HVAC Systems & Airflow Control Flashcards

Under NFPA 105, smoke dampers in smoke control systems must be inspected and operationally tested at what minimum frequency after the first year of service?

Answer: Every 4 years

NFPA 105 requires operational testing of smoke dampers every 4 years (after the initial 1-year test), although authorities having jurisdiction may require more frequent testing.

A corridor smoke damper that fails to close during an operational test should be:

Answer: Tagged out of service and the deficiency reported to the building owner for repair

A failed smoke damper must be taken out of service, documented, and reported to the building owner for prompt repair; no workarounds that leave the smoke control system impaired are acceptable.

When multiple smoke dampers are connected to a single exhaust fan in a shaft smoke exhaust system, which control arrangement is required?

Answer: Only the damper on the fire floor opens; all others remain closed

In a shaft exhaust smoke control system, only the damper on the floor of fire origin opens to direct exhaust from that floor; closing all other dampers maximizes smoke extraction at the fire floor.

A fire damper installed in a duct that passes through a 2-hour fire-rated floor assembly must be rated to resist fire for at least how long if the duct is used for non-combustible HVAC service?

Answer: 2 hours

The fire damper must match the fire-resistance rating of the assembly it penetrates; a 2-hour floor assembly requires a damper with a minimum 2-hour fire-resistance rating.

Which of the following best describes the role of a 'position indicator' on a smoke damper actuator?

Answer: It provides a local and/or remote signal confirming whether the damper is open or closed

A position indicator (end switch or feedback signal) confirms the actual blade position to the fire alarm or building automation system, verifying the damper has fully responded to its control command.

In a hospital HVAC application, smoke dampers in isolation rooms are required to maintain which airflow relationship to control infection and smoke simultaneously?

Answer: Negative pressure relative to adjacent spaces under normal conditions, with smoke control taking precedence during alarm

Infection-control isolation rooms are maintained at negative pressure under normal conditions, but IBC and NFPA 90A require the smoke control sequence to override HVAC operations during a fire emergency.

What is the effect of installing a fire damper in a supply duct without providing adequate clearance for the damper blades to fully open?

Answer: Restricted blade travel reduces airflow and may prevent full damper closure during a fire

If blade travel is restricted by insufficient clearance, the damper cannot achieve its rated open position (reducing system airflow) or its rated closed position (compromising fire protection).