Alternatives in propellant

[Lifted047]

Hydrogen Peroxide

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.

@++