Compressed Gas Cylinder Use

[imp]

Some gases, such as oxygen, helium, and nitrous oxide, for example, are stored, transported, and used from high-strength cylinders having very high internal pressure, perhaps several thousand pounds per square inch (psi).

 

The witches' tale about such cylinders is that if one is tipped over and the valve broken off, the "jet propulsion" action of the released gas will drive the tank forward at dangerous speed.

 

Can anyone confirm/deny the truth in this old tale? Imp.

[insane_alien]

yeah this happens. its more like a rocket than a jet though. if you could get it to go in a straight line then there is the potential for a kilometer or two of flight with some of the bigger cylinders.

 

typical pressures are around 300Barg (rougly 300 atmospheres).

 

most cylinders have a big plastic bit to prevent the neck being smashed off.

[Rocket Man]

iirc, "myth busters" did a take on this one.

they managed to completely remove the valve almost instantly with the cylinder lying horisontal facing a cavity brick wall.

the cylinder went dead straight with no modifications, put a neat hole through the test wall and nearly made it through the next wall (also cavity brick... yay for foresight)

 

i personally am a fan of pneumatic propulsion. but it works so much better when the propellant has more mass. like water for example.

[insane_alien]

how about a Xe cylinder. one atom of that has more mass than a couple of water molecules

[Rocket Man]

true, but as a whole, water liquid is more dense than xenon gas. so i'd expect you'd get more propellant mass in a cylinder using the cheap stuff.

[YT2095]

typical pressures are around 300Barg (rougly 300 atmospheres).

 

most cylinders have a big plastic bit to prevent the neck being smashed off.

 

agreed, I have a 2L medical O2 bottle here and that`s 315Bar (when full).

although there`s no plastic other than the regulator knob and the pressure meter.

 

27 Bar on the He bottle, no marking on my CO2 bottle, and I can`t read my propane tank but it`s 18.6Kg.

[Rocket Man]

the plastic is normally only there for transport, it's a big round thing that encompasses the entire valve set. purely protective.

[imp]

true, but as a whole, water liquid is more dense than xenon gas. so i'd expect you'd get more propellant mass in a cylinder using the cheap stuff.

 

Hey, maybe I'm more dense than water, but it's incompressible. So, if you fill a tank with it under pressure, suddenly release that pressure (like break off the valve), a little bitty squirt of liquid will be evident, and the pressure will then be zero,. and nothing further will happen.

 

This is why pressure vessels like boilers are proof-tested for containment strength and leakage by using liquid, generally water, as the medium, instead of gas.

 

Am I all wet here? Imp.

[YT2095]

it`s well known that you Only fill water rockets 2/3s the rest is for compressed gas.

 

so IMP, your argument doesn`t hold water LOL

[grifter]

lol too much H20 for my liking! and word to the wise, IMP the pressure wont be zero, It'll be 1 bar

[swansont]

it`s well known that you Only fill water rockets 2/3s the rest is for compressed gas.

 

I thought the optimal fill was ~1/3 water and ~2/3 compressed gas. Of course, that might depend on pressure.

 

 

edit: 40% fill from this data: http://www.geocities.com/wrgarage/perform1.htm

[insane_alien]

water IS compressible. not by much but you can squash it to the point where it will form a type of ice.

[YT2095]

I thought the optimal fill was ~1/3 water and ~2/3 compressed gas. Of course, that might depend on pressure.

 

 

edit: 40% fill from this data: http://www.geocities.com/wrgarage/perform1.htm

 

is it? I dunno, I know it had Something to do with 2/3`s (trust me to get it right but backwards) LOL

[insane_alien]

In soviet russia, backwards gets you!

[imp]

it`s well known that you Only fill water rockets 2/3s the rest is for compressed gas.

 

so IMP, your argument doesn`t hold water LOL

 

I believe the argument implied FILLING the tank full of water. Yes, liquids are slightly compressible, most less than 1% at 3,000 psi. Forgive use of antiquated units, it's the way I learned things in the Frozen Water Age.

 

Thought we were talking about storage tanks for gas products, not rockets.

 

But thinking things through is what we're all here for, right? Imp.

[Rocket Man]

Thought we were talking about storage tanks for gas products, not rockets.

 

true, but we were also talking about the propulsive behaviour of compressed gasses so i thought the simple water rocket was appropriate.

 

as for proportions, it really depends on the nossle diameter. a fine nossle will use a different water level to a wide nossle.

 

compressing water into ice; was it 15 or 40 different types of ice that form under different conditions?

[grifter]

compressing water into ice; was it 15 or 40 different types of ice that form under different conditions?

 

neither, there are 14 phases of ice they are:

 

amorphous ice (three forms low, high and very high density)

Ih

Ic

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