关键词: 外浮顶油罐,    , 自动通气阀,    , 通气量,    , 阀杆高度,    , 溢油

Abstract: The structural style and working principle of the external floating roof tank's automatic breather valve were briefly introduced.Fixed the analogical standard of the oil vapour space between the factory end and the floating plate when it was unrisen.The volume ofthe roof tank decides the heat affecting volume calculate the tank throughtout and the breathing area of the breather valve.According to the fluid steady flow mathematical equation,deduced the height computing formula of petroleum production flowing into the automatic breather valve.Definite the design height that the valve handle must possess when the breathing area was given.And then analyze the oil spill reasons of the established oil tanks,which may be caused by the lacking of breathing area or the design height of valve handle,and the problems must pay attention to in future design.

Key words: External floating roof tank,    , Automatic ventilation valve,    , Ventilation,    , Stem height,    , Oil spill