Nitrogen purging

[cook42]

Is there a simple way of purging linesets with nitorgen? Is it best to put the linesets totally togetter and start from the inside out? Plus with a 5/16 or 3/8 line how do you purge that line without burning up your gauges? I've done different was and just looking for the best and quick way. Getting ready for 410a units.

Thanks

[beenthere]

Doesn't matter if you braze inside first or outside.
I use an old hose so it doesn't matter if it gets hot or not.

[obxtech]

.

[flange]

not to be smart, but you shoud be purging already with r-22. only put together as many joints as you can do in a day, tape ends and flow nitro while brazing at a very low pressure. On some of these newer VRV systems you could be installing piping for days or weeks striaght. purging while brazing as in addition to treating the piping properly such as sealing all ends when not attaching piping. May seem tedious, but this is how it should be done. Thats why you see older systems still running thirty years later, they were done right, unlike a lot of todays hackers.

[cook42]

Doesn't matter if you braze inside first or outside.
I use an old hose so it doesn't matter if it gets hot or not.

So in other words you use a heat sink on the service valves when you are brazing using your old hoses ?

[beenthere]

A damp rag to protect the service valve.

The hose is old, and only for brazing. Its seal isn't the greatest.
I have a couple older hoses that are find for purging nitrogen while brazing, but not for any thing else.

When ever you replace your hoses. Save one or two, just for brazing.

[troyorr]

Make a short (12 inch) extension tube out of copper with a 1/4 flare nut on one end and a 1/4 male on the other. Won't hurt your oses then.

[quiet mike]

I recently purchased a small little device with a tap on one end to attach a hose, and it's attached to the larger end of a piece of rubber in a "cone" shape, tappered down do a small piece of hollow copper tubing, small enough to fit into a 3/8 line and will work easily with PVC and copper tubing up to 7/8.

Basically, it corks the end of the line set with a tap to attach a hose, we connect ours to the nitrogen bottle and blow from the highest point to the lowest point and after sautering, leak test with nitrogen, vacuum ect.

As far as lineset replacement, I have seen so many references to the need for "replacement" and just as many for for "if not desired, ect."

I also removed the valve stems, and place a damp rag on the valves to help cool as much as possible.

[Tiger93rsl]

I just use my guages I push N2 in the high side and leave my low side open, and wrap wet rags around the service ports.

[bmathews]

Thats why you see older systems still running thirty years later, they were done right, unlike a lot of todays hackers.

The thing I find humorous about this comment and I can't say for sure, due to my age 30 years ago was a mere 10 and my job at the time was shoveling grain and corn. But old timers I've talked to, claim they never even pulled a vacuum when they started units up. They find humor in the importance we place in proper vacuuming of new systems.

[beenthere]

But old timers I've talked to, claim they never even pulled a vacuum when they started units up. They find humor in the importance we place in proper vacuuming of new systems.

Lot of them just purged with R22, and that was it.
And they charged them, either with a charging timer, charging cyclinder. Or by beer can cold.

In reality though. How many of those systems that were just purged when they were installed 30 years ago, ran trouble free, is questionable.

The owners of many of those homes sold the home less then 10 years later. So the old timer can't tell you the trouble that system had later on.

Some of those systems were flare connections, made it easier.

Airquips, also eliminated brazing and vacuuming.

And many times those old timers are telling you about heir experience with airquip fitting units.(of course they didn't vacuum)

[MichaelDinPC]

Interesting... I've NEVER heard of anyone purging nitro through a lineset while braising. Is it just to help keep the heat down or...?

[beenthere]

Prevents oxidation inside the copper while you braze.

[aircooled53]

I just use my guages I push N2 in the high side and leave my low side open, and wrap wet rags around the service ports.

Now, here is a tech. that knows what he is doing.

[JBM1000]

I use a low pressure regulator that will adjust to less than .250 positive psi and this is after I prove there is no oxygen with a oxygen sensor. Then you weld every joint down to the last an adjust the regulator as needed. On the very last joint I always have a tiny pinhole and at that point I cancel nitrogen and right at zero psi I cap the pin hole.

Have cut open just to be nosy and it's true, there is little if no oxidation findable!
So do it right or be a hack. I owe that knowledge to an old timer pipe fitter whom took the time to "tell me off for being an idiot" first, then took pity and personally showed me and set me up with the right regulator etc. I take no credit for the procedure.