pulling a vacuum

[-80guru]

(tongue in cheek). I don't know why you guys watch the gauge for pulling a vacuum. You know you should be watching the time instead, you know it takes about 30 min to an hour for a good vacuum.... Now how bout that for hackery. LOL. I worked for a shop once when I told a few guys I had purchased a new micron gauge I was laughed at and told why would you need that. I was speechless.

[dhvac]

i got that from the last company i worked for both bosses (father and son) said i was wasting my money and they dont help one little bit

once i used one i have never gone back


i also have a competitor i help out from time to time that thinks they are a waste of time and money

[duct dr]

Originally posted by -80guru
(tongue in cheek). I don't know why you guys watch the gauge for pulling a vacuum. You know you should be watching the time instead, you know it takes about 30 min to an hour for a good vacuum.... Now how bout that for hackery. LOL. I worked for a shop once when I told a few guys I had purchased a new micron gauge I was laughed at and told why would you need that. I was speechless.

I don't see how anyone can go by the "time" method for pulling vacuum. On large systems (above 5 tons) that use 1 1/8 and 5/8 linesets, it's going to take way longer than an hour to reach max vacuum. Length of the lineset is a factor also. If you don't use a micron guage how can you tell when you've reached the minimum 500 microns. I have yet to hear an instructor say "you don't need a micron guage while pulling a vacuum." And I darn sure wouldn't admit that to any manufactures.

[mark beiser]

My evac rig with a Yellow Jacket 69075 micron gauge.
The picture is old, I use C&D core removers now because I had problems with the seals in the Yellow Jacket ones.
I also have a ball valve to blank off the sensor now.


That 296 micron vacuum is on a system that was badly contaminated with moisture and non condensables. It took about 15 minutes to get that after sweeping the system with nitrogen.

I routinly get down to around 100 microns on new systems where I am evacuating just the coil and new refrigerant lines that don't have any oil in them.

[Edited by mark beiser on 10-20-2006 at 10:24 PM]

[steve3871m]

Many times I have to leave my vac and gauges on overnight to get a wet system down.

Since the hacks like the 15 or 30 minute rule or when it says 29", here how I explain to them or anybody else.

If you have a 1 quart pan of water on the stove and you "can't see" the water inside, but you can see that it is boiling how do you know how full it still is?

Then I see the light bulb click on and the start to understand why to use a micron gauge.

[jcon04]

looking to buy a micron gauge. seen this one on this website. It's from TPI 605 digital micron gauge. Has anybody heard anything good or bad about this product, it cost is $90. This is the web address, hope it works.

http://www.iaqsource.com/pdf/605datasheet.pdf

[alpha480v]

I always use a micron gauge, down to 500 microns or less. It's just the way I was taught, and it's good service practice I believe.

[duct dr]

I couldn't agree more alpha.

[jhthornt]

I've only used the Yellow Jacket SuperEvacIII and it worked flawlessly.

After following several threads here it was aparent that nobody upgrades to something better after they use the 60975, although some have had trouble with the core removing valves.

[_hl4e_halflife_]

Guys, Guys, This is a state-of-the-art micron gauge which is attached to my old Welch Duo-Seal 2-Stage belt driven vacuum pump (Model 1400). It can still pull down to about 800-900 microns. Only problem is it needs a new shaft seal

[icehouse]

Since we're on the topic of vacuum, I have a question. First off I pull a vacuum whenever I have to open a system, I also use a micron guage. I've been getting conflicting statements on "how" to pull the vacuum. Some say pull from one side only i.e the vapor line, others say pull from both sides at the same time. Which is correct, or does it matter? I take pride in my work and always want to learn more. Thanks, Bill

Install hoses from manifold on both high side and low side, 3/8" line to vac. pump, 4th line to refrigerant tank. tee on vaccuum pump for micron gauge.
Open high side handle on gauge manifold, vacuum pump handle, start pump.
Observe low side gauge to see if it goes into vacuum, if it does continue to pull down to 15" hg, then open high side handwheel. If you do not see low side going into vacuum, then you have a restriction. Continue evacuation to 500 microns(250 on Manitowac Ice machines),close hand wheels on manifold and observe micron gauge. Rapid rise=leak, slow rise=moisture. No rise after 15 minutes= URgood

[scottsacavsfan]

Either way will achieve the same effect, but the time it takes to do that will vary.

The best way is to pull from both sides, hooking the micron gauge up to the farthest point from the vac pump (which would be the coil in almost all cases).

Now, you could hook one hose to one side of the system, your micron gauge to the other side of the system aswell... but that'll take a long long time.

Or, you could do what most people do... using a 4 port gauge system, hook 2 hoses to the unit, one for the micron gauge, and one to the pump. Shut the pump one down and let it sit. If it goes up past 500, you need to keep going (or fix your leaky hoses). Not the 100% accurate way, but it's (in this writers opinion) plenty good enough for all but very very touchy systems.

This is the method that I use
And I will have to say has made me a ton of money
I find more leaky evaps this way then any other.
If I cant get 500 there is a leak and I find it

[square2round]

I use the same setup that Mark does. With the ball valve at the sensor and stainless hoses.

Mark, without the ball valve between the sensor (in the picture), did you still open the valves or add refrigerant to the system with the sensor on the port?

I also have the same problem with the o-ring in one of their core tools. Looks like it's been chewed. I'll have to replace it before I use it again. Have you had better luck with C&D?