Decagon Devices MAS-1 Manuel de l'opérateur - Page 14
Parcourez en ligne ou téléchargez le pdf Manuel de l'opérateur pour {nom_de_la_catégorie} Decagon Devices MAS-1. Decagon Devices MAS-1 18 pages. 4-20 ma soil moisture sensor
Également pour Decagon Devices MAS-1 : Manuel de l'utilisateur (20 pages)
Imprimer la page
MAS-1
5
Calibration
The current transmitted by the MAS-1 is proportional to the dielec-
tric permittivity of the medium surrounding the sensor, and therefors
the volumetric water content (VWC) of the medium. We can cal-
culate the VWC by applying a calibration equation to the current
transmitted by the MAS-1. The following are generic calibration
equations for common growth media. Applying these equations will
generally result in accuracy of
conductivity of the medium is less than 8 dS/m If you wish to use the
MAS-1 in a medium that is not listed below, if you need better than
6% accuracy, or if you are working in a high salinity material, then
you should develop a custom calibration for your particular medium.
See www.decagon.com for step by step instructions on developing a
custom calibration. Decagon can also develop a custom calibration
for your medium; contact Decagon for more details on the calibration
service.
5.1
Mineral Soils
A single calibration equation will generally result in good accuracy
for all mineral soil types with electrical conductivity < 8 dS/m. VWC
is given by
V W C = 0.00328 mA
If your data acquisition system is not capable of higher order mathe-
matical operations, the mineral soil calibration can be approximated
by the following linear model. This will result in slightly worse ac-
curacy at low VWC, with errors becoming large above 35% VWC.
5.2
Potting Soil/Peat
The following equation can be used to covert MAS-1 transmitted
current into VWC in potting soil and peat potting mixes. Please note
that different potting soil types are quite variable, so this calibration
6% VWC as long as the electrical
2
V W C = 0.0479
11
5 CALIBRATION
0.0244 mA
0.00565
mA
0.391
(3)
(4)