Supported sensors

Sap Flow Tool can perform sap flow calculations on data from sensors based on four measurement principles:

  • HRM (Heat Ratio Method) sensors
    • SVP (Sap Velocity Probe): 1st generation ICT International HRM sensor
    • HRM-SFM (HRM Sap Flow Meter): Latest generation ICT International HRM sensor

  • HFD (Heat Field Deformation) sensors
    • HFD (Heat Field Deformation): 1st generation ICT International HFD sensor
    • HFD-SFM (HFD Sap Flow Meter): Latest generation ICT International HFD sensor

  • TDP (Thermal Dissipation Probe) sensors

  • Dynamax Dynagage (Heat Balance) sensors

Sap Flow Tool is also able to import and visualise data from any other sensor or measurement device (even non-ICT International data).

SFM sensor


The Heat Ratio Method (HRM) is a modification of the Compensation Heat Pulse Method (CHPM). The HRM improves on the CHPM by allowing very slow flow rates and even reverse sap flow to be measured. This allows water flows to be monitored in stems and roots of a wide range of different species, sizes and environmental conditions, including drought.

Developed by the University of Western Australia and partner organisations, ICRAF and CSIRO, the HRM sensor has been validated against gravimetric measurements of transpiration and used in published sapflow research since 1998. Burgess, S.S.O., 2001 "An improved heat pulse method to measure low and reverse rates of sapflow in woody plants", Tree Physiology 21, 589-598.

For more detailed information click here.

HFD sensor


The Heat Field Deformation (HFD) technique is ideally suited to sapflow research projects that require the measurement of extended radial sapflow profiles to accurately map hydraulic architecture of trees.

Similar to the HRM sap flow sensor the HFD sensor can measure high sapflow rates as well as low to zero and reverse sapflow. Hence as both sensors can measure in the same range the HFD sensor provides an extension of the HRM method making both sensors highly complimentary to each other in most sapflow measurement applications.

For more detailed information click here.

TDP sensor


The Thermal Dissipation Probe (TDP) directly measures sap velocity which can be converted to volumetric flow rate given an accurate measurement of sapwood area for the tree. TDP is an uncomplicated and inexpensive method ideally suited to whole plant transpiration measurements on large diameter trees.

The principle of measurement was developed by Dr. Andre Granier of INRA in France and has been widely adopted by the plant science research community since 1996.

For more detailed information click here.

Dynagage sensor

Dynagage heat balance method

The Dynagage sap flow sensors are designed for measuring the sap flow, and thus the water consumption of plants. These energy balance sensors measure the amount of heat carried by the sap which is converted into Real-Time sap flow in grams or kilograms per hour. The sensors are non-intrusive and not harmful since the plants are heated up 1°C to 5°C typically.

The principles of heat balance sensors are scientifically proven and references exist for most major crops and many tree species. Unlike other methods, Dynagages require no calibration since sap flux is directly determined by the energy balance and rates of heat convection by the sap flow.

This technology is an affordable and practical way to measure the water use by plants of agricultural, economic and ecological importance. Plants in greenhouses, nurseries or natural environments can be measured with the same ease. Dynamax introduced the first sap flow sensor prototypes in 1988 and today offers a full range of sensors from 2mm up to 125mm.

For more detailed information click here.

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