SpudFiles

Ragnarok wrote: Let's just say that petrol, half a dozen pressurized bottles of hydrogen and fire do not mix.

Well I will just keep this in mind.

Also D_Hall's reply was hilarious.
I think I'd consider his reply as well respected as he deserves to be.
But I wouldn't go as far as telling the guy to get a new hobby. 8)

Truthfully, if you just want to watch and hear H2 and O2 go boom, slip a small plastic bag (1 quart) over your electrolysis beaker and seal it with a rubber band around the beaker. Wait until the bag loosely fills with gas and just light the plastic bag with a match... BOOM.. ok you're done... Rolling Eyes

Then proceed straightway to design yourself a proper propane cannon...

One of the more fun ways I've seen (never tried) is to put liquid soap on the top of the electrolysis machine and then hold a match to the bubbles that float up

And I don't really feel like starting with something too dangerous. Plus how much fun would it be to make a cannon or a rocket fueled purely by water. Much more impressive to talk about (even if it doesn't perform as well). Plus it's cheaper.

Deli wrote:Plus it's cheaper.

Wrong. That is only the case if you don't pay your electric bills or buy propane in little 1oz canisters... a single shot from a propane cannon takes approximately 0 propane, but separating that much water takes approximately >0 energy, if you get my point. Electrolysis is not exactly energy efficient.

Yeah, but if you crack open a hand-cranked flashlight (the ones that advertise to never need batteries) and just use muscle power, you have free H2 and O2 (well, you have to pay the water bill). Gotta be crafty when you are cheap.

Deli wrote:And I don't really feel like starting with something too dangerous. Plus how much fun would it be to make a cannon or a rocket fueled purely by water. Much more impressive to talk about (even if it doesn't perform as well). Plus it's cheaper.

It's probably best you stop talking about it this point and start studying and doing something about it. Your lack of real world experience is showing badly here.

Starman, Recombining water in the quantities I am contemplating isn't very dangerous. Maybe a bang, at worst I blow some PVC apart (which is why you do everything remotely). I know what I'm doing.

Propane, on the other hand, carries risks. A leak in a propane tank would be more dangerous than a leak in a tank holding Hydrogen and Oxygen. And it's bad for the environment.

Deli wrote:Yeah, but if you crack open a hand-cranked flashlight (the ones that advertise to never need batteries) and just use muscle power, you have free H2 and O2 (well, you have to pay the water bill). Gotta be crafty when you are cheap.

I cant believe I am even responding to another idiotic post of yours...
One of those flashlights costs as much as a tank of propane, and probably, over its entire life span will not create as many BTUs as tank of propane...

edit: OMFG would you please shut up? You know nothing on the subject and are making false statements based on your lack of knowledge. Fallacies litter the ground everywhere you go, and I am getting tired of trying to clean them up after you.

Deli wrote:Starman, Recombining water in the quantities I am contemplating isn't very dangerous. Maybe a bang, at worst I blow some PVC apart (which is why you do everything remotely). I know what I'm doing.

Propane, on the other hand, carries risks. A leak in a propane tank would be more dangerous than a leak in a tank holding Hydrogen and Oxygen. And it's bad for the environment.

And combining propane (C3H8) and O2 into CO2 and H2O in the quantities I contemplate isn't very dangerous either.

"Bad for the environment"? You really really don't want me to go down that trail...........

I've built a cannon using H2 and O2. It's a mini but it turned out to be very expensive. It would be about $120 if I didn't already have everything beforehand. I used a fuel cell on it which is much more efficient than stick two elctrodes in water and catching the bubbles that come up. Click here to see it. There I have also answered many of the questions already asked.

Propane, on the other hand, carries risks. A leak in a propane tank would be more dangerous than a leak in a tank holding Hydrogen and Oxygen. And it's bad for the environment.

Ever had one of those moments when you realised that you should have just stopped talking before you looked like a complete moron? In case you haven't guessed already, that moment ocurred somewhere early on page one of this discussion.

Propane is bad for the environment, is it? I can guarantee that you will get over 5 000 shots out of a 14oz. tank of propane in an average sized launcher, and that this will do less damage to the environment than the manufacture of a SINGLE hand cranked flashlight. And you know that plastic they're made of? It takes a hell of a lot longer to decompose than the steel that propane tanks are made of, and is unlikely to be recycled.

Also, unless you're adding some sort of odourant to your oxy/hydrogen mix, a leak in a propane tank is considerably less dangerous. Take a look at this, and superimpose it onto an image of your house to get an idea of a what a significant oxy/hydrogen mix leak could do. To give you a hint: if you were inside the house when it went off, there likely wouldn't be any evidence of a body.

Hi,

Yeah I have seen a H_2 O_2 cannon. My primary school physics teacher demonstrated it .. it was a steel can of about 1 liter with a spark plug in it, plugged with a large rubber cork.

We were pretty impressed with the BOOM, and the cork shooting down a bucket from a chair. But we were only 11-12 year old kids..

Anyway, sure it´s possible to make a cannon like that, and it´s not going to be like really dangerous high explosive .. etc. Just do it.

The most difficult is to make the fuel.. electrolysis requires quite some power to work fast, and some patience trying and failing to make the equipment (try google for it; it´s been done before).

I´d say, DON´t try acid and metal (for the hydrogen). The last time It tried, it heated and went out of control, and I was only lucky not to get hit when it blew .... (well OK I was stupid .. aluminium...)

Regards
Soren

I'm going to second DYI's post. Do you have any idea how many people on this site have made propane-powered cannons? Do you have any idea how many propane-powered grills there are in the US? And how often do you hear about one blowing up?

Propane is cheaper, easier, more predictable, and safer.

besides, i'm sure you are familiar with the hindenburg? It is proven that static electricity started the huge fire. Hydrogen is easily vulnerably to electricity. You could easily do this, i suggest you use one inch boots, electrical gloves, and cover your carpet. I don't want to read tomorrows newspaper and see a guy blew up his house. You must also have a water safety system (The gases are allowed to flow through water into a safe chamber). They used this system on mythbusters to capture farts.

I've tried messing w/ electrolysis to get a combustible fuel... had a leak in the chamber which ignited, couldn't see it burning b/c h2 burns clear basically and eventually a big fireball in my face. And that was a minimal amount of fuel. This idea is just not plausible unless you have a couple g's to spend on buying a large fuel cell and materials able to withstand the pressures. (and paying you electric bill).