Apologies for blurry images! Part of a kitchen gas safety system that we put in. The new system consisted of two CO2 sensors mounted at the same level of the extract canopy above the gas cookers, and monitored the CO2 concentration during kitchen use. This system was an update on the older one, as rather than just shutting off the gas when the extract fans failed, it has a bypass button on the panel, which keeps the gas on, so the chefs can finish off lunch, dinner, etc. The CO2 sensors will shut off the gas when a critical level of CO2 is reached. All connections were numbered and connected up to a wiring diagram, linking the gas valve, fire alarm panel, emergency stops and CO2 sensors. Wish I'd taken more pictures now, as it was done before Christmas!