Campbell Scientific CS705 Tipping Bucket Snowfall Adapter - Manual (Page 11)

CS705 Snowfall Adapter
11. Fasten the catch tube of the CS705 to the mounting pole using the band
clamps and storage mount (see FIGURE 4-1).
12. Connect the hose to the 0.5 inch stub at the base of the funnel (see
FIGURE 4-1).
13. Place the pail below the rain gage and place the other end of the hose in it.
5. Overview
The CS705 is manufactured by Campbell Scientific and is based on the paper
“Measuring Winter Precipitation with an Antifreeze-Based Tipping Bucket
System” presented at the 1996 Western Snow Conference (McCaughey and
Farnes, 1996). The design possesses inherent delays and is not suitable for real
time precipitation measurements. Three design factors contribute to
measurement delays:
• air / antifreeze mixture temperature
• surface tension in the overflow tube
• precipitation form
All precipitation falling into the catch tube eventually flows through the overflow
tube and is measured by the tipping bucket gage. A delay of minutes is expected
for liquid precipitation so long as a minimum volume of water (≈0.03 inches) is
reached. A delay of several hours (up to tens) is expected for snow. Lightest
density snow at very cold temperatures has the longest delay.
The CS705 converts the TE525WS Texas Electronic Rain Gage, into a year-
round precipitation gage. The CS705 is intended for use only during winter.
Like any sensor, optimum performance is obtained by regular site visits. Any
antifreeze-based precipitation gage orifice is susceptible to capping or snow
bridging.
The CS705 is coated with a smooth black coating to minimize
surface adhesion and maximize solar loading, but snow bridging
may still not occur. NOTE
5.1 Antifreeze
Campbell Scientific recommends a 1:1 mixture of propylene glycol and ethanol
(PGE). PGE is available from Campbell Scientific in a package of four, one-
gallon containers. Antifreeze can only be shipped in multiples of four gallons
via UPS Ground and cannot be shipped outside of the continental United
States.
5.1.1 Standard Car or RV Antifreeze is NOT Recommended
Standard car or RV antifreeze consists of propylene glycol or ethylene glycol,
which have a specific gravity >1. This allows a layer of water to sit on top of
the antifreeze that may freeze and form an ice cap that prevents snowfall from
being dissolved into the solution. Mixing the antifreeze with ethanol solves the
specific gravity issue and prevents the ice cap. PGE is also more
environmentally friendly.
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