Siemens OP921 Photoelectric Smoke Detector

The Siemens OP921 is an intelligent, addressable photoelectric smoke detector using light-scatter sensing to detect visible smoke particles, well suited for open-area detection as well as in-duct installations. UL 268 and UL 268A listed, it performs continuous self-testing with full diagnostics every ten seconds, features automatic environmental compensation and remote sensitivity adjustment, and includes built-in ISOtechnology short-circuit isolation for up to 252 isolation points per signaling line circuit.