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The Artful Bodger
11-17-2014, 03:14 AM
My home gas kit which I use for brazing and heat treatment of tools etc is Oxy/LPG.

LPG in NZ is 60% propane and 40% butane (more or less).

I am on a rather slow learning curve to get the best out of this! For starters, can anyone please suggest pressures to set?

General tips on how to set it up and adjust for best flame and any other insights greatfully accepted.


John

PTSideshow
11-17-2014, 06:16 AM
http://i35.photobucket.com/albums/d200/ptsideshow/assorted/welding%20books/Books0274.jpg (http://s35.photobucket.com/user/ptsideshow/media/assorted/welding%20books/Books0274.jpg.html)I just set it like a regular acetylene torch tip by the drill size of the orifice.
Now our propane is a different mix and your heating values will be different, maybe lower? It also will take a while to learn the speed to travel. As I have a tendency to out run the preheat.
http://i35.photobucket.com/albums/d200/ptsideshow/Tools/WElding%20equipment/DSCF0013.jpg (http://s35.photobucket.com/user/ptsideshow/media/Tools/WElding%20equipment/DSCF0013.jpg.html)
This is what our propane tips look like on the right.
You have to move slower, preheat longer and the cut kerf edges will be rougher. I use the plasma, for most cuts.
http://i35.photobucket.com/albums/d200/ptsideshow/Tools/WElding%20equipment/DSCF0010.jpg (http://s35.photobucket.com/user/ptsideshow/media/Tools/WElding%20equipment/DSCF0010.jpg.html)
Here are a couple of I beam chops.
I use it mostly for bending and heating.
See following post for more photos of the tip.

PTSideshow
11-17-2014, 06:19 AM
http://i35.photobucket.com/albums/d200/ptsideshow/Tools/WElding%20equipment/DSCF0008.jpg (http://s35.photobucket.com/user/ptsideshow/media/Tools/WElding%20equipment/DSCF0008.jpg.html)
A propane tip on a regular torch body
http://i35.photobucket.com/albums/d200/ptsideshow/Tools/WElding%20equipment/DSC03246.jpg (http://s35.photobucket.com/user/ptsideshow/media/Tools/WElding%20equipment/DSC03246.jpg.html)
http://i35.photobucket.com/albums/d200/ptsideshow/Tools/WElding%20equipment/DSC03245.jpg (http://s35.photobucket.com/user/ptsideshow/media/Tools/WElding%20equipment/DSC03245.jpg.html)
http://i35.photobucket.com/albums/d200/ptsideshow/Tools/WElding%20equipment/DSC03248.jpg (http://s35.photobucket.com/user/ptsideshow/media/Tools/WElding%20equipment/DSC03248.jpg.html)
The two part propane tip, front,inside,and back.

ironmonger
11-17-2014, 07:49 AM
I just set it like a regular acetylene torch tip by the drill size of the orifice.
Now our propane is a different mix and your heating values will be different, maybe lower? It also will take a while to learn the speed to travel. As I have a tendency to out run the preheat.<<snip>>

What you interpret as outrunning the preheat is too low a setting on oxygen pressure. Sometimes the same result is due to the oxygen valve on the main handle not opened all the way. The preheat is unnecessary once the cut begins. Oxygen actually burns the iron and the exothermic reaction releases enough heat to keep the cutting action going. Many industrial cutting machine operations turn off the preheat once cutting begins.

The charts that you have are a good staring point for setting up the torch, but are just that... a starting point. It is important to use the correct size tip, as the cutting orifice size is critical to good cuts and is directly related to material thickness. The cutting speed is also critical. Too fast and you outrun the exothermic cutting action, to slow and you end up re-welding the cut with the preheat flame.

In the case of acetylene it is easy to set up the torch without any gauges on the regulator at all. Open the fuel gas valve on the handle about 1/2 to 3/4 turn and then start bring up the fuel pressure while trying to light the fuel gas. Continue increasing the pressure until the flame 'leaves' the tip. At this point, with the handle oxygen valve wide open and the cutting torch oxygen valve open 1/4 to 1/2 turn, slowly increase the oxygen pressure until you get a neutral flame. Then depress the cutting lever and increase the oxygen pressure until the preheat flame goes past neutral and balance the cutting torch oxygen setting and the regulator pressure until the cutting lance is sufficient to cut the stock. This last bit is something that needs to be arrived at by practice and experience... and this practice is brought about by needing to use a torch that has a damaged gauges. Sometimes the boss doesn’t care to hear excuses... just cut the pipe already...

paul

ironmonger
11-17-2014, 08:06 AM
PT, I saw that you have two in line check valves in your oxy/propane rig.

I saw these guys at Fabtech a few years ago:
https://www.youtube.com/watch?v=hH1xIWR5f8U

I stopped using check valves and installed flash arrestors after seeing the video... contrary to what my wife says, I am trainable :>)

The check valves that so many of us used to use are useless and only serve to reduce the available pressure at the torch. you can test the pressure drop by monitoring gas flow out of the tip (submerge the tip in water and watch for the bubbles) raise the regulator pressure and see how high the gauge rises before gas starts to flow. Adding more check valves only increases the pressure drop even more and if you are using the regulator gauges to set the gas pressure you need to factor these pressure drops into consideration when setting up.

more info
http://iigas.com/fba.htm

paul

The Artful Bodger
11-17-2014, 01:09 PM
Thanks everyone, some useful information there!

EddyCurr
11-18-2014, 11:54 AM
I saw these guys at Fabtech a few years ago:
https://www.youtube.com/watch?v=hH1xIWR5f8U

I stopped using check valves and installed flash arrestors after seeing the video... +1 in favour of flash arrestors.

It may be different now, but when I sought these out locally they were difficult to
find. Vendors told me my usage didn't warrent them and to just settle for valves
like everyone else. IOW - this is what we've got, so it's what you really need. Mine
ultimately came from an online source.

I've never seen a video demonstrating the difference. It isn't emphasized, but notice
how at 0:10, he uses the quick connects to remove both hoses from a lit torch without
consequence. Thanks, ironmonger.

TAB, is the decision to use LPG instead of acetylene a gas cost/insurance retention matter?

.

The Artful Bodger
11-18-2014, 01:14 PM
EddyCurr, LPG I can buy from the hardware store but acetylene requires me to rent a cylinder at exorbitant prices (or I could buy a cylinder but there is no local filling point).

Renting the oxygen cylinder is plenty expensive enough.

If I find out more about compressed air/LPG for heating I might switch to that.

I only want to do brazing and heat treating tools, for welding I have arc and mig and for cutting I have a plasma set.

ironmonger
11-18-2014, 02:50 PM
Artful

Keep an eye on craigslist for an oxygen concentrator. I found one locally a few years ago, and it came with a 2000 psi portable cylinder filler compressor. It makes about 5 LPM, and is quite happy to run unattended. You can then try to find an oxygen cylinder that some one bought and never recertified and fill that, you will never have to take it in for another refill.

In the states many gas suppliers charge rental based on the length of time that you have the cylinder, which makes refilling theirs a problem, but even if you could I would never refill a cylinder that I didn't own, as the O2 form the concentrator is only 95% or greater oxygen, but it is not 100% as the cylinder is supposed to be. My torch has never complained about the lack of purity :>)

I use it mostly to fill my little R cylinders, which are about 6" in dia. and about 16" tall. Handy but really expensive to fill commercially.

paul

rowbare
11-20-2014, 08:06 AM
Artful
Keep an eye on craigslist for an oxygen concentrator. I found one locally a few years ago, and it came with a 2000 psi portable cylinder filler compressor.

What make/mode is the cylinder filler compressor? I already have a concentrator I use for a glass torch, it would be nice to be able to fill cylinders with it too.

bob

flylo
11-20-2014, 08:48 AM
I have 2 oxygen concentrators that ran 15 bay muffler shops, on my to do list to hook one up & use with LP. Also have a moterized torch cutter & was amazed how smooth a cut can be when not done by hand.


Artful

Keep an eye on craigslist for an oxygen concentrator. I found one locally a few years ago, and it came with a 2000 psi portable cylinder filler compressor. It makes about 5 LPM, and is quite happy to run unattended. You can then try to find an oxygen cylinder that some one bought and never recertified and fill that, you will never have to take it in for another refill.

In the states many gas suppliers charge rental based on the length of time that you have the cylinder, which makes refilling theirs a problem, but even if you could I would never refill a cylinder that I didn't own, as the O2 form the concentrator is only 95% or greater oxygen, but it is not 100% as the cylinder is supposed to be. My torch has never complained about the lack of purity :>)

I use it mostly to fill my little R cylinders, which are about 6" in dia. and about 16" tall. Handy but really expensive to fill commercially.

paul

kf2qd
11-20-2014, 09:30 PM
http://i35.photobucket.com/albums/d200/ptsideshow/Tools/WElding%20equipment/DSCF0010.jpg[/IMG] (http://s35.photobucket.com/user/ptsideshow/media/Tools/WElding%20equipment/DSCF0010.jpg.html)
Here are a couple of I beam chops.
I use it mostly for bending and heating.
See following post for more photos of the tip.

Can't blame process gases for poor technique. Most commercial cutting is done with oxy propane as it actually heats faster and more evenly for less cost. BTU's per cubic foot is about double that of acetylene. Surface finish is excellent.

Acetylene is for welding. Inner flame has all the heat which makes it easy to use as a very concentrated heat source.

flylo
11-20-2014, 09:52 PM
Anyone ever use the gasoline & oxygen cutting outfits? I've only see youtube vids but the look impressive.

Willy
11-20-2014, 10:15 PM
Can't blame process gases for poor technique. Most commercial cutting is done with oxy propane as it actually heats faster and more evenly for less cost. BTU's per cubic foot is about double that of acetylene. Surface finish is excellent.

Acetylene is for welding. Inner flame has all the heat which makes it easy to use as a very concentrated heat source.

Have to agree, I've been using oxy/propane for cutting heavy steel sections (5/8"-2") for years and have always gotten very nice smooth cuts using this combo. Now with plasma for anything smaller I don't even need an acetylene cylinder any more.
Although I do miss oxy/acetylene welding.

Below a link to a short video showing the cut produced from a machine guided oxy/propane torch in a very thick section of steel.

https://www.youtube.com/watch?v=Zy3g4-D1ZeA

macona
11-20-2014, 10:30 PM
What make/mode is the cylinder filler compressor? I already have a concentrator I use for a glass torch, it would be nice to be able to fill cylinders with it too.

bob

They were using one of those for my grandpa too. It was a compressor unit that sat on top of the oxygen concentrator, the bottle laid down on top of it and had a quick release that went on the side of valve assy. I dont know who made it though. He does not need it anymore.

bob ward
11-21-2014, 06:07 AM
Why does an oxy/lpg cutting tip need to be different to an oxy/acetylene cutting tip? Obviously something to do with the fact that LPG and acetylene are different fuel gases, but what?

Willy
11-21-2014, 09:32 AM
My home gas kit which I use for brazing and heat treatment of tools etc is Oxy/LPG.

LPG in NZ is 60% propane and 40% butane (more or less).

I am on a rather slow learning curve to get the best out of this! For starters, can anyone please suggest pressures to set?

General tips on how to set it up and adjust for best flame and any other insights greatfully accepted.


John

Have a look at this video from Smith Equipment on basic guidelines for setting up an oxy/propane cutting torch. I'd forgotten all about it until this thread came up. I remember copying this video onto a dvd a couple of years ago and sending it to my brother-in-law when he purchased an oxy/propane cutting unit. In lieu of my help these instructions have served him well.

https://www.youtube.com/watch?v=f2amO0T3vkQ

Willy
11-21-2014, 09:34 AM
Why does an oxy/lpg cutting tip need to be different to an oxy/acetylene cutting tip? Obviously something to do with the fact that LPG and acetylene are different fuel gases, but what?

Acetylene requires a different oxygen to fuel ratio than propane. Also because of slightly lower heat propane cutting tips require more preheat flames than an equivalent acetylene cutting tip. In addition to this due to the larger number of preheat holes in a propane cutting tip the construction of most oxy/propane cutting tips is two piece.

They are easier to manufacture this way since the inner portion consists of simple splines inside of an outer shell for the preheat flames vs what would be many drilled holes if it was of one piece construction.
In addition to them being recessed, the shape of the splines, straight or v-shaped depending on the type of gas used (Propylene and MAPP vs propane and natural gas) also helps anchor the flame to the tip due to these gases being slightly slower burning than acetylene.

ironmonger
11-21-2014, 05:08 PM
What make/mode is the cylinder filler compressor? I already have a concentrator I use for a glass torch, it would be nice to be able to fill cylinders with it too.

bob

My concentrator is an Invacare and the pressure pump is a Invacare Venture Homefill II
The fill cut-off is preset at 2000 psi, and while I could probably diddle it higher, I always have at least two spare O2 cylinders, and I see no reason to stress the compressor beyond it's design point.

paul