The body has flanges for wall mounting. Power is supplied from an external source. The nominal supply voltage of the signaling device is 24 volts. Gas alarms have digital indication, current output in the standard 4 - 20 mA., Light and sound signaling and three control outputs of solid-state relays. The power supply, current output and control signals are connected through sealed cable glands. Gas alarms are designed to measure the concentrations of the following gases: methane, propane, hydrocarbon vapor, methanol, alcohol, formaldehyde, carbon monoxide, carbon dioxide, chlorine, hydrogen, hydrogen sulphide, hydrogen chloride, ammonia, nitrogen oxide, nitrogen dioxide, oxygen, sulfur dioxide.