Foam induction to sprinkler systems to enhance knockdown

[kurnal]

Came across an American Viking sprinkler system whilst working in a new warehouse today (in the UK). The system looks fairly conventional except for a large 500 litre foam tank next to the valve group - the system induces foam concentrate into  the water stream I guess to enhance the knockdown.
Have googled for more info with very little success- please can anybody point me towards a source of more information on the benefits of this system?

[Ashley Wood]

What was being stored in the warehouse? Buckeye, and Ansul are 2 manufacturer that i know of who make the kit to do this i.e foam bladder tanks, inductors, proportinators etc. I have recently done some work for USAF in the UK. I was auditing existing foam systems, sprinklers and monitor systems. The sprinkler systems that had foam enhancement were protecting hangers. They used AFFF at 3% stored in a bladder tank, it was then introduced into the water supply to the sprinklers via a foam inductor. The foam supply ran for 15 minutes after that pure water was discharged. Does that sound the same?

Best regards

Ashley

[John Webb]

Kurnal,
I did some work in the 1980s on putting foam through ordinary sprinklers to protect a machinery area where there could be a diesel fuel fire. We had a 4m by 4m tray filled with 800 litres of diesel and containing pipework etc to form obstructions. Sprinklers were set at 4m above the fire on a 3m by 3m spacing. I don't have the results to hand but I recall FFFP was the most successful at achieving near-extinction. The work was for a client and I'm fairly certain was never published publicly.

[kurnal]

Thanks for the replies. This is a new building and none of the commissioning certs were available, or the fire strategy so I am a little in the dark.
As to the warehouse it is for palleted storage of small steel pressings for the automotive industry in block storage on the floor. The building is ADB compliant without sprinklers but the insurance company has requires sprinklers and has classified the contents of the warehouse  as Category 4 because the steel pressings are contained in plastic bins!!!!!! Thats cost someone a tidy penny. Though I guess they may have considered the worse case scenarion that the warehouse may be stacked high with idle plastic pallets and bins- it may make sense that way.
The tank is a bladder tank. I have asked for all documentation in order to complete the risk assessment,

[Mike Buckley]

I had some experience with a foam induced sprinkler system in Coventry. It was never used in anger but the main thing to remember was to isolate the foam tank before testing the sprinkler otherwise the foam gets sucked into the system.

[John Webb]

If the plastic bins melt when heated or burning there obviously is the potential for a liquid fuel fire. I've seen this happen on a small scale with stacks of empty washing-up liquid bottles being alight. In this case spray from a HR was sufficient to extinguish the fire and solidify the melted remains. What a job 'turning over and damping down' was, however, with the bottles stuck together!
Could the need for foam be eliminated by using fire-retardent plastic for the bins? Just a thought.

[kurnal]

Took the time to read through BSEN12845 today.
This standard recommends induced Afff for sprinkler systems in warehouses where polypropylene bins are housed. So thats where its come from though I still am having problems coming to terms with a relatively small quantity of bins housing a large quantity of steel pressings being a special hazard over and above cat 4.
I still wonder if it has been specced as a warehouse full of empty stacked polypropylene bins.

[Fishy]

Under CDM, there should be a building Health & Safety File.  One of the things that should be in there is the design criteria for the safety systems associated with the building.  You MIGHT be lucky and find the reason why the system has been spec'd how it is in there.

Wouldn't do any harm to ask...