Patent ID: 8448824

Claim:
A flow metering device comprising: a housing including a cavity; an input conduit in fluid communication with the cavity; an output conduit in fluid communication with the cavity; a chamber which is in fluid communication with the cavity and which includes a compressible member comprising an elastomeric membrane configured to store energy; and an actuation shaft disposed in the cavity,the actuation shaft including at least one moveable seal defining at least one flow space within the cavity and configured such that when the actuation shaft is disposed in a charging position the input conduit is in fluid communication with the chamber through a flow space, when the actuation shaft is disposed in a dispense position the chamber is in fluid communication with the output conduit through a flow space and the input conduit is never in fluid communication with the output conduit, and wherein the elastomeric membrane is disposed over the chamber and is configured to distend into the chamber as flow material enters the chamber.