Abstract: A pressure relief valve assembly is described including a valve body having a sleeve portion, a slotted portion and axial extension legs, all of which are integrally formed as one-piece by injection molding from plastic. The legs are hooked at free ends to restrain a compression spring which biases a one-piece, plastic washer into a seated position over the slotted portion. The washer is substantially planar, but with inner and outer circumferential lips, each having a rounded profile. The lips are spaced apart by a medial planar surface area. The inner and outer lips engage inner and outer surfaces, respectively, around radial slots formed in the slotted portion which act as a valve seat. The washer also includes an upwardly extending projection opposite the sealing surface which receives the spring radially inward such that the spring exerts an even force on the washer.

Abstract: A plastic relief valve assembly is provided having a one-piece valve body, with a sleeve portion and a slotted portion, and a valve. The slotted portion includes a plurality of radially disposed inlets. The valve includes an axial portion and a radial portion. The radial portion extends angularly over the radial inlets in a seated position and the axial portion extends into the valve body for quick connection therewith by a groove and rib combination provided on the valve and valve body, respectively. The radial portion of the plastic valve is flexible, and the valve opens when fluid pressure reaches a predetermined level. A plastic antidrain valve is also connected to the valve body. A fluid filter incorporating the combined plastic relief valve assembly/antidrain back valve is also provided.