Gas Appliances

devices used in residential and public buildings for food preparation, for heating water and rooms, and for artificial cooling. They use as their energy source the heat generated during the combustion of gas. Gas appliances usually consist of a gas burner and an attached gas pipe, a heat exchanger, and a device for removing the products of combustion. In addition, gas refrigerators have a cooling device and chamber.

Gas appliances are divided into household types, such as gas stoves, water heaters, and refrigerators; heating appliances; and restaurant appliances, such as restaurant gas ranges, ovens, cauldrons, and boilers. In most cases gas appliances are equipped with gas burners of the atmospheric type. Gas under a pressure of up to 500 mm of water comes out of a nozzle and draws with it into the stream 40 to 60 percent of the atmospheric air necessary for combustion. Part of the gas, supplied with “primary” air, burns in the inner cone of the flame formed on the burner. This cone is clearly outlined and is greenish blue. The rest of the gas burns in the outer cone, which has a blurred outline and is pale blue. The “secondary” air feeds the outer cone directly from the environment. A burner flame should not have yellow ends, and the inner cone should not touch the heating surfaces. In such a case the concentration of carbon monoxide in the products of combustion could increase beyond permissible limits. To eliminate yellow ends, the quantity of primary air is increased by means of an air-regulation valve.

The burner capacity of household gas appliances varies from 0.02 to 5 cu m per hr (calculations based on natural gas). A cork shutoff cock is attached to the gas pipeline before the appliance. Gas appliances are equipped with automatic devices that can cut off the gas supply when the appliance is out of order and can regulate the burner capacity according to technical requirements. Gas burners are placed in the open or in furnace chambers. When they are located in the open, the products of combustion pass into the area in which the burner is located; when furnace chambers are present, the products are drawn into chimneys.