Regulations require that cargo pumps in tankers carrying grade D liquid cargo shall be isolatedfrom sources of vapor ignition by（）.

单项选择题Regulations require that cargo pumprooms on tank barges (constructed in 1965) carrying grades B or C liquid cargoes have power ventilation systems which can completely change the air in （）.

A.1 minute
B.3 minutes
C.5 minutes
D.10 minutes

单项选择题Petroleum cargo tanks should not be topped off at deck level when loading on a cold day because（）.

A.a subsequent temperature rise will cause the cargo to overflow
B.air pockets may cause the cargo to bubble out of the ullage hole
C.the increased viscosity of the product requires higher loading pressure which increases the chances of a spill
D.the tank valve may be stiff and a spill will occur before the valve can be closed

单项选择题One of the principal dangers inherent in liquefied petroleum gas is（）.

A.as it warms up it becomes heavier than air
B.the way it reacts with sea water
C.the strong odor it produces
D.its low temperature causes frostbite or freezing

单项选择题Inerting means（）.

A.the introduction of inert gas into a tank with the object of reducing the oxygen content to below 8% by volume
B.the introduction of inert gas into a gas free tank for the purpose of reducing the oxygen content to below 8% by volume
C.the introduction of inert gas into a cargo tank during cargo discharge to replace the volume of discharged cargo
D.All of the above

单项选择题In setting the valves on a steam-smothering system on a tank vessel，the master control valve to cargo tanks should be（）.

A.open and individual tank valves open
B.open and the individual tank valves closed
C.closed and the individual tank valves closed
D.closed and the individual tank valves open