EML ARG100 User Manual - page 6
UM-780-400-SBS Manual – V2.00
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2.Introduction
The ARG100 is EML’s recommended solution for professional water industry applications such as
water authorities and companies. It is EML’s longest serving product which has been used on
thousands of professional standard weather stations.
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 the 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. Although the ARG100 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 where possible. 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 (
www.emltd.net
).
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.
WARNING! Remove packing piece! 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 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.
Levelling the rain gauge
The ARG100 can be mounted directly on to any flat surface, and securely fastened as desired, for
example by using three rawbolts to a paving slab. However, it is recommended that the rain gauge is
mounted to the RGB1 baseplate, which can then be mounted to any flat surface. This makes levelling
of the rain gauge easier. The two methods are now described.