As you guessed from the title, it’s time for some fire. This one takes the form of some pyrotechnics I was asked to build for a Samsung commercial a while back.
I wasn’t really given much info as far as storyboard or anything like that, just something along the lines of the following:
- Fire effects to go with a post apocalyptic scene
- No explosions
- Smoke effects
- We may get you to help with set dressing
- We have practically no budget and we need it ASAP
So not really much to go off there. I figured since explosions were out, we were probably looking more at maybe spot fires and the occasional large gas fire. Filming always means we need to be able to control it on and off over and over again and it needs to be safe. So actually lighting something on fire isn’t the best idea.
Obviously at this point I’d decided on gas fires with valve controls etc. so we can ignite it and turn it off whenever we needed to. So to do that we need the following:
- A container of gas
- Some hosing
- Some hosing connectors
- A pressure regulator
- An on/off valve
- A burner/hot end (the bit the fire comes out of)
Part 1 is real simple there. The easiest place to find a gas cylinder that is safety approved, easy to get filled and won’t raise any eyebrows is the backyard. Everyone in Australia has a BBQ of some sort and that means, more than likely, a gas cylinder.
The first problem I hit with this, is the fact that the pressure coming out of this bad boy is way to much to just jam a tap into and start cranking. So we needed a way to drop that pressure down a lot and still have some control. Again, the humble BBQ holds the answer.
That little UFO looking thing attached to the BBQ hosing is actually a regulator. But we have a problem. That’s all connected to the BBQ hosing and can’t be unscrewed without ruining the BBQ. Fortunately replacements for these can be purchased for outdoor kitchen burners etc. from your local hardware store. The great thing about that, is that’s also where you can get the rest of the required items for this build. I already had some clear tubing so it’s basically some nylon tape, a barbed hose connector, and the regulator. Obviously I didn’t want any leaks in unexpected places, so I nylon taped each thread before assembling the basic cylinder regulator valves.
Let me take a moment here to point out that using normal clear PVC tubing is not a good idea. In fact none of this really is. PVC can react to the gas and split/degrade. But it only had to last for 2 days of filming and I’d be keeping a keen eye on the whole thing as if my life depended on it. We also had the appropriate fire extinguishers and a medic on standby at all times.
So the final part of this is the burner head. I used some copper piping and the appropriate endcaps/T-pieces to make this part. Mostly because it’s easy to work with (not requiring any serious tools) and is a great heat sink. The copper comes in a roll, so you just basically unravel as much as you need and use some silver solder to join the endcaps and T-Pieces. Make sure you get the right solder otherwise you’ll find you need an oxy torch to join things. Personally, I got lazy and did it on the stove top. Yes, in a pinch you can actually braze/solder plumbing over a gas stove if you choose the right solder. If you choose the wrong solder…well…it’s like trying to melt the one ring.
Anyways, after some soldering and a wee bit of fun with the cutting disc (angle grinder), we end up with several models of “insta-fire” burners. Why the different shapes? I honestly wasn’t sure which was going to give the best effect and would cover our needs. The coil was the best in the end, but the horse shoe rigs were just as good from the right angle.
Some things to note:
- No, holes are not better than cutting slots. Gas doesn’t care for your idea of shapes. Trust me, slots is easier
- This can make a fire anywhere from camp fire to afterburner. Be careful.
- Yes, this is still a really retarded and stupid idea. Don’t do it.
- Yes, you need fire extinguishers, medics, emergency plans, a very bloody long electric igniter and emergency shut off.