UM-780-303-ARG314 Manual
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2.
Introduction
The ARG314 is
EML’s
recommended solution for many hydrological or meteorological applications
such as weather stations and flood warning systems. The ARG314 is a versatile gauge suitable for
climates with all types and intensities of rainfall. The injection moulded UV-stabilised material from
which the gauge is made means that the ARG314 is an extremely robust and versatile instrument,
ideal for applications where data precision and accuracy are critically important.
The internal tipping bucket mechanism has been designed to ensure maximum performance
repeatability.
Traditional cylinder-shaped rain gauges are inaccurate due to the effect of wind blowing over the
orifice. The physical presence of the gauge causes air to accelerate, carrying rainfall away from the
collecting vessel. The effect of this can be up to a 20% reduction in rainfall catch. The unique
aerodynamic shape of the EML range of scientific standard rain gauges reduces this effect, ensuring a
high level of confidence in the accuracy of our measurements.
3.
Site and Installation Requirements
Choosing a site
A rain gauge site is often a compromise between exposure requirements and operational constraints.
The ideal site is level ground with a uniform scattering of objects in the surrounding area thus reducing
overall wind speeds. However, these objects should not be too large to cause eddying or high gusts to
occur near to the gauge, or so close to prevent rain from entering the gauge. The gauge should ideally
be no closer than at least twice the height of the obstruction. Extensive details on rain gauge siting
best-practice can be found in Chapter 6 of the
WMO Guide to Meteorological Instruments and
Although the ARG314 rain gauge is designed to operate in higher wind
speeds, care must still be taken to avoid over-exposing the gauge where possible. Large expanses of
open flat land should be avoided. If the application is very specific, such as monitoring a building site,
then the siting of the rain gauge is largely prescribed by use. Those users who wish to enquire more
fully into rain gauge exposure are referred to the EML website for more technical information and
papers (
NOTES:
No two rain gauge designs are ever likely to produce identical results, and even two identical
rain gauges can give slightly different catches even when sited close to each other.
If the gauge is to be operated in the area of livestock then a fence will almost always be required to
prevent damage from and to the animals.
ATTENTION! Remove packing piece and fit levelling feet!
The tipping-bucket mechanism is
immobilised before shipping to prevent damage in transit. To release the mechanism for use, remove
the funnel assembly from its base by loosening/removing the three screws and then lifting the funnel.
Remove the piece of foam from under the bucket mechanism. This foam may be saved and used
whenever the rain gauge is transported. The ARG314 is supplied fully assembled except for the three
levelling feet, which need to be fitted to the gauge. There should be a locking nut above and below
the gauge base, and the feet should be positioned below, as in Figure 2.
