External Sprinklers for Waste Storage Area

[Gasmeter]

I'm considering using a small bespoke sprinkler system to protect a bin storage area, what I have in mind would just have a mains supply and four heads (ish).  There are 8 x 1100 litre plastic wheeled (Euro) bins containing mixed waste, cardboard and glass; they can't be moved elsewhere and are tight against a high value building with non-fire rated glazing above, there is not enough space to enclose them in a secure compound. Does anyone have experience of non-standard sprinkler/drencher systems like this?

[kurnal]

Is this area protected from frost?

[BLEVE]

Dry pipe system may be better from a tamper/vandal aspect also.

Depending on the pressure of the main but would think booster would be required.

could probably do some back of the ciggy box calcs when I get half a chance.

Maybe look at secure fence/gate at a distance to prevent arson. Other than that, what is the construction used in the building facade? How far above the bins is the glazing, what material is are the frames?

i.e. calculate duration of fire, heat release and heat flux,then determine effect on structure etc. 

[Gasmeter]

The area is off a service road which ramps down to basement floor level, it's not possible to provide a vandal proof level of security due to the location.  The glazing starts about 2m above the waste storage area and is PVC framed double glazed units, the building itself is late '60s 9 storey steel frame and block.  I don't know the local mains pressure yet, but am getting the static pressure and flow rate checked; as it shares the site with a hospital I'd like to think the Water Authority provide decent pressure, but who knows    I would expect about 800kW output from a single cardboard filled 1100ltr bin, so there's potential for several thousand kW output from all of them together.  Dry pipe is probably the answer to the frost problem, but anything that adds expense may thwart my efforts to protect this area, however, I know our insurers would have apoplexy if they saw the risk.  Thank you chaps, your help is much appreciated 

[Midland Retty]

As an 'aside' be aware that some Water Authorities drop mains pressure at night due to leaks in the town mains system.

Often the source of the leaks cannot be readily be identified and repaired, or are in locations which would prove too costly to disturb, or would cause major disruption (ie digging up major trunk roads etc). So leaks are left for quite sometime before they are addressed.

I've seen several sprinkler systems reliant solely on mains pressure, without any consideration given to water storage or boosters.

So your water board may tell you mains pressure is fine during the day, but be sure to ask what pressures are expected at off-peak times.

[wee brian]

I heard tell of some LA's using a self contained mist system for their bin stores (enclosed of course).

I suppose if you went, off standard, then all you need are four heads and some pipe (plus whatever the water bylaws want (backflow valve etc).

[Phoenix]

Putting in a bespoke drencher system is going to require expensive testing, servicing and maintaining over the remainder of the lifetime of the building.  Establishing the correct design fire size will have to err on the side of safety and that is likely to lead to a substantial fire size that will require large volumes of water.  So large pumps may be required unless a tank can be sited on the roof which will not be cheap or easy.  Duplicate supply pumps may be required.  Relying on main pressure might be problematic as already pointed out.

On the whole, it may appear expensive and disruptive to replace the windows so that there is a line of fire resistance between the bins and the rest of the building, but it may be that this is likely to be the most cost effective solution in the long term.  Once the fire separation is provided it will be simple and cheap to maintain and could be supplemented with heat detection possibly linked to an ARC.

Stu

[SeaBass]

Have you considered an automated extinguisher system?

There are a number on the market, the best known probably being the Firetrace system. I've been involved with them before, and providing they are installed correctly they are  effective.   The only real draw backs being that  they have a limited amount of extinguishant (but do the calcs and link the system to the FAS and it's really not as problem)and the cylinders are subject to the same service regimes as ordinary fire extinguishers, which can be expensive shock  if you have a lot of systems and haven't budgeted for their replacement. (I won't be doing that again)

[AnthonyB]

If the service regime for extinguishers is correctly followed it shouldn't be as expensive as you may think, despite the industry trend to bin everything at 5 years that's not what the codes say and you should get 10-20 years out of an appliance.

A purpose built water mist system could be an alternative to a traditional sprinkler system, being all self contained and no water supply issues.

[BLEVE]

AB is spot on a fogex or similar system is probably the better option. Costs more but faster response and knock down vs trad sprinkler or system of local fabrication.

[wee brian]

I dont think he has walls or a roof so mist wouldnt be much use.

[Gasmeter]

Many thanks for all your replies; I think as Anthony suggests, low pressure water mist might do the trick, nozzle pressure is about 4 bar so it should suppress the fire even though it's in the open air, if it's linked to the building's fire alarm system then a response would be fairly speedy.

[nearlythere]

What would be the benefit of linking to the buildings FA system Gasmeter if the storage area is outside?
Would a fusible link over the bins to operate a sprinkler not be adequate?

[AnthonyB]

FA link would allow buliding occupants to investigate & bring more first aid firefighting equipment to damp down with, or alternatively call the brigade, also evacuate if risk of the fire entering the building.

Out of hours if the FA has an ARC link would trigger rapid brigade response.

Don't forget the OP said the store is against the buliding with fire vulnerable access to the interior above the risk, so it is important for a fire to be discovered as soon as possible, as much for property protection as life safety.

[kurnal]

I dont think he has walls or a roof so mist wouldnt be much use.

Gasmeter if you have no roof how are you intending to trigger the sprinklers?