NiCrome "hotwire" ignition for propane flame effects

I'm going to give a run-down of the nicrome ignition system (aka Juniper) that we used on 2PiR this year.

2PiR uses high velocity, high speed, computer sequenced effects. Because of these traits, it is poorly suited for more conventional pilot flames, such as the low pressure stainless steel wool style or the bernzomatic torch type. If you are making a flame effect for anything that is not high-repetition, high velocity, and terrible on pilots, please consider a different style of pilot than hotwires.

Reasons for using NiCrome:
-Can be extremely reliable
- Won't blow out: good for use in areas you can't access easily
- Can ignite extremely short bursts somewhat more reliably than "orange flame" pilots (this is a debatable point, keep in mind that we started using NiCr wires as a last resort)
- It can look really cool if done well

Reasons to not use NiCrome:
-You need between 9 and 12 amps to get it to autoignition temperature (for propane), at 120 volts, that is a whole bunch of watts. This style is not recommended for generator use.
- You will need to either get a power supply that is 12v x (effects * 15) amps if you are running the ignitors in parallel. If you run them in Series, you can run a bunch (we got 16) on one circuit, but you have the Christmas Lights problem if anything goes wrong.
- They need to be protected very well from shorting to the chassis or shocking bystanders (more on this later)
- It's way overkill for most effects
- The wires look like the inside of a toaster, and that's uncool.

Step 1 Me talking you out of using NiCrome

So if you are reading this, you have probably built a flame effect or two. If you really haven't gotten deep into ignition woes, just quit reading here and don't worry about stuff like this. Normal, dumb, steel wool and 1/2 psi propane will work amazingly well for making a yellow flame that will light just about anything.

If you are doing something for an art car or whatever, just know that from here until the finished project was (for us) around 80 man hours, 4 priority shipments from McMaster, and a whole lot of wasted money. Your mileage may vary, but using a system like this will be amazingly expensive and time consuming compared to more conventional pilots.

Comments

[gadlen]

 That is just fantastic! Thanks for sharing your experience and writing this up! You'd think it would be easier to make fire, eh?   2 pi r rox!

[Bigev]

Great Trogdor reference there.

[DrStoooopid]

I see that you've got the tanks on their side. You do realize that this could cause a potential problem, because liquid can cause a backflash. Also, propane is heavier than air, which means any escaping vapor, or leaks will hang at ground level, so if you have a stray spark, you've got yourself a problem.

[seraphus]

Those aren't our tanks. Those are our vapor accumulators. They contain no liquid (assured now, since we regulate down from tank pressure). Liquid there would be disastrous for our valve diaphrams. I'm unfamiliar with this backflash scenario, but in terms of escaping vapor, we leak test our system at all plumbing after initial setup, and check all the QR's or any other adjusted fittings before any run. We are generally running these at events where having leaking raw propane is unacceptable (as even though it is smellable at 1/100 flammable concentration, it gives the appearance of carelessness).

[DrStoooopid]

That's good to hear....carry on.

[seraphus]

What is this backflash?

[BuildAnything]

I need help igniting propane for a a stunt limo I built. I added a propane tube to the side of the limo to make it appear on fire. Can you help?

[Tetranitrate]

Some more footage from the fire arts festival:



Great project, I'm looking forward to more.

[seraphus]

quit watching the silly dancing game. :)

[ichipoodle]

Yeah!!!!!!!!!!!!!!!!!! FFFFFFFIIIIIIIIIIIIIIIIIIIIIYYYYYYYYYYYYYYAAAAAAAAAAAHHHHHHH!!!!!!!!!!!!!!!!!!!! Tetranitrate, you need to ship me everything pyro related! All hail the fire king! Lol, this instructable is cool though...

[ll.13]

Wow, totally awesome! but why Ayumi Hamasaki ??

[crapflinger]

....is the guy in the fire suit playing DDR?...that's hilarious!!

[Tetranitrate]

Dance Dance Immolation. You can see the sign for it in the third picture on the intro step.

[seraphus]

yeah, DDI is our group's sister project.

[Tetranitrate]

Oh cool, I didn't know you guys had done both of them. You should post a DDI instructable.

[seraphus]

I'd rather write my entire life story than try to document any of the eight or nine major systems of DDI. It's so terribly complex, I'd get lost just starting. Also, DDI existed two years before I got involved with this group, I've just been involved with small systems of the whole. Also, insert some cop-out about trade secrets of artists here.

[!Andrew_Modder!]

where do you get NiCrome? other than online? (home depot, etc?)

[Ben Dejo]

A toaster is a good source of NiCrome wire.

[seraphus]

used nicrome is twitchy at best. You can use old nicrome, but the stuff in toasters has really low coil density, so it isn't going to heat up as well. It is also designed for a duty cycle of about 5 minutes, and not to be immersed in flames. The idea of Nicrome is to make an elegant ignitor solution, it is expensive to do right.

[that one guy]

I disagree, unitednuclear.com has nicrome, which I used to make near 100 igniters for $3 (total, not each) I even made an instructable on my igniters, although Iv'e already come up with a cooler version (Instructable to come).
http://www.instructables.com/id/E5XKVTSF5R8MR8Y/

[seraphus]

I don't understand what you disagree with, but using nicrome to ignite a solid fuel or wick is a completely different problem from igniting high flow propane.

[!Andrew_Modder!]

where in the toaster? lol? or any other places to get it?

[allanf0]

I imagine the heating elements of toasters and all sorts of other things would be made from NiCrome

[seraphus]

Yes, they are nicrome, no they are not really up to the task of igniting anything aflame with reliability. Going to nicrome wire ignition is a step away from "cheap and easy" and towards difficult and costly, I put this instructable up here mostly as a warning as to why this is a more difficult solution than people imagined. Low pressure propane pilots are far superior in almost all applications.

[!Andrew_Modder!]

damn. someones goda send me there old toaster :-P any offers? ahh? ahh? i pay (little bit)

[killerjackalope]

something you should know is that nicrome wire is very easily replaced by small gauge constantan (another resistant wire) I recognixed this when my dad and i revived a pre-piezo ignition gas lighter that was run on a 2 solution chemical battery unfortunatley the nicrome wire was long turned to dust and i remember the resistance experiments in physic went into school got out some constantan and a bunsen followed by a transformer with croc clip terminals at 12V the wire itself could burst into flame so I made a small coil to lower the heat and found the perfect ignition coil for the lighter and the bunsen but basically using the right length of wire is all it comes down to as long as it resists creating heat

[westfw]

Is there an instructable yet on propane flame projectors in general?

[seraphus]

for liability reasons, I really don't expect to see that published. Ever.

[computer_gui]

Couldn't you just put a large disclaimer? I would be very interested to know how everything worked out, not because i have the time or money to create such a thing but just because it would be interesting to know how such a thing would work.

[seraphus]

There are so many people around here making dangerous fire equipment by not following NFPA scheduling ratings on pipe and not having safety systems, I fail to see how putting disclaimers will improve this situation. Everyone SHOULD know the fire codes when they do something like this, but people who rush build s*** in their garages poison the well for everyone, including me.

[trebuchet03]

Everyone SHOULD know the fire codes when they do something like this, but people who rush build s*** in their garages poison the well for everyone, including me.

That seems like a great instructable in itself -- just on safety and ratings. It seems, that if the well is already poisoned, people will continue to attempt garage stunts - weather you inform them or not.

[edrabbit]

nice write up! These things are great when they work, a pain when we melt through them. hehe