small stem sap flow sensors

Sap Flow Sensors

Measuring sap flow in small stems, petioles, flower or fruit pedicel or peduncle is vastly challenging.

Our sap flow sensors have met this challenge.

The Phyto-Sensor SF-4M and SF-5M are the product of over 50 years of sap flow research and allow plant physiologists to measure, and monitor, sap flow on small diameter stems.

 

related products

 

Tomato TranspirationThe SF-4M model is suitable for stems, petioles, pedicels or peduncles with diameters between 1mm and 5mm.

The SF-5M model is suitable for stems, petioles, pedicels or peduncles with diameters between 4mm and 10mm.

The sensor’s probe is made as a hollow collapsible heat-insulating cylinder. A heater and a pair of bead thermistors are located inside the cylinder.

A signal conditioner provides powering of the heater and conditioning of the output signal.

The probe is connected by a standard 1-meter cable to the waterproof box with the signal conditioner inside.

The output cable length should be specified in the order if required.

The SF-4M and SF-5M are connected to the range of data loggers Edaphic Scientific support. Alternatively, we can assist you in connect the sap flow sensors to your existing data logging system. Edaphic Scientific also provides training, assistance with installation, and on-going assistance with data interpretation and analysis.

 

specifications
  • Measurement range: 0 to 100% of maximum sap flow
  • Output: SF-4/5M: 0 to 2 VDC, linear; SF-4/5Mi: 4 to 20 mA
  • Supply voltage: 10 to 30 VDC @ 400 mW max
  • Accuracy: Not specified
  • Heating power (typical): 30 mW
  • Suitable stem diameter (mm): SF-4M: 1 to 5; SF-5M: 4 to 10
  • Warm up time: 5 min
  • Overall dimensions of the sensor (mm): SF-4M: 30 × 30 × 40; SF-5M: 30 × 35 × 40
  • Cable length between probe and signal conditioner: 1 m (custom lengths available)

 

more details

sap flow diagramThe SF-4M and SF-5M sap flow sensors are a modification of the thermal dissipation method (TDM) with symmetrical allocation of temperature sensors in relation to the heater. In classical Granier TDM sensor, the upper temperature sensor is located in the heater. Therefore, the temperature difference is maximal at no flow. In our sensor, the temperature difference is zero at no flow, and it is increasing with the sap flow acceleration. Also the output signal is sensitive to the direction of the flow.

Dr Yuri Ton, and his team at Phyto Sensor Group, developed the SF-4M and SF-5M from industrial water flow measurement methods, and from sap flow sensors designed by Russian scientist V. Karmanov in 1959.

The signal from the sap flow sensors is positive, zero or negative, depending on the direction of flow. The higher the flow, the greater the output signal. With small scale lysimeters, the output signal can be calibrated to give volumetric sap flow and transpiration rates for specific plant species and organs. Alternatively, data can be analysed as a proportion of maximum sap flow. That is, maximum sap flow, or the highest output voltage signal, is 100% sap flow and all remaining data are corrected against this value.

The TDM Measurement Principle Explained

 

manual and additional information

Phyto Sensor Sap Flow Manual

Interpretation of Raw Measurements

How to measure sap flow in small stems, branches and petioles

Flowers, sap flow and transpiration