Campbell Scientific CS725 Snow Water Equivalency Sensor - Manual (Page 9)

CS725 Snow Water Equivalency Sensor
1. Introduction
The CS725 sensor is primarily designed to measure the SWE (Snow Water
Equivalency) in a snow pack.
The CS725 obtains a measurement by passively monitoring the attenuation of
naturally existing electromagnetic radiation, due to the presence of potassium
and thallium. As snow accumulates on top of the ground, the CS725 measures
a decrease in the normal background radiation levels. The higher the water
content, the higher the attenuation of the radiation.
The CS725 has several characteristics that make it an excellent sensor for SWE
measurement applications.
• The sensor is non-contact. It is installed simply by mounting it above the
snow surface.
• The measurement is passive.
• Its performance is not affected by adverse weather conditions.
• The sensor’s measurement covers a large surface area. Typically 50 to
100 m 2 (538 to 1076 ft 2 ) when mounted 3.0 m above the ground.
• It is effective with any type of snow or ice.
Proper operation of the CS725 is dependent on suitable amounts of potassium
(K) and thallium (Tl) being present in the ground. Since the radiation levels
will vary from site to site, the CS725’s performance can also be site specific.*
*No special licenses or precautions are required to install or operate the CS725.
2. Specifications
Power Requirements: 11 to 15 Vdc
Power Consumption: 180 mA
Measurement Time: Continuous, 24 hours/day
Output Format: RS-232 (1200 to 115200 bps)
Default is 9600 bps
Measurement Range: 0 to 600 mm (0 to 23.6 in) of water equivalency
Accuracy: ±15 mm (±0.6 in) for 0 to 300 mm (0 to 11.8 in)
±15% at 300 to 600 mm (11.8 to 23.6 in)
Resolution: 1 mm (0.004 in)
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