The location of the detection instruments is integral to the effective operation of the fire and gas system, and yet there is no standard template against which the location of many of these devices can be determined. Fire & Gas mapping, modelling of the protected area and the likely dispersion pattern of smoke, gas, or vapour can be used to assess the effectiveness of the current system or to determine the requirements of a new system. Fire & gas mapping techniques may be used to identify the optimum position for gas detection devices based upon a modelled gas release scenario.