Rate-of-Rise(ROR)
React to the sudden change or rise in ambient temperature from a normal baseline condition. Any sudden temperature increase that matches the predetermined alarm criteria will cause an alarm. This type of heat detector can react to a lower threshold condition than would be possible if the threshold were fixed. A typical alarm may sound when the rate of temperature rise exceeds 12° to 15°F (6.7° to 8.3°C) per minute.
Fixed Temperature(FX)
If the temperature of the center disk rises to the detector’s rated temperature (135°F or 194°F) the fixed temperature element activates. This closes contacts in the detector to fire the latching circuit which turns on the detector’s LED and transmits the alarm condition to the fire alarm control panel.
The fixed temperature element is non restorable and, when activated, the detector must be replaced. The need for replacement is indicated when the center disk (see illustration) has fallen free. After replacing the detector, the control panel reset switch may be operated to reset the system.