Mains smoke alarm

[jon3674]

I am looking to put some new mains smoke alarms in to replace the old battery powered ones i currently have, but i am very confussed about the various ones on offer, for instance what is the difference between:

1. Ionisation mains alarm

2. photo optical mains alarm

3. photo electric mains alarm

Many thanks in advance for help given

 

[Tim 77]

Ionisation: Ionisation smoke alarms are particularly suited for fast-flaming fires (used eg. on landings)


Optical: Optical smoke alarms respond fast to smouldering fires (used in living rooms, bed rooms and hallways)


Ionisation or Photoelectric?

While all smoke alarms are designed to detect smoke, certain sensing technologies react differently to certain types of fire.
Photoelectric sensing technology is generally more sensitive (than ionization sensing technology) at detecting large particles.
Large particles tend to be produced in greater amounts by shouldering fires. These fires may smoulder for hours before bursting into flames.

Ionization sensing technology is generally more sensitive (than photoelectric sensing technology) at detecting small particles. Small particles tend to be produced in greater amounts by flaming fires. These fires consume combustible materials rapidly and spread quickly.

 

[breezer]

first you should be aware, not all, but most mains smoke alarms have a battery back up, this works just like a battery operated smoke alarm, when the battery goes flat it beeps

2 + 3 are the same

one is more sensative than the other.

optical works by smoke bouncing infra red light onto a light sensative sensor

ionisation uses a radioactive material (less than on a lumious watch) it compare 2 chambers, smoke enters one (other is sealed) and current drawn goes up, instant alarm condition

 

[Tim 77]

And for good measure I'd stick a rate of rise heat detector in your kitchen.(just not right above your oven)

 

[breezer]

now you are taking the mick, ROR should NEVER be fitted in a kitchen

to be honest i wouldnt bother with the kitchen, not much to burn, lots to start a fire if left un atended, but not much to burn, unlike lounge = sofa, carpets etc

 

[Tim 77]

now you are taking the mick, ROR should NEVER be fitted in a kitchen

to be honest i wouldnt bother with the kitchen, not much to burn, lots to start a fire if left un atended, but not much to burn, unlike lounge = sofa, carpets etc

I'm not a fan of fixed temp, seen too many pack up.
A rate of rise is ideal is the op comes come p**sed, sticks the chip pan on and nods off!

 

[Tim 77]

now you are taking the mick, ROR should NEVER be fitted in a kitchen

http://www.screwfix.com/app/sfd/cat/pro.jsp?id=11312&ts=54655

 

[breezer]

that is not a true ROR detector

besides its for a fire alarm the OP wants to add mains detectors, not a fire alarm.

you have to draw the line somewhwere, besides if they are they P then they wont hear alarm, next you will be saying fir more sounders, then we are back into the realms of true fire alarms

your one say it trips at 57 degrees, info on ror is clicky

 

[Tim 77]

, next you will be saying fir more sounders,

And a beacon in every room

 

[breezer]

only for the hard of hearing, or if hungry, bacon in every room

 

[Tim 77]

, or if hungry, bacon in every room

Now you're talking!!