On 25/11/2018 18:18, wrote:
snip

Ionisation is the type that detects the fastest on the whole. But if one produces repeat false alarms it needs replacing with something less hairtriggery. Failure to do so results in people ignoring then disabling. The legal requirements fail to address that, resulting in nonfunctioning systems sometimes.



And your authority for that is?

Cf:

"Ionisation smoke alarms have traditionally been used throughout
properties for many years. Designed to react quickly to fast flaming
fires, ionisation smoke alarms are most sensitive to small particles.
When fires produce little or no smoke but the fuel is subject to rapid
combustion, the ionisation smoke alarm is the quickest to sense its
presence. These fires tend to originate from materials such as paper and
clothing. "


"Less prone to false alarms than ionisation, optical smoke alarms are
slightly quicker at detecting slow smouldering fires that tend to
produce a lot of smoke. Also known as photo-electric alarms, this quick
response time to smouldering fires is down to the optical smoke alarm's
high sensitivity to large particles in the air. The optical sensing
chamber effectively "sees" when smoke is present, as the large particles
block and cause an infrared light to scatter."

https://www.safelincs.co.uk/smoke-alarm-buying-guide/

+ similar views from others sources

And the main cause of death in domestic fires is smoke inhalation.

--
Robin
reply-to address is (intended to be) valid