Which two of the following are needed to perform a periodic test of a projected...

Projected beam smoke detectors are testednot with actual smoke, but by simulating obscuration usinglisted toolssuch as atest switchoroptical filter.

NFPA 72 (2022), Section 14.4.2.2.6.2:

“Projected beam-type smoke detectors shall be tested by introducing an obscuration in the beam path using an optical density filter or a method approved by the manufacturer.”

Some systems includelisted test switchesfor functional checks without disrupting alignment.

Correct answer: Using a listed test switch, Using an optical filter

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