Patent attributes
A safety mechanism (401) comprising: (i) an obstructing member (412,414) moveable between a first position where fluid flow is permitted, and a second position where fluid flow is restricted; (ii) a movement mechanism (416,418); (iii) a wireless receiver (360), optionally a transceiver, adapted to receive a wireless signal such as electromagnetic or acoustic. The movement mechanism (416,418) is operable to move the obstructing member (412,414) from one of the first and second positions to the other of the first and second positions in response to a change in the signal being received by the wireless receiver (360). The safety mechanism also has (iv) a valve (401) in a casing sub; the valve (401) being adapted to move from one of the first and second positions to the other of the first and second positions, and then back to the first of the first and second positions.
