The Smoke Gun

Smoke that can be turned on and off when needed is an essential requirement for the making of television programmes. Generated in special devices known as smoke guns (although terms such as smoke machine and smoke generator are also used), they are heated either electrically or by gas.

Most of these devices employ a common principle: smoke fluid is passed through a small bore tube or restricted passage which is heated to a critical temperature. The super-heated fluid, which is pressurised, emerges from a nozzle, vaporising into white smoke.

Although this is the basic principle, there are other important features which must be incorporated in the design before any smoke gun can work efficiently and safely. Thermostats, pressure by-pass pipes and indicator lights are just some of the features.

Studio guns

Most studio smoke guns are electrically heated which means they are tethered to a mains supply. However, this is not unduly restrictive because the heat exchanger is provided with a heat retaining block which enables the gun to be disconnected and carried around for several minutes after disconnection. Usually, however, an extended mains lead is used.

Gas guns

Hand-held guns working from small camping-gas cylinders work on a similar principle, but are ignited by match or spark. They must be turned off immediately after use to protect the heat exchanger coil from burning out. This limits their use for short intermittent bursts.

Outdoor smoke machines

Again, the principle is the same, but these devices have a very large coil heated by a gas burner fed with bottled propane. Pressurisation is achieved by hand-pumping air into the fluid container.

Using the smoke gun

In the majority of cases, smoke guns are used to create foggy atmospheres or fire scenes. For these they are either set down on the studio floor and allowed to run, or picked up and carried about. Other requirements, however, demand that they be supplied with hoses to produce a point source of smoke or spreaders to direct it under a door. However, smoke fluid, when cooled, condenses back to liquid so additions to the nozzle end must be kept short. Smoke guns should never be pointed directly at any part of the body.

1. A smoke gun designed for use in TV and movie studios

Equipment for studio work must be portable and easy to handle.

2. The right equipment for the job

Large special effects departments are able to call upon a range or indoor and outdoor smoke guns.