The RPX Probe is a measurement head for GasFinder3-DC analyzers that provides a path average concentration in the 0.5m active measurement path (ambient atmosphere). The RPX Probe can be used with the GasFinder3-DC in Hazardous Area: Class 1, Zone 1, IIC (Groups A,B,C,D).The analyzer can be mounted locally or remotely up-to a maximum of 100m cable length. Fiber optic cable carries the laser light from the GasFinder3-DC to the remotely mounted stack/duct probe (Transceiver). The active measurement path is formed by the laser light passing through the stack/duct and being returned by a retroreflector mounted on the opposite side of the duct. The laser light is then collected on a photodiode and the signal is carried back to the analyzer via CAT6 cable.