A blowout preventer (BOP) (pronounced B-O-P) is a specialized or similar mechanical device, used to seal, control and monitor and gas wells to prevent , the uncontrolled release of crude oil or natural gas from a well. They are usually installed in stacks of other valves. The earliest blowout preventers; Regan Type K Annulars were used, beginnin.
[pdf] The closing time of annular BOP preventers The main disadvantage of the annular preventer in a drilling rig is the time required to close it. The annular preventer takes three to ten times the fluid volum.
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