Casella CEL Tipping bucket rain gauge - Manual (Page 5)

positioning. Both body and funnel are manufactured from aluminium alloy,
with an accurately machined septum ring with an aperture of 400 cm
2 .
(200cm 2 version is now also available)
The measurement accuracy for the various tip sizes is shown in Figure 2.
3. CONSTRUCTION
The rain gauge is manufactured entirely from non-corrosive materials. The
base and septum ring are cast in Aluminium Alloy LM25, heat treated and
protectively coated.
The outer ring and funnel are fabricated from aluminium alloy sheet and again
protectively coated.
Stainless steel mesh is employed to protect the inlet and outlet ports from
the ingress of foreign bodies.
The heater unit on heated rain gauges is operated via an adjustable thermo-
stat which controls the supply to two power resistors. The thermostat is
factory-set to switch the heater on at 3
o C to ensure that the mechanism is
kept above freezing point.
Construction
The heater requires a 24 V AC supply, which can be obtained from the
isolated and fully protected -TR26 Mains Transformer available from Casella
CEL.
A cable carries the power to the heater and returns the signal from the
“tip” switch.
Page 5 of 16
Tipping Bucket Rain Gauges
User Manual