SOIL MOISTURE PROBE - HMS 9000
HMS 9000 is a soil moisture sensor for the measurement of water content in soils, based on the principle of the electrical capacity measurement. This appliance developed in association with the INRA (French Institute for AGRONOMIC Research) has been studied for several years and represents currently a reference concerning measurement of soil moisture.
This device presents a very high level of integration since it contains all its electronics in the tube which constitutes it (External diameter is about 22 mm). The up to date technologies are present in this device since reliability and performances have been guidelines during this project.
HMS 9000 is open to all systems of dataloggers but can also be used alone thanks to the addition of a small reading unit (MICROTERM 4800) that will allow to exploit all HMS 9000 possibilities. By its very integrated design, HMS 9000, allows measurements from 3 cm depth to several meters. This is possible thanks to the addition of simple extension tubes.
HMS 9000 is connectable on all types of dataloggers (available on the market). Its particularly low electrical consumption allows a continuous use during several weeks without intervention.
HMS 9000 is fully programmable by the user. This programming concerns parameters of the probe as well as A and B coefficients used in the soil permittivity/soil moisture equation.
HMS 9000 is calibrated (as a permittivimeter) in our factory, thanks to a set of standard materials. The method used for this calibration has been approved by the INRA institute. This method is based on measurements conducted in alcoholic solutions whose composition and proportions are carefully identified. Calibration of HMS 9000 can be re-done at any time by the user by following the alcoholic method.
Key Advantages
HIGH PERFORMANCELIGHT
VERY ACCURATE
INRA patent
(French Research Institute in Agronomy)
TECHNICAL CHARACTERISTICS
Depth measurement : from 25 mm to several meters depth.Influence zone in the soil : Ř 25 mm
Resolution : 0,025 point of permittivity (0,1% of volumic humidity)
Accuracy : One tenth (1/10e) of water content point.
Type of measurement : dielectric permittivity of the soil (linear correlation with the water content of the soil).
Range : 0% to the value of water saturation in the soil (soil water content: Hv).
Temperature measurement : -10°C to + 54°C on independent output (4-20 mA).
Integrated soil salinity influence correction device: maxi. conductivity : about 5mS/ cm.
Power supply : from 8 V to 24 Volts.(D.C)
Number of outputs : 3
S1: 4-20 mA: soil dielectric permittivity.
S2: 4-20 mA: soil temperature.
S3: RS 232/ 5 Volts. (to MICROTERM 4800).
Driven by microprocessor
Outer diameter of the probe : 22 mm.
Length : 32 cm.
Weight : 150 grams.
Waterproof : under 2 meters of water (IP68).
Output cables Lengths :
5 meters standard (longer cable available on demand) (2 x 4-20mA).
2 meters standard for the RS 232 output.
(the 2 x 4-20mA cable is delivered nude at its end. The RS232 cable is delivered with a mini-waterproof plug (IP65).
Reading on RS 232 output (S3): by connection with the MICROTERM 4800 unit (optional).
Geometry of measure : by couple of electrodes:
Electrode 1: Ring-shaped. (influence on measurement : 2%)
Electrode 2: needle type / Ř=2mm. (influence on measurement : 98%)
The electrode n°2 is deliverable in two possible lengths.
2,4 cm (standard influence area).
6,0 cm (dilated influence area).
(Please, inform our service, before ordering because calibrations are different for short or long electrodes).
Calibration (probe & soils) : programmable type .
- Factory calibration for the probe as a permittivimeter.
- Gravimetric calibration for soils. Each user has to calibrate its soils for the HMS 9000.
Meanwhile, we propose to the operator 3 pre-calibrated curves in order to use HMS 9000 immediatly without soil calibration :
- A first curve (A&B coefficients put into the probe memory). Mean accuracy
- Two pairs of A&B coefficients suggested for sandy soil and silty-clayey soil. The accuracy will be here better. The best accuracy will be obtained by a specific soil calibration. We mean the soil where the measurement will be done (gravimetric calibration method)
 Other views  |
|
• Very high resolution (about 1600 points from 0% to 50% of Hv).
• Measurements in situ of soil water contents in agronomical field or other...
• Fine humidity measurements and that from the first centimeters of depth.
• Monitoring of soil water content at any depth.
• Hydro-dynamic characterizations of soil, hydric status, etc...
SDEC France
Z.I de la Gare
BP 27 Reignac sur Indre
37310 Tauxigny
France
Ph : +33 2 4794 1000
Fax : +33 2 4794 1713
e-mail : click here