Just as with TDP sap flow flow sensors, heat-pulse sap flow sensors also work on a temperature-based measuring principle. A major difference, however, is that HP sap flow sensors do not require continuous heating, but only a short heat pulse of a few seconds is applied. Depending on the measurement method used, the direction-dependent propagation as well temporal dynamics of the heat pulse is then recorded and based on that flow speed and flow direction of the xylem sap flow is determined. Several measuring points along the measuring needles enable the radial sap flow profile to be recorded.
Compared to the TDP method, energy consumption of HP sap flow sensors is drastically reduced, enabling the use of this type of sap flow sensors also in battery operated low-power applications such as in the IoT field (see IoP).
We currently offer the following different versions:
- SF-HP-N3D2, with three 30 mm long sensor needles. The upper and lower measuring needles are each 6 mm away from the middle heating needle and each have two measuring points at 10 mm and 20 mm from sensor head.
- SF-HP-N3D3, with three 35 mm long sensor needles. The upper and lower measuring needles are each 6 mm away from the middle heating needle and each have three measuring points at equal distances from each other at 5 mm, 17.5 mm and 30 mm from the sensor head.
Customized needle lengths and measuring point positions (e.g. for small plant diameters) are possible on request!