CMC - Certified Marine Chemist Flammable and Combustible Materials Questions and Answers

Question 1

According to NFPA 30, a liquid with a closed-cup flash point at or above 100°F (37.8°C) is classified as what type of material?

Accepted Answer

Combustible Liquid

Answer

Flammable Liquid

Answer

Volatile Liquid

Answer

Inert Liquid

Question 2

A Marine Chemist is testing a tank that previously contained hexane (vapor density ≈ 3.0). If any residual vapor is present, where should the chemist expect to find the highest concentration?

Accepted Answer

Concentrated in the lower portions and sumps of the tank.

Answer

Evenly distributed throughout the tank.

Answer

Stratified in a layer near the top of the tank.

Answer

Adhering only to the vertical surfaces of the tank.

Question 3

A cargo tank containing residual flammable vapors is tested and found to be at 50% by volume (well above the UEL). A Marine Chemist advises the crew to begin ventilation to bring the tank to 0% LEL. What is the primary hazard during the initial phase of this ventilation process?

Accepted Answer

The atmosphere will pass through the explosive (flammable) range.

Answer

The oxygen level will drop to a dangerously low concentration.

Answer

The ventilation will cause a static electricity discharge.

Answer

The concentration of toxic components will increase tenfold.

Question 4

Hot work is planned for a bulkhead in a vessel's engine room. The adjacent space is a fuel oil tank that has been emptied but not cleaned. Which of the following is a valid method, per NFPA 306, for making the adjacent fuel tank safe for this hot work?

Accepted Answer

Cleaning the fuel tank until it is safe for hot work.

Answer

Securing a fire watch on the opposite side of the bulkhead.

Answer

Pressurizing the fuel tank with compressed air to prevent vapor leakage.

Answer

Testing the engine room side only for flammable vapors.

Question 5

A vessel's storeroom contains a large pile of rags soaked in linseed oil that were used for maintenance. What is the primary, unique fire hazard associated with these materials that a Marine Chemist or Competent Person should be concerned about?

Accepted Answer

Spontaneous combustion

Answer

Corrosive reaction with steel

Answer

Rapid oxygen displacement

Answer

High vapor pressure

Question 6

A Marine Chemist is testing a tank that has been inerted with nitrogen. The oxygen meter reads 5%, and the chemist attempts to use a standard catalytic combustion-type Combustible Gas Indicator (CGI) to check for flammable vapors. The CGI reads 0% LEL. Why is this LEL reading unreliable?

Accepted Answer

Catalytic combustion sensors require a minimum oxygen concentration to function correctly.

Answer

The nitrogen gas chemically neutralizes the flammable vapors.

Answer

The CGI is not calibrated for use in atmospheres containing nitrogen.

Answer

The low temperature of the nitrogen gas prevents the sensor from working.