a piston positioned inside a valve housing; the valve housing having an interior cavity, a bottom opening, and an inlet nozzle having an inlet opening and an interior wall surface; the piston comprising a flange, a neck section, a body section, and a base; the piston further comprising:

a slit comprising an upper slit section, a first lower slit section and a second lower slit section, wherein the upper slit section divides the neck section into a first piston neck section and a second piston neck section and wherein the first and second lower slit sections are formed at an angle to a longitudinal axis and divide a lower part of the neck section into an actuator, the actuator configured to push against the two lower slit sections to cause the upper slit section to open, said slit extends through at least part of the neck section below the flange so that a fluid flow path is formed between the slit and the interior wall surface of the valve housing; and

wherein the flange is in contact with the interior wall surface of the inlet nozzle to force at least a portion of the first piston neck section and the second piston neck section into contact with one another.