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
Under NFPA 306, what oxygen concentration range is considered 'safe' for normal entry into a marine vessel space?
Answer: 19.5%–22.0%
NFPA 306 defines a safe oxygen atmosphere as 19.5% to 22.0% by volume for normal entry.
Which document must a Certified Marine Chemist issue before hot work is permitted in or near a confined space on a vessel?
Answer: Certificate of Fitness
A Marine Chemist Certificate of Fitness (or Safe-for-Hot-Work certificate) is required before hot work begins on or near vessel spaces.
A cargo tank that previously held benzene is classified as 'Not Safe for Workers' primarily because benzene's IDLH is:
Answer: 50 ppm
NIOSH sets benzene's IDLH at 500 ppm, but OSHA's permissible exposure limit (1 ppm) and carcinogenicity mean even low concentrations preclude worker safety.
When a hazardous material spill occurs in a vessel's bilge, the FIRST action under MARPOL Annex I is to:
Answer: Transfer the mixture to a slop tank and prevent overboard discharge
MARPOL Annex I requires preventing unauthorized overboard discharge; spilled oily mixtures must be contained and transferred to a slop tank pending proper disposal.
The Lower Explosive Limit (LEL) of a flammable vapor represents the concentration at which:
Answer: The air-vapor mixture is too lean to ignite
The LEL is the minimum concentration of flammable vapor in air below which ignition cannot propagate because the mixture is too lean.
Which containment method is most appropriate for a deck spill of a water-reactive hazardous liquid on a vessel?
Answer: Apply dry absorbent material and prevent water contact
Water-reactive materials can generate toxic or flammable gases when contacted with water; dry absorbents contain the spill without triggering the reaction.
A marine chemist testing a tank finds 18% LEL for methane. This atmosphere is classified as:
Answer: Safe for workers but not hot work
NFPA 306 generally permits worker entry when flammable gas reads below 10% LEL, but readings of 10–20% LEL typically require 'Safe for Workers but Not Hot Work' designation depending on site conditions.