Actuators, Controls & Automatic Operation Flashcards
7 cards from real FSD practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Actuators, Controls & Automatic Operation flashcards as text
What is the primary function of a fusible link in a fire damper?
Answer: To hold the damper open and release it when heat causes it to melt
A fusible link holds the fire damper in the open position and melts at a rated temperature, releasing the damper to close under spring pressure.
At what temperature is the most common standard fusible link for fire dampers in typical HVAC duct systems rated to melt?
Answer: 165°F (74°C)
The most commonly used fusible link for fire dampers in standard HVAC ductwork is rated at 165°F (74°C), well above normal operating temperatures but detectable during a fire.
Which type of actuator is required for smoke dampers that must respond to signals from a fire alarm system?
Answer: Electric or electro-pneumatic actuator
Smoke dampers require electric or electro-pneumatic actuators to receive and respond to electrical signals from fire alarm or building automation systems.
What does a 'spring return' feature in a smoke damper actuator ensure?
Answer: The damper returns to its fail-safe position upon loss of power
A spring return mechanism ensures the damper moves to its fail-safe position — typically closed for smoke dampers — whenever electrical power is lost.
What is the typical fail-safe position for a smoke damper actuator?
Answer: Fully closed
Smoke dampers are designed to fail in the closed position to prevent smoke from migrating through ductwork during a fire or power failure.
Which signal most commonly triggers the automatic closure of a smoke damper in a commercial building?
Answer: An electrical signal from the fire alarm control panel
Smoke dampers are activated by electrical signals from the fire alarm control panel (FACP), which detects smoke via detectors and sends closure commands to connected actuators.
Which organization provides listings and certifications for fire and smoke damper actuators under standards such as UL 555 and UL 555S?
Answer: Underwriters Laboratories (UL)
Underwriters Laboratories (UL) tests and certifies fire and smoke damper actuators, maintaining listings under UL 555 for fire dampers and UL 555S for smoke dampers.