ReplyThis 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...
Professional Member
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.
Professional Member
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...
You cannot cheat an honest man. But that doesn't stop people trying!
Professional Member*
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.
Professional Member*
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.
Professional Member
Not possible at the time. No room in the schedule for doing work twice. Not to mention the price of a wasted fitting. $$$Originally Posted by FrostyBeer
Professional Member*
I mean like on some scrap in some spare time
Professional Member
good point
Professional Member
Professional Member*
Nice!! Did you take that pic?
Professional Member*
Awesome pic man... I remember learning about this is school, must admit I have never done it... ;/
Regular Guest
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.
Professional Member
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.
Regular Guest
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.
Professional Member*
Thats a real good comparrison shot, I just sent that to all my guys as a reminder.
Professional Member
Went to Turbo Torch's site and they say you have to use a regulator before the flow meter and the max inlet pressure is 50 psi, is this true with all of the flow meters?
Do all flow meters have the glass or plastic indicator tube, any metal?
The prices aren't bad, $50/
Where does one find an oxygen sensor?
Thanks
Global Moderator
A combustion analyzer has one. Just put the probe in the open end of the tubing and watch the O2 drop from 20.8% to 0%.
Professional Member
woa, that would be expensive, but at the end of the sensors life it would a great time to experiment to find the lowest flow rate for ones technique. Just wish they had a metal protective cover for those glass tubes.
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