The detector’s operation and sensitivity can be tested in place. Model 2400TH has the same specifications as Specifications Diameter: 5.5 inches (140 mm) Height: 3.14 inches (80 mm) Add 0.5 inches (13 mm) for 2400TH Weight: 0.7 lb. (310 gm) Operating Temperature Range: Model 2400 — 0° to +49°C (32° to 120°F) Model 2400TH — 0° to 38°C (32° to 100°F) Operating Humidity Range: 10% to 93% Relative Humidity Non-condensing Maximum Air Velocity: 3000 ft/min (15m/s) Locking Alarm: Reset by momentary power interruption Electrical Ratings System Voltage: 12/24 VDC Maximum Ripple Voltage: 4 Volts peak-to-peak Start-up Capacitance: 0.02 ?F Maximum Standby Ratings: 8.5 VDC Minimum; 35 VDC Maximum 120 ?A Maximum Alarm Ratings: 4.2 VDC Minimum at 10 mA 6.6 VDC Maximum at 100 mA Alarm current must be limited to 100mA maximum by the control panel. If used, the RA400Z Remote Annunciator operates within the specified detector alarm currents. Reset Voltage: 2.5 VDC Minimum Reset Time: 0.3 S Maximum Start-up Time: 34 S Maximum model 2400, but also features a restorable, built-in, fixed temperature (135°F) thermal detection unit. These detectors are listed to UL 268 and are latching type system detectors. When latched in alarm, the detectors must be reset by a momentary power interruption.