The favourable price of the sensors allows the use of quite a lot of sensors. Any Datalogger, which is able to measure µV Signals with a resolution of at least 10µV, i.e. 0.25 °C (copper-constantan-thermocouples), can be used to record the readings. UP offers a wide range of Dataloggers like Skye datahogs (1-16 channels) and the Delta-T logger type DL-2e (15 - 60 channels). For the conversion of microvolts into temperature you can use a mean value of 40µV per degree Celsius - if you do not measure the stem temperature you will have to do this anyway.

As sap velocity can vary around the circumference of a tree, more than one probe may be installed. The following list may be useful:

• 1 sensor for trunks or stems of about 70mm diameter
• 2 sensors for trunks from 125mm diameter on
• 4 sensors for trees greater than 200mm

However, for uniform trees in a closed canopy, only one probe per tree is needed.

NOTE: The sensors should be powered continuously and a typical data-collection interval of 10min is recommended - the sensors need at least 30 minutes after installation and heating to show an equilibrium. The sensors need 1 differential input at the datalogger!

Other loggers with more input-channels etc are available.

Please complete our questionnaire at our downloadpage to ask for detailed quotations.
Constant current source (ccs)

We offer a special constant current source which provides the required heating perfor-mance (120mA constant current output, temperature stabilised!). You can connect max. 3 sensors to 1 power-supply unit.

All sensors are connected in series. If you do not connect three sensors to one current supply, you have to use UP blind-connectors with a bridge installed inside.