Comparing the Hysteresis and Window Comparator Switch Output Mode

In the realm of flow switch output, there are two primary operating modes: Hysteresis and Window Comparator. We will explore their similarities and differences in this article.

Hysteresis mode operates by turning on the switch when the flow exceeds the set value and turns it off when the flow falls below the set value. For instance, if the set value is 100L/min and the hysteresis value is 10L/min, the switch will turn off when the measurement drops below 90L/min. This mode is suitable for applications that require a single set point, such as monitoring airflow purging in an ionizer to ensure it meets the specific flow rate requirement.

The switching function of hysteresis is widely favored and commonly used in flow switches. It is defined as the difference between the switch point and the reset point. Various switching variants exist, including mechanical presets by manufacturers, and electronic configurations that allow full adjustability over the measuring range using external software, configuration modules, or integrated displays with control buttons. This versatility makes hysteresis essential, as setting the switch point and reset point to the same value would lead to oscillation and system instability.

On the other hand, Window Comparator mode relies on two set values, a lower limit, and an upper limit. The switch output turns on or off depending on whether the flow falls within this range. For instance, with set values of 90L/min and 120L/min, the switch will activate if the measurement falls between 90 to 120L/min. This mode is suitable when both lower and upper limit set points are needed, such as monitoring airflow for spray painting to prevent uneven painting caused by excessive or insufficient flow rates.