The 0.75-in. (19-mm) diameter FR-75D heat-flow sensor (HFS) generates a dc mV signal directly proportional to the heat flux flowing through the sensor.
Sensitivity is 22 Btu/ft 2 -hr)/mV or 69 (W/m 2 )/mV over a temperature range of 22 to 300°F (30 to 150°C). Nominal impedance is 240 Ω with a heat-flux range of ±3,000 Btu/ft 2 hr (±10,000 W/m 2 ). An optional thermistor or thermocouple directly monitors temperature letting a single sensor monitor, measure, and control heat flux and temperature simultaneously. The units are targeted for studies and measurements of hypothermia, diving, protective clothing, and athletic metabolism. Other areas include general research in life sciences, thermophysiology, cutaneous heat loss, kinisiology, and anesthesiology as well as other areas.