| 摘要 |
A drive valve comprises a valve body (2) having an obturator organ (5) for opening and closing gas passage in the valve, a manually-active command knob (10) for activating the obturator organ (5), and a key lock (17), mounted on the knob (10) and equipped with first blocking means (21, 22) for blocking rotation of the knob (10) and second blocking means for enabling extraction of the central barrel (19) of the lock (17) with respect to the external body (18) of the lock (17). The lock (17) is activatable by a user key (100) enabled for unblocking the first blocking means (21, 22) but not enabled for unblocking the second blocking means (27), and by an operator key (200) enabled for unblocking the first and the second blocking means (21, 22; 27) and enabled to block the second blocking means (27) in a configuration which is such as to render the user key (100) unable to unblock the first blocking means (21, 22). |
