Practice Test Geeks(CMC) Certified Marine Chemist Practice Test
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CMC Toxic Gas Detection & Monitoring Flashcards

6 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 6 CMC Toxic Gas Detection & Monitoring flashcards as text

  1. What is the ACGIH TLV-TWA for benzene?

    Answer: 1 ppm

    ACGIH has established a TLV-TWA of 0.5 ppm for benzene (carcinogen), while OSHA's PEL is 1 ppm; Marine Chemists typically reference the more protective ACGIH value.

  2. Which gas detector principle is LEAST affected by silicone contamination?

    Answer: Infrared (IR) sensor

    Infrared sensors are not poisoned by silicone compounds, making them more reliable in environments where catalytic bead sensors may be compromised.

  3. A Marine Chemist takes a gas reading in the vapor space of a cargo tank from the deck level ullage port. What limitation applies?

    Answer: Sample may not represent the entire tank atmosphere, especially near the bottom

    Single-point ullage sampling does not represent stratified or heavier-than-air gases that accumulate at lower levels; full vertical sampling is required for accurate assessment.

  4. When is bump testing of a gas detector required by best practice?

    Answer: Before each use to confirm sensor response

    Best practice and ANSI/ISA standards require bump testing (brief exposure to known gas) before each use to verify all sensors respond correctly.

  5. What hazard does elevated CO2 present in a poorly ventilated marine cargo hold, aside from toxicity?

    Answer: It displaces oxygen, creating an oxygen-deficient atmosphere

    CO2 is heavier than air and can displace oxygen in enclosed cargo holds, producing a potentially fatal oxygen-deficient atmosphere even at sub-toxic CO2 concentrations.

  6. A Marine Chemist documents a "Not Safe" certificate for a vessel tank. Who has authority to override this certificate and allow entry?

    Answer: No one — entry is prohibited until a Safe certificate is issued

    A Not Safe Marine Chemist certificate is legally binding under OSHA 1915.14 and NFPA 306; no shipboard or yard officer can authorize entry until a qualified Marine Chemist reissues a Safe certificate.