Knowing Subsurface Safety Valve- API14A

Key features of ball and
flapper valves. A ball valve
has a sphere with a hole
through it, allowing flow
through the valve when the
hole is aligned with the tubing.
Rotating the ball 90˚ places
the solid part of the ball in the
flow stream, stopping flow
(top). The more common
flapper valve works like a
hinge with a spring. When the
flow tube is down, the flapper
is open, and when it is pulled
up, the flapper closes
(bottom).
Charlie Chong/ Fion Zhang