RELIEF VALVE

摘要

A relief valve comprises a cylindrical body (1) with an inlet opening including a seat into which the working end of a piston (2) abuts. A spring (6) presses the piston (2) to the seat through an adjusting nut (3) mounted to move on a thread of the internal surface of the body (1). The piston (2) is provided with radial openings (10) arranged in a single plane extending perpendicular to the axis of the stem (12) and communicating with an axial opening (11) of the stem (12). The external surface of the stopper (4) is provided with a shoulder for receiving a manual valve control key, and a drain tip (13) is fixed at the end of the stem (12). According to the second modification, a needle (14) is mounted in an axial bore of the stem (12) to form a needle-type valve with an axial bore of the piston (2). The needle (14) is provided with a threaded boss (16) engageable with the thread on the internal surface of the stem (12), said internal surface of the stem (12) is provided with longitudinal fluid passages (17), and a drain tip (13) is fixed at the end of the stem (12).