单选题The storage device for nitrogen-pressurized hydraulic fluid，which is used in closing the blowout preventers is called the（）.A actuatorB annulusC accumulatorD annular preventer

Before doing any work on a hydraulic system equipped with accumulators, you should

A.drain the accumulators and purge with oxygen

B.bleed off all stored energy from the accumulators completely

C.charge the accumulators to prevent system energy loss

D.pump the hydraulic fluid into the accumulators to prevent fluid loss

Hydraulic machinery failures are commonly caused by contamination of the hydraulic fluid and ______.

A.fluid friction

B.fluid turbulence

C.component misalignment

D.pressure surges

Overheating of the hydraulic fluid in an electro-hydraulic anchor windlass can result from a/an( ).

A.overload on the pump motor

B.low fluid level in the reservoir

C.low fluid viscosity around the shaft seal

D.high oil level in the sump

The storage device for nitrogen-pressurized hydraulic fluid，which is used in closing the blowout preventers is called the ______．

A.Actuator

B.Annulus

C.Accumulator

D.Annular preventer

Leakage of hydraulic fluid from around the shaft of a hydraulic motor may be caused by ______.

A.permanent loss of pump suction

B.worn shaft seals

C.high level in the oil sump

D.low motor RPM

The major cause of trouble in a mechanical-hydraulic governor is contamination of the hydraulic fluid by ______.

A.dirt

B.fuel oil

C.governor cooling water

D.fuel oil tar(焦油)

If you install a new hydraulic hose in a hydraulic system, the hose must be long enough to allow for contraction to prevent

A.failure of the hydraulic hose

B.excessive flow through the line

C.friction in other areas of the hydraulic system

D.overheating of the hydraulic fluid

A hydraulic accumulator aboard a ship is designed to ______.

A.store fluid under pressure

B.act as a fluid reservoir

C.provide overpressure relief

D.replenish fluid to a system