foam discharge outlets in tank farm 1

[jhgf]

Hi!

I want to design low-level foam outlets at a diked area of a diesel storage tank farm. The outlets shall be directed to the dike wall in order to discharge foam to the wall and then to the liquid surface. Does anybody know at which minimum height below the top of the dike wall the outlets have to be placed? I want to avoid that foam is poored over the dike wall respectively in not diked areas.

Thanks to all!!!

 

[cdafd]

Interesting have not seen that design before:

but::

http://www.williamsfire.com/Files/PRODUCT CLASSES - OLD/TANK PROTECTION.pdf

http://www.chemguard.com/pdf/design-manuals/D10D03200.pdf

http://buckeyetest.com/foampdfs/F_Dike.pdf

 

[chicopee]

Does that mean you want the foam to bounce back from the wall to the liquid surface?

 

[chicopee]

Since firemen direct their extinguishing agent at the base of the fire, I would direct my nozzles at the maximum height that the liquid would attain within the diked area.
You can always speak with your state fire marshall for recommendations.

 

[stookeyfpe]

After reading this post for a 3rd time, I'm wondering why a containment dike foam-water system is required? The tank battery contains a Class II combustible liquid and such a system is not required by NFPA 30.

 

[jhgf]

@stookeyfpe

the client wants such a system. the tankfarm is located in iraq and ambient temperatures can rise up to flashpoint temperature of diesel (+55°C).

thanks

 

[DavidCR]

I´ve no a response, but I want to share some thoughts...

I suppose what your objective is to pour the foam and extend it uniformly, on the surface of the fuel pool, safe from the wind, turbulence, impingement, etc. expecting that it would work similar as a tank foam chamber.

The best approach is to buy a "listed", "approved" or "tested" deflector if you can find one.

Illustrations from the manufacturers (like those mentioned by cdafd), looks that a pipe 45° bend towards the wall do fine, and no specific height is mentioned.

I reckon that a low expansion foam would not require a specific pouring height, but it can be important on mid or high expansion foam.

Thinking of foam chamber deflectors, the Williams Spectrum LW9, etc., it looks that a specific deflector would work better than a bent pipe. I think a low expansion foam would work fine with any device but some would perform better. If I was allowed to design a personal idea, I´d try to use very efficient foam makers and copy a deflector similar to a foam chamber. But your client should know that it may not be the correct approach.

If it was the case, I´d try to avoid fixed dike devices and use fixed or mobile monitors with guaranteed and tested foam makers and/or nozzles, that you can point to any area of the dike. And you can get advice from manufacturers of what type of devices would work better for throwing foam in your conditions. I think this would do a more rational use of costly foam in case of fire too.

 

[IFRs]

I think I'd look at film-forming foams.