Casella CEL Software for the Rainfall gauge system - Manual (Page 9)

4. THE TIPPING BUCKET RAIN GAUGE
Casella Tipping Bucket Rain Gauges are reliable and extremely robust
devices. Some versions have a built-in logger to store rainfall data while
others can have a heater fitted to the base of the unit to prevent freezing.
Three main versions of tipping bucket rain gauge are available:
¤ Standard non-heated version,
¤ Standard heated version for those customers who require accurate
and reliable rainfall data under more severe weather conditions,
¤ Non-heated version constructed to meet the framework directive of
the UK Environment Agency for tipping bucket rain gauges.
This User Manual covers only non heated Tipping Bucket Rain Gauges
equipped with a built-in logger. For specific information about the other
versions, please refer to the Tipping Bucket Rain Gauge User Manual:
HB3166.
4.1 Principle Of Operation
The rain gauges comprise a light weight injection moulded plastic divided
“tipping bucket” assembly with stainless steel pivot pins that rest upon
stainless steel pins in the support assembly. The use of pins produces a
rolling rather than pivoting motion when the bucket tips, which reduces the
likelihood of friction.
Rain collects in one side of the bucket, which tips once a predetermined
volume of water has been collected. The tipping action discharges the
Figure 2: Accuracy of 0.1 mm, 2.0 mm and 0.5 mm tip versions
Tipping Bucket Rain Gauge
Accuracy / 100 Tips
0
5
10
15
20
25
1 10 100 1000
Rain fall in mm/Hr
Erro
r
P
e
r
10
0
Tips
0.1mm Tip
0.2mm Tip
0.5mm Tip
Max U.K
recorded -
Devon
Light Moderate Heavy
Classification WMO 5%
Tipping Bucket
Page 9 of 24
Rainfall Logging System -
User Manual