Abstract: A sensor assembly having a sensor reservoir with probe for fire sprinkler and other systems to monitor and measure the internal characteristics of a pipe system wherein the sensor reservoir is directly connected to the pipe system, allowing the sensor reservoir to fill with the fluid contents of that system and to have a probe be in direct contact with the fluid contents of that system without altering the fluid flow dynamic within the piped system. The probe can transmit data to a controller and, based upon programmed criteria, interact with other devices, e.g., if the temperature probe reports a low temperature of the internal fluid characteristics, the controller can activate a heater linked to the controller so that pipes or sprinkler heads will be further resistant to freezing or other compromising conditions.