PSSR Exit Exam • Set 6 Question 14 of 30

What is the function of a self-contained breathing apparatus (SCBA) positive pressure demand valve?

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Direct Answer

Option A: Maintains positive pressure inside face mask so toxic ambient gas cannot leak inward

A self-contained breathing apparatus with a positive pressure demand valve maintains a constant pressure slightly above ambient inside the face mask. This critical safety design ensures that if any seal breaches, clean air flows outward, preventing toxic gases from leaking inward.

All Options

Maintains positive pressure inside face mask so toxic ambient gas cannot leak inward (Correct Answer)

Increases cylinder pressure automatically

Filters carbon monoxide from surrounding room air

Heats incoming breathing air to 50 degrees C

Detailed Explanation & Context

Relevant Framework: STCW 2010 Manila Amendments • DG Shipping E-Learning & Exit Exam Standards • Personal Safety & Social Responsibilities (PSSR).

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More Questions in PSSR Set 6

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Q1 What is the purpose of Risk Assessment before carrying out non-routine shipboard tasks? Q2 Under MARPOL Annex IV, what is the requirement for discharging sewage from an approved sewage treatment plant into the sea? Q3 What safety device is fitted on gas cylinders to prevent overpressure explosion in a fire? Q4 What precaution must be taken before opening steam lines or boiler blowdown valves? Q5 What color coding is universally used on ships to identify Emergency Fire Fighting Equipment locations? Q6 What precaution is required when storing oxygen and acetylene cylinders in gas welding stations? Q7 What action must a seafarer take if a piece of power machinery exhibits abnormal vibration or strange noise? Q8 Under the Maritime Labour Convention (MLC 2006), what fundamental right is guaranteed to all seafarers? Q9 What safety equipment is required when handling battery banks containing liquid sulfuric acid? Q10 What is the primary danger of using carbon dioxide (CO2) in a fixed engine room fire extinguishing system?