Patent ID: 6129521
Filing Date: 2000-10-10
Classification: F04B

Abstract:
A safety valve apparatus for feeding liquid from a tank to a diaphragm pump in which a central rod to which at least one pumping diaphragm is attached is reciprocally slidable by air pressure to forcibly pump out the liquid, said safety valve apparatus comprising:a housing defining a space, a liquid balance port that is always providing communication between said space and the tank, a liquid chamber, a liquid flow-in port through which the liquid from the tank flows into said liquid chamber, and a liquid flow-out port through which the liquid from the tank flows out of said liquid chamber;a valve rod slidably disposed in said housing, said valve rod having a first end disposed in said liquid chamber and a second end disposed in said space;a valve body connected to said first end of said valve rod for opening and closing said liquid flow-in port; anda diaphragm disposed within said space and being attached between said second end of said valve rod and an inner peripheral wall of said space in order to partition said space into at least a liquid balance chamber communicating with said liquid balance port and another chamber,wherein an effective liquid pressure receiving area of said diaphragm is larger than an effective liquid pressure receiving area of said valve body, so that, when said diaphragm pump is in an inoperative condition, said valve rod slides toward said liquid chamber to close said liquid flow-in port, and, when said diaphragm pump is operated to generate negative pressure in said liquid chamber, said valve rod slides toward said liquid balance chamber to open said liquid flow-in port.