Fire Effects – Safety

The Crucible is gearing up for a new event, Inferno: A Fire Circus July 15 – 16 2011. It’s going to be interesting. I’m designing the main fire effect system that’s going to be deployed around the event space. It consists of 16 poofers: 4 on stage left, 4 on stage right and 2 on each of the three walls facing the stage. There’s going to be a lot of fire.

I’m going to be posting a number of blog entries about designing and building the system. They’re not a complete how-to guide to create poofer, accumulator or propane based fire effects. They’re merely a summary of the tips and ideas I’ve gotten from people much smarter than me. If you want to make your own fire effects, consider taking a fire effects class from The Crucible.

Here’s something else to consider:

Warning: Playing with fire is dangerous. Do not try this at home.

Following the information provided in this post and other posts is dangerous.

This will burn you.

This will burn down your garage.

This will burn down your house.

This will burn down your neighbor’s house.

Consider yourself warned and don’t try this at home.

General information on safety.

Working with fire effects means that you need to be thinking about what’s going to go wrong and how you’re going to deal with it. At some point, something that you don’t expect will happen and being prepared can mean avoiding a whole world of hurt.

There’s a number of pieces of safety equipment that you should have handy. Two of the best are  a large CO2 fire extinguisher (or 2) and a wet bath towel. The CO2 fire extinguisher works well with this type of fire (class B & C) and should allow you to put out a small fire and avoid a lot of messy cleanup. If you use a dry chemical based fire extinguisher, it should also put out a small fire but there will be lots of messy chemicals to clean up afterward. For more information on various types of fire extinguishers, see the article on wikipedia.

A wet bath towel is a really effective tool to put out small class A fires. Wrapping a wet towel around something that catches fire can quickly put out the fire. Without getting deep into the process of how fire works, suffice it to say that it does this be cutting off the oxygen supply and absorbing some of the heat. If you want more of the details on why this works, I’ll encourage you to take the Fire Safety Training that’s offered at The Crucible.

Propane as a fuel makes for some fairly interesting fire effects. But there are some things that you should know about propane. Let’s start with propane being heavier than air. This means that leaking propane will sink to the floor and pool there. When enough propane is pooled on the floor, gets to the right propane / oxygen ratio to burn and it finds an ignition source, the whole pool of propane will burn. If you’re standing in the middle of it, that’s going to put a serious damper on your day.

A small spray bottle filled with soapy water makes for an excellent leak detector. Spray every plumbing connection between the propane tank and the exhaust pipe while the system is under pressure. A great and safe way to do this is to use compressed air. Got an air compressor handy? Use it to pressurize the system and then spray soapy water on all the connections. If any of them start to create bubbles, there’s a leak that needs to be fixed. Fix it before charging the system with propane. And soap testing should be done before each time the system is run.

Propane is corrosive to many types of seals and rubber so propane rated seals and rubber should be used. The hose used to connect the propane tank to the effect should be LP rated. The seals in the valves and solenoids should be compatible with propane. Materials like ptfe or teflon, buna-n or nitrile and viton.

The first connection from a CGA 510 adapter used to connect to the propane tank should be a 1/4 turn valve. This gives a very quick and easy way to shut off the fuel in the case of a problem. Instead of multiple turns of the tank’s valve, a short 1/4 turn of the handle and the fuel is shut off to the system.

The reason for using LP hose to connect to the propane tank is so that the tanks can be remote from where the poofer is located. Like 15 – 20 feet away. This way if something goes wrong with the poofer and the system needs to be shut down quickly, the 1/4 turn valve on the propane tank that’s away from the problem can be easily turned and the fuel supply is shut off.

Strap the propane tanks to something is not going to fall over, like a fence. The last thing that you want to happen is for the propane tank to fall over and for the valve to be cracked. That’ll put a lot of propane in the local area very quickly and nothing good can come from it.

Make sure people are at least 6′ away when igniting poofer. That includes the operator. Propane can burn at up to 3,614 degrees F. It’s interesting to play with, fun to watch but definitely not good to touch.

NFPA 160 is a really good starting point to understand how to safely use flame effects in front of a live audience. The local fire codes and the local fire marshal has the final say as to what’s considered safe and what’s not. Read the local fire codes. Talking with fire marshal and develop a good rapport with them. It’ll go a long way in keeping everyone safe.

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