Fire

General principles of operation
Fire effects are potentially dangerous and difficult to film, for this reason control is imperative – the fire must not be able to spread or become too fierce in order to ensure extra takes are possible.

The most controllable and simple, and therefore preferred way of producing fire is to use gas. It is relatively clean and safe and is very controllable because it can be regulated in its flow. However, gas burns in certain ways, which may not give the effect you desire, if this is the case other fuels will have to be used; this can complicate the job.

Gas fires
The operator has one or more gas bottles with gas hoses leading to the equipment. If possible the operator will light the gas by hand, but may do it remotely with a piezo, match head or wick type igniter. Other gases may be introduced into the flame to change its colour. The equipment will stay alight until it is shut down.

Other fires
If a smokier, redder fire is required diesel is usually used, but as it is not very volatile, it is relatively hard to light, so it is usually used as a vaporised spray and often combined with gas in a ‘diesel trough’. The equipment will stay alight until it is shut down; the effect is very dirty and for exterior use only.

If you require flames to ‘stick’ to things, fuel gel mixtures are used and painted onto surfaces, for example if you need flames to shoot up a door, the door is first painted with a fuel gel, then lit with a gas burner. Different fuels give different flame colours and characteristics. This will make a ‘proper’ fire and once it is lit, it will either burn itself out, or will have to be put out.
A minimum of two technicians will attend; they will bring fire-fighting equipment.

First considerations
Before you light it be sure that you can put it out.

Decide what the effect should look like and talk it over with your supplier, he will suggest the best way of achieving the desired effect. Try to use gas if possible, but if you are unsure what you will get, ask to see tests.

Fire is a natural phenomenon that you are trying to harness to your needs and with all the will in the world it may not do what you want. Your job will be easier if you understand its physical properties.

Check with your location that they will allow the effects you require.

Special insurance may be required and the location may impose extra constraints upon the production.

If the location is unknown to the supplier, they may want to do a reccee, and the more information they are given, the better, so provide all that you can.

Budget expectations
Fire equipment is generally not too expensive to hire, but you will need at least two technicians, you may need special insurance and any extinguishers used will have to be paid for. Extra time may also be needed for preparation and rehearsals. A series of world events has had a global impact on insurance costs so charges may be dramatically higher than previously experienced.

If you use liquid fuels there may be additional cleaning costs and the use of extinguishers is more likely as is the need for masks if there are unpleasant/toxic fumes about. If water is used as a means of extinguishing the flames there will usually be an extended clean up period.

On larger jobs you may need a dedicated standby fire crew, your supplier can discuss this with you.

It is common for the technicians to wait until a crew has packed up and then scout a building fully to ensure that nothing is still smoldering. This may add an hour or more on to their shoot times.

Questions to ask
Can I see your show reel?
Can I see the equipment in operation/the effect, before the shoot?
Will you provide a risk assessment?
What is your safety procedure?
Are you happy doing these effects? They won’t do effects they are uncomfortable about.

Problems to watch out for and things to do
- If it all goes wrong, can you still put it out?
- Small things can cause big problems, so you really have to think laterally and liaise closely with your supplier.
- Some studios and facilities won’t allow propane (orange cylinder) to be used, so liaise with both supplier and facility and also check about storage of flammable gases.
- It is generally better to use experienced film suppliers for fire standby cover, who are used to the requirements and don’t disappear if there is a real fire elsewhere.
- If you are using fire in a studio, watch out for the heat build up at ceiling level and toxic fumes from anything burning – there could well be health and safety issues.
- If you are outside, rain is generally not too much of a problem, but wind really can be. Generally wind speed is lower early in the morning and later in the day, so schedule shoots for then.
- If wind blows out the flame beware of the gas build up that may occur before the supply has been shut off. Remember that propane and butane are heavy gases and so by the time you smell them there could be a lot of it around at a lower level.
- Freshly applied hairspray on models, fluffy clothing etc can catch fire very quickly, as can some synthetic cloths, freshly applied solvent glue on sets and models. The gases that these solvents produce may cause a fire to ‘jump’ across considerable distances to their source.
- Fire often looks more dramatic if you over crank the camera slightly. This works especially well with scale models, it is also often easier to shoot against black.
- Smoke alarms and sprinklers can be triggered by accident so ask if they can be safely isolated
during the shoot.
- Fire produces smoke, this may mean that you have to wait for it to clear between takes.

Know the jargon
Blow-out Emission of gas blows out the flame – can be dangerous
Bottles/cylinders Gas bottles
Butane/propane/gas Butane and propane are both types of gas – butane comes in blue bottles and propane
in orange.
Clean A clean flame is blue and emits no soot or smoke
Diesel trough Equipment for burning gas and diesel together
Dante Huge version of a flame-thrower that pumps fuel to an outlet and produces flames
similar to an oil well fire
Fire balls A sudden, short emission of ignited gas
Fish tails Equipment for making broad sheets of flame
Flame blanket A flame proof blanket used for smothering flames.
Flame forks Equipment that performs as named – flames at a window type effect
Flame-front The line where a burning object/material starts to burn. i.e. drop a match onto petrol,
the “wave of fire’ that flashes across is the flame front.
Flame projectors Pyrotechnic devices that emit a jet of fire for a few seconds
Flame thrower Fun
Flash back arrestor A safety device usually fitted to gas bottles – some equipment will not work correctly with one
Flash over The effect of a sheet of fire shooting across a ceiling or out of a room
Gas mortar A cylinder containing a gas/air mix used to project a fireball
Gels Liquid fuel based jelly
Heat haze Equipment powered by gas for that ‘desert look’
Heavy Gas is heavy and sinks to the floor/low areas
Igniters (match head) Small pyrotechnic devices used for lighting gas at a distance by push button
Lance A tube with flames coming out of the end
Leak testing (fluid) Soap and water – use to test joints
Liquid Equipment usually uses gas vapour, some run on liquid gas – the effects are usually bigger with liquid
Mix The mix of air and gas changes the flame colour
Piezo Electric ignition system
Regulator Alters gas pressure from the bottle (flame size)
Residual heat Left over heat once the fire is out – i.e. things stay hot
Smokey/Sooty A flame that is orange with black sooty smoke – makes things dirty
Straight through Valve used on a bottle without regulator or flash back arrestor
T-bars T shaped bar giving lots of small flames
Vapour The gas, not liquid from the bottle – the usual way of using propane or butane