Overfill prevention device for storage tanks

摘要

An overfill prevention device for storage tanks includes an elongate tubular housing having a liquid flow passageway. A normally open main valve and a normally closed vapor retaining bleed valve are associated with the fluid passageway. Closure of the main valve interrupts the primary flow of liquid through the passageway and closure of the bleed valve prevents any further liquid from entering the tank and also prevents the escape of vapors from the tank. Operation of the main valve is controlled in significant part by a valve latch assembly which is carried by the housing and a relatch assembly which is carried by the main valve. The relatch assembly ensures operative engagement of the main valve with the valve latch assembly upon movement of the main valve from the intermediate position to the open position. Operation of the main valve and vapor retaining bleed valve is also controlled indirectly by a plurality of floats which are maintained in a float chamber extending adjacent the liquid passageway. Deflecting fins are also provided in the fluid passageway for preventing damage to the main valve when an elongate measuring member such as a gauge pole is inserted into the tank for measuring the level of liquid therein.