CMC - Certified Marine Chemist Atmospheric Hazard Testing Questions and Answers

Question 1

According to OSHA and general safety practices for marine confined space entry, what is the correct sequence for atmospheric testing?

Accepted Answer

Oxygen, Flammable Gases, Toxic Gases

Answer

Flammable Gases, Oxygen, Toxic Gases

Answer

Toxic Gases, Oxygen, Flammable Gases

Answer

Oxygen, Toxic Gases, Flammable Gases

Question 2

A Marine Chemist tests a cargo tank that previously held gasoline. The combustible gas indicator reads 100% of the Lower Explosive Limit (LEL). What does this reading signify?

Accepted Answer

The gas concentration has reached the minimum level required to be explosive.

Answer

The atmosphere is at its richest concentration to support combustion.

Answer

The tank is safe for hot work as the gas level is at its upper limit.

Answer

The tank atmosphere is inert and cannot support combustion.

Question 3

A Marine Chemist is called to certify a space for hot work. The initial oxygen reading is 23.5%. Which of the following is the most appropriate immediate action?

Accepted Answer

Identify and eliminate the source of the oxygen enrichment before proceeding.

Answer

Certify the space as 'Safe for Hot Work' as there is ample oxygen.

Answer

Begin ventilating the space with nitrogen to lower the oxygen level.

Answer

Proceed with testing for flammable and toxic gases immediately.

Question 4

Which of the following spaces would specifically require certification by a Certified Marine Chemist (CMC), rather than a Shipyard Competent Person (SCP), before hot work can commence?

Accepted Answer

A fuel tank that has been emptied and cleaned for repairs.

Answer

A dry cargo hold that has been confirmed empty and clean.

Answer

A freshly painted but well-ventilated ballast tank.

Answer

A newly fabricated, un-coated vessel module.

Question 5

A Marine Chemist is evaluating a space where workers may be exposed to hydrogen sulfide (H2S). The OSHA Permissible Exposure Limit (PEL) for H2S is a ceiling of 20 ppm. The Time-Weighted Average (TWA) is not the primary limit. What does a 'ceiling limit' mean for worker exposure?

Accepted Answer

This concentration must never be exceeded, even for an instant.

Answer

The average exposure over a 15-minute period cannot exceed this limit.

Answer

The average exposure over an 8-hour shift must remain below this value.

Answer

Workers can be exposed to this level for up to 30 minutes per workday.

Question 6

When testing a deep or stratified atmosphere within a permit-required confined space, what is the OSHA-recommended practice for positioning the sampling probe?

Accepted Answer

Test at approximately 4-foot intervals in the direction of travel and to each side.

Answer

Test only at the top, middle, and bottom of the space.

Answer

Take one sample from the geometric center of the space.

Answer

Place the probe at the lowest point of the space where heavy gases might settle.