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Micro brazing torch - any good?

Six O Two

(Marco)
TM Tech has a really good selection of tips and accessories for the meco welding torch. They're US based though, so you'll probably be dinged for shipping.

I use a small smith-type torch, but with propane specific gentec tips which I bought online at torchtips.com a long time ago.
I've got an oxy-propane setup similar to @Rauce with an oxygen concentrator and bbq propane bottles. There's definitely a few things that are trickier than OA: lighting the torch as Rauce mentioned, and also figuring out if you've to the proper air/fuel mix - the cone is a lot easier to see in an OA setup. But for me it beats having to worry about the fire hazard associated with having OA tanks in my garage, and also the cost and hassle of refilling them.

You'll only need one regulator on the propane bottle. A used o2 concentrator will set you back a few hundred dollars, but it's a one-time expense.
 

PeterT

Ultra Member
Premium Member
I was going to ask about propane storage in a garage. Is it an insurance no-no or just not recommended for the standard safety reasons. I went to NG on my BBQ years ago so the only propane I have is the typical torch.
 

Tom O

Ultra Member
I’m not sure my son keeps putting the propane outside and the Ox/act is inside as well as 2 welding tanks.
 

historicalarms

Ultra Member
many years ago a dude I wqas working with cut a galvanized culvert off with OA and got very sick from the fumes off the galvanized. O H & S visited our site & claimed we could use propane torch to cut galvanized without it fuming off as bad....still ordered to use masking tho.
 

Rauce

Ultra Member
Premium Member
A used o2 concentrator will set you back a few hundred dollars, but it's a one-time expense.

If one is close enough to the border to make a trip they can nearly free. I think it’s because they usually get paid for through insurance down south and there isn’t much of a used market. I paid $100 for mine in Rochester and showed the customs agent a printout of the Craigslist ad and they didn’t charge me anything in duty or taxes.
 

Mcgyver

Ultra Member
I’m not sure my son keeps putting the propane outside and the Ox/act is inside as well as 2 welding tanks.

Industrial practice is acetelyne and oxygen can be stored inside (but with certain safety protocols followed) and propane must be outside in a cage. As it was explained to me, the reason is propane tanks have a mechanicl safety value. Being mechanical, it could possible fail filling the place with propane, whereas the other tanks do not have mechanical safety valves
 

Rauce

Ultra Member
Premium Member
Industrial practice is acetelyne and oxygen can be stored inside (but with certain safety protocols followed) and propane must be outside in a cage. As it was explained to me, the reason is propane tanks have a mechanicl safety value. Being mechanical, it could possible fail filling the place with propane, whereas the other tanks do not have mechanical safety valves
Does this change if the tank is connected to something?

In my experience propane on a cart connected to a regulator/torch or on a forklift was fine.
 

Susquatch

Ultra Member
Moderator
Premium Member
As it was explained to me, the reason is propane tanks have a mechanicl safety value. Being mechanical, it could possible fail filling the place with propane, whereas the other tanks do not have mechanical safety valves

Could be.

But I suspect that the real issue is that propane in storage tanks is a liquid. Propane liquid has a very high coefficient of thermal expansion. Even a minor increase in temperature can cause the tank to be filled over its capacity which results in a liquid release into the room when the pressure relief let's go.

That's all deliberate. If the mechanical pressure relief fails, then the tank will rupture from hydraulic expansion.

Whether the valve fails or not is a moot point. Either way you have a room filled with heavier than air combustible gas. In some ways the rupture might be safer than the pressure release because the amount of propane might exceed the upper flammability limit. But that's an academic argument and not a good game I ever want to play.

Most cylinders are refillable. Typically, they are filled to the 80% level by volume or by weight. In almost all cases, this is done by a human being (who isn't perfect) using a weigh scale or an overflow valve. Once the fill is complete, they start closing the valve. So extra fluid usually gets in the tank. I'm sure there is no shortage of folks who want them to "put a little more in there......" too.

Mind you, thermal expansion is more likely sitting out in the sun. But a tank filled in the winter by volume and then brought inside isn't a very good scenario.

So ya, those refillable tanks belong outside.

In a perfect world the little torch cylinders would be ok. But even they are not risk free.
 

Susquatch

Ultra Member
Moderator
Premium Member
Does this change if the tank is connected to something?

In my experience propane on a cart connected to a regulator/torch or on a forklift was fine.

Not really. See above.

Yes, people park propane lift trucks inside. No they shouldn't. Yes, people bring propane bbq tanks inside. No they shouldn't.

The only reason I have the small torch tanks inside is because I trust human greed. No mass production seller of those tanks is ever gunna give me more propane than I paid for and they are all filled by weight not volume.

The 80% fill rule was established to minimize the chance of hydraulic expansion. It can't prevent human errors.
 

Mcgyver

Ultra Member
Does this change if the tank is connected to something?

In my experience propane on a cart connected to a regulator/torch or on a forklift was fine.

I doubt anything changes, might just be risk mitigation, i.e. the one on the tow motor has to be indoors, the other five refills in the corner do not. I phrased it as "as it was explained to me" as that is the extent of my knowledge and I dont claim expert status. But it made sense and was from a 30 veteran plant manager....of course that is no guaranntee he's 100% right about everything (although he might dispute that lol) but he knows more than I about it.
 

Engmaxx

(Michael)
I have one of these air-acetylene setups on a small acetylene tank: https://www.amazon.ca/Turbo-0386-0835-PL-8ADLX-B-Extreme-Acetylene/dp/B001J060VS. Might be right for you. Works really well for small jobs and you only have the one tank to deal with. I bought my whole set used with a tank for around $75 years ago. Search 'Turbo Torch' in kijiji and you will find plenty at reasonable prices some including tank, like this: https://www.kijiji.ca/v-tool-other/london/acetylene-b-bottle-with-torch/1651401493?undefined. Not sure where you are located.
 
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Mcgyver

Ultra Member
On the subject of pressure and propane tanks, I can remember (must have been 20-30 years ago) the late John Chapman's account at a TSME (model engineers) meeting of blowing up one of the small propane bottles, you know, the hand held ones. Back in the days when TSME met at a lecture hall at 999 Queen Street West. An apropos location; 999 was the old and original Bedlam like Toronto mental hospital. Before that, political correctness, it was called the Toronto Lunatic Asylum. A good place for TSME meetings!

Anyway, John was old school, wore a jacket at meetings an such and told a good story. .

He dug a pit in a vacant lot, Newmarket or Richmond Hill? can't remember, doesn't matter. He built a substantial fire in the pit and put into the fire a propane bottle with some water (don't try this at home kids). It was sealed of course and it had a suitable pressure gauge connected such that the gauge stuck above the edge of the pit.

John got some distance way and watched the gauge through a telescope. He said nothing happened for the longest time. Pressure got up to 2700 psi (irrc) and them BOOOM. I don't recall him saying windows broke but it was so loud everyone came out their houses looking around wondering and asking what was that? John decided the smart course of action was to also mill about asking what was that!

He said they never found a bit of tank, gauge or shrapnel


20201016-toronto-lunatic-asylum3.jpg
 
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DPittman

Ultra Member
On the subject of pressure and propane tanks, I can remember (must have been 20-30 years ago) the late John Chapman's account at a TSME (model engineers) meeting of blowing up one of the small propane bottles, you know, the hand held ones. Back in the days when TSME met at a lecture hall at 999 Queen Street West. An apropos location; 999 was the old and original Bedlam like Toronto mental hospital. Before that, political correctness, it was called the Toronto Lunatic Asylum. A good place for TSME meetings!

Anyway, John was old school, wore a jacket at meetings an such and told a good story. .

He dug a pit in a vacant lot, Newmarket or Richmond Hill? can't remember, doesn't matter. He built a substantial fire in the pit and put into the fire a propane bottle with some water (don't try this at home kids). It was sealed of course and it had a suitable pressure gauge connected such that the gauge stuck above the edge of the pit.

John got some distance way and watched the gauge through a telescope. He said nothing happened for the longest time. Pressure got up to 2700 psi (irrc) and them BOOOM. I don't recall him saying windows broke but it was so loud everyone came out their houses looking around wondering and asking what was that? John decided the smart course of action was to also mill about asking what was that!

He said they never found a bit of tank, gauge or shrapnel


20201016-toronto-lunatic-asylum3.jpg
Sounds fun!
 

JustaDB

Well-Known Member
FYI propane explosions called BLEVE Boiling Liquid Expanding Vapour Explosion
I was a volunteer firefighter in my home town for 7 years. We watched a lot of video on BLEVE's. Scary.

Once responded to a call at an oil well battery SW of town. It had been hit by lightning during a recent rainstorm, ignited some crude spilled on the ground & the fire worked its way under a large propane tank. It BLEVE'd, the neighbours heard it & called it in.

We arrived onsite, along with another local fire department. There was second propane tank right beside the blown one & the fire was still burning underneath. Nobody wanted to get close to this thing w/ a pumper, so we put on the longest reach nozzle we carried & a buddy & I started crawling on our bellies towards the fire, through a freshly seeded field. They kept on feeding us line & we'd test the range every so often. Once we got close enough, we just poured the water on.

At one point the tank relief valve released, shooting propane into the air which immediately ignited. Helluva sight! I think I wet myself as my buddy hunkered down behind me. You wanna talk adrenaline rush! At the same time, we knew we were going to be OK, as the valve was working. Kept on spraying water, changing pumpers out as the tanks MT'd. The water followed the drill furrows downhill towards us, which wouldn't have been bad, but they also carried some oil, which was on fire, too. Every so often we had to roll one way or another to avoid getting burned.

Fire eventually put out, sprayed more to cool everything off, went & had a looksee. That BLEVE'd tank looked like a sardine can, opened up along the seam at the top.

Ah, the good ol' days.
 
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