One of the main advantages of gas, as a fuel, is its ease of control. It can be turned up or down, on or off, quickly and simply, manually or automatically. A wide range of devices has been developed and those used in domestic appliances are dealt with in this chapter. Controls may be used for a variety of purposes including:
• to provide safe cut-off in the event of hazards due to pressure failure or fire
• to give protection from the results of flame failure • to control for time, temperature or pressure • to provide safe ignition.