Which detection method detects vapors?

• A. Fixed temperature
• B. Rate of rise
• C. Smoke
• D. Vapor

Answer: (D)

Vapor detection is about sensing vapor‑phase molecules in the air, such as flammable fuel vapors that can accumulate and spread before ignition. Among the options, only a detector designed to sense vapors will respond to those airborne molecules. Fixed temperature detectors react to heat at a set threshold, not to vapors. Rate of rise detectors respond to how quickly the temperature climbs, not to vapor presence. Smoke detectors detect airborne particulates from combustion, not vapor concentrations. So the detector that detects vapors is the vapor detector.