Halon fire extinguishers are NOT effective when used on which types of fires?（）

A . Dry chemical B . Halon C . Low velocity fog D . Steam

A . a blanket of bubbles formed on the surface of the fire B . smothering C . cooling D . isolating the heat from the fuel

A . Nitrogen B . Carbon dioxide C . Sodium D . Oxyge

A . outside B . on class C fires C . in an emergency D . on class B fire

A . breaking the chain reaction B . smothering the fire C . cooling the fire D . coating the fuel with a nonflammable surface

A . shutting off the air supply B . cooling the fuel to below ignition temperature C . dispersing the fuel D . removing the source of ignitio

A . soda acid B . foam C . CO D . sand

A . at least annually B . whenever it is below its required weight C . only if the extinguisher has been used D . before every safety inspectio

A . base of the equipment B . top of the equipment C . power source D . source of the fire

A . Electrically non-conductive B . Relatively inexpensive C . Effective against chemicals containing an oxidizer D . All of the above

A . Conducts electricity B . Difficult to store C . Large volume necessary to be effective D . Ineffective in powdered metal fire

A . the heat B . the fuel C . the oxygen D . any of the above

A . soild materials such as wood or bales of fiber B . flammable liquids C . a piece of electrical equipment D . combustible metallic solid

A . cooling B . smothering C . chemical action D . All of the above

A . cooling B . chemical action C . smothering D . inerting the air

A . generators B . oil drums C . the bridge controls D . combustible metal

A . a mattress B . spilled liquids such as oil or paint C . high voltage electrical gear D . a trash ca

A . Fires in electrical equipment B . Flammable oils and greases C . Class "A" fires in ordinary combustibles D . Materials containing their own oxyge

A . cooling B . smothering C . shielding of radiant heat D . breaking the chain reactio

A . cooling B . smothering C . chemical action D . All of the above

A . at the top of the flames B . at the base of the fire near the edge C . in short quick bursts D . toward the upwind side of the fire

A . Carbon dioxide B . Water (stored pressure) C . Foam D . Carbon tetrachloride