The KAL-D series combines the features of our legendary KAL-K thermal flow switch with a compact size. The KAL-D uses the calorimetric principle to monitor the flowrate of non-viscous water-based liquids. The sensor tip is heated to a few degrees above the liquid temperature. As the liquid flows across the tip, it is cooled by the liquid. The amount of cooling is proportional to liquid velocity. The liquid velocity is compared to the setpoint which is field-adjustable by the user. A transistor switch is activated when the flow setpoint is reached. The KAL-D series has a smooth measuring probe with no moving parts making it exceptionally reliable and insensitive to dirt and solids. The insertion type probe allows for flow monitoring with minimal system pressure loss.