Passive fire defense development parts are accustomed to resist, retard and isolate flames as well as the related smoke and fumes: they don't in them selves extinguish flames for this reason These are classed as 'passive defense'. Teach setting up occupants on the right use in the fire alarm method, https://www.thesafetycentre.co.uk/blog/ems-wireless-firecell-systems-from-the-safety-centre/