Models 5251B, 5251RB and 5251H are intelligent sensors that utilize a state-ofthe-art thermistor sensing circuit for fast response. These sensors are designed to provide open area protection with 50 foot spacing capability as approved by UL 521. Model 5251B is a fixed temperature sensor with 135°F fixed temperature alarm. Model 5251RB is a rate-of-rise temperature sensor with 135°F fixed temperature alarm. Model 5251H is a high temperature sensor with 190°F fixed temperature alarm.
SPECIFICATIONS Diameter: 6.1 inches (155 mm) installed in B210LP; 4.1 inches (104 mm) installed in B501 Height: 2.0 inches (51 mm) Weight: 4.8 ounces (137 gm) Installation Temperatures: –4°F to 100°F (–20°C to 38°C); 5251B and 5251RB; –4°F to 150°F (–20°C to 66°C); 5251H Operating Humidity Range: 10% to 93% Relative Humidity Non-condensing Mounting: B210LP flanged base; B501 flangeless base; B501 with RMK400 recessed mounting kit Voltage Range: 15 to 32 Volts DC Peak Standby Current: 300 µA @ 24 VDC (one communication every 5 seconds with LED blink enabled) LED Current: 6.5 mA @ 24 VDC Fixed Temperature Rating: 135°F (57°C); 5251B and 5251RB; 190°F (88°C); 5251H Rate of Rise Detection: Responds to greater than 15°F/min.; 5251RB