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Originally Posted by n-e-w Jerz!

It should be labeled as such. But I don't remember if it actually says "research" on said label....

Ours just say Co2 followed by some standards.

Originally Posted by hvac5646

Our fifty lb tank is aqua-blue, now that you mention it.

Cost us fifty-six buck to fill it. We still have about a 1/4 tank left from our initial purchase last year.

It should be labeled as such. But I don't remember if it actually says "research" on said label....

Originally Posted by n-e-w Jerz!

Think your looking for "research grade" nitrogen. It comes in a aqua blue cylinder, pharmaceutical and biotech companies use it. but its a bit more expensive.

Our fifty lb tank is aqua-blue, now that you mention it.

Cost us fifty-six buck to fill it. We still have about a 1/4 tank left from our initial purchase last year.

Think your looking for "research grade" nitrogen. It comes in a aqua blue cylinder, pharmaceutical and biotech companies use it. but its a bit more expensive.

Originally Posted by hvac5646

CO2 is charged as a braze purge in gas state, not a liquid. Plenty of ways to take what you say on condensation.Care to expand?

On the CO2 molecular weight being lower than nitrogen...that is a plus because the CO2 will show smaller leaks than nitro will.


Quote Unless of course CO2 is indeed the refrigerant being used... Then of course the action changes. Nitrogen also does not convert as much as carbon dioxide does when brazing temperatures are realized. If you really want to get trick, use argon. End quote


Co2 is the end of the combustion process...it cant "convert" as you put it at brazing temps.

Not going to get into a pissing for distance contest with you, never said you can't use it, quite the contrary.

However, if not done properly, will chill the piping and cause a ton of condensation to from inside the pipe.

Nitrogen is pretty much idiot proof (until a better idiot shows up to the job site).

The "convert" I was referring to is the potential of flash steam when the potentially liquid Co2 hits the warm temps.. Not anything else.

If the technician were to overfeed the Co2 is when things will happen in negative manner... Stupid is as stupid does.

GT

Originally Posted by hvac5646

Jeez... do I have to spell it out for you step by step?

Of course the hose is clean and is re-cleaned after after each test. According to mfg specs it is cleaned with isopropyl alcohol. And the test hose is dedicated.

We clear now Mizer Johnson, boss?

Condescension doesn't become you, clover.

Originally Posted by VTP99

Here is what I would like.....
dry co2 in a aluminum cylinder

that's what we use.

Here is what I would like.....
dry co2 in a aluminum cylinder

Originally Posted by jtrammel

Cleaning your hoses with alcohol and getting out a mirror to blow against, how long does it take you to do an install. I'm all for using good practices and make a point to do them but around here my customers or boss aren't gonna let me spend 3 days on a simple changeout.

No, you only do it once with each new bottle of CO2. You don't test it every job.

Originally Posted by hvac5646

All what stuff? Boss has had his service procedures in place a long time. They are part of a routine any business follows.

Cleaning your hoses with alcohol and getting out a mirror to blow against, how long does it take you to do an install. I'm all for using good practices and make a point to do them but around here my customers or boss aren't gonna let me spend 3 days on a simple changeout.

Originally Posted by jtrammel

How do you find time to do all of this stuff, I barely have time to think I'm so buisy.

All what stuff? Boss has had his service procedures in place a long time. They are part of a routine any business follows.

Originally Posted by GT Jets

I think this discussion went way off track.
.

Co2 in the meantime causes condensation because it is in a liquid state when released and that change of state can cause WAY more issues than static moisture in "dry nitrogen". Nitrogen is in a gaseous state and does not cause the condensation issues.

GT

CO2 is charged as a braze purge in gas state, not a liquid. Plenty of ways to take what you say on condensation.Care to expand?

On the CO2 molecular weight being lower than nitrogen...that is a plus because the CO2 will show smaller leaks than nitro will.


Quote Unless of course CO2 is indeed the refrigerant being used... Then of course the action changes. Nitrogen also does not convert as much as carbon dioxide does when brazing temperatures are realized. If you really want to get trick, use argon. End quote


Co2 is the end of the combustion process...it cant "convert" as you put it at brazing temps.

Originally Posted by hvac5646

Jeez... do I have to spell it out for you step by step?

Of course the hose is clean and is re-cleaned after after each test. According to mfg specs it is cleaned with isopropyl alcohol. And the test hose is dedicated.

We clear now Mizer Johnson, boss?

How do you find time to do all of this stuff, I barely have time to think I'm so buisy.

Originally Posted by chuckcrj

It better be a brand new hose, otherwise the residue could be from what was in the hose. Even a brand new hose could have oil residue left in it from the manufacturing process.

Jeez... do I have to spell it out for you step by step?

Of course the hose is clean and is re-cleaned after after each test. According to mfg specs it is cleaned with isopropyl alcohol. And the test hose is dedicated.

We clear now Mizer Johnson, boss?

Trick would be CO2 purge, CO2 pressure test and CO2 leak check with a CO2 detector.

Cut down on some steps it would ;-)

I think this discussion went way off track.

The OP mentions purge, not evacuation.

Purging with nitrogen is to "displace the oxygen during the brazing process", you have to realize that the moisture content is pretty much irrelevant in most of our uses.

Co2 in the meantime causes condensation because it is in a liquid state when released and that change of state can cause WAY more issues than static moisture in "dry nitrogen". Nitrogen is in a gaseous state and does not cause the condensation issues.

So what's the argument? Because dry nitrogen should not be used because it is not lab quality? Give me a break.

Something to realize too, the molecular structure of nitrogen is a bit larger than that of o2, this incompatibility is where the moisture discussion becomes moot.

IMHO using CO2 will cause more problems than they will eliminate.

Unless of course CO2 is indeed the refrigerant being used... Then of course the action changes. Nitrogen also does not convert as much as carbon dioxide does when brazing temperatures are realized. If you really want to get trick, use argon.

GT

Originally Posted by hvac5646

One good test I learned is to release about 75psi thru a 1/4 hose and let the gas hit a mirror. If it leaves behind a film or residue there is oil and an undesirable amount of moisture in the tank. Than you have to run your gas thru a filter drier or take the unpure tank back.

It better be a brand new hose, otherwise the residue could be from what was in the hose. Even a brand new hose could have oil residue left in it from the manufacturing process.

Remember that how deep a vacuum goes and how well it holds is a measure of dryness.

Most of the time a single pass with the vacuum pump draws the system down to around 200-225... and it rises to less than 400. Now that is a good vacuum for residential work... even 410. If it is stubborn... a triple evac will allow me to go below 200 with a rise to less than 300 if I wanted to do so.

Now I fully realize in refrigeration work deeper vacuums are desirable, and sometimes necessary.

In residential work... the difference is negligible.

Experience... many years (in my case decade +) and probably over a thousand systems opened and closed... teaches one what is necessary ans what is splitting hairs.

Originally Posted by jtrammel

I don't want to add time, although there is usually plenty to do while pulling a vacuum. I don't have an inert gas moisture meter so I have to trust what the supplier gives me.

One good test I learned is to release about 75psi thru a 1/4 hose and let the gas hit a mirror. If it leaves behind a film or residue there is oil and an undesirable amount of moisture in the tank. Than you have to run your gas thru a filter drier or take the unpure tank back.

I don't want to add time, although there is usually plenty to do while pulling a vacuum. I don't have an inert gas moisture meter so I have to trust what the supplier gives me.