Steam cannon

inonickname · Sat Mar 28, 2009 4:37 am

Well accord into here water boiled in an enclosed chamber with propane or mapp can reach 500 psi. Assuming you could build a chamber, barrel and valve that could tolerate such temperatures and pressures do you think this would be viable as a method of powering micro scale pneumatics?

Downsides would of course be reheating/boiling times and the flash-boiling steam from the nozzle which would no doubt give 3rd degree burns..but both of these are hardly worse than an ETG, are they?

Boiling time could be lowered with a smaller chamber (this would also lower the amount of steam).

Any thoughts/ideas/opinions on using steam to power our cannons?

SPG · Sat Mar 28, 2009 5:46 am

Ages back we discussed this (sorry, don't you hate it when people say things like that?) and I think someone even made one, Jack will no doubt be along in a second to give you the url.

Anyway the point is, that it's perfectly doable. Possibly better as a burst disc gun though than a valve as that way you know you have a built in safety. If you're going for micro-calibres then i would have thought the best thing would be to work out how to inject water into a pre-heated chamber, rather than heating water up in the chamber, it'd give more of a pressure spike instead of s steady build.

inonickname · Sat Mar 28, 2009 5:55 am

Gah...I guess that's true for everything on the internet. I did see someone manufacture something similar from a kettle but it was extremely crude and unsafe.

Another concern I have with it is that a large amount of the thrust is focused through a de laval nozzle or similar- unsure if the power use would be effective here. Rockets also make use of flash boiling.

On/off topic: That large stainless steel tank I got from the dump a while ago might be used for...A steam rocket cart

SPG · Sat Mar 28, 2009 6:14 am

Oh and there is of course this baby.

Mr Perkins' Extraordinary Steam Gun of 1824, 900psi steam and 1000 shots a minute. So it goes to show it's do-able.

What plague, what pestilence would exceed, in its effects, those of the steam gun?

jackssmirkingrevenge · Sat Mar 28, 2009 7:22 am

SPG wrote:What plague, what pestilence would exceed, in its effects, those of the steam gun?

My favourite was "no fecundity could provide population for its attacks. . . ."

Which is basically saying:

~ MR PERKINS` EXTRAORDINARY STEAM GUN ~

Mows down people faster than they can reproduce!

Looks like this idea but at high pressure using lead balls. Sweet.

rp181 · Sat Mar 28, 2009 8:02 am

Actually, steam is much worse than a ETG. When you get hit my a ETG, there is some flash heat, and some pressure. Get hit by steam, and it stays on you, and water is a good heat conductor. Steam is MUCH worse.

Not only will the chamber have to handle heat, it has to handle corrosion.

jeepkahn · Sat Mar 28, 2009 8:09 am

rp181 wrote:Actually, steam is much worse than a ETG. When you get hit my a ETG, there is some flash heat, and some pressure. Get hit by steam, and it stays on you, and water is a good heat conductor. Steam is MUCH worse.

Not only will the chamber have to handle heat, it has to handle corrosion.

Not to mention with the pressures behind the steam, it will remove the parboiled flesh exposing new flesh to be cooked and removed and again and again.... in a split second.... loss of digits is quite possible in a fast way...

My brother was a boiler tech in the Navy, you should here some of the highpressure steam leak stories...

SPG · Sat Mar 28, 2009 8:29 am

jeepkahn wrote:
rp181 wrote:Actually, steam is much worse than a ETG. When you get hit my a ETG, there is some flash heat, and some pressure. Get hit by steam, and it stays on you, and water is a good heat conductor. Steam is MUCH worse.

Not only will the chamber have to handle heat, it has to handle corrosion.
Not to mention with the pressures behind the steam, it will remove the parboiled flesh exposing new flesh to be cooked and removed and again and again.... in a split second.... loss of digits is quite possible in a fast way...

My brother was a boiler tech in the Navy, you should here some of the highpressure steam leak stories...

Excellent sounds right up our street then, doesn't it?

psycix · Sat Mar 28, 2009 3:53 pm

I can remember that someone tried this.
A very small chamber took over 45 minutes to heat up/boil with a torch...

john bunsenburner · Sat Mar 28, 2009 4:15 pm

Well you would need some kind of shock heating, I am not quiet sure if it wouldn't be more effcient to heat up lets say 100psi CO2 to get 200 or even more psi CO2 tht is less dense and therefore more efficient...

jeepkahn · Sat Mar 28, 2009 4:16 pm

you'd have to get the water pretty hot to hit 500psi, If i recollect correctly, for every 1lb of pressure it raises the boiling point about 4 degrees f., but that's just a genralization from the internal combustion world... I'm sure one of the ME guys can give the exact temps, but I'm thinking it's about 2000f, to hit 500psi....at which point any pressure you release is i the form of steam...

perkins gun was basically a gravity fed larger bore constant flow bbmg...

inonickname · Sat Mar 28, 2009 6:55 pm

Sure, it will have it's downsides and it would just be quicker to use a fridge compressor...and the flash boiling steam will damage anything in front of the barrel. I was just comparing it to an ETG as the kind of thing you wouldn't want your fingers in front of.

Could these times be lowered by adding pre boiled water (say from a kettle) and pre pressurizing before heating?

jonnyboy · Sat Mar 28, 2009 8:19 pm

jeepkahn wrote:
rp181 wrote:Actually, steam is much worse than a ETG. When you get hit my a ETG, there is some flash heat, and some pressure. Get hit by steam, and it stays on you, and water is a good heat conductor. Steam is MUCH worse.

Not only will the chamber have to handle heat, it has to handle corrosion.
Not to mention with the pressures behind the steam, it will remove the parboiled flesh exposing new flesh to be cooked and removed and again and again.... in a split second.... loss of digits is quite possible in a fast way...

My brother was a boiler tech in the Navy, you should here some of the highpressure steam leak stories...

I assume a hybrid could do worse as the pressure is higher and it could be hotter...

D_Hall · Sat Mar 28, 2009 8:33 pm

jeepkahn wrote:My brother was a boiler tech in the Navy, you should here some of the highpressure steam leak stories...

Former Navy here....

Yes, high pressure steam is nothing to be trifled with. We would keep cans of broom handles around. The handles were for finding steam leaks. Keep in mind....

At those temperatures, steam doesn't just immediately condense back out. So you can't see a steam leak any more than you can see an air leak.

Result? You can hear it, but where is it?

You hunt for it with the broom handle. When the handle gets cut in half, that's when you've found your leak.

NASTY stuff.

edit: And for what it's worth, steam turbines (read: Navy) use dry steam. "Dry steam" is the accepted term for water that is past it's critical point. In other words... Roughly 700 degrees (and about 3000 psi).

editagain: And since the OP was asking about 500 psi... That implies approximately 470 F.

rp181 · Sat Mar 28, 2009 8:42 pm

Bit unrelated, but i was reading a FORBES magezine, and there was a article about high pressure steam pipe repair in vital applications. When the steam can't be turned off and there is a leak, they send it out to a company that machines a clamp (we are talking HUGE pipes) in less then 24 hours. They clamp it all up, and inject a rubber that needs to hold the steam until they get around to turning off the system for a real repair. They do this while the pipe is at 6000PSI steam. They have one death every 300 man years of work.

Steam cannon

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