Heat, or rate of rise detectors?

messy, Why should a suitable rate of rise not be sufficient? How big an area is the workshop. If smoke/dust/fumes are being evolved, normally, why is this not controlled under COSHH?

messy, Why not rate of rise then? I am guessing, not hundreds of people doing repairs at the same time then? By soldering I am guessing soft soldering with an electric soldering iron? This will not evolve much fume, if it does, or it is done on a regular basis then the "client" needs to address this under COSHH surely. Grinding/cutting with a hand held angle grinder, possibly Again, not much fume or dust, for a small operation, depending on what they are working on, and it will tend to settle, or stay in the operators breathing zone, it is doubtful it will reach a high level mounted detector in any volumes sufficient to cause a false alarm. The heating of bolts and nuts with oxy-acetylene or a propane "plumbers" type torch? Yes you will get a large volume of heat rising directly above an oxy torch, however, in a large open building volume the heat would dissipate by mixing due to the moving air currents anyway. You could get smoke from this, and this could affect a local detector, even a rate of rise. Can you not look at the workshop layout and where the operations are undertaken and site the detectors in locations where they will not be affected? Why are you still insistent on a smoke detector? Whose system is in there, what type of comms is on the existing detectors, what panel is fitted? This could make a difference to the selection of devices as well.

It is important to establish and consider the layout of this premises. It's a two bay single storey warehouse unit, with an office and loo in one corner & the only MOE - 2 x final exits - via the open warehouse unit. ie the office is an inner room). Then, five other rooms (one a portacabin) have been placed around the perimeter of the warehouse space, giving a total of 6 inner rooms all of which use the same warehouse space as their sole MOE route to the two final exits. Hot or dusty works occur on occasions in every room except to 2 x loos and office. There is some lone working (or perhaps 2 or 3 staff) possible on overtime in the evenings or weekends etc. Currently, there is no means to raise the alarm whatsoever - manual or automatic. It is not possible to use vision panels or lower the height of the partitions forming the inner rooms. Neither is it possible to alter the layout. The entire escape strategy revolves around letting those in the inner rooms know there is a fire: 1) in the open space access room, and 2) in one of the other inner rooms. My view is to install an L3 AFD system with (thanks to Paul's advice) rate of rise in all inner rooms and SD in the access room, with an isolation key which will turn off the SD when hot works are taking place (see earlier post re control measures). OK, it could be said that switching off the SD when hot works are taking place in the access room may be seen as foolish when the risk of fire is heightened. But there will be staff in the access area during that time who can raise the alarm (probably quicker than a smoke detector and definitely quicker than a RofR heat detector). In any case, AFD is most effective in empty rooms, and when this access room is unoccupied, the SD will be switch on. SD is the only way to raise the alarm of a fire in the access room quickly enough to allow those elsewhere in the building enough time to reach either of the 2 x final exits (both of which are accessed via the access room). Due to the occasional hot works and very limited smoke dust created, a ventilation system simply would not be cost effective. I hope this info creates a better picture of the circumstances of this address