What does the R next to a heat detector symbol indicate?

What does the R next to a heat detector symbol indicate?

• A. Remote indicator
• B. Resettable feature
• C. Rate of Rise heat detector
• D. Radiation detector

Answer: (C)

R indicates a rate-of-rise heat detector. This type detects a rapid increase in temperature, and it will alarm when the temperature climbs quickly, even if the final temperature hasn’t reached a fixed threshold. That’s different from fixed-temperature detectors, which trigger at a specific, steady temperature. In diagrams, the R is used to distinguish rate-of-rise detectors from other device types, and it isn’t signaling a remote indicator, a resettable feature, or a radiation detector.

R indicates a rate-of-rise heat detector. This type detects a rapid increase in temperature, and it will alarm when the temperature climbs quickly, even if the final temperature hasn’t reached a fixed threshold. That’s different from fixed-temperature detectors, which trigger at a specific, steady temperature. In diagrams, the R is used to distinguish rate-of-rise detectors from other device types, and it isn’t signaling a remote indicator, a resettable feature, or a radiation detector.