-2007, 05:36 PM

Originally Posted by ryand

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

regular gauge hoses or special vacuum hoses?

**boat racer** · 09-25-2007, 06:05 PM

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** · 09-25-2007, 06:21 PM

Originally Posted by gsxr

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** · 09-25-2007, 11:08 PM

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** · 09-25-2007, 11:13 PM

Originally Posted by 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.

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)

**acemechanical** · 09-25-2007, 11:26 PM

Got it.
Thanks Jon.

**jtrouse** · 10-03-2007, 02:08 AM

A quick suggestion. When your done, leave all ball valves capped off in the open position. The hole through the ball won't make an "impression" in the ball's seal material and tear it some when later opened. I think this is why the ball valves built into vacuum pumps have a bad reputation for not sealing well. Leave them capped off in the open position.

**allstar08** · 10-03-2007, 10:06 PM

I have been doing this way longer then I want to admit, but the thought of removing the cores to pull a faster vac never occurred to me. What a awesome idea!! I just picked up the yj micron gauge and I love it. I will be adding the tree to my set up next. I see that I need the super vac set up now. I am pumped to try this on my next big system, so I don't have to leave it on overnight.

**gsxr** · 10-03-2007, 10:20 PM

I ordered the YJ kit 93865 on Tuesday I cant wait to try it out

**BigJon3475** · 10-03-2007, 11:34 PM

I'm getting the 93865 kit in 1 week. premium lines, (although I might fabricate some copper ones) two core removal tools, and vac. tree with dual ball valves. I'm stoked. My reg. charging manifold none of the hoses hold under 1100 microns. They will pull down to 120 but when isolated rise back to 1100 and in some cases 1150 and that's with all new neoprene seals.

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