Butterfly valve assembly

A butterfly valve assembly comprising:

• a butterfly element configured to control fluid flow through a main conduit;
• and
• a butterfly controller configured to control the butterfly element, comprising a first chamber for receiving fluid at a first pressure, a second chamber for receiving fluid at a second pressure, and an actuator responsive to the first pressure and the second pressure;
• and
• a relief valve arranged to regulate the first pressure in the first chamber within a predetermined pressure range, wherein the relief valve comprises an adjustment mechanism for adjusting the predetermined pressure range;
• a shut-off valve actuated by a solenoid and arranged to control the second pressure of fluid in the second chamber of the butterfly controller by switching between supplying to the second chamber of the butterfly controller (i) fluid from the main conduit downstream of butterfly element, and (ii) fluid from a source other than the main conduit downstream of the butterfly element, the shut-off valve thereby being operable to move the butterfly element to its fully closed position.