EML ARG100 User Manual - page 11
UM-780-400-SBS Manual – V2.00
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P a g e
6.Maintenance and Calibration
Basic Maintenance
To ensure reliable and accurate measurements it is recommended that the following checks are
carried out at each visit to the rain gauge (if the gauge is still connected to a data logger and the logger
is operating, care must be taken to avoid tipping the bucket when carrying out these checks).
1.
Inspect the funnel and filter for any damage or blockage. At certain times of the year,
particularly autumn, leaves may accumulate in the funnel, dirt and dust can also block the
filter preventing or reducing the flow rate to the buckets beneath. The leaves can easily be
removed from the funnel and the filter cleaned by removing the end cap from the filter tube,
remove the stainless-steel filter gauze carefully, clean and re-fit the filter and cap.
2.
Check that the gauge is still level. Small movements may occur over time.
3.
Remove and clean any dirt from the tipping bucket, being careful not to tip the bucket should
the rain gauge still be logging.
4.
During any occasion when the rain gauge is disconnected from the logger, it is good practice
to check the balance arm of the tipping bucket for stiffness. The easiest way to do this in the
field is to try and balance the bucket in its centre position, it should be very difficult if not
impossible to achieve this, if the bucket balances easily then examine the bucket closely for
any dirt or wear on the pivot pin and bucket tubes.
NOTE: A spares kit is available with filter, cap, and screws. Contact EML sales (
sales@emltd.net
) for
more information.
Calibration
The sensitivity of the rain gauge is accurately calibrated during the manufacturing to a nominal
0.2mm/tip using a purpose-built calibration rig supplying an adjustable constant head of water
allowing accurate calibration of the rain gauge. Each rain gauge is supplied with its own calibration
figure to three decimal places. All gauges are calibrated to a tolerance of 2% of the 0.2mm tip value.
A re-calibration and overhaul service is also offered to customers; EML recommends re-calibration
every 12 to 24 months depending on applications.
For information on how we calibrate the rain gauges see British Standards document BS 7843-1:2012
and the CIMO Guide to Meteorological Instruments and Methods of Observation (Chapter 6). These
documents describe the processes of bucket balancing, static calibration at a fixed intensity, and
dynamic calibration using variable intensities