Fluid-proportioning device for adding a predetermined proportion of a soluble substance to a fluid in a conduit

Claim 1

In a fluid-proportioning device for proportionally feeding a liquid-dissolved substance into liquid that flows through a conduit, and for counteracting excessive feed of such substance after a period of zero flow rate, by a liquid bypass system around a flow-restricting passageway in the conduit, the improvement which comprises, in combination: a tank in said liquid bypass system for storing the soluble substance; a bellows coaxially positioned in said tank and largely filling it, said bellows having one end connected to said inlet and an opposite end including at least one opening, said opposite end being formed as a stop plate resting on said substance in said tank; intake means connecting said bellows and said conduit upstream of said passageway; outlet means connecting said tank and said conduit downstream of said passageway; a ball check valve and a valve seat for the same, interposed on said outlet means between said tank and said passageway; a pressure-sensitive diaphragm having a spring-biased projection thereon to urge said ball check valve out of said seat; a first walled chamber, housing said diaphragm; a second walled chamber superposed on said first chamber and having a common wall therewith, said common wall having an opening therethrough, and a diaphragm in said second chamber located substantially parallel to said diaphragm in said first chamber and attached to opposite walls of said second chamber, said second chamber being connected to said intake and outlet means for shifting, through the diaphragm in said first chamber, such ball check valve to effect said proportional feeding; and spring means resiliently supporting said ball check valve to bias the pressure-sensitive diaphragm in the first chamber to fully close the ball check valve when such flow rate falls to zero.