| 摘要 |
<p>A valve body comprises a first sealing seat and a second seat opposite the first. The valve element is selectively controlled so that, in addition to the position in which a bearing surface thereof rests on the first seat to ensure tightness of the device and of the circuit on which it is mounted, the valve element can be placed in a median position between the two seats, so as to provide a maximum flowing section between the valve element and the valve body for draining the circuit. In intermediate positions, another bearing surface of the valve element works in cooperation with the second seat, the valve element being held in a position selected between the first median position and a resting position on the second seat, thus limiting the flowing section between the valve element and the second seat to control the discharge of the circuit.</p> |
