SFM1 Heat Ratio Method Sap Flow Meter
The original Heat Ratio Method tree and plant water use instrument
The SFM1 Sap Flow Meter is a self-contained logging sensor ideal for field and laboratory measurement of plant water use. Storing plant water use data at a user defined frequency on an SD card, the sensor is suitable for measuring plant water use over extended periods. Data is stored in a CSV format and accessible via Combined Instrument Software (CIS). Optional external power from a 20-volt power supply or solar panel the SFM1 to be used for continuous sap flow monitoring.
The SFM1 Sap Flow Meter utilises the Heat Ratio Method (HRM) principle that is able to measure high, low and reverse flow rates in both small woody stems & roots as well as large trees (Burgess et al., 2001). Like the Heat Field Deformation (HFD) principle, the HRM SFM1 is the only instrument that can measure zero flow and reverse sap flow rates. If you are interested in remote access to data, please check out the SFM1x – a member of ICT International’s family of IoT devices.
Developed to measure plant and tree water use, the SFM1 is a highly regarded instrument for use in the study of tree and plant water use, both for research and management purposes. Core to the success of the instrument is a methodology that has been proven in scientific publications and adopted globally for the study of tree and plant water relations.
MEASUREMENT
| Output Options | Raw Temperatures: °C Heat Pulse Velocity: cm hr-1 Sap Velocity: cm hr-1 Sap Flow: cm3 hr-1 (Litres hr-1) |
| Range | -100 to +100 cm hr-1 |
| Resolution | 0.01 cm hr-1 |
| Accuracy | 0.5 cm hr-1 |
| Measurement Duration | 120 seconds |
| Heat Pulse | User Adjustable: 20 Joules (default) approx. Equivalent to a 2.5 second heat pulse duration, auto scaling. User Adjustable: Minimum interval, 3 minutes, recommended minimum 10 minutes. |
DATA
| Computer Interface | USB |
| Data Storage | MicroSD Card |
NEEDLE DESIGN
| Needle Diameter | 1.3 mm |
| Needle Length | 35 mm |
| Measurement Positions | 2 per measurement needle |
| Measurement Spacings | 7.5 mm and 22.5 mm from the needle tip |
| Dimensions L x W X D | 170 x 80 x 35 mm |
| Weight | 400 g |
POWER
| Internal Battery Specifications | |
| Battery | 960mAh Lithium Polymer, 4.20 Volts fully charged |
| External Power Requirements | |
| Bus Power | 8-30 Volts DC, non-polarised, current draw is 190mA maximum at 17 volts per logger |
| USB Power | 5 Volts DC |
| Internal Charge Rate | |
| Bus Power | 60mA – 200mA Variable internal charge rate, maximum charge rate of 200mA active when the external voltage rises above 16 Volts DC |
| USB Power | 100mA fixed charge rate |
| Internal Power Management | |
| Fully Charged Battery | 4.20 Volts |
| Low Power Mode | 3.60 Volts – Instrument ceases to take measurements |
| Discharged Battery | 2.90 Volts – Instrument automatically switches off at and below this voltage when no external power connected. |
| Battery Life: | With a recommended power source connected, operation can be continuous.
Approximately 1.5 days with a heat pulse of 50 Joules and a measurement interval of 30 minutes – no external power present to recharge battery. |
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