SM150T User Manual 1.0
Technical Reference
33
Technical Reference
Specifications
Volumetric water content
Accuracy
3.0% vol over 0 to 70% vol and 0-60 °C
Measurement range
0 to 100% vol with reduced accuracy
6
Salinity error (see p.34)
5% vol over 100 to 1000 mS.m
-1
and 0-60% vol
Output Signal
0-1
V differential ≈ 0 to 60%
vol nominal
Output compatible with
GP1, GP2, DL6, DL2e, HH2, HH150
Temperature
SM150T must be fully buried to accurately
measure soil temperature
Sensor accuracy
0.5 °C over 0-40 °C
not including logger or cabling error
Output
Resistance:
7
5.8
kΩ to 28
kΩ
Output compatible with
GP1, GP2, DL6
8
, DL2e
Cabling error contribution
(to temperature readings)
Negligible for GP1, GP2, DL6 (any cable length)
Negligible for DL2e (with 5m cable)
9
Maximum cable length
100 m (GP1, GP2 & DL6 data loggers)
100 m (DL2e: water content measurement)
25 m (DL2e: temperature measurement)
Power requirement
5-14 VDC, 1 8mA for 0.5 to 1 s
Operating range
-20 to +60 °C
Environment
IP68
Sample volume
55 x 70 mm diameter
Dimensions
143 x 40 mm diameter
Weight
77 gm (without cable)
6 In water (no soil present) the reading may not be 100% vol. It depends on a0 and a1 but can still be
used as a quick check that the unit is working. See page 24.
7 See Appendix 2 on page 49.
8 Note: The DL6 has only one temperature channel. The DL6 error contribution to SM150T temperature
measurement is negligible compared to the accuracy of the SM150T temperature sensor itself. The two
only become comparable below -15C.
9 DL2e logger users can apply a correction in the Ls2Win logging software (for cable lengths >5m)
