The 600-9FS is a true mass flow switch in an unobstructed straight-through flow path. Featuring dual alarm levels and SPDT 5 A relays, the device incorporates two sensors. The first is used to measure the temperature of a fluid for temperature compensation, while the second is heated a few degrees above the fluid temperature. The technology behind the 600-9FS incorporates mass flow rate and the thermal transfer from the pipe wall to the fluid. The device includes no hot probes, which are typically inserted into the fluid during thermal dispersion. This field-adjustable unit is suitable for applications that use 0.5 to 1.5 W to achieve a wall temperature difference of approximately five to ten degrees. Engineers will find that the power required to maintain the constant temperature is proportional to the mass flow rate and it is determined in calibration. A calibration chart for each meter is standard, and special construction materials are available upon request.