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The System Sensor 2251TB is an Intelligent Addressable Photoelectric Smoke Sensor w/ Thermal (135°F / 57
Model OP121 is UL 268
It responds to regular polls from the control panel and reports its type and the status (open/normal/short) of its Initiating Device Circuit (IDC)
Rotary Switch Addressing
• Magnetic test feature
Siemens OP121 Conventional Photoelectric Smoke Detector System Sensor 1451 The System Sensor 2251TB isThe microprocessor controlled, self diagnostic circuitry contained in the Siemens photoelectric (conventional) smoke detector, Model OP121, eliminates an installers need of using burdensome sensitivity test equipment. The Model OP121 auto sensitivity feature originates from its internal, self monitoring circuitry, providing dynamic verification of sensitivity and or required maintenance. This detector type is commonly found on the following Siemens
