Gas alarm panels are installed to give visual or audible and visual indication of a depleted gas supply. Panels can be installed at any point in a gas distribution system, as long as they can be connected to an appropriate signalling device. These devices include, but are not limited to, pre-set and adjustable contact gauges and pressure switches, depending upon the application. The use of an intrinsically safe barrier on units operating in hazardous areas is recommended. Gas alarm panels are available in a single or two channel versions. The single channel alarm panel is most suitable for manual manifolds while the two channel panel can be used with semi-automatic manifolds, where the status of both sides can be easily monitored.