Non-solvent flamethrower fuel mixes

[cyclonite4]

This is my first new thread in the big world outside of the water cooler, so I'll keep it simple.

I'm in the process of building a flamethrower (inspired by the flamethrower thread), and I've decided to build a backpack chamber from PVC pipe (metal cylinders cost more and are much heavier).

What I'm trying to brainstorm (with the help of willing members), is a fuel, or mixture of fuels, that will both perform the duties of a relliable fuel (by burning easily and consistently, to help things catch alight), and not damage the PVC chamber (by dissolving PVC or reacting with it).

I know that most alcohols are fairly safe with PVC, but the problem with using alcohols as a fuel by themselves, is that they burn much too fast. The presence of a slow burning component that doesnt attack PVC is whats needed. I was thinking that either denatured alcohol or isopropanol would (or maybe a blend) would act as the volatile component, the difference being that isopropanol is more volatile but shorter burning, and denatured alcohol burns a little bit longer. Both of them, from my observation, do nothing to PVC.

I would have posted this in the original flamethrower thread, but I thought that this thread is specifically based on fuel, rather than flamethrowers in general.

Can anyone think of any long-burning fuels that don't affect PVC, or know of any effective fuel mixes?

Any help is appreciated.

[Skean Dhu]

You could try a mix of Alcohols, kerosene and/or citronella tiki torch fluid I'm not exactly sure how reactive these are with PVC so it would be best to test it and look up information on them. There is also the option of buying a few dozen sterno cans, and emptying the contents into the PVC fuel chamber, as this is just gelled ethanol.

However I think it would be best if you invested in a metal cylinder, when it comes to improvised weaponry and explosives I think saftey is one thing you shouldn't skimp on. I under stand the weight and price issues, but I'm sure you could find a used CO2 fire extiguisher for under $40 on ebay S/H included. The integrity of a metal pressure rated cylinder would make the entire operation a lot safer.

[cyclonite4]

The PVC pipe im using can hold around 260psi. Kerosene is a petroleum derivative (a hydrocarbon) but I dont know if its has solvent properties.

If I wanted fire extinguishers, I wouldn't have to pay for them anyway ;) . Weight is the problem.

Plus, I already have the piping (100mm diameter, good pipe), so I'm saving on resources. I'd probably only be compressing the fuel to 75-100 psi so pressure holding is not a problem.

[kingspaz]

Could the tank not be lined with fibreglass, using a chemical resistant resin?

[cyclonite4]

I was thinkin PTFE would make a better liner as it is more chemically inert... and according to a source I have, insoluble in all solvents to 300 degrees celcius.

Another thing is the hose im using is also plastic.

[knowledgehungry]

Just use a PTFE hose.

[cyclonite4]

And where do I get a PTFE hose? I've looked for PTFE products within my local hardware store and all I can find is PTFE thread sealing tape, and PTFE thread sealing copound.

I was thinking of ways I could use the compound, but I've found that it doesn't dry, It's designed to act as 'liquid tape'. Maybe I could mix it with epoxy?

[knowledgehungry]

Check Ebay. I'm sure they have it.

EDIT: w00t Senior Researcher baby!

[cyclonite4]

Ah, yes. The wonder of Ebay. :d

I see your excited that your a senior researcher now, I was excited when I got promoted to bottle washer. :p

I like the sound of gelled ethanol, but where do I get it? I've tried the hardware store, camping store (which is where I thought it would be), and even the supermarket.

[Skean Dhu]

Its sold in the little chaffing dish thingies, about 3"diam x 2" high, In the US its marketed by Sterno for the most part.
Do none of your Automotive/big box hardware stores carry fuel line replacement hose?
Its going to be inert for the fuels your useing as thats what its designed to be in contact with.

[cyclonite4]

I'll check an automotive store once I find a local parts dealer.
I keep getting funny looks when I ask about Sterno or gelled fuel/ethanol.

Is fuel line hose very bulky? I have some kind of hose that belonged to a car, but I don't think it's fuel line hose because it's very wide and seems to be made of some kind of compressed foam/plastic.

[Anthony]

And where do I get a PTFE hose?

Presumably, the place that can coat your PVC fuel tank with PTFE, at an affordable price would be able to point you in the right direction?

How big does your fuel tank have to be, and why is weight such an issue?

A 1kg powder fire extinguisher weighs very little.

or are you an evil terrorist who wants to evade metal detectors?

[cyclonite4]

Nah, I'm not a terrorist (I'm only 16 and I have no real enemies), and this thing is too large to fit through a scanner or go unnoticed (plus the handheld part is metal). I'm making this for fun/curiosity.

The tank consists of 2x 100mm x 50cm class 18 PVC cylinders (31.41 L, but only filled to about under 30 L with fuel). A fire extingisher of estimately the same size is much more than a kilogram.

The place I can get PTFE compound is the hardware store, and I haven't found any PTFE hose there.

[akinrog]

What about neoprene (sp?) hoses. Neoprene hoses are used for LPG tanks. They are very resistant to oils and oxidants.

[Skean Dhu]

Noone gives you funny looks on the internet.....But in person its usually best to ask for it by the trade name instead of the IUPAC name, I mean if someone were to ask you for some "Gelled ethanol", or "ethyl hydroxide with gelatinous additives", you'd give them a funny look too. Try asking for chaffing dish refills, contact your local catering company, and they might be willing to sell you some. Or find some snobby market place with all sorts of obscure cuts of meat and weird herbs, they'll probably have them or know where you could get them. Also find an RV store, they should carry a camping stove that uses these for heating.
http://www.chaferdepot.com/
Here's what they look like http://www.sterno.com/sterno/sterno_retail/welcome.aspx
If you can't find standard automotive fuel hose, your country's in more trouble than we first thought.

PS heres some handy search tips:
Take advantage of the multitude of search engines
Find out what you are looking for is supposed to be used for
find out the trade name(s)
get a mental image of what your looking for
check stores that have even remote possibilities of carrying what your looking for, things are always in the last place you'd think to look

[cyclonite4]

And I guess it has the bonus of pressure capability... do you mean the kind of hose on propane tanks?

[streety]

I like the sound of gelled ethanol, but where do I get it? I've tried the hardware store, camping store (which is where I thought it would be), and even the supermarket.


Looking at their website they say their technology is patented so you should be able to find the formulation. It might work out cheaper making it yourself rather than buying it if you're going to be using a lot of the stuff.

Following a quick search of the US patents office the following might be of use:

Rapid-gelling biocompatible polymer composition and associated methods of preparation and use (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=/netahtml/search-adv.htm&r=6&f=G&l=50&d=PTXT&p=1&p=1&S1=(((gelled+AND+ethanol)+AND+burn)+AND+denatured)&OS=gelled+AND+ethanol+AND+burn+AND+denatured&RS=(((gelled+AND+ethanol)+AND+burn)+AND+denatured) ) 6,624,245

Freestanding plastic container for controlled combustion of alcohol-based lighter fluid (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=/netahtml/search-adv.htm&r=3&f=G&l=50&d=PTXT&p=1&p=1&S1=(((gelled+AND+ethanol)+AND+burn)+AND+denatured)&OS=gelled+AND+ethanol+AND+burn+AND+denatured&RS=(((gelled+AND+ethanol)+AND+burn)+AND+denatured) ) 6,755,877

Liquid fire starter composition (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=/netahtml/search-adv.htm&r=15&f=G&l=50&d=PTXT&p=1&p=1&S1=(((gelled+AND+ethanol)+AND+burn)+AND+denatured)&OS=gelled+AND+ethanol+AND+burn+AND+denatured&RS=(((gelled+AND+ethanol)+AND+burn)+AND+denatured) ) 5,990,057

Fuel gel for charcoal or wood fires (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=/netahtml/search-adv.htm&r=22&f=G&l=50&d=PTXT&p=1&p=1&S1=(((gelled+AND+ethanol)+AND+burn)+AND+denatured)&OS=gelled+AND+ethanol+AND+burn+AND+denatured&RS=(((gelled+AND+ethanol)+AND+burn)+AND+denatured) ) 4,436,525

Pressure dispensable gelled alcohol fuel (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=/netahtml/search-adv.htm&r=23&f=G&l=50&d=PTXT&p=1&p=1&S1=(((gelled+AND+ethanol)+AND+burn)+AND+denatured)&OS=gelled+AND+ethanol+AND+burn+AND+denatured&RS=(((gelled+AND+ethanol)+AND+burn)+AND+denatured) ) 4,365,971

Ignition method with pressure dispensable gelled fuel (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=/netahtml/search-adv.htm&r=25&f=G&l=50&d=PTXT&p=1&p=1&S1=(((gelled+AND+ethanol)+AND+burn)+AND+denatured)&OS=gelled+AND+ethanol+AND+burn+AND+denatured&RS=(((gelled+AND+ethanol)+AND+burn)+AND+denatured) ) 4,261,700

I haven't read through any of them but it's a starting point.



In light of nbk2000's subsequent post the patent no's have been included. You live and learn :)

[nbk2000]

Calcium acetate is used to gell alcohol. Read that in an old popular mechanics article.

When posting links to patents, you must always included the patent number, as the links are time-limited and expire, making them useless after a couple days. So, without the numbers, we've no way of knowing what patents you linked to.

[cyclonite4]

Thanks for all the help everyone.

I'd just thought I'd say I've made a few decisions concerning the flamethrower:
- I am going to stick to just using methylated spirits or 'sterno'
- I am using only one PVC cylinder, dropping the volume in half (I don't really want or need the extra fuel capacity, this is just a project fueled by curiosity).

I'll keep you all updated with how it goes.

[david jenkins]

Flame Throwers are pretty bad ass and old school!why P.V.C. for anything? when it comes
to a flame thrower you need the best of the best! period!!!It sounds like you're talking about something pretty small! We'll at least I hope so anyway!Flame Throwers are straight forward in design. Hydraulically, the best lines and fittings are always used.Valve design goes along way in making sure the operator doesn't get his hand soaked in flamable liquid!Tanks are typically the best available. And the system has been tested tried and true!Never the less operating a Flame Thrower is an very dangerous occupation if If it were!
Radiant heat energy is what the Flame Thrower operator has to deal with.You're basically
squirting a thick gelatinizes stream of gasoline through the air W/ minimal evap or vaporization. This increases the distance it can travel in a high velocity state through the air
giving the maximum forward effect of the flame(The notorious tongue effect)!
If you're going to make a Flame Thrower.Why don't you you make one?
I'ts all about gelled gasoline!!

[festergrump]

WOW! After having read that, David, I must go back to the drawing board and do some revamping of my designs. You certainly put us all straight. While I'm at it I might want to check out the forum rules again because obviously there have been some changes... :rolleyes:

[nbk2000]

But he has such a neat signature! :p

[Jacks Complete]

Aye, but he is at least moderately energetic with his post.
With a few return codes, it would be quite a good first post, aside from his missing the thread title saying "Non-solvent"!

Has anyone thought of spraying something solid, like a powered metal? You could blow it through with compressed air, or a high-volume, low pressure blower.

If you are just going to play around and try it (which, in the UK is a five year minimum sentence now! Asshats!) try and find a large metal syringe, of the kind vets used to use. (A large plastic one will do, actually)
Fill it full of meths, light the end, and spray it! It can't burn back, as long as you keep pushing it forward, or just stop (don't draw it back to be safe) It won't have much range, but it looks cool.

There is a water toy that uses a giant tank and a giant syringe with a valve in it, which is quite cheap. You might be able to get one and try it with meths. Just strip the lead off the tank, and drop it into the bottle. Or fill the tank!

Meths is pretty much inert when it comes to reacting with things like plastic, unless alight! You can always do a soak test by filling it and leaving overnight.

I really have to move somewhere less oppressive...

[cyclonite4]

Spraying powdered metal doesn't sound too easy to regulate, although it would produce a lot of heat. Wouldn't a given amount of metal powder when atomised, just explode (deflagrate instantaneously) rather than burn?

Maybe spraying a solid fuel such as metal powder, with a small amount of CO2 to stop instant deflagration, would work.


You are quite right david, but my first model will be built out of PVC as a 'prototype' model. A non-solvent mix would still be good for a metal version though, because the rubber pressure sealing components need to last, and not suddenly fail.