Campbell CS650, Instruction Manual

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CS650 and CS655 Water Content Reflectometers
8
TABLE 6-2. Relative Dielectric Permittivity Specifications
CS650 CS655
Electrical Conductivity
Range Solution EC 0 to 3 dS/m 0 to 8 dS/m
Range Bulk EC 0 to 3 dS/m 0 to 8 dS/m
Accuracy†
±
(5% of r 0.05 dS/m)
Precision‡ 0.5% of bulk electrical conductivity (BEC)
Temperature
Range –50 to 70 °C
Resolution 0.001 °C
Accuracy† ±0.1 °C (for typical soil temperatures
[0 to 40 °C] when sensor body is buried in soil),
±0.5 °C for full temperature range
Precision‡
± 0.02 °C
Sensing Volume* 7800 cm 3 3600 cm 3
* Sensing Volume approximately 7.5 cm radius around each sensor rod and 4.5
cm beyond the end of the rods
†Accuracy specifications are based on laboratory measurements in a series of
solutions with dielectric permittivities ranging from 1 to 81 and solution electrical
conductivities ranging from 0 to 3 dS/m.
‡Precision describes the repeatability of a measurement. It is determined for the
CS650 by taking repeated measurements in the same material. The precision of
the CS650 is better than 0.05 % volumetric water content and 0.01 dS/m electrical
conductivity.
7. Installation
If you are programming your datalogger with
Short Cut
, skip Section 7.3 ,
Datalogger Wiring
(p. 9)
, and Section 7.4 ,
Programming
(p. 10)
.
Short Cut
does
this work for you. See Section 4 , QuickStart
(p. 1)
, for a Short Cut tutorial.
7.1 Orientation and Placement
The CS650 measures the bulk dielectric permittivity, average volumetric water
content, and bulk EC along the length of the rods, which is 30 cm for the
CS650 and 12 cm for the CS655. The sensor rods can insert vertically into the
soil surface or buried at any orientation to the surface. Install the sensor
horizontal to the surface to detect the passing of wetting fronts or other vertical
water fluxes.
The sensitive volume depends on the surrounding media. In soil, the sensitive
volume extends approximately 7.5 cm (3 in) from the rods along their length
and 4.5 cm (1.8 in) beyond the end of the rods. Consequently, if the sensor is
buried horizontally closer than 7.5 cm from the soil surface, it includes air
above the surface in its measurements and underestimates soil water content.
The thermistor used to measure temperature is in contact with one of the
stainless steel rods at the base of the epoxy sensor body. Because of the low