单选题Fires in escaping flammable gas are quickly brought under control by（）A stopping the flow of gasB reducing the chemical chain reactionC increasing the oxygen supplyD cooling below the autoignition point

An inert gas system on a tanker should be used to ______.

A.prevent the generation of flammable or combustible gas in tanks

B.blow out cargo lines to prevent the build up of gas concentrations

C.dilute tank atmospheres to keep gas concentrations below the lower explosive limit

D.prevent fires in the pumproom by continually displacing flammable vapors

If you have a liquefied flammable gas barge in tow，which is NOT required of you with respect to the barge and its cargo ________．

A.Make periodic inspections of bilges

B.Keep the barge under constant surveillance

C.Have a properly certificated tankerman or at least one licensed officer on board the towing vessel

D.Verify ullage readings

Any open flame can’t exist in this business building

A.Yes. We’ve removed all the flammable gas.

B.Yes. We’ve searched everywhere for flammable liquid

C.Yes. All the flammable liquid and gas have been removed already.

D.Yes. We’ve removed all the liquid, gas and wood which can be burned

A fire of escaping liquefied flammable gas is best extinguished by ______.

A.cooling the gas below the ignition point

B.cutting off the supply of oxygen

C.stopping the flow of gas

D.interrupting the chain reaction

The use of portable electrical equipment in the pumproom on tank barges is prohibited unless ______．

A.The pumproom is gas-free

B.Spaces with bulkheads common to the pumproom are either gas-free，inert，filled with water，or contain grade E liquid

C.All other compartments in which flammable vapors and gases may exist are closed and secured

D.All of the above

How does an inert gas system on a tanker function to prevent explosions in cargo tanks?

A.De-energizes the "charged mist" effect

B.Maintains a positive pressure on the vent header to cool the flammable vapors

C.Inert gas filters out the flammable vapors from the cargo tank spaces

D.Inert gas dilutes the flammable vapor and air concentrations to keep them below the lower explosive limit

You are testing a tank that contained gasoline by using a combustible gas indicator．Under testing，the tank sample caused the needle to move rapidly to 100 on the dial then fall to zero．What is the concentration of flammable gas ________．

A.Less than the flammable range

B.Within the flammable range

C.Over the flammable range

D.The explosimeter is defective and giving a false reading

A、sometimes

B、some time

C、some times

D、sometime

The most frequent cause of fires aboard tankers is due to ______．

A.Improper gas freeing

B.Leaking of cargo pump glands

C.Tobacco smoking

D.Spontaneous combustion

A flame screen ______.

A.permits the passage of vapor but not of flame

B.prevents the passage of flammable vapor

C.prevents inert gas from leaving a tank

D.permits vapors to exit but not enter a tank