micron gauge

TH3 M0L3

I couldn't agree more and couldn't have put it better my self!

If we go back to the original statement that you can never remove moisture from POE by vaccing then I still have trouble agreeing with that.

On the grounds of that you could then go as far as saying that there is no point in pulling a vac on a system with POE as any moisture in the system will be absorbed by it and impossible to remove. (I do know we don't vac to only remove moisture, we vac to remove all the non-condensables too)

Not all systems use filter driers, just look at all the splits.....

beenthere

When you install or have to open a system for service that uses POE oil.

You still want to remove as much moisture from the line set and coils as you can.
So vacuuming is still an important process, to minimize the moisture left in the system/line set, and or coils as much as possible.

What you don't remove. The POE will absorb. And the filter drier has that much more moisture it must remove.

Mini splits generally don't have room for a drier. So its probably a matter of lack of space then any other reason that they don't have driers.

Vacuuming removes moisture, nitrogen and CO2, and O2(combined, even without the moisture they're just air).

You would be surprised how much moisture isn't removed from mineral oil by vacuuming.

If you have the time, and curiosity.

Take a baby food jar. Drill a hole in the top. Insert a fitting that you can hook your vacuum pump to. And that can be sealed to the lid.
Then add 1 table spoon of water the the jar. And then add 4 times as refrigeration oil to the water, as you put in water(yes, 4 tablespoons).

Put the lid on. And if you have an electronic/digital scale, weight.
Then connect your vacuum pump to it. And run your pump as long as you have patience for. And yes, use your micron gauge. Look how long it takes to get a good vacuum(supposed good vacuum).

After 3 hours, you will still see water under the oil.



PS: No. The baby food jar will NOT implode from the vacuum. I wouldn't advise hitting it with something. But it was under a vacuum when it was bought with baby food in it.

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TH3 M0L3

I hope I never gave the wrong impression, I always perform a vacuum on any system I expose to the atmosphere.....always!

I think the reason they dont have driers is because it causes extra resistance on the refrigerant. If you use a drier, it will have a similar effect as either extending the pipe run, or adding extra bends in the pipework. For the splits to be more efficient, and have longer pipe runs, the driers are omitted....
I could be wrong though

You are preaching to the converted

Yes, you are right. I would be surprised. But that, I guess, would depend on how much moisture is in the oil.
I can't imagine that amount of water in the system that it would form a layer under the oil, unless the oil was contaminated from the suppliers, or your vacuum pump failed during a vac and you did not have a check valve on your pump.....then it'd draw in loads of moisture....

It's the time I lack. I know you will never pull a decent vacuum for as long as you have moisture present, and the jar wont make much of a mess if it did implode....
the pressure difference between the atmosphere and the jar would be less than 1 bar (about 14 psi) as it will be in some sort of vacuum.....another reason why using a vacuum to perform a system tightness test is highly inaccurate.....

beenthere

I use to take care of a bubble for a tennis court.

At 5"wc pressure in it. You couldn't open the handi cap emergency exit if you were in a wheel chair.
And if some one helped you open it. You were blown out the door with the chair and generally fell out of the chair.
The pressure had to be kept below 2"wc for that door to work right.

this bubble is 150' long and 40 foot high. And help up by only 1.75"wc under normal operating conditions.

So 14PSIG difference is a lot for many objects/containers.

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beenthere

Test/experiment number 2.

Same jar. After cleaning and drying it out.
Place 5 drops of room temp water in it.
Connect vacuum pump and micron gauge.
Start pump and time it to see how long it takes to remove that water. It won't take long.

While you set up for the above mentioned experiment. Set a container with an ounce of water in it out side. And have it covered. You want the water in it to be the same temp as the outdoor air. Hopefully its 30°F outside(it won't freeze sitting there while other test is going on).

After indoor test is done. Wipe out jar. Set it outside for 5 minutes(let it get as cold as it is outside). Then add 5 drops of water from the cold container you set outside earlier. Hook up your vacuum pump and micron gauge. And time how long it takes to remove the water. And the ice you just made.

At 20°F. It takes rough;y 24 hours to remove 1 of moisture(1 refrigeration drop, is 1/20 of a gram).

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westman

Should you change the oil between every job?

beenthere

Yes, you should.

If I'm doing only new line sets and evap coils. I don't change it between everyone.

Do one old line set, and or coil though. Change it. It makes a big difference in time.

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earl964

If we don't use one we are told to pack up our stuff and go work some place else. New refrigerant cost way to much.

Mr freeze

When doing refrigeration work you suppose to use micron gauge, I use every time you dont know how far down , I do cascade from -120f to -255f system.You have to pull these system down to 100 Micron it might take 2 day with two vacuum pump running and heat lamps. This is other way that the system is tight on leak when you have the micron gauge on the system. Pluse refrigerant is cost pre pound is high on these system 6 pound cost is 2,000 and up.Refrigerant pre pound cost for now days All my guys have their micron gauge and they all use them from system that run 1/2 pound to 600 pounds.

Rusty999

Great post on the use of micron gauges. Also I love the different viewpoints. Good point about the standing vacuum test. Here how I learned it: Pull system down to 1000 microns, then break vacuum with dry N2. Do this 3 times (triple evac). Pull down to 400 and allow too sit 45 min. If the reading climbs, then holds ( ex to 1500-2000) it's moisture. If it continues a slow climb without stopping, it's a leaker.

My understanding about mini splits is that a LLD isnt used because technically there's no liqid line outside the unit (types may vary). Both lines are low pressure, thats why theres no svc fitting on the second line. The metering device is in the condenser outlet like alot of general motors cars, so what you would think would be the liquid line has refrigerant flashing inside, which I guess would make it part of the evap circuit.

joeyd

I design and manufacture electronic service tools for the HVAC/R industry. I will soon be going to market with a new micron gauge, and I am looking for a few experienced service professionals who would like to participate in the evaluation of this new product. Preferably, a candidate would be one who uses micron gauges on a daily basis, has used a number of different products, would be willing to test my product over a number of weeks (preferably in conjunction with their own favorite gauge), and finally, provide an objective evaluation as to its overall performance and usefulness. In exchange for this effort, he/she will be given a gauge from the first production run at no charge, regardless of the favorable/unfavorable nature of the evaluation.

If you wish to be considered, please send me a private message, and I can provide more details.

Thanks,

JoeyD

Air Medic

I'm with Earl. Refrigerant is way to expensive for this kind of money wasting.

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HVAC Joe

This sums it up. 'Nuf said.

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avoiding Jersey, where my wives lurk.

HintonAC-LeoTav2

What kind of micron gauges are you guys using? I was using a Fieldpiece SVG2 for about a year now and it is already crapping out on me (it reads 1880 microns when open to the atmosphere). I need something durable and worth the money. Fieldpiece makes a great Electric meter and amprobe however their vacuum gauge and superheat/subcooling meters are not up to par even if you baby them.

nimnux

digital gauges are more accurate and also expensive

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rlynch33

i use mine to verify for leaks when i"m done with any repair ETC.. Professionals use them.

combs custom cooling

I used to use my sman3 and my JB micron gauge every time. now that I have a testo 557 I use it and the JB. I do this because i noticed that sometime the micron meters get stuck in a vacuum even when exposed to atmospheric pressure. I think its worth it though for the customer and of course I pride myself on having a low rate of call backs.

chuckcrj

As for which micron gauge is the best, the Bluvac hands down.

With the leak rate indicator you can tell exactly what is happening inside the system.

It is very sensitive and will reveal any leaks in your vacuum setup.

It is the one JoeyD talked about in his post above, from Aug, 2010.

acefurnacefixer

you cant and should not even attempt to put in a A/C system with out using a micron gauge.I use one every time I install or repair the pipeing side of a system. if i dont achive 50 microns, then i am not sure that my joints are tight. Your manifold is for charging a system......not to tell you if you have a tight system......thats the job of the micron gauge.

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beenthere

50 microns? A lot lower then needed.

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