text: The Symons Pan / Tank  is a standard instrument of the UK Met Office. It is a steel container 1.83 m (6 ft) on a side and 0.61 m (2 ft) deep, sunk into the ground with an above-ground rim of 0.076 - 0.1 m (3 - 4 in.) and is painted black internally. Its evaporation rate is lower than the Class A pan and conversion factors must be used.