Water Spray Protection Design for Storage Tanks under Heavy Wind

[pplbb2012]

Hi Everyone here,

I met a review question from client regarding to the water spray protection for storage tank, they wonder how the cooling water and spray system were designed to against the heavy wind (40m/s) when fire happen.

Honestly speaking, I had never consider such issue, the quantity of cooling water was usually designed according to the firefighting hours and protected area.

Can somebody here give me any advice how the wind impact can be accounted in the ring spray system? Any design guide that I can find?

Thanks in advance.

 

[skdesigner]

NFPA 15 and the nozzle datasheets give guidance for "outdoor installations", while FM Global datasheet 4-1n discusses minimum starting pressure for "moderately intense wind".

Given that 40 m/s (90 mph) is hurricane speed, I don't imagine you'll find too many prescriptive-based solutions. Contacting a nozzle manufacturer is probably the best avenue.

 

[pplbb2012]

Appreciate Skdesigner for your great guide and support!

I was going to discount the wind load since two extreme conditions (fire and hurricane) won't happen concurrently, however, the discounted wind speed shall still be issue noticed me.

 

[chicopee]

"...two extreme conditions (fire and hurricane) won't happen concurrently..." I don't agree with that statement. Many fires are started during tornadoes and hurricanes.

 

[DavidCR]

Just some thougths...

Ideally a lab test will tell how much of the water is not inpinged in the surface.

Variables to consider: placing more nozzles closer, bigger K, narrower cone, extra pressure, extra flow. Maybe playing with these parameters may lead to a reasonable "overdesign" that maybe the client will accept.

If the wind is that high, and the tank separation is big, what is the cooling effect of the wind?. I reckon, that in case of a hurricane the wind itself may have a strong cooling effect.
The spray cooling is suposed to cool radiated heat, in case of a strong wind the heat received by the tank surface will require a modeling analysis to decide what is the heat received by convection.