A heavy valve or assembly of valves fitted at the top of an oil well during drilling and closed in the event of a blowout.
More example sentences
- The safety of oil drilling depends on the reliability of a blowout preventer.
- There is now an ROV in the water 24/7, keeping careful watch over the relief well's blowout preventer.
- You may have been the first person to detect a problem with that blowout preventer.