<p>The valve has a valve guard (2) with an unloader (22) that is arranged in a non-rotational manner relative to a valve seat (3). An annular flow passage (20) is arranged with respect to the valve seat. A cylinder-shaped lock sleeve (25) is provided with a base area with a non-circular outer contour. The unloader is provided with a central section (28) formed with an axial through-going concentric opening. The central section of the unloader is arranged on the lock sleeve for guidance and anti- rotation of the unloader.</p>
