Propane safety

Discussion in 'Burners and their construction' started by purpleparachute, Jul 20, 2022.

  1. Looking to start home casting with small (6kg) propane fired or smaller electric (if I can find something decent) furnace.

    Chicken shit scared of propane bottles and gas safety, I have so many questions and don't know where to go to get answers. I have small (plumbers torch sized) propane bottles already that I have used for years without much issue but these others would be about 10 times the size.

    e.g. if I can smell gas from a 'closed' bottle and suspect a leak, what the f**k do I do??

    What are the temperatures (when it's stored) that a propane tank could spontaneously combust/freeze/crack?

    Is there any sense to storing it outside in a metal locked box or would this exacerbate any leakage issues/pressure explosions? what about in very hot (40c) weather?

    Can canisters be carried safely in a car? do they need strapping down? does it matter if it is on it's side to travel?

    Surely if it is something used in domestic bbq's it can be used safely? Is it just the extra heat threat from the molten metal that is the real danger?

    Does the furnace HAVE to have air input? What's the thinking/science behind this?

    What do you all do to be safe? I know it's a question we try and avoid so we can keep having fun but I really need to know or my home foundry will never get off the ground..

    Is there a course I could do?

    Thank you for any thoughts!
     
    Last edited: Jul 20, 2022
  2. Mantrid

    Mantrid Silver

    They are widely used in many situations. So are perfectly safe.
    I think the biggest danger is if the place where they are stored catches fire and they are exposed to very high temps for prolonged period of time.
     
  3. rocco

    rocco Silver

    The odorant they use in propane is pretty powerful stuff, sometimes the smell will linger for a long time after the tank is filled, so it's not necessarily indicative of a problem but if you smell it and you're concerned then it warrants a little closer inspection, use a solution of dish soap and water in a spray bottle, spray it on the valve, seams and rupture disc, any leak would cause lots of soap bubbles. It's also good practice to do this to regulator, hoses and valves you attach to the tank to ensure your connections are secure and leak-free.
    The tanks are safe stored at any temperatures you're going to get in something like an outdoor shed, the performance of the tank will suffer at very cold temperatures, so in very cold temperature or very high fuel flow rates, you might find it necessary to warm the tank, when necessary, I'll put the tank in a tub of warm water.
    Not sure it's necessary but I usually transport my tank in a milk crate, it keeps the tank vertical and prevents it from rolling around in the car.
    As far as other safety concerns, it's largely common sense, such as positioning propane tank and hoses such that they won't be exposed to flame or extreme heat.
     
    Petee716 and Tobho Mott like this.
  4. Ah ok that makes sense and I got that sorted pretty much my studio is fairly safe in terms of fire...though I should prob check my extinguisher works still!
    I have a ceramics kiln which will be for burnout (not tested it at home yet, though I know it is in good nick and fires ok) so this could be another potential fire risk I suppose. I'll likely not be firing up the furnace until this has been fully tested though, I plan on getting my LW process down pat and just pouring pewter until I'm ready to do the hot stuff.
    No idea how long the kiln is going to last as I am planning on abusing it something rotten but you gotta try these things from time to time, especially if you have limitations on funds, space etc.
     
  5. Milk crate - that's genius I'll have to get me one of them :)

    I've used that method with the soap before with my argon bottle (there was no leak I was just paranoid!) - so a leak isn't necessarily disaster but you got to deal with it asap right? What would you do, take the bottle to the dealer or something? What if you couldn't do that straight away e.g. day job, so the leak would potentially continue for a bit - I'm guessing that would be really stupid to not prioritise getting it the hell off your premises immediately??

    I remember the 'snow' you'd get on tanks that were almost empty when pouring at uni, yes we did the same, big bucket of warm water. So there is no 'danger' per say to a cold tank, just that it might mess up your melt? How about temps where the bottle could crack, are they quite tough and is it all regulation thickness?

    Sorry for the deluge of questions!
     
  6. One other thing, sometimes my small propane burner 'flares' (shoots out a big jet of flame, usually the orange kind not the blue) I think it is only when the bottle is fairly new and the fuel sloshes up to the neck of the bottle quickly - would this potentially happen with a tank too? I guess not because the hose is between the burner and the tank right?
     
  7. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I don't see operating a propane foundry furnace (outside) as being any more dangerous than a bbq/grille, but handling molten metal requires more care than chicken and beef! ....but with proper personal protective equipment and common sense, I think home casting can be done safely. -Lot's of us have been doing so for many years. Ask questions.

    Best,
    Kelly
     
  8. Tops

    Tops Silver Banner Member

    I have had more trouble with the one pound cylinders (one or two that leaked from their internal valves, solution was to leave them attached to a device with its own valve) than with the full sized ones with shut-offs used on grills, cutting torches, etc...I like to test 'new' and 'new used' gas fittings and connections with soapy water.
     
  9. Mantrid

    Mantrid Silver

    I dont think they can crack. The steal they are made of is malleable not brittle like cast iron. They could potentially burst under very high internal pressure but I suspect they are designed that the valve will give way before the tank. Im not 100 percent certain about this, but it just seems more logical to design them that way. Somebody else here will probably know or will take the time to find out.
     
  10. Petee716

    Petee716 Gold Banner Member

    One thought I would add here is that unless a ventilation system has been very thoughtfully and carefully engineered, this is strictly an outside activity.

    Pete
     
  11. rocco

    rocco Silver

    The tanks are indeed designed with a specific point of failure in the event of excess pressure. On North American spec tanks it's built into the main valve, not sure what's used on U.K. or E.U spec tanks but there would be something similar.
     
  12. Zapins

    Zapins Gold

    Interestingly if you lit a match or put a giant spark trough the gas inside the cylinder it would not explode. Because fire needs oxygen to burn and there is only propane inside. Furthermore because the tank is pressurized with pure propane gas no oxygen can sneak inside. So no explosion is possible.

    If you let the cylinder leak into a room of oxygen and then ignite it thats when you might have problems depending on the concentrations.

    If you keep your cylinder outside where gas cannot build up the only issue you'll potentially have is if the leak is very fast and then is ignited you'll get some flames coming off the cylinder or hose. Both pretty unlikely since there aren't a lot of ignition sources wandering around the neighborhood.

    Pretty boring and safe for the most part. Not like the James Bond movies
     
  13. rocco

    rocco Silver

    For those who don't know, be aware that propane is heavier than air so it can "puddle" in low areas, like your basement so, storing your tanks outside, like Zapins suggests, is a very good practice.
     
  14. Mantrid

    Mantrid Silver

    Our science teacher had an impressive experiment to demonstrate this.
    Take metal tin with metal lid that compresses on (not screw on)
    Have hole at bottom just large enough for rubber gas pipe
    Have small hole in lid.
    Put gas pipe in bottom hole and attach to gas supply.
    Gas fills tin and comes out hole in lid.
    Light gas coming out hole in lid. So you hve a nice little flame.
    Remove gas pipe from bottom hole and switch off gas.
    Flame at top continues to burn because tin is full of gas.
    Teacher then carries on with lesson while flame burns away. Teacher tells kids it will just go out when it uses up all gas.
    Couple of minutes later the lid explodes of the top with a loud bang frightening the kids to death. Very funny but probably cant do anymore with H&S and hyper sensitive kids these days and over protective parents sueing the school
    Explanation
    As the gas in the tin is used up it is replaced with air that comes in through the hole in the bottom that the pipe was removed from. When the ratio of gas to air reaches a certain point it results in a smal explosion in the tin blowing the lid off.
    Teacher used it as a demonstration of how a gas filled room can explode when the door is opened letting air in.
     
  15. rocco

    rocco Silver

    That reminds me of one of my teachers that had a very dramatic demonstration of grease fires. He'd heat a beaker of veg oil up the smoking point, set it alight, than attempt to put out the fire with a beaker full of water. The result was a massive fireball that completely engulfed the teacher for a second or two. BTW, the teacher wore ppe similar to what we might use for a cast iron pour and during the demonstration, the students would line the perimeter of the room as far from the demo as possible.
    The teacher would d0 this every September with his grade nine class, always on the same desk in the middle of the same classroom, that room had a large black scorch mark on the ceiling. He said his reason for doing this was because his wife had once been badly burned attempting to put out a grease fire in her kitchen with water. I suspect the rules now would prohibit such a demonstration today which is a shame because it had quite an impact, I'd be very surprised if any of his students ever burned themselves in the same manner his wife once had.
     
    Last edited: Jul 21, 2022
  16. Jack Meckes

    Jack Meckes Copper

  17. I was working night shift at a newspaper press and we had a fire safety person give a talk but no demonstration about the same issue. A co-worker said if she had an oil fire on the stove she'd throw a container of flour onto it to put it out and try as I might I could not convince her that would cause a dust explosion. I'd seen a fireball from this this first hand when a student threw fine sawdust into the high school incinerator back in the 1980's. My avatar image is the local gasworks about 1986 with an airborne railcar mounted propane cylinder inside the fireball which landed a block away on top of a vacant shop.
     
  18. Hi Kelly, thanks I know this is probably sounding really elemental to everyone but this discussion is really helping so thank you for the replies. I'm actually less concerned about the molten metal bit as I know mostly how to mitigate this (still have some concerns around fumes from melting and radiant heat control), it's just the gaps in knowledge around use of gas that are concerning me at the moment. I'm thinking of trying to find a course where I can ask questions until I'm blue in the face :p
     
  19. Hi Pete, could you elaborate on that? Do you mean because it is an asphyxiant? Or because of the danger of explosions? Do you get small amounts of gas leaking as you burn it in the furnace?

    Would it only be a danger indoors in the event of leak during storage and unknown quantities of gas accumulating in the workshop? I plan to run it in the garage, mostly to keep the noise down, but the doors will be open. I may install an extraction system but need to investigate this. If temperature (hot/cold) is not an issue I'll store it outside in a locked metal box when not in use.

    Edit: on second thought if the bottle did leak whilst stored outside, would it being in the box (so the gas can't disperse) then lead to an explosion risk on opening the box and letting air in? Not sure I fancy that worry each time I go to use it!

    Second edit: sorry REALLY basic question - the propane and oxygen 'oxidise' and are a fire risk together, or just in the presence of a flame as well? Is this where the fire triangle comes in? did an online work based fire extinguisher course waaay back so this is ringing some bells.
     
    Last edited: Jul 22, 2022
  20. Oh mate that's not helping haha :eek::confused:
     

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