Control apparatus for a water supply system

Claim 1

A control apparatus for a water system having a motor operated pump for pumping water through a delivery line to one or more valved outlets, the control apparatus including a valve body having an inlet chamber adapted for connection to a pump and an outlet chamber adapted for connection to a delivery line of a water system and a valve seat intermediate the inlet and outlet chambers, pressure operated motor control switch means responsive to the pressure in said outlet chamber for energizing the pump motor when the pressure in the outlet chamber reaches a selected lower switch operating pressure and for de-energizing the pump motor when the pressure in the outlet chamber reaches a selected upper switch operating pressure, said valve body having a diaphragm bowl in open communication with said outlet chamber and coaxial with said valve seat and a diaphragm peripherally attached to said diaphragm bowl and extending across the bowl to define an expansion chamber therewith, a valve member in said inlet chamber cooperable with said seat for controlling flow therethrough, the valve member having a stem extending through the seat and engageable with the diaphragm for movement into and out of a seated position under the control of said diaphragm, a pneumatic pressure bell attached to said diaphragm bowl at the side opposite said expansion chamber and pneumatically charged to apply pressure to the diaphragm in opposition to the fluid pressure in the expansion chamber and such as to allow seating of the valve member when the pressure in the outlet chamber rises to a preselected value intermediate said upper and lower switch operating pressures, and bypass means for passing a restricted flow of water from the inlet chamber into the outlet chamber when the valve member is seated, the improvement comprising: a diaphragm stop plate fixed to said bell and shaped to extend closely adjacent the diaphragm when the pressure in the outlet chamber rises to said preselected value at which the valve member is seated for limiting expansive movement of the diaphragm whereby the restricted flow of water from the inlet chamber through the bypass causes the pressure in the outlet chamber to rapidly build up to said upper switch operating pressure, said valve member being movable by said diaphragm from a seated position when the diaphragm engages said diaphragm stop plate to a fully open position when the diaphragm has moved a preselected distance away from the stop plate, said diaphragm bowl being spaced from said stop plate a distance substantially greater than said preselected distance to allow continued contraction of said diaphragm chamber after the valve member has moved to its fully open position, whereby said bowl engages the diaphragm to limit contraction of the expansible chamber only after the diaphragm has displaced a selected volume of water, the volume of said pressure bell above the diaphragm stop plate being substantially larger than said volume of water displaced by said diaphragm as it moves between said stop plate and said diaphragm bowl and such that the pressure change in the outlet chamber necessary to move the diaphragm between the stop plate and diaphragm bowl is small as compared to the differential between said upper and lower switch operating pressures.