Is AFFF suitable foam for deisel tank farm 1

[ContractorDave]

If anyone has a quick answer it would help here. I have an engineering firm who is also interested in supplying the foam for my tank farm project telling me AFFF is not suitable for deisel fuel protection in NFPA11 low expansion applications, and are pushing AR-AFFF.... at something like $40,000.00 more. One company tells me it's fine, this guy says it's not even safe. Any thoughts?

 

[stookeyfpe]

AFFF is fine. You don't need alcohol type concentration (ATC)-AFFF.

 

[ContractorDave]

Thx Stookey

Just curious but what do you make of this statement: "I wasn't kidding when I said AFFF was not suitable. We would not even recommend our own AFFF for this application. I understand the desire to limirt cost overruns, but utilizing AFFF as the agent here would not be deemed a 'safe' way to save."

 

[stookeyfpe]

I suspect it is a case of what I call engineering by marketing folks. I can't count the number of times I've had salesmen tell me all the merits of something and when I sit down and study the product, I find all sorts of limitations that were never mentioned.

 

[MJCronin]

lightecho..

I have designed facilities that store No. 2 FO/diesel and have not required an AFF foam system.

According to my understanding of the requirements of NFPA-30 2000, the flash point of No.2/diesel is low enough such that an active fire protection system is not required.

What fire code/local code provision forces you into an AFF system ?

-MJC

 

[ContractorDave]

MJC

The AHJ is asking for protection as per NFPA 11. There are four 210'd x 42'h fixed cone roof tanks = 345,000 barrels plus each. The Fire Marshall had a minimum size of tank that would require NFPA 11 coverage and these were above that.

D

 

[DavidCR]

I´m not a foam expert but here is my comment.

Even they are not required on NFPA30 we protect in our company the disel fuel with foam chambers, due to high value risks.

There is an issue dealing with the heat resistance of the foam, some concentrates like FP tend to be recomended by some manufacturers for fires of fuel oils and crudes that are considered "hot fires" since the time involded in fire combat is longer than other fires. Others mention that since foam is 94%-97%-99% water, heat resistance is not very important, and the more effective the foam the better it is regarless of what may happen to the foam if the fire gets complicated; etc, etc, and I really don´t want to mention all the vendor arguments, pros and cons.

So maybe that idea of AFFF no suitable for diesel may be realated with this. Anyway, any good AR-AFF will be more effective than any AFFF since it is a better more expensive product in general, and FP is an older technology and since it´s ben recomended by some manufacturers instead of AFFF, now that FP is not preferred since it is a dirtier old product in some cases, there is a tendency to recomend AR-AFFF instead, at least from what I´ve have observed.

I´m sure that if you mention this to any foam manufacturer, it will say that I´m not really clear and his arguments will start to enrich your criteria considering you local conditions, and that´s why I mention this ideas in order not to be define the issue, but for you to take the best for your case, if you are not capable to access to test results or perform your own tests, you will have to follow manufacturer recomendations in an intelligent way.

For me the issue is not clear yet, for us, we have used FP and since it´s been given some important problems with equipment that´s not been maintened properly and the user wants to change to AFFF, since AR-AFFF is quite expensive and the risk is relatively low.