Inside a pipe brazed with nitrogen

[Eric S]

Just a cool Pi I took on an install six months ago. It's a 2 1/8 return line on a Leibert XD system. They tell you in class that you flow Nitrogen to prevent oxidation on the inside of the pipe but it's pretty cool to see it for yourself. The picture shows a 10 foot length of pipe and a brazed 45.

[Lightning_Boy]

This is exactly the reason why I use a flowmeter, 3 psi is all it takes for a couple of minutes and it'll save a call back later when drier's plugged or worse...

[FrostyBeer]

Sweet pic for sure!

I'd like to see the same shot but without nitrogen being purged through.

Probably be a cool side by side comparison to show non believers.

[Eric S]

I'd like to see the same shot but without nitrogen being purged through.

Not possible at the time. No room in the schedule for doing work twice. Not to mention the price of a wasted fitting. $$$

[stopro1]

Sweet pic for sure!

I'd like to see the same shot but without nitrogen being purged through.

Probably be a cool side by side comparison to show non believers.

[FrostyBeer]

Nice!! Did you take that pic?

[syndicated]

Without nitrogen it looks the same as the outside of the pipe. In school my teacher had us do all types of brazing and soldering then cut our joints down the middle to check penetration and heat control. You could tell who used nitrogen and who didn't.

[FrostyBeer]

I mean like on some scrap in some spare time

[Eric S]

good point

[pecker head]

Awesome pic man... I remember learning about this is school, must admit I have never done it... ;/

[steve638]

The flow rate for pruging with nitrogen is 3-5 CFH----That's cubic feet per hour-----which is not alot of nitrogen. I usually go 10CFH.

[Eric S]

How do you measure/calculate the CFH you are using? Is it the same flow rate for different pipe sizes?

I always just put 2 or 4 psi on the gauge. That puts more CFH in a larger pipe than a smaller one.

[steve638]

How do you measure/calculate the CFH you are using? Is it the same flow rate for different pipe sizes?

I always just put 2 or 4 psi on the gauge. That puts more CFH in a larger pipe than a smaller one.

Flow meters can be purchased at any welding supply house........you'll save a ton of money on nitrogen. As far as the flow rate for different size pipes, I would assume the larger the pipe the more flow you would need. The correct procedure is to put an oxygen sensor at the end of the pipe and when you 0% oxygen you start brazing. Oxygen sensors can be quite expensive though.