Mark Controls Corporation

Donald E Carlson

A backflow preventer in a fluid conduit permits flow from the inlet to the outlet of the preventer when the inlet is pressurized and prevents reverse flow upon termination of flow through the preventer. An apertured diaphragm between the inlet and outlet closes a valve seat between the outlet and a vent passage when the inlet is relatively pressurized. A check member upstream of the diaphragm closes the diaphragm aperture if the outlet is relatively pressurized and maintains the diaphragm aperture closed upon pressurization of the inlet until after closing of the vent valve seat. A second vent communicates with the interior of the preventer and is closed by a portion of the diaphragm upon pressurization of the interior. A relief port in the chamber includes a temperature responsive element that opens the relief port once ambient temperature reaches a preselected level. The inlet includes an internally threaded sleeve within the housing that may be secured to an externally threaded fluid hydrant. The sleeve allows the preventer to be attached to a hydrant, but prevents its removal after a key in the sleeve is removed.

Frostproof backflow preventer

A hydrant for controlling the flow of water from an underground supply includes a casing connected at its lower end to the supply and its upper end to a nozzle for delivery of water from the casing. The flow of water from the supply to the casing is controlled by a main valve operated by a handle on the hydrant casing. An ejector purge apparatus drains the casing after the flow of water through the casing has been terminated by the main valve in order to prevent frost damage. The ejector purge apparatus includes a purge valve controlling flow from the supply through a conduit to a location outside of the hydrant casing. The conduit includes a flow constricting element and a port adjacent the flow constricting element that is in fluid communication with the casing. Flow through the purge valve and the flow constricting element results in venturi evacuation of the water within the casing. The purge valve is maintained in an open position for a limited time by a motion dampening dash pot after closure of the main valve to allow complete evacuation.

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Highland Park, IL, United States of America

Donald E Carlson