On 22/01/13 19:33, Brian May wrote:
On 22 January 2013 16:57, Russell Coker <russell@coker.com.au <mailto:russell@coker.com.au>> wrote:
If you had a house made of solid relatively airtight concrete including a concrete roof with solid shutters then it doesn't seem that you would need any water protection system. If you had a house of a typical suburban design then it seems that no reasonable amount of water would save it unless you also have water inside the roof cavity to stop embers that get through gaps in the tiles.
It doesn't seem like adding water will be guaranteed to save a house that wasn't already fairly safe without the water.
Don't forgot that most houses burn down after the fire front has passed. If the house survives or not depends on if there is somebody around (risking their necks) to put out the small spot fires before they result in the house burning down.
Of course exceptions exist. Have heard that one house had its roof blown away, after which there was no saving it.
The other problematic area in the Marysville's fire was the gas cylinder venting valves pointing at other houses, and resulting damage, including broken windows which embers could enter.
I see a number of problems with the sprinkler system:
* Relying on mains water pressure or mains electricity is a big no no, there probably won't be any. That fire truck up the road will be using all the water pressure, and a tree will be down across the power lines. * If it is a petrol/diesel pump, somebody has to be able to start it. Plus it may not start when required. * The system would be very exposed as the main fire front passes. * If you start it before the fire front, you use up all your water before it is needed (after the front passes). * If you start it as the fire front is passing through you get burnt. Plus the water will evaporate and has no affect whatsoever. * Ideal is to start it after fire front has passed, but you have to be around (and exposing yourself to danger) to do so. * After fire passes there is no guarantee that you will get water where it is needed (to put out the spot fires).
So a sprinkler system that gets its supply from tanks and has diesel/petrol powered pump, that somehow can be activated after the main fire front has passed might be a good thing. Although not as good as being there to put out spot fires with a wet mop (yes, I have heard stories of people saving their houses with nothing more then mops and a bath previously filled with water). The problem is with activating the sprinklers at the appropriate time. And obviously you can't rely on mains power, telephone, ADSL, 3G, etc, which you normally would use for remote control applications.
The usual way is to use thermal sensors, and of course it needs to auto-start the pump that uses local storage.