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 solution for field and laboratory measurement of plant water use in ecophysiological experiments. 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.
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.
- Continuous plant water use measurement (in litres), for crops and trees
- Robust sensor and standalone meter with onboard calculations of plant water use
SFM1 Heat Ratio Method Sap Flow Meter
SKU: SFM1
Categories: Ecophysiology, Plant Water Use, Sap Flow
Tags: Tree Monitoring Solutions, Urban Environmental Monitoring Solutions
Brand: ICT International
Specifications
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 | -10 to +45 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. |
Accessories

Sap Flow Meter Installation Kit (SFM-SK1)
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This product has multiple variants. The options may be chosen on the product page
