FST Smoke Detection 4

Question 1

When is a smoke detector NOT required in an elevator machine room under NFPA 72?

Accepted Answer

When the elevator machine room is in a fully sprinklered building and sprinkler activation initiates recall

Answer

NFPA 72 and ASME A17.1 allow sprinkler activation alone to initiate elevator recall when the machine room is fully sprinklered, eliminating the smoke detector requirement for that function.

Question 2

What does an obscuration level of 4% per foot indicate about a photoelectric smoke detector's listed sensitivity range?

Accepted Answer

The detector alarms at moderate smoke density within the typical listed range

Answer

NFPA 72 specifies that smoke detectors must be listed within a sensitivity range of 0.5% to 4% per foot obscuration, so 4% per foot is at the upper (least sensitive) end but still within the listed range.

Question 3

Which spacing reduction factor applies to smoke detectors installed in a beam pocket ceiling where beams project more than 18 inches below the ceiling?

Accepted Answer

Treat each beam pocket as a separate ceiling compartment and space detectors accordingly

Answer

When beams project more than 18 inches below the ceiling, NFPA 72 requires treating each beam pocket as a separate ceiling compartment for detector spacing purposes.

Question 4

What action should a fire safety technician take when a smoke detector consistently activates at low sensitivity but passes sensitivity testing?

Accepted Answer

Inspect and clean the detector, then retest

Answer

Consistent nuisance alarms at low conditions often indicate contamination; the correct first step is inspection and cleaning per manufacturer instructions before further action.

Question 5

Which installation location is PROHIBITED for a standard spot-type smoke detector under NFPA 72?

Accepted Answer

In a bathroom with a shower

Answer

Bathrooms with showers are high-humidity environments where steam can cause false alarms; NFPA 72 does not require and advises against standard smoke detectors in these locations.

(FST) Fire Safety Technician Certification Practice Test

(FST) Fire Safety Technician Certification Practice Test

FST Smoke Detection 4