According to example configurations herein, a fluid sample flow including particulate matter passes through a conduit. One or more optical sensors monitor optical energy scattering off of the particulate matter in the fluid sample flow as it passes through the conduit. A magnitude of the optical energy sensed by the one or more optical sensors varies depending on particulate matter present in the fluid sample flow. An analyzer monitors the magnitude of the optical energy sensed by the one or more optical sensors and detects changes in the optical energy. A change in the optical energy can indicate a change in the particulate matter present in the fluid sample flow. In response to detecting the change in the optical energy, the analyzer initiates one or more functions such as recalibration, purging, execution of diagnostics, etc.