Hazardous Materials Management & Containment Flashcards
7 cards from real CMC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Hazardous Materials Management & Containment flashcards as text
Inerting a cargo tank to prevent flammable atmosphere buildup is achieved when the oxygen content is reduced to below:
Answer: 8%
An inert atmosphere typically requires oxygen concentration below 8% by volume to prevent ignition of hydrocarbon vapors regardless of their concentration.
During hot work near a void space adjacent to a fuel tank on a vessel, the marine chemist must verify that the bulkhead surface temperature does not exceed:
Answer: 200°F (93°C)
NFPA 306 guidance indicates that adjacent bulkheads should not exceed 200°F (93°C) to prevent heat transmission that could ignite materials on the opposite side.
Which type of fire extinguisher is CONTRAINDICATED for a Class B (flammable liquid) fire in a marine engine room?
Answer: Water jet extinguisher
A straight water jet on a flammable liquid fire can scatter burning fuel, spread the fire, and create steam explosions in hot machinery spaces.
What is the primary purpose of a 'gas-free' certificate issued by a marine chemist for a vessel tank?
Answer: To certify the atmosphere is safe for worker entry and cold work
A gas-free (or Safe-for-Workers) certificate indicates the atmosphere meets safe conditions for entry and cold work, but not necessarily hot work.
When a flammable liquid is heated above its flash point, the primary hazard that increases is:
Answer: Sufficient vapor generation to form an ignitable mixture above the liquid surface
Above the flash point, the liquid generates enough vapor to form an ignitable air-vapor mixture that can be ignited by a spark or flame.
Under MARPOL Annex II, noxious liquid substances (NLS) in Category X must be pre-washed before a vessel's slop tank can be discharged to sea. The pre-wash water must be discharged to:
Answer: A port reception facility
MARPOL Annex II Category X substances require pre-wash residues to be discharged to shore-based port reception facilities, not to sea.
A marine chemist conducting a pre-entry inspection finds a sludge residue of an unknown viscous material in a tank. The safest initial identification step is to:
Answer: Obtain cargo records, MSDS/SDS, and test representative vapor samples remotely
Consulting cargo records and SDS before physical sampling allows hazard identification without exposing personnel to unknown chemical risks.