Sap Flow System
HRM Sap Flow Meter is a self contained, stand alone instrument for the measurement of sap flow or transpiration in plants.
Utilising the Heat Ratio Method (HRM) principle the Sap Flow Meter is able to measure both high and low flow rates in both small woody stems & roots as well as large trees.
Like the Heat Field Deformation (HFD) principle the HRM Sap Flow Meter is the only instrument that can measure zero flow and reverse sap flow rates. Making it the most powerful and flexible instrument for the direct measurement of plant water use.
Heat Ratio Method (HRM) is an improvement of the Compensation Heat Pulse Method (CHPM). Being a modified heat pulse technique power consumption is very low using approx 70 m Amp per day at a 10 minute temporal sampling interval under average transpiration rates.
The HRM needles have two radial measurement points for the charaterisation of radial sap flow gradients making
measurements more accurate. Through microprocessor control, the inner measurement point can be activated or deactivated dependent on the specific wood anatomy of the species being measured. This provides a great flexibility in stem diameter range from >10 mm diameter woody stems or roots to the world's largest Redwood trees.
This enables water flows to be monitored in stems and roots of a wide range of different species, sizes and environmental conditions including, drought or water stress.
Data can be manually processed using a spreadsheet such as Excel by opening the comma separated values (CSV) file provided by the Sap Flow Meter. More powerful and immediate processing can be achieved by directly importing the data file into the Sap Flow Tool Software. Thus providing instant 2 dimensional and 3D graphing of the raw heat pulse velocity and processing of sap velocity and sap flux. The entire data set can be instantly reprocessed if correction factors require modification or additional information becomes
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