Micron gauge vs U tube manometer

[heetseeker]

I asked my contractor if he pulls a vacuum after he charges the system and asked about using a micron gauge which I learned about on this site. He says he uses a U tube manometer which accomplishes the same thing. Is he correct?

[ct2]

yea , the little bitty marks on that U-tube measure microns

[dash]

Actually I remember those days,micron guages haven't always been around,we didn't all grow up in a electronics/digital age.


U-tube filled with Mercury,was used before digital,read in inches of mercury,not microns.


Is this guy as old as me?

I remember getting one for refrigation work,way back in the late 60's,had it mounted to a huge belt driven vacuum pump.


I surprised any one would still be using one today,sure he's not pulling your leg?

[dan sw fl]

Originally posted by heetseeker
He says he uses a U tube manometer which accomplishes the same thing. Is he correct?

If his age = 74 +, he is correct.

[heetseeker]

No he wasn't kidding. He seems to be in his mid fifties.
Maybe that is also why he said he never heard of using nitrogen with brazing with 30 years in the industry. He uses 15% silver solder for brazing but no nitrogen. How important is the nitrogen since I have read on this site that you still get ash with the nitrogen?

[mark beiser]

A U tube manometer couldn't possibly have the resolution at low microns that a micron gauge has. It would be only slightly more accurate than a compound gauge....

[heetseeker]

Do you have to pull a vacuum to more than a certain level or just to a certain level. Is the precision a signicant factor?

[beenthere]

You won't get any ash with if you braze with nitrogen flowing through the pipe while you braze.

I find it hard to believe anybody still uses a u tube for vacuum. But its possible.

You should have asked him to see it, its a museum piece.

[AllTemp]

Originally posted by beenthere


You should have asked him to see it, its a museum piece. Not true Yellow Jacket still sells them I have one, manufactured by The Scot & Fetzer Company, never used it. Bought it from that surplus equiment place on the internet... In Indiana near John...

Wish it were a musuem piece I'd sell it,lol

[beenthere]

Originally posted by AllTemp

Originally posted by beenthere


You should have asked him to see it, its a museum piece. Not true Yellow Jacket still sells them I have one, manufactured by The Scot & Fetzer Company, never used it. Bought it from that surplus equiment place on the internet... In Indiana near John...

Wish it were a musuem piece I'd sell it,lol

Ain't seen one since the 70's.

Thanks for the update.

Why did you buy it.

[AllTemp]

Originally posted by beenthere

Originally posted by AllTemp

Originally posted by beenthere


You should have asked him to see it, its a museum piece. Not true Yellow Jacket still sells them I have one, manufactured by The Scot & Fetzer Company, never used it. Bought it from that surplus equiment place on the internet... In Indiana near John...

Wish it were a musuem piece I'd sell it,lol

Ain't seen one since the 70's.

Thanks for the update.

Why did you buy it.

Just looked interesting saw it in their catalog and it was cheap....

[Freezeking2000]

heetseeker
Member

I would not get over excited or worried, i almost never use a micron gauge and have never used nitrogen to braze a few lines on a residential cooling unit. I pride myself on quality work and I have never ever had a problem with a small system due to not using nitrogen or a micron gauge unless it was a severe burnout or sucked in moisture.

Relax and let the man install you new system.

[heetseeker]

freeze
Why do you say you have not had a problem with a "small"
system. I will have a 4 ton and a 1.5 ton a/c placed. Are you talking small in relation to commercial jobs? How do you get rid of moisture in the system without a micron gauge?

[Shophound]

Freezeking may not have a problem doing it his way, and he very well may take pride in his work, but I couldn't do it that way, myself. I've pulled brazing trash out of pistons and changed replaceable core suction line driers that were full of crap. Moisture makes the system acidic, which eats away at compressor windings. Non-condensibles rob the system of efficiency and shorten lifespan of compressor.

My take...a CLEAN system is efficient. If it has very little trash, moisture and non-condensibles and is maintained well, it stands a chance to run well for a long time.

[ct2]

Originally posted by beenthere

You should have asked him to see it, its a museum piece.

I've got one! made by the Meriam Comp out of cleveland...

How do you add fluid on one of these things . the fluid is a silver color , do you just pour it in








ok , I know it's mercury, I was just being sarcastic

[dash]

Originally posted by shophound
Freezeking may not have a problem doing it his way, and he very well may take pride in his work, but I couldn't do it that way, myself. I've pulled brazing trash out of pistons and changed replaceable core suction line driers that were full of crap. Moisture makes the system acidic, which eats away at compressor windings. Non-condensibles rob the system of efficiency and shorten lifespan of compressor.

My take...a CLEAN system is efficient. If it has very little trash, moisture and non-condensibles and is maintained well, it stands a chance to run well for a long time.



Freeze says he never had a problem,I'd say one that he's seen,or knew was caused by such practices.

I've known guys that say that about a lot of bad practices.

[Black Adder]

If you are measuring in inches wc there is no way you are going to know how deep a vacuum you are pulling. A micron gauge measures in thousands of an inch. If you don't pull a deep enough vacuum you are wasting your time, gotta get the vac down to where the moisture will boil. A micron gauge is the only way to go.

[Jultzya]

Originally posted by heetseeker
How do you get rid of moisture in the system without a micron gauge?

With a vacuum pump you silly, the gauge is just that... a measurement! :D

[Jultzya]

Originally posted by beenthere
You should have asked him to see it, its a museum piece.

Dwyer makes several different ones, also look in your Grainger catalog... many are listed in the book (in a couple of places)

May be a dinosaur in the refrigeration industry, but they sure are common in the heating industry! :D

[heetseeker]

I would like to know if you can pull all the moisture out of a system while monitoring with a U tube manometer as well as with a micron gauge. If you need to pull a vacuum to a specific number or just greater than a number. In the last case the micron gauge would not seem as necessary.

[DeltaT]

Years and years and years ago some of us would use a U tube which was about 4 foot high which senses pressure in a system, not molecular activity (temperature), which most of the "micro gauges" sense today.

You could see if a fly landed on one of the lines if you knew how to read them. Some old calibration labs still have these types of tubes sitting around if you look.

I find these types of posts rather interesting and funny in that tons of systems, many still in service today, were built, started and tested with these type of "low tech" devices and workmanship way before all this new, gotta do, devices were even thought of. And, from my experience, we had a lot less headaches and a lot more maintenance to do since the systems would work for a pretty long time.

Even in the residential market many of our present replacements are over 20 years old but we mostly know that our "new" replacement stuff will be extremely lucky to make it that long even with all the "high tech" devices we use to install and start them up.

[beenthere]

Originally posted by jultzya

Originally posted by beenthere
You should have asked him to see it, its a museum piece.

Dwyer makes several different ones, also look in your Grainger catalog... many are listed in the book (in a couple of places)

May be a dinosaur in the refrigeration industry, but they sure are common in the heating industry! :D



LOL...

I still use a u tube for neg pressure gas valves.

I meant, its a dinosaur using mercury for reading vacuum.

If you look at some micron charts, you'll see they still have a cross reference to inches vacuum mercury.

[Black Adder]

"I would like to know if you can pull all the moisture out of a system while monitoring with a U tube manometer as well as with a micron gauge. If you need to pull a vacuum to a specific number or just greater than a number. In the last case the micron gauge would not seem as necessary."


The lower the vacuum the lower the boiling point of water, at 500 microns I believe that the boiling point is close to 0 degrees. You can pull all the moisture out with a vac pump and a U tube for measuring, but to be sure you have a deep enough vacuum you should really use a micron gauge. I still can't believe that a U tube will have small enough increments to let you know when you are a 500 microns.

[beenthere]

Black, which came first, 29.6"mercury, or 500 microns.

[heetseeker]

beenthere
If 29.6" of mecury is the same as 500 microns then I don't see a problem getting a deep enough vacuum since inches are pretty easy to measure[altho I have no idea how a u tube makes a vacuum]. Are you saying that altho the method is dated it can do the job?
Also if the installer doesn't use nitrogen while using silver solder does the problem with ash cause problems soon after the install or any time in the future.Does it gum up a valve or block an orifice?

[beenthere]

Neither a u tube, nor a micron guage makes, or pulls a vacuum, they are devices used to measure the amount of vacuum the vacuum pump has pulled, and to see if you have you removed contaiments to a safe level.

There are thousands of systems that nitrogen was not used when brazing and they work fine 20 years later. There is also just as many that had problems shortly after they were installed.

So not using nitrogen while brazing is a gamble IMHO.

[Freezeking2000]

I am a firm believer in adding a sporlan filter drier to all systems at the air handler. That being said i would not expect and non-refer man to think the only way to remove moisture from a system is thru a vac pump. I have had systems so full of water that you had to hammer the pipes to move the ice blockage which you could hear banging down the pipe to the rack. You know the system cleaned up fine and we never put a vac pump on it. I have also had small systems (under 1 h.p) that have had moisture problems (moisture freezing in TXV)which were solved with no micron gauge or the customer having to pull the cooler of all his product. This is all achieved thru filter drier technology. I do believe the most importent thing to do is remove all non-condensables and have a relatively clean system and a good filter drier. I am not saying that a good dry system is not assured using a micron gauge and nitrogen, but good refrigeration practices can be achieved with non of the hype. I have a supco micron gauge i have used a few times on troubled systems that had severe moisture contamination caused by a broken H20 evap loop but thats about it.

When i talk of small systems I am refering to any system under 5 tons.

[Freezeking2000]

I have been with this employeer for 9 years so i get to see my work still running in supermarkets in Connecticut. This includes mini-splits ect and i have yet to see a failure of my installs i could point to moisture.

I do not condone hackery and i always evac a system and do a proper leak check.

[heetseeker]

Beenthere
One of the contractors I am considering doesn't use nitrogen for brazing and uses the U tube. He has good references and is a comfort specialist for A/S. I don't want to dismiss him from consideration just because his methods are older. If the ash causes problems early on and the eqipment is under warranty I might take the chance. If it will be a long term problem then there is more potential expense for me.
Assuming that he is pulling a vacuum on the lines would a U tube manometer be able to tell him that the vacuum is strong enough. He say he has been doing it that way for 30 years.

[beenthere]

Freeze, I think your talking about shell filters, with valves to change out the core. Some thing you don't find on little resi a/c's.

If we find a sight glass on a chiller showing moisture we keep changin filters till it shows its dry, and no moisture in the oil.
On rack systems don't you check the oil for moisture on a regular basis?

I think the general topic is pulling a vacuum on a new system.

[beenthere]

Heatseeker, the u tube has been around longer then the micron guage.

So there should be no problem there.

Again IMO its a gamble without nitrogen, but I work on stuff thats been running for 30 years and they didn't use nitrogen.

I would recommend getting an extended warranty though.

[Freezeking2000]

I am talking about c163 driers(some flair some not) and i put a 303 on any 1/2 hp or larger unit that i suspect has a moisture problem. I am not much of a believer in suction filters as the pressure drop goes un-noticed and it will eat the compressor.


And no we do not test rack oil for moisture, i think we would see temp problems before we had oil moisture due to operating at lower temps.

[heetseeker]

Beenthere
Thanks for your help. I would be getting a 10 year parts and labor agreement so I don't think I am taking too big a risk. From all the talk I have read on this site about nitrogen and micron gauges I lost some faith in this contractor.

[sadlier]

The International Mechanical Code, along with many manufacturers, requires evacuation to at least 500 microns. 500 microns is about .02" mercury above absolute zero. I don't think that the U-tube manometers of today are set up for such a fine measurement. Using a water manometer won't work, not that it would have to be about 34' high, but because the water in the manometer would vaporize before the evacuation is reached.

[Black Adder]

beenthere

" Black, which came first, 29.6"mercury, or 500 microns."

I am sure that 29.6" merc came first, only problem is that 29.6" mercury is about 10,000 microns. 500 microns is equal to about 29.97" mercury. Pretty hard to see on a u tube. Truth be told, the boiling temp of water even at 10,000 microns is 53 degrees, A funny thing is that Ford service manuals only call for a vacuum of 25,000 microns which puts the boiling temp at over 80 degrees, wonder why so many vehicle comps fail.

[dan sw fl]

Originally posted by Black Adder
beenthere

" Black, which came first, 29.6"mercury, or 500 microns."

I am sure that 29.6" merc came first,
only problem is that 29.6" mercury is about 10,000 microns.

500 microns is equal to about 29.97" mercury.
Pretty hard to see on a u tube.

Truth be told,
the boiling temp of water even at 10,000 microns is 53 degrees,

A funny thing is that Ford service manuals only call for a vacuum of 25,000 microns which puts the boiling temp at over 80 degrees, wonder why so many vehicle comps fail.



Black ADDER, .. Those #s don't seem to ADD up right

[beenthere]

sadlier, we're talking a Mercury u tube, not water.

[beenthere]

Heatseeker, your welcome.

And hope everything works out great for you, and you keep us up dated.

[dan sw fl]

Originally posted by heetseeker
I asked my contractor if he pulls a vacuum after he charges the system ... Is he correct?

How do you vacuum AFTER a charge?
... Timing might be off just a tad.

[beenthere]

Originally posted by dan sw fl

Originally posted by heetseeker
I asked my contractor if he pulls a vacuum after he charges the system ... Is he correct?

How do you vacuum AFTER a charge?
... Timing might be off just a tad.


LOL...

I missed that part.

[heetseeker]

So the vacuuming is done during the charge? Does that mean that you can't recover any moisture if somebody charged your system with an inadequate vacuum previously. If you get acid in your system , can it be fixed or do you need a brand new charge? Where does the acid do its damage?

[beenthere]

On a new system, the vacuum is pulled on the new line set, and indoor coil.
The outdoor unit is factory charged.

After the vacuum is pulled and verified that it is holding and at a deeop enough level, then the lines can be static charged if the system requires more charge, or the valves can be opened.

Acid damages the electrical windings in the compressor.

If it has to be changed out because of acid, the cleanup filters are also installed.

He may have just said it backwards, and done it right.

[heetseeker]

beenthere

Much thanks for answering so many of my questions. You have been very kind.

[sadlier]

Originally posted by beenthere
sadlier, we're talking a Mercury u tube, not water. Mercury U tube is what I spoke of first. Water U tube was thrown in since, if the water didn't boil off, the distance would be 1/4" which is much more easily readable.

[beenthere]

Originally posted by sadlier

Originally posted by beenthere
sadlier, we're talking a Mercury u tube, not water. Mercury U tube is what I spoke of first. Water U tube was thrown in since, if the water didn't boil off, the distance would be 1/4" which is much more easily readable.

Sorry, saw the water comment and jump to conclusions.

Guess I got my excersise for the day yesterday.