DAHUA Airshield Wireless Optical Smoke Detector HY-SA21A-W2(868)

The DHI‑HY‑SA21A‑W2(868) from Dahua is a wireless optical (photoelectric) smoke detector designed for reliable early fire detection in residential and light commercial settings. It uses split‑spectrum sensor technology to improve accuracy and reduce false alarms, sampling the air every 10 seconds. Upon detecting smoke, or in case of a fault or low battery, it triggers both an 85dB audible alarm and a visual LED alert. A single integrated button allows testing and silencing of alarms for approximately 12  minutes and the unit has a long battery life of up to around 3 years using a replaceable 3 V CR123A lithium battery.

Wireless communication is handled via the 868 MHz band (868–868.3 MHz), supporting two‑way transmission with frequency hopping and AES‑128 encryption to enhance reliability and security. In open space conditions, its radio range can reach up to 1 000 m, making it suitable for larger installations or multi‑zone coverage.

The detector is surface‑mounted, with a coverage area of 20–40 m² when mounted on a ceiling with a height less than 8 m and complies with EN 14604:2005 + AC:2008 standards.