User Manual SPA Snow Pack Analyser
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3. Installation
3.1. Measurement site
A representative measurement site is horizontal and is not located in a basin or on a ridge. It is free of
influences from trees or rocks and is not exposed to intensive winds. An undisturbed accumulation of the
snow pack has to be guaranteed.
3.2. Framework
Fig. 4: SPA framework Fig. 5: Connection construction with foot
First the basement framework is placed on the ground. It is delivered separated in two parts each with
about two 3 m long beams connected with cross-beams. The side with the two round cross-beams is for
the installation of the mast and the fixation of the suspension, the side with the rectangle cross-beam is
used for fixing the sensors. The inner L-shaped cross-beam can be located at three position, depending
on the installation height of the sloping sensor of 1.5, 2 or 2.5 m.
The two parts of the framework are connected with a connection construction consisting of a u-profile,
screws and a foot. It is important to install the framework with an initial tension to resist the forces of the
spanned sensors. This is achieved by connecting the two parts of the framework in a small angle, support
it with the foot and fix it with the screws. The height of the foot should be at least 10 cm.
After the installation of the basement the mast is installed on the inner cross-beam. The mast holds the
snow depth sensor, the rolls for the sloping SPA-sensor and the housing for the measurement and
communication devices. It is recommended to install the snow depth sensor before erecting the mast. The
mast is supported with two steel wires to be spanned to the near edges of the basement.
3.3. Snow depth sensor
The snow sensor is an ultra sonic sensors using transit time measurement. It is installed on the top of the
mast using the extension arm. The installation height has to be 1 m above the expected maximal snow
depth. The extension arm should be orientated on one side of the framework to guarantee a snow
measurement free of influences. Ensure that the area of the snow depth measurement is free of
constructions, sensors or cables and that it will be undisturbed during the complete winter season. Use
barrier tapes to prevent accidental entering of the area.
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