steam cannon

[Hotwired]

I think the boiling point of water is only 100 degrees C. So heating it up to 500 is overdoing it, 100-200 degrees would be easier and just as effective but slower.

An equal mass of steam at 500* is 2.5x the pressure of steam at 200* that would be why you would heat it up more.

Steam is a gas just like all the others and the gas laws still apply.

I personally wouldn't do it because if a steam cannon leaks you have extra problems along the lines of high pressure high temperature gas which sucks even more than just high pressure gas spraying onto you.

Not to mention a lot of things won't work at that kind of temperature like rubber/plastic seals that aren't designed for steam or being roasted.

[Matheusilla]

Solder melts at about 600 degrees. If you have money, buy steam pipe. Some ball valves might melt, just use common sense to pick a good one. If you want to use a pressure gauge get one made for steam (scrounge around a scrap yard for that one). Oh yeah, don't burn yourself

[chaos]

if solder melts at 600 degrees why did the dude on the video say different?

personally i wouldn't use steam for the same facts as hotwired said. ouchies imagine 200psi steam in ya face, then if your lucky enough to still have a face, imagine the scaring from it.

[Matheusilla]

chaos: It depends upon the alloy of the solder. You need way more heat to do silver soldering, for example.

[lukemc]

the solder will not melt. my dad was working on water piping in my room and could not get the pipe up to enought temerature because the was still water in it water can only reach a certain temeratur. that is why you can put a paper cup with water in it on a fire and the paper wont burn. so as long as you still have some water in the pipe it wont melt the solder. my suggestion fill the thing almost all the way with water so you can reach the desired pressure and still have it cool enought to not melt

[spudthug]

uncalled for???? no i think it wasnt and u guys were posting nonsense and saying it couldnt be done...dur it can be done its been posted on here...


and people hate it when u post before searching

edit: the solder will melt...i guarentee u right now solder doesnt melt at 600 degrees lol...unless u have like ultimate steroids solder..u can melt most solder with a lighter....plus u r not supposed to use thick solder for copper pipe and silver solder would probably not for copper because

1. u have to get the pipe to about 2000 degrees...

2. silver solder costs over 20 a foot.....

[DAltar]

i saw the episode and felt they did a poor job, i believe they should have gone with a burst disk of some sort. this would allow the pressure to be let out of the cannon without the use of a fancy valve.

[MisterSteve124]

Well the solder wouldn't melt as long as you did it right. If you have a chamber big enough then you dont have to heat it right where the joints are. You can heat it in the middle of the pipe which wouldn't melt the solder. A ball valve would be fine as long as the heating source is not that close to it. Personally I think it would be cool and everything but I don't see the point when you could just fill one with compressed air quicker and easier and get better results.

[spudthug]

do you know how many propane torches itn would take and how long it would take to heat up more than a 2"x1' chamber??? a big chamber is not going to happen

[Killjoy]

Spudthug,
silver solder is made for copper pipe. Its mandated for all residential, commercial, and industrial copper piping applications because it doesn't have lead in it and as we all Know Lead+Water= Eventual Brain Damage.
And since when does silver solder cost $20 bucks a foot, i can get a 10 ft roll for 6 bucks.

[boilingleadbath]

Steam has a lower molecular mass and a higher heat capacity than air, so it actually out preforms air in a pneumatic cannon, all other things being equal.

Also, the provided reason for needing to heat the water above 100*C is wrong.
Instead, higher temperatures are needed because, as the pressure increases to more than 1 atmosphere (that's normal pressure), the boiling point does too.

Google 'vapor pressure water' for more info.
(and yes, this <i>is</i> why we use pressure cookers)

[paaiyan]

Theoretically speaking, if you can heat a tank of water to about 390 degrees Celsius and get the pressure up to around 225 atmospheres, you would have reached the critical point of water at which the liquid state no longer exists. Your cannon would have unimaginable power.

[hi]

so, would it work?


i have everything but the barrel, which will be made of iron. the ball valve is 3/4'' and the chamber is a 8'' 3/4'' nipple made out of iron. So i can heat it effectively with a single blow torch.

And for the guy that said it wouldnt be as powerfull as a nomal pneumatic, you are wrong. because the gas (steam) is really hot, it will propel the projectile farther. If you were on spudtech before it closed, there was a really long desscusion on it. it was determined that with normal compressed air you could not break the sound barrier, but if the gas was heated to a high tempature it could break the sound barrier at the same pressure. i cant explain it, but i beleave it.

[judgment_arms]

First off to answer you question, provided the ball valve doesn’t fail, yes.

Now here’s an idea:
Make a coaxial out of gas pipe, make the piston from wood (undersized to allow for the expansion of wood), and use leather for the seal face. Have a heavy spring behind the piston to keep it closed until it hits the desired pressure, about 500PSI, fill the area in front of the piston (what would normally be the pressure chamber) two thirds full of water and load it with a projectile such as a steel ball bearing. For me I’d just throw the thing in the forge well I’m workin’ steel, I suppose you could use a blow torch, but I’m not sure if that’ll give you enough heat. When the thing hits the “popping pressure” it’ll fire the gun, kind of like a burst disk, only slower and reusable.
Whadoyathink?

[hi]

i thing it would work, but i dont know if leather would work, and the wood would be hard to get right, maybe the piston should be made of copper. this would have to be fairly small if you wanted it to work with a blow torch, and would be really hard to get right. the spring would have to be really stiff, and it would still leak around the piston. if you found a really good sealing face, it would work.

i just hade the greatest idea, make a big fire and wait for the coles to settle, then heat i up in there, the pull it out with pliers and gloves, then put it in a vise and fire. that would kinda work, and the fuel would be free.