The blind shear ram cuts through the drill pipe and seals the well, preventing oil from gushing out.

This is to prevent oil escaping into the environment.

For example, tests showed the cement was not strong enough to prevent oil and gas from escaping.

(This is important to prevent oil from bubbling up when the potatoes are dropped in.)

Further changes were made in 1990, this time to the breather system to prevent oil being drawn into the air filter.

The Saudi Government is trying to place floating booms around the islands to prevent oil from reaching the shore.

What kind of cream can I use to prevent excess oil?

Oil spill specialists said there is no practical way to prevent oil from reaching the beaches.

None of this would prevent oil from generating more heat than light in a referendum campaign, out of all proportion to its long-term relevance.

After 1990, a variety of programs were instituted to cut the chances of a spill and to prevent oil from spreading.