FSD HVAC Systems & Airflow Control 4 — Questions and Answers
Question 1: Which test is used to verify that a smoke damper actuator will close the damper within the required time after receiving a control signal?
- Hydrostatic pressure test
- Operational test per NFPA 105 (Correct answer)
- Velocity pressure measurement
- Thermal imaging scan
Correct answer: Operational test per NFPA 105
NFPA 105, Standard for Smoke Door Assemblies and Other Opening Protectives, includes operational test requirements that verify smoke damper response time upon receiving a control signal.
Question 2: A fire damper in a curtain-type (multi-blade) configuration differs from a single-blade design primarily in that:
- It uses a fusible link rated 50°F higher
- Multiple interlocking blades fold into a pocket when open and drop closed as a curtain when triggered (Correct answer)
- It requires an electric actuator rather than a spring-return mechanism
- It can only be installed in vertical duct applications
Correct answer: Multiple interlocking blades fold into a pocket when open and drop closed as a curtain when triggered
Curtain-type fire dampers use multiple interlocking blades stored in a side pocket when open; upon fusible link release, the blades deploy across the duct opening like a falling curtain.
Question 3: What is the significance of the 'E' suffix in a smoke damper's leakage classification (e.g., Class II E)?
- The damper is rated for elevated temperature airflow
- The damper is tested for leakage at elevated temperature per UL 555S (Correct answer)
- The damper has an emergency manual release
- The damper meets energy efficiency standards
Correct answer: The damper is tested for leakage at elevated temperature per UL 555S
The 'E' suffix in UL 555S leakage classifications indicates the damper has been tested and rated for leakage performance at elevated temperatures (250°F), verifying it maintains containment in hot smoke conditions.
Question 4: When sizing a fire damper for installation in a duct, which factor determines the required damper size?
- The rated airflow in CFM only
- The outside dimensions of the duct or the rough opening in the rated assembly (Correct answer)
- The static pressure class of the duct system
- The BTU output of the connected HVAC unit
Correct answer: The outside dimensions of the duct or the rough opening in the rated assembly
Fire damper size is determined by the duct outside dimensions or the rough opening in the rated wall/floor assembly, ensuring the damper sleeve fits properly and seals the penetration.
Question 5: In a dedicated smoke exhaust system, smoke dampers on floors not involved in a fire are typically:
- Left in their normal open position
- Closed to prevent smoke from spreading to those floors via the exhaust shaft (Correct answer)
- Opened fully to maximize total system exhaust capacity
- Disabled to reduce fan load
Correct answer: Closed to prevent smoke from spreading to those floors via the exhaust shaft
In a dedicated exhaust smoke control system, dampers on uninvolved floors are closed so the exhaust fan draws smoke only from the fire floor, maximizing extraction efficiency and preventing spread.
Question 6: What must be provided at a fire damper installation location to allow for inspection and maintenance per IBC and NFPA 90A?
- A permanently illuminated indicator light
- An access door or panel of sufficient size to inspect and reset the damper (Correct answer)
- A dedicated circuit breaker in the electrical panel
- A posted placard showing the damper's fire-resistance rating
Correct answer: An access door or panel of sufficient size to inspect and reset the damper
Both IBC and NFPA 90A require an access door or panel adjacent to each fire damper so inspectors and technicians can visually inspect the damper, replace fusible links, and reset the assembly.
Question 7: Which scenario would cause a fire damper fusible link to be replaced without restoring the damper to full operation?
- Routine annual inspection with no alarm history
- The link melted during an actual fire event and the duct is confirmed smoke-free
- The link is replaced with a higher-rated temperature link to reduce nuisance trips (Correct answer)
- The link is replaced with an identical-rated link and the damper blades are confirmed unobstructed
Correct answer: The link is replaced with a higher-rated temperature link to reduce nuisance trips
Substituting a higher-rated fusible link than specified in the listing changes the product's listing compliance; the damper would then fail to respond at the correct temperature, violating its UL listing.
FSD HVAC Systems & Airflow Control 4
Which test is used to verify that a smoke damper actuator will close the damper within the required time after receiving a control signal?