A referenced pressure valve for a fluid system having a housing including: an inner wall enclosing a cavity providing fluid communication between the inlet and the outlet; a rim in the cavity defining a bypass passage circumscribed outwardly by the inner wall and inwardly by the rim, an upstream passage located between an upstream end of the cavity and the rim, and a downstream passage located between the rim and a downstream end of the cavity. A rib extends outwardly from the rim to the inner wall through the bypass passage, and a piston assembly, received within a chamber circumscribed outwardly by the rim, includes a piston movable relative to the rim between a position in which the piston obstructs the flow path at the upstream passage and a position in which the piston is at least partially clear of the path to permit flow along the path.