A movable seal for interfacing between a first surface and a second surface includes a floating portion attached to a non-floating portion by a flexible coupling portion, wherein the non-floating portion is coupled to the first surface by nesting in a groove on the first surface, and wherein the non-floating portion forms a seal between the first and second surfaces when the first surface moves relative to the second surface in a first direction, and wherein the non-floating portion does not form a seal between the first and second surfaces when the first surface moves relative to the second surface in a second opposite direction.

A movable seal for interfacing between a first surface and a second surface includes a floating portion attached to a non-floating portion by a flexible coupling portion, wherein the non-floating portion is coupled to the first surface by nesting in a groove on the first surface, and wherein the non-floating portion forms a seal between the first and second surfaces when the first surface moves relative to the second surface in a first direction, and wherein the non-floating portion does not form a seal between the first and second surfaces when the first surface moves relative to the second surface in a second opposite direction.

In one aspect, a modular filter assembly for filtering fluid that flows in a flow direction therethrough is disclosed. The assembly includes a first housing section having a first filter element; a second housing section having a second filter element; and a connector disposed between the first and second housing sections. A housing includes the first housing section, the connector, and the second housing section. The flow direction is through the first and second filter elements in series.

A movable seal for interfacing between a first surface and a second surface includes a floating portion attached to a non-floating portion by a flexible coupling portion, wherein the non-floating portion is coupled to the first surface by nesting in a groove on the first surface, and wherein the non-floating portion forms a seal between the first and second surfaces when the first surface moves relative to the second surface in a first direction, and wherein the non-floating portion does not form a seal between the first and second surfaces when the first surface moves relative to the second surface in a second opposite direction.

A movable seal for interfacing between a first surface and a second surface includes a floating portion attached to a non-floating portion by a flexible coupling portion, wherein the non-floating portion is coupled to the first surface by nesting in a groove on the first surface, and wherein the non-floating portion forms a seal between the first and second surfaces when the first surface moves relative to the second surface in a first direction, and wherein the non-floating portion does not form a seal between the first and second surfaces when the first surface moves relative to the second surface in a second opposite direction.

A movable seal for interfacing between a first surface and a second surface includes a floating portion attached to a non-floating portion by a flexible coupling portion, wherein the non-floating portion is coupled to the first surface by nesting in a groove on the first surface, and wherein the non-floating portion forms a seal between the first and second surfaces when the first surface moves relative to the second surface in a first direction, and wherein the non-floating portion does not form a seal between the first and second surfaces when the first surface moves relative to the second surface in a second opposite direction.