Patent ID: 7879248

Claim:
A filter system comprising: a distribution valve operable to direct a received fluid stream to a first outlet during a first cycle and a second outlet during a second cycle; a filtering system including first and second filters and operable to: filter at least some fluid output from the first outlet of the distribution valve during the first cycle with the first filter while back-flushing the second filter; and filter at least some fluid output from the second outlet of the distribution valve during the second cycle with the second filter while back-flushing the first filter; a first valve for coupling fluid from the first outlet of the distribution valve through the first filter in a forward direction and through the second filter in a reverse direction; a second valve having an inlet for receiving fluid for controlling the reverse direction fluid flow through the second filter to control back-flushing duration, the second valve comprising: a flow conduit including the inlet and an outlet for passing reverse direction fluid flow from the second filter during back-flushing; and a float mechanism for controlling fluid flow through the flow conduit comprising a control conduit and a float disposed within the control conduit, a time for the float to travel through the control conduit in response to fluid introduced into the control conduit and reach the flow conduit and impede flow between the inlet and the outlet of the flow conduit setting a back-flushing duration, wherein the back-flushing duration is set to sufficiently back-flush the second filter and to be less than a duration of fluid flow in the forward direction through the first filter; a third valve including another float mechanism for receiving fluid for controlling reverse direction fluid flow through the first filter to control back-flushing duration during the second cycle; and a fourth valve for providing fluid to the third valve to cause the float mechanism of the third valve to impede flow through the third valve during the first cycle; a fifth valve for coupling fluid from the second outlet of the distribution valve through the second filter in a forward direction and through the first filter in a reverse direction during the second cycle; and a sixth valve for providing fluid to the flow conduit of the second valve to cause the float mechanism to impede flow through the flow conduit of the second valve during the second cycle.