Passive fire protection design factors are utilized to resist, retard and isolate flames plus the affiliated smoke and fumes: they don't in on their own extinguish flames therefore They're classed as 'passive protection'. Most radio-interlinked alarms have An array of 150 meters in an open Room and approximately fifty meters https://www.thesafetycentre.co.uk/blog/ems-wireless-firecell-systems-from-the-safety-centre/