The installation of carbon dioxide gas monitoring alarms cannot be underestimated. Serious thought should be put into planning for the best locations to install a device. In every instance a risk assessment is the key to safety.
The correct location of the monitor(s) must consider the potential sources of gas leaks and the location of expected human occupants in the area. In addition, local and state regulations must be understood and considered to ensure all guidelines and codes are met.
Where large areas need to be monitored, it is advised that no single monitor should cover a free air volume in excess of 80m^3, or 2,825 cubic feet. For example, assuming a 8 foot ceiling, a single monitor could cover an 18x20 square foot room. The installation of additional monitors should also be considered where the design of an area includes complex shapes, contains obstacles, has a lack of ventilation or air circulation. Note that CO2 is heavier than normal air, and will flow down stairs or collect in low lying areas. Also consider enclosed spaces within the area like storage closets, coolers, and equipment rooms.
Assuming the device is used in a totally open area, no more than 10 meters or 32 feet should be between CO2 monitoring devices. However, each installation should be considered individually to account for the particular layout and any varying or enclosed spaces within the footprint.
The above does not constitute an endorsement of the location of any CO2 monitoring device. It is merely intended to provide relevant education as to the device's operation in varying enclosed spaces.