Description
The DAB-V can be run open or closed and is actuated by annulus overpressure on a rupture disc. There is a second rupture disc with a higher pressure rating that, when burst, will return the ball to the initial position.
A latching mechanism is used to prevent the valve from accidental actuation; tubing pressure will also generate an additional positive force holding the valve in the initial position.
In an HP/HT environment an additional valve can be run above the BHA to protect the tools/samplers etc from over pressure during pressure tests.