A principle of the rain gauge function lies in an utilisation of "tipping bucket" mechanism to get electrical pulses in dependence on a precipitation quantity. The main difference between MR2 and MR3 is variant dimension of rain gauge aperture, for MR2 is the catching area 200cm2, for MR3 500cm2.
The rain gauges are made from corrosion resistant materials. Its cylindrical casing is made from stainless steel, the funnel is made from plastic. Metal circle in the upper part of the rain gauge clips the exact surface size for the falling rain. The tipping bucket mechanism is placed inside the rain gauge body on the plastic base.
Together with the bucket there are also:
- a water level for checking the rain gauge horizontal position
- a terminal board for the cable connection,
- arresting screws for calibrating
- two openings for water outflow
- a heating system including thermostat
- three screws for adjustment of the horizontal position
The tipping bucket mechanism (movable body and immovable holder as well) is made from plastic, the bucket axis is from stainless steel wire. Above the outflow opening there is a spring attached, preventing gross mechanical impurities from entering the outflow. The spring is extended in some kind of "antenna" which vibrates and breaks the layer of impurities around the funnel outflow.
The heating is provided by thermal resistors placed under the funnel in a space near the tipping bucket on the rain gauge base. The funnel is warmed by means of heat transmission from that space. The thermal resistors provide heating also for the rain gauge outflow openings. The switching on and off of the rain gauge heating is controlled by thermostat.
The rain gauge is fixed in the 1 m height above the earth surface. The rain gauge stand consist of two circular bases, connected with an iron tube. The lower circular base is fixed with bolts to the underground basal concrete stone (weight 50 kg) The rain gauge is attached to the upper circular base. The stand surface is protected by zinc coating, top coat is in white color.