Acetylene generators - how dangerous?

My father used an acetylene generator in his (commercial) shop. This thing was made in the 20s or 30s, so they'd never heard of OSHA, EPA, or Homeland Security. The acetylene generator looked a lot like a horizontal 20 gallon air compressor, sans motor.

The tank was filled with water. The "pump" was actually a hopper and clockwork sort of mechanism which released grains of carbide into the tank in response to the fall of pressure in the tank.

There was some sort of interlocked double doored air lock like thing between the hopper and the tank which was operated by the wind up mechanism. I recall hearing it "ticking" as it was working.

As I remember, the tank pressure was low, no more than 15 PSI, regulated down to 5 PSI for the torch. The whole end of the tank would unscrew, to let you get inside with a rake to clean out the spent carbide residue. I don't recall any blowout plugs per se.

It worked fairly well if you were using it all the time. But if you let it sit up for a while the mechanism would get balky, and it wouldn't drop carbide. I remember my father cussing and tapping on it to get it to drop carbide.

By the late 50s he quit using it, and just bought bottles of acetylene from the same place he was getting his bottles of oxygen.

Gary

Gary Coffman wrote: .(clip) The whole end of the tank would unscrew, to let you get inside with a rake to clean out the spent carbide residue (clip) ^^^^^^^^^^^ When I was a kid, I mounted a miner's lamp on my bicycle handebars. One of the things I remember is that cleaning the thing involved disposing of a watery-pasty slurry which stank to high heaven. I imagine the job of raking out the spent carbide residue from your father's tank was really unpleasant. That alone would make me want to avoid an acetylene generator.

Off topic a little further, we just got a machine which generates breathing oxygen for my wife (she has heart trouble.) It just plugs into a 120v outlet, and delivers breathing oxygen to one of those plastic nose-hoses. How do it work?

Yeah, it is about half the size of a propane tank. It looks like it would hold maybe 2 gallons or so. It has to be more than 5 Lbs. Anyway, for what I do with it, the Propylene works very well.

I won't store Acetylene indoors, it is just too dangerous. The Propylene is dangerous, too, but there are about 3 more ways Acetylene can make a big boom.

Jon

aren't you refering to an O² concentrater? not really the same as being hooked up to a bottle: through a process of vacuum, solonoid/switches/pumps and an activated filter, it delivers a stream of enriched(?)20%(?)mixture...

By clever use of a filter media which lets the oxygen through and slows down the nitrogen. It's not a generator, its a concentrator. However, a properly set up concentrator can produce essentially pure oxygen. Might not be pure enough for good results cutting, though.

Here's a web page descibing it (unfortunately, the web is now also clogged with spamsites trying to sell these to people who don't need them...so tracking down actual infomration has become needle-in-haystack work).

I made a slight effort to see if there were small industrial scale machines available for replacing cylinders, and could not find any amid the spamming of medical devices.

Yeah, it stank to high heaven. (Guess whose job it was to clean out the generator.)

It pumps air through permeable membranes which pass oxygen slightly more easily than nitrogen. After passing through several layers of membrane, the amount of oxygen in the output gas is enriched the desired amount. Won't work for welding though. Welding and cutting oxygen needs to be better than 98% pure. The concentrators don't get it that high.

Industrial oxygen preparation is done by fractional distillation of liquid air. Nitrogen boils at -196 C while oxygen boils at -183 C. By controlling temperature, they let the nitrogen boil off, leaving the liquid oxygen behind.

Gary

Mongke:

I was taking a jewellery course a couple of year ago I advised my insurer in writing that I was going to be taking my small acetyene tank in the house and they didn't increase my rate or ask me not to do it. I have a jeweler friend who has a propane tank in his small store just below a number of apartments and he hasn't had any problems getting insurance and his landlords insurer has never shown any concern.

However if your running a business no matter how small and you don't carry business insurance, your house policy isn't worth the paper it's written on, that's a fact not an opinion. From the amount of gas your using it sure sound like a money making operation to me. My son is an adjuster and some of the horror stories he tells me would scare the crap out of you. The fact that you have dangerous gases in the house isn't the problem. The problem is you haven't supplied your insurer with the information they need to calculate their risk, it's that simple. We live in a post 9/11 world and insurers are really playing hardball.

Every insurance company has different rules so in my opinion advise yours in writing and let the chips fall where they may.

First thing is that you'll need an injector-style torch to handle the low pressure out of the generator. I've seen these in both Smith's and Victor's catalogs, I've never seen one on the shelf. These have different internals than what the standard torches do. Next, you'll have to find some way of disposing of the residue which is mostly slaked lime with some impurities. And it stinks. There was a welding supply shop in my home town that made their own acetylene, filled tanks from three states around. They had tons of white sludge laying around, it wasn't really suited to agricultural application because of the impurities in it. The city would get on them about it, the piles would disappear and then, soon after, there'd be more. Never did find out where it went. You might have a problem finding small quantites of bulk carbide, there's the 10 lb tins for miner's lamps and then there's the 100 kg. drums, not much in between. I'm not sure it would be a paying business for occasional use. Once wet, carbide evolves gas continuously, there's no easy "off" switch or valve with it.

You might want to look into oxy-propane or oxy-propylene for your brazing needs. Either would be cheaper than using acetylene, if you're really using that much. And if you are, you might want to look into getting a larger bottle, the cost/cu.ft. goes way down on the larger bottles. Around here, the refill price is about the same if it's an MC or an 80 cu.ft. tank, it's mostly the handling and overhead that costs the money, the gas itself is pretty cheap.

Stan

That's not necessarily so. My father's generator produced about

10 PSI. That was regulated down to 5 PSI for use with a normal Harris torch.

Just heat it up (some residual acetylene will burn off, supplying most of the heat once you get it started). That'll turn it into quick lime. I used to peddle that to the neighbors for use in their outhouses to *control* stink.

The latter is serious truth. Lease the biggest bottles your supplier carries. That'll save tons of money over time.

Gary