Alternatives in propellant

[CHK6]

I was watching a documentary on the sinking of the Kursk. They say the primary fault was a faulty line leaking hydrogen peroxide on some metal pipes that formed a gas that expanded inside a torpedo. Eventually causing an explostion that caused a fire which set off the other ordinance in the sub.

What peaked my interest was that hydrogen peroxide and the metal it mixed with had a liquid to gas volume expansion ratio of 1:600 or around there of. (Enough to rip through torperdo casing like a bomb.) I know in the past we talked about Helium as an alternative to CO2 or Nitrogen. But what about newer ways to refill HPA tanks? Something more economical, faster to dispurse at tourneys and scenerios, and safe.

I'm no where even close to knowing my Chemistry (I took more Physics in college just to bypass Chemistry class), but if I recall can't you mix hydrogen peroxide with another element that seprates the oxygen and water and give you an expansion ratio around 1:300?

So instead of relying on a field with a compressor we might have a two part test tube that you slip into your tank that causes a chemical reaction. Your tank gets refilled with oxygen and the water would be discharged by some purge valve. Sorta like glow sticks with peroxide and luminal. Both are seperate untill the seal between the two are broken and the chemical recation takes over.

I know it sounds far off, but almost plausible. Now I think about it, same concept for instant inflatable rafts, but apply HPA tanks to the picture.

[Butterfingers]

The reaction would probably be too slow to do any good. I mean we have guns dumping 20 BPS now. Chem reactions can't keep up.

C02 flashes from liquid to gas nearly instantly and it still cant keep up.

BTW the hydrogen peroxide reaction yeilds pure oxygen and water. The ripping probably wasent because of gaseous overpressure but rather the oxygen mixing with the fuel to cause an explosion.

[CHK6]

Not on a shot per shot bases, but rather to refill tanks off field without the use of a compressor.

The documentary was very very specific. The gas expansion ratio was 1:600 or greater and it was over pressure that blew the torpedo casing apart. (Do a search on the web and you can read all about it.) When the casing blew it caused a fire and that fire two minutes later set off the ordinance. They went on to show proof in an experient that only took a minute or two with a very small sample of HTP (aka hydrogen peroxide) and the metal and it exploded a test tube. They also went on to talk about how this same disaster happened in a English sub.

The reaction is extremely fast and produces a highly pressurized gas (oxygen) and water. It's just in the Kursk case the amount of HTP was a lot and there was a lot of that specific metal that overcame the strength of the casing.

[314159]

pure oxygen in high pressures(concentrations) will cause a lot of things to burn explosivley if a heat source is near.

if you mix hydrogen peroxide, with an acid, you get the reaction as decribed above. the problem is that unless you use a strong acid, and a strong base, you aren't going to get much gas out. acids eat metal, so the tank would have to be lined will a non reactive plactic, or glass, if either of these had a fault in them, the acid would eat at the metal in the tank and BOOM.

[nutz]

Originally posted by 314159
the tank would have to be lined will a non reactive plactic, or glass, if either of these had a fault in them, the acid would eat at the metal in the tank and BOOM.

- i know fiber wraped tanks us something like glass so i dont that would be the problem... i think the main benifit of what CHK6 could potentially cause a problem of over pressuring unless there was a way of slowly releasing extra gas to prevent overpressurizing and explosion... that would probably raise the tank cost to near $1000 and no one would buy them

[ShinyGuy]

The biggest problems I see are that the reaction would not only have to produce a suitable gas to use as propelent (non-flamable, not spongy, etc.) but i would have to not produce hazardous byproducts and be cheaper than buying compressed gas. If I'm not mistaken pressurized nitrogen is chemically produced fairly near the pressure of the bulk tanks and very little, if any, compressing is done. I don't know what waste chemicals are produced in the process however.

[314159]

fiber rapped tanks are just aluminum rapped with carbon fiber. acid will eat through aluminum.

for this to work.
-you would need the reaction to take place in a area of the tank that that is not going to be desolved with acid.

-you will need to have a dumping system for the water (or other byproducts) produced, and a anti siphon system so that it does not get in the gun.

-you will need to regulate the speed of this reaction

-you will probally need a heat sink or cooling device if you need the reaction to take place at a fast rate (lots of things like to burn when they get hot in a 100% oxygen envyroment).

-find a better gas to work with, pure oxygen is not the greatest gas to work with, an should be handled like an explosive because it will cause lots of things to burn verry rapidly and uncontrollibly.

[nerobro]

With the huge mix of materials in our guns, inert gasses are ideal. Or relitevly inert gasses that will phase change to be stored as a liquid. Storing gas as a liquid, rocks, figureatively speaking. It take something huge in volume and makes it tiny.

That's what make co2 so cool. And being stored ina liquid it's somewhat self regulating, so long as the tank maintains temprature. If you could come up with a way of making co2 maintain temprature, you'd have one heck of an airsystem.

Nitrogen, thankfully has big enough molucules not to leak quickly out of high pressure air tanks. Helium has been suggested before. But it will leak out of tanks, and may damage the tanks on the way. sorta how co2 soaks into black o-rings.

any other ideas are welcome. Inert is a good thing

[Doc Nickel]

Bypassing the minor problems such as far higher costs per tankful, transport and handling of a toxic, highly reactive chemical (you and I would have a rather hard time buying hydrogen peroxide in any concentration stronger than the 3% stuff you get the grocery store) and the great deal of latent heat generated during the reaction process...

... Keep in mind the gasses generated are hydrogen, a flammable gas, and oxygen. Forgetting the obvious danger of pressurized hydrogen gas, oxygen tends to violently oxidize oils. Meaning that, without the presence of any heat, spark, flame or ignition source, oxygen can spontaneously erupt in flames, or even explode simply on contact with petroleum products like oil or grease.

If you look, you'll often see tank pressure guages marked "not for oxygen service" or something similar. This means the guage probably has a drop or two of oil on the internal mechanism, and using it in an oxygen system could possibly cause a fire or explosion.

Doc.

[Hamster Huey]

It has already been made clear that due to flammability concerns and the high price (relative to HPA) of getting hydrogen peroxide solution in sufficient concentration make hydrogen peroxide's use as a tank filler impractical.

Still, the thought is cool, and the idea works well enough that there are numerous programs exploring the use of HP as a propellant. So for the sake of the intellectual discourse, let's throw safety and money out the window and try to come up with a working system - just for giggles.

There's no need to be playing around with acid first of all. You could easily and safely evolve oxygen gas from HP with the use of a catalyst (I think MnO2 was what we used in high school chem). Since catalysts are not consumed in a reaction, one could imagine a tank permanently coated on the inside with some catalyst. As for controlling pressure, one would have to find a catalyst that lowered the reaction energy _just_ enough to generate sufficient O2 pressure at ambient temperatures while not generating explosive pressures at temps slightly higher. This, I think, would be your hardest task. The reaction would be highly sensitive to temperature changes, maybe even more so than flash boiling CO2. You might be forced to install a bleeder valve that would vent if the internal pressure got too high.

So if you're rich, insane, and well insured, this project is well within the limits of possiblity. If you decide to go for it, just be sure to let me know. I want to be far away when you start shooting flames out your barrel

[Jack_Dubious]

If im not mistaken...maybe a WWII nut might back me up on this...but Hydrogen Peroxide was the main ingredient for the Germans rocket projects...eg. the V1 and Komet. I think it was combined with a fuel to help stabilize the reaction. Either way...it was some nasty stuff.

[Doc Nickel]

Actually, I believe the Komet used nitrogen tetroxide and something else, as a fuel that self-combusted merely by being mixed, no ignition necessary. They called the two chemicals A Stoff and C Stoff, as I recall... Literally A stuff and C stuff.

Perhaps it was B and C... anyway, both chemcials were nasty poison, where breathing the fumes or getting a few drops on your skin was almost always fatal. Get a good splash on you and the chemicals would dissolve a fair chunk of your flesh before you died.

The worst was that both were clear, thin liquids that gave off a lot of vapor... If a whiff of vapor from one chemical made contact with vapor or liquid of the other chemical, it would spontaneously ignite and/or explode. Several Komets were lost simply to refueling accidents.

As an aside, The Apollo missions used similar self-igniting chemicals; nitrogen tetroxide and unsymetrical dimethyl hydrazine.

Doc.

[Dzerzhinsky]

I sure hope noone tries and uses anysort of concentrated H202 for their guns, it would be realy dangerous. For instance, there is an explosive known as HTMD, something the government doesnt want u to know about. It can be made easily from h202, but im not gonna tell u houw to make it. H202 is explosive alone in higher concentrations, this stuff is rotten!!! Anyhow, i dont know why i got onto that, i just dont think anyone should be playing with hydrogen peroxide. And please please please dont go and try to make concentrated h202 by boiling it down, if it gets too concentrated the heat will set it off....I dont want to be like a father or anything, i just dont want some innocent kid dyeing because he thought he had enough 7th grade chemistry experience to do something like this himself.

[CHK6]

Instead of harping on the idea, why not take the concept and use different chemicals instead? I know extremely little about chemistry in general. But after reading these posts I think we have a few PhDs in our presence but with no imagination. The idea I presented was just a spark of the possiblity of obtaining high pressure with very little chemical mass.

What I was eluding to was doing something simular if the first cases wasn't possible. Instead of thinking of what can't be done how about what can be done.

I heard a sang that went something like this. "If the people that say 'it will never work' or 'it can't be done' use their energy towards actually doing something other than wasting breath then greater things may come."

[Miscue]

I'd like to see a combustion paintball gun.

[Lifted047]

Now I'm only in High School, but I've been told that Hydrogen Peroxide breaks down into Water and Hydrogen after a period of time (Edit-Looked up, H202=Chem. Makeup). So if you were going to do this, you would have to watch out what kind of catalyst you use and what happens with the Water Molecule, I don't know if you still follow. The Peroxide would break down, if this theory stand and the H20 would bond with something, so you would either be using H20 as a propellent, or have a good quantity of it left in your tank. The left over O2 (Oxygen) Molecule left over might, and I don't know about this yet, could create some kind of chemical reaction, explosively, depending on the catalyst you use. If there are any doctors in the house, could you help with this? I'm going to look for a reaction that might produce a stable gas in the next few days.

[Jack_Dubious]

Doc,
Looking it up i found that....the Germans in thier rocket motors (Walter rocket motors) they used a mixture of T-Stoff(which is %80 Hydrogen Peroxide with phosphate), and a catalyst. The catalyst used originally was Z-Stoff, potassium permanganate. But it was later replaced with C-Stoff, methyl alcohol and some hydrazine hydrate.
You are right tho...you get any of this stuff on your skin, you would be definately calling in sick to work the next day. :P


JDub

[Movieboy007]

I definitely know my chem and bio and the reaction can go as such

The Hydrogen peroxide can be mixed with a rather cheap enzyme called Catalase commonly found in liver. This enzyme actually also exists in your blood, which is why hydrogen peroxide can bubble when it mixes with your blood. The Hydrogen Peroxide (H2O2) then breaks into two parts, Oxygen Gas (O2) and Water (H2O).

The Actual equation, for those of you who can understand is as follows:

2H202 + Catalase-> O2 + 2H2O

Using what we chemists call stoichiometry, we can analyze this equation. The Hydrogen peroxide and Oxygen are in a 2:1 molar production ratio. So, say we begin with 17 g or .5 mol of Hydrogen Peroxide we will yield .25 mol of Oxygen or 5.6 L (at standard temp and pressure) or 8 g of oxygen. So on a mass basis we get a 17:8 ratio in an ideal world. The world however is not at all ideal.

Essentially, the production of oxygen from hydrogen peroxide is probably not a very efficient method of production. Electrolysis of water would be far more efficient and cost effective, however, could never be done on a paintball field. In addition, the volatility of oxygen and the threat of explosion limits its productivity on the field. Helium would be much more stable (its boiling point is extremely low, somewhere around 85 Kelvin which is around -185 Celsius or about -300 degrees celsius (damn cold))and it is the most stable element on earth. All in all, Oxygen BAD, Helium GREAT, Nitrogen GOOD.

[Hamster Huey]

HMTD (not HTMD) is a very sensitive explosive that is used in blasting caps or as a detonator. H2O2 is one of the reagents that can be used to make it. If you try to cook it up at home, I can only assume that you're either very very stupid or...well, I guess that's it.

A 17:8 mass ratio isn't all that bad. As mentioned, 17g of H2O2 will generate 5.6L of gas. This corresponds to upwards of a 400-fold increase in volume. Not as good as flash-boiling CO2 (about 500-fold volume expansion), but nothing to sneeze at, either.

CHK6 - I've been trying to think of what other gases we could evolve to use as propellants, but frankly, I can't think of any good ones. Either the gases themselves are flammable/caustic/poisonous, or the reagents required are expensive/flammable/caustic/poisonous. Anyone else have any ideas?

[Redkey]

If you really must reinvent the wheel...

Liquid Nitrogen will expand at a 700 to 1 ratio. It's liquid temperature is -325 F and is stored in self venting 22 psi tanks to prevent rupture.

I made a little test fixture with a valve and a gauge on it to see how quickly it would build pressure when contained. Using a small amount < 3 CC of LN2 in a 0.5 inch diameter hole that was about 3 inches deep produced 700 psi in about 2 seconds. This was a very very crude experiment... done more to see how difficult this would be than to actually get something useful out of it.


Or... if you really want to get way out there... use airbag inflater charges. They are very very fast, create lots of gas and are incredibly expensive to buy.

[Pand0ra]

In my opinion there's really only two ways to go. The use of hydrogen peroxide, or anything like that is simply not possible in paintball. Way too dangerous, and 90% of the time toxic.

We could improve the way we use the CO2, by using heat exchangers or heaters to get rid of the liquid.
Helium and nitrogen in a liquid state are for me a bit too hard to handle on a field, and request the use of dewars to keep them liquid. They're also more expensives than CO2.
The advantages we could get with those two gazes are low compared to the drawbacks.

The other solution is to use higher pressures in our botles. It could be interesting to do some calculations to find which is the optimum pressure to get the smalest tank possible with the current materials available.

@++