Thread: My Bush Fire House protection system

Originally Posted by newhue

Good idea Keith, sorry you probably feel we are all having a go. But how many Litres per second do you think it will run. I'd imagine with the intense heat the sprinkler would have to be like an irrigator to do good. It may only have to be for 2 to 4 minutes, but it needs loads of water, at the critical time of the fire head.

I know it's not saving the house, but would a bunker be money better directed.

I will do a time test when its done and see how long it takes to empty one of those 1000litre IBC tanks I have.
I have a concrete bunker but its full of guns
Could always hide in there too

Originally Posted by Lotz-A-Landies

When you think about locating sprinklers, you should remember that the normal "windward" side is irrellevant because the fires generate their own weather conditions and will draw air into the fire. This means there will be a wind, often quite strong, heading into the fire.

Also because of this wind relying on a single set of sprinklers may mean that the spray will be blown off the roof. It may be better to rely on a greater number of smaller sprinkler heads located all over the roof and eves.

Thats true but we are not in heavy bush, there is pasture on two sides. I am planning for an unlikely event of a treetop fire from one of two directions.

Did some volunteer work on a farm out the back of Licola aftyer the fires a few years ago. The owners of the farm have a large substantial hut down on the Macalister river. This hut survived a fire that, as noted previously, melted pipe underground. It survived because they had a simple gravity system consisting of a water supply up the hill and a trickle line on the roof. You apparently don`t necasarily need a lot of water, just a wet roof- gutters. This way the wind did not blow the water away as in if it was a spray. The surrounding area of the hut was toasted. A metal out house and pump shed where melted slag. As for our house. Just recently been cleaning out the gutters for summer. Yard has been cleared of the usual crop of fallen branches etc after winter. Ember attack would be our major threat. If the three twenty meter plus pine trees we have in our yard ever got alight things would get a bit more interesting.
Cheers Hall

what about instead of water us fire fighting foam,uses less water and it lasts on the ground/structure a long time.we had home made foam puter outers made using the venturi system.we just used a bit of 1 inch pvc plastic threaded to take 38mm fire fighting hose with the venturi drilled and tapped into the side we used a sheep drench backpack to carry the foam around,

[ame="http://www.youtube.com/watch?v=777vfvZlUWc"]http://www.youtube.com/watch?v=777vfvZlUWc[/ame]

A few things to consider, a house is vulnerable from ember attack for (about) 30min prior to the fire arrival, is extremely vulnerable during the passage of the fire, and then subject to ember attack for a number of hours after the fire has passed.

Fires attack houses from a combination of methods

• embers, look where leaves collect now as this is where embers will also gather
• piloted ignition, where radiant heat loads are high but not enough to cause autoignition, if an ember lands then it may be enough to cause flaming combustion. Horizontal surfaces/internal corners are most at risk.
• Direct flame impingement/radiant heat.

One of the major things to overcome is the entry of embers into the house interior, through doors, windows, vents, weepholes, roof voids etc.


The fire induced winds can peak at very high speeds, IIRC Canberra was 200+kph (and included a fire induced tornado) and significant damage was caused by the wind creating 'openings', by lifting tiles/roofing etc.


Think how you will activate any sprinkler system if you are not home. The first casualties will be power and communications especially in a rural environment. If you are not home and want to start the system remotely, you probably need to be looking at 40000+ litres as you won't know how far ahead of fire impact you will be starting the pumps. This will also apply if you decide to start the pumps and relocate leaving the house in the care of the sprinklers. (be prepared to let the pump run to destruction)


As well as a sprinkler system look at window shutters etc as windows are the weakest link in any building and 'most' glass will fail before the 40kW/m2 radiant heat (Bal FZ) is reached. Look towards bronze or stainless insect screens across the whole of the window on the (forest) exposed side.


Lastly you will need large water droplets, rather than a mist to try and reduce the windblown effect, this will increase the amount of water you will need in reserve.


Food for thought




Martyn

Originally Posted by Hall

Did some volunteer work on a farm out the back of Licola aftyer the fires a few years ago. The owners of the farm have a large substantial hut down on the Macalister river. This hut survived a fire that, as noted previously, melted pipe underground. It survived because they had a simple gravity system consisting of a water supply up the hill and a trickle line on the roof. You apparently don`t necasarily need a lot of water, just a wet roof- gutters. This way the wind did not blow the water away as in if it was a spray. ...

This is what I was sugesting, using Micro spray heads along and under the eaves and around vulerable ares may be sufficient. It will also use less water by targetting the important spots and not waste water in spray being blown away.

We have always recommend blocking downpipes (plastic bags around a tennis ball generally works) and filling gutters with water... this eliminates it as an entrance for embers, now you can concentrate elsewhere...(sprinklers still required on roof even if just on brow line)

maybe a misting line around under eave level... unsure if spraying onto doors/windows would be correct but worth thinking about

Remember that any wood piles need to be well away from house, not just wood for burning but any wood. If you have wood chips/pine bark in garden they are also at risk of spreading the fire..

Fill baths, buckets pots etc etc with water so you have a supply no matter what...this can help in the critical time afterwards to extinguish ember or burn areas..

If you have a fire hose have it protected in some way (small cabinet etc) so that UV and heat from fire etc is less likely to damage it before you or anyone else can use it... mark it clearly.

Lots of good advice there. Thanks.
I plan on 13 sprinkler heads around the eaves as we have a verandah all round. The posts are three metres apart and a sprinkler will go on every other post.
Threaded the ends of the galv pipe, welded on a couple of tabs, screwed the sprinkler head to one end and attatched it to the post.
I am having a ball valve on each riser so I can control which sprinklers are on. To save water I can turn off the ones on the leeward side if necessary.