SR02 - Rain gauge 200cm2

Collection area 200 cm2
Pulse output after 0.2 mm of rainfall
Long-term resistance to adverse weather conditions
Low cost
SR02 / V contains internal heating for year-round operation

SR02 (/V) is a rain gauge with a catchment area of 200 cm² designed for measuring liquid (and solid) precipitation using the "split tipping shuttle" mechanism. By flipping it, pulses are generated, which must be further recorded in the connected registration unit. Each pulse represents 0.2 mm of precipitation.

Mechanical design

The rain gauge is made of quality materials that are weather-resistant for a long time. Its cylindrical shell, funnel and circle at the top, which creates a precise surface for the falling rain, are made of aluminum alloy. A spring is located above the outlet opening of the funnel, preventing the penetration of coarse dirt into the outlet.

The tilting shuttle mechanism is located on a plastic base inside the body of the rain gauge, where there is also a spirit level for checking the horizontal surface, locking screws for calibration, holes with a grid for water leakage, three adjusting screws for adjusting the horizontal surface, and terminal blocks for connecting cables.

Measurement principle

The precipitation measurement is based on the principle of counting pulses from the overturning of a divided tilting shuttle located below the funnel outlet. Rain or melted snow flows through an opening in the center of the funnel into the upper half of the divided inclined shuttle. When the upper half is filled with 4 ml of precipitation, the shuttle flips over. At the same time, water flows out of the now lower half of the shuttle and the other half of the divided shuttle is placed under the funnel outlet. The alternation of filling and tipping the shuttle continues for the entire duration of the rain.

A ferrite magnet embedded in the shuttle body closes the reed contact encapsulated in the shuttle holder each time it is flipped. The connected recording unit can calculate from the number of pulses and the delay between the pulses both the total amount of precipitation and the maximum intensity of rain and can also perform dynamic correction of the pulse weight to increase the accuracy of the measurement

Rain gauge location

It is recommended to use an S201 stainless steel stand and a concrete foundation tile to fasten the rain gauge. The stand ensures easy adjustment of the rain gauge to a horizontal position, and at the same time its high resistance to adverse weather conditions. The height of the stand is such that the collecting surface of the rain gauge (upper edge of the funnel) is located 1 m above the ground.

Heated version of the SR02/V rain gauge

The heating of this small type of rain gauge is performed by heating resistors located under the funnel on the base plate of the rain gauge. The metal funnel is heated by shared heat in the same way as the tipping shuttle tray. Separate heating resistors are also located at the outlet openings of the rain gauge. Switching the heating on and off is controlled by a thermostat located in the body of the rain gauge.

To put the heating into operation, it is necessary to connect the rain gauge to an AC voltage of 48V. A suitable source of this voltage can be ordered together with the rain gauge.

Basic technical parameters

Parameter	Value
Diameter of the collecting area	159,6 mm
Collection area	200 cm²
Sensitivity	0,2 mm/puls
Measurement accuracy	± 1% from captured precipitation at an intensity of up to 20 mm/h, ± 2% from captured precipitation at an intensity of up to 60 mm/h, ± 10% from captured precipitation at an intensity of up to 200 mm/h,
Output	pulse (switching contact, switching time type 50 mS)
Switching ability	24 V DC, 0,05 A
Weight	1,9 kg
Operating temperature	0 °C až +60 °C
Height above ground (S201)	1 m

Technical parameters of the heating section of the SR02/V rain gauge

Parameter	Value
Operating temperature	-30 °C .. +60 °C
Supply voltage for heating	42 .. 46 V AC
Heating capacity	48 .. 57 W
Switch-off temperature of the heating section	+15 °C ±3 °C