The Model SW100 operates on the thermal principal of flow measurement.Its electronics provide a constant wattage to the sensor, heating it above thetemperature of the fluid. Flow of the fluid causes removal of heat from thesensor, measured as a reduction in temperature. Therefore, the measure of massflow velocity is the sensor’s temperature above the fluid temperature.The ROCK utilizes an advanced Mass-Balanced sensor which causes each sensingelement to respond equally and indifferently to changes in temperature. Thisfeature eliminates the “hunting” problem inherent in three-element, unbalancedthermal flow switches.