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LT-2M
LEAF TEMPERATURE
SENSOR |
Back to all Phytech's Products |
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The LT-2M sensor is designed for monitoring absolute
temperature of leaves. The sensor has a semiconductor bead thermistor equipped with
a special clamp for attaching it directly to the leaf under study.
There are two basic requirements when conducting measurements of a leaf temperature:
· Minimal effect on the leaf temperature;
· Maximal thermal contact between leaf and sensor.
The LT-2 sensor’s design generally meets both requirements. A miniature
bead thermistor has extremely fine glassy cover. It is also spring-loaded
that provides firm but gentle contact to the leaf surface. The thermal
conductance of thermistor body is small but not negligible. Because of
this conductivity, the difference between leaf and air temperatures may
cause a systematic deviation, which has been estimated as 10% of the
leaf-air temperature difference. Usually, the leaf-air temperature
difference does not exceed ± 5 °C and, therefore, the appropriate
maximal deviation may be estimated as ±0.5 °C respectively. If the
leaf-air temperature difference is known, the correction can be applied to
the result of measurement. Absolute measurements of leaf temperature can
be fruitfully used for investigating temperature gradients in plants (Fig
1) and for testing technological regimes (Fig 2).
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Fig 1. An example of diurnal monitoring of
air (red), soil (black), leaf (green) and flower bud (blue) temperatures
in greenhouse roses. Being the same during nighttime, the temperatures
dispersed after sunrise. Midday values: Air temperature - 27.5 °C; Leaf
temperature - 24.5 °C; Flower bud temperature - 31 °C; Soil temperature
– 20 °C. |
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Fig 2. The test of three alternative regimes
of cooling overhead sprinkling of greenhouse tomatoes: 15 s, 45 s and 30
s. Each test continued until the leaf-air temperature difference returned
to its initial value. Apparently, the 45-sec sprinkling produced the best
cooling effect, which continued about 25 minutes. |
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LT-2M unit includes two leaf temperature sensors and two-channel dc powered signal
conditioner with optional power adapter for unipolar power supply.
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SPECIFICATIONS:
Measurement Range: 5-50 °C typical
Instrumental accuracy: ± 0.2 °C
Stability: ± 0.5 °C over 1 year period
Leaf-Air Temperature Difference Effect: less than
+10%´(Tl-Ta), where Tl-leaf temperature, Ta - air temperature
Overall dimensions: 35 x 15 x 15 mm3
Output: 0-2 V or 4-20 mA (optional)
Supply Voltage: +15 Vdc ± 10%
Optional power adapter operates on 10 to 30 Vdc
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