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AFF Exit Exam • Set 6 Question 25 of 30

Fire alarm system thermostats are actuated by:

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Direct Answer

Option D: The difference in thermal expansion of two dissimilar metals

Thermostats used in fire alarm systems, particularly bimetallic types, operate based on the principle that two different metals expand at different rates when heated. This differential expansion causes the strip to bend, closing an electrical contact and triggering an alarm.

All Options

A
Light scattering effects across laser sensors
B
Air pressure changes inside trunk compartments
C
Moisture tracking limits inside structural wiring panels
D
The difference in thermal expansion of two dissimilar metals (Correct Answer)

Detailed Explanation & Context

Thermostats used in fire alarm systems, particularly bimetallic types, operate based on the principle that two different metals expand at different rates when heated. This differential expansion causes the strip to bend, closing an electrical contact and triggering an alarm.

Relevant Framework: STCW 2010 Manila Amendments • DG Shipping E-Learning & Exit Exam Standards • Advanced Fire Fighting (AFF).

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