Hazardous Materials Otsu-4 | Special Flammables, Mixed Fuels, and Self-Heating Cases

Question 1

A plan calls for acetaldehyde to be poured into an open weighing tray in a workroom at 25°C. Its representative boiling point is 20.1°C and its flash point is −38°C. The room has an ordinary exhaust fan.

Which revision of the plan is most appropriate in light of these properties?

Accepted Answer

Avoid open handling; use a cooled, closed system and handle only the minimum quantity with explosion-protected ventilation and ignition-source control

Answer

Conclude that no liquid can exist above its boiling point and that fire precautions are unnecessary

Answer

Proceed with open weighing as long as the ordinary exhaust fan is started directly above the tray

Answer

Store the material with its cap open because a substance whose flash point is below room temperature has already burned away

Question 2

An old diethyl ether container is found on a shelf outside controlled cool, dark storage. Its opening date and stabiliser condition are unknown, and it may have contained air in the headspace for a long period. A worker proposes heating and distilling the contents for reuse.

Which initial action is most appropriate?

Accepted Answer

Isolate it from normal stock without unnecessary movement, obtain a specialist peroxide-hazard assessment under the facility procedure and SDS, and do not casually open, heat, or concentrate it

Answer

Evaporate the entire contents immediately because heating always renders peroxides harmless

Answer

Open it in direct sunlight because light stops peroxide formation

Answer

Assume every hazardous component has evaporated during storage because ether has a low boiling point

Question 3

A steam line with a surface temperature of 110°C runs near piping that contains carbon disulfide. There are no open flames or electrical sparks. Carbon disulfide has a representative autoignition temperature of 90°C.

Which assessment of the ignition hazard following a leak is most appropriate?

Accepted Answer

Because the hot surface exceeds the autoignition temperature, it can ignite the material without a spark; leak prevention, separation, and temperature control are required

Answer

A steam line cannot be an ignition source because it produces no flame, regardless of its temperature

Answer

A temperature near the boiling point of water is irrelevant to an assessment of flammable liquids

Answer

Autoignition temperature is the temperature at which a container begins to melt and is unrelated to vapour ignition

Question 4

Carbon disulfide may have entered a deep water-filled recovery tank. Its relative density to water is about 1.26, and its water solubility at 25°C is about 2.16 grams per litre.

Which investigation plan is most appropriate before recovery begins?

Accepted Answer

Because it is denser than water and not completely soluble, control ignition and exposure hazards and investigate possible accumulation at the bottom of the tank

Answer

Inspect only the water surface because every Category 4 hazardous material floats

Answer

Treat the tank as a uniformly mixed, harmless solution because any substance with some water solubility dissolves completely and instantly

Answer

Enter the tank without ventilation because a liquid with a relative density above one cannot produce flammable vapour

Question 5

A kerosene tank may contain 3% gasoline by volume. In one experimental data set, pure kerosene had a flash point of about 46°C, while the 3% gasoline mixture had a flash point of about 17°C to 18°C. The liquid is currently at 20°C.

Which handling decision is most appropriate for this mixture?

Accepted Answer

Because the liquid temperature exceeds the mixture's flash point, isolate it as contaminated fuel capable of producing flammable vapour, do not use it, and arrange proper treatment

Answer

Treat its flash point as about 46°C and use it in a kerosene heater because it is 97% kerosene

Answer

Heat it in ordinary equipment to evaporate the small gasoline fraction and restore safe kerosene

Answer

Treat it as safer than pure kerosene because mixing cancels the flammability of both materials

Question 6

Waste oil of unknown origin from several businesses is scheduled for heating in an indoor distillation unit. No flash-point check was performed at receipt, and the gas detector near the unit is past its inspection date.

Which decision is most appropriate before heating begins?

Accepted Answer

Suspend heating; establish the oil's origin, composition, and flammability, then reassess equipment compatibility, ventilation, detection, explosion protection, and ignition-source control

Answer

Assume used oil contains no volatile components and heat it without a functioning gas detector

Answer

Begin heating and open a window only if an odour appears, because advance characterisation is unnecessary

Answer

Mix all waste oils first so their properties average out and a flash-point test can be omitted

Question 7

A 30% methanol-by-volume aqueous solution is kept in an outdoor container. One data set gives this concentration a flash point of 36.3°C, and extreme heat has raised the liquid temperature to 38°C. Spark-producing maintenance is planned nearby.

Which assessment is most appropriate before authorising the hot work?

Accepted Answer

The liquid is above its flash point, so an ignition hazard remains; stop the work and apply isolation, concentration checks, and ignition-source controls

Answer

Because the solution is 70% water, it cannot form flammable vapour at any temperature

Answer

Any aqueous solution is nonflammable under the Fire Service Act regardless of its composition

Answer

Dilution with water makes the flash point infinite, so spark-producing work may begin immediately

Question 8

An alcohol burner is being used outdoors in bright daylight. Its flame is no longer visible, but the burner and fuel container remain hot, and no one can confirm that the extinguishing procedure was completed. A worker is about to add fuel.

Which response is most appropriate?

Accepted Answer

Stop refuelling, complete and verify the prescribed extinguishing procedure, allow full cooling, and refuel only under ignition-free conditions

Answer

Treat the absence of a visible flame in daylight as proof of extinction and add fuel slowly

Answer

Refuel while the burner is hot because the added fuel will vaporise more quickly and safely

Answer

Pour fuel onto the outside of the burner to test whether a flame remains

Question 9

At a business that uses vegetable oils, washed and tumble-dried towels are about to be packed tightly into a deep basket while still warm at closing time. A small amount of oil may remain in the towels.

Which measure best prevents spontaneous ignition?

Accepted Answer

Remove them immediately, spread them so heat can escape, cool and air-dry them fully, and handle oil-wiping cloths under the facility procedure, such as soaking them thoroughly in water before disposal

Answer

Stack the warm towels densely because washing guarantees that oxidative heating cannot occur

Answer

Compress and seal the warm towels in a plastic bag to exclude air

Answer

Apply additional heat before leaving so the remaining oil evaporates faster

Question 10

A warehouse proposal would place Category 4 organic-solvent containers and Category 6 oxidising-liquid containers on the same rack, with leaks from either group draining into a common spill tray. The oxidising liquid does not normally burn as a fuel itself.

Which assessment of the proposal is most appropriate?

Accepted Answer

Oxidising liquids can intensify combustion of combustibles, so the containers and spill trays should be segregated to prevent contact during a leak

Answer

The arrangement is safe because a liquid that is not a fuel cannot increase a solvent fire hazard

Answer

Sharing a spill tray makes their chemical properties identical because both materials are liquids

Answer

Category 6 liquids act as extinguishing agents and are safest when stored directly above Category 4 containers