CAE AND THE NEW STANDARD UNI 11452:2012

Standard UNI 11452:2012, which is part of national legislation since july 2012, specifies metrological requirements for instruments measuring intensity of liquid precipitation to the ground and defines a parameter based on the evaluation of measurement accuracy to classify such instruments.

In addition to the characteristics of equipment, for the catching rain gauges only - as the CAE one is - are furthermore described procedures for laboratory and on ground calibration tests.

This standard, which represents the first national reference for the definition of catching rain gauges performance, is the result of the experience gained by the Air Force Meteorological Service and the University of Genoa during the activity carried out for the World Meteorological Organization (WMO).

CAE has always taken care of the accuracy and reliability of its own equipment and made its PMB25 catching rain gauges available from the beginning to the University of Genoa for the experimentation.

The Company, in addition to the historical theme of accumulated rainfall, turned its attention to the rainfall intensity for the first time during the Intercomparison organized by the WMO in Vigna di Valle in 2009. On that occasion the CAE rain gauge was rated as the most accurate of its category both in the field and in the laboratory tests, with outstanding results especially when combined with the short response time of the instrument.

Starting from that experience and from the need to create something more than simple guidelines to classify measuring instruments and rainfall intensity, the new standard UNI 11452:2012 was created. As said, it goes further and also defines, for catching rain gauges only, procedures and equipment for their certification.

The standard UNI 11452:2012 identifies for the rainfall equipment a class based on the specific performances of accuracy, which are expressed in terms of maximum error committed in a minute compared to a precipitation sample generator and of the criterion of containment of the impulse response within that time interval.

There are 3 categories identified – A, B, C – depending on a maximum permissible level (MPE) and on the time of the impulse response.

CAE rain gauges are classified under the A category, where maximum errors in measurement of the reference intensity at 1-minute scale are equal or less than ± 3%.

The “Hydrometry Working Group” - which CAE participates in - within the “UNI-CEI General metrology Commission” has also integrated and defined the characteristics of equipment which calibration tests had to be carried out with.

CAE, in order to carry out and certify an effective and proper calibration of its rain gauges in accordance with the standard, has produced a first-of-its-kind automatic machine for the calibration that fully reflects what is specified by the UNI EN ISO 10012:2004.

This machine allows CAE to attach a calibration certificate in each rain gauge placed on the market with the consequent certainty for the Customer that he is buying a product of high quality and reliability. 

One more time CAE shows up as a company able to anticipate the needs of the market.