<p>A volume control valve in accordance with the invention is formed in a valve body which is adapted for insertion into a valve fitting. The valve body includes a valve seat insert and a valve disk. A sealing element is disposed between the valve seat insert and the valve fitting. The sealing element is carried on a supporting piece such that a first face of the sealing element is disposed on one side of the supporting piece and a second face is disposed on the other side of the supporting piece. The supporting piece is held against shoulders in the body such that the valve seat insert is prestressed by a predetermined amount by the first face. The second face is deformable against the fitting to accomodate different fitting depths.</p>
