A circular evaporation pan, 6 feet in diameter and 2 feet deep, made of unpainted galvanized iron. The pan is buried in the ground so that about 4 inches of the rim extend above the surrounding ground and the water surface is maintained at about ground level. (BPI stands for Bureau of Plant Industry, USDA, which introduced this instrument.)
BPI PAN
Meaning of BPI PAN in English
Environmental engineering English vocabulary. Английский словарь экологического инжиниринга. 2012