How should low-flow protection be specified for industrial heating elements?

Low-flow protection for industrial heating elements should be set from the real heat-transfer duty, not the nameplate. Calculate the minimum flow and resulting watt density if the pump fails, then set the trip point, often 30–50% of rated flow, allowing for sensor lag. The interlock must cut the heating circuit directly, with the sensor on a stable, air-free straight run. Ask the supplier for the logic diagram and measured trip value; verify by simulating flow loss, checking shutdown time, reset mode, and that sheath, watt density, and temperature control match the application.