Fire Protection Water Reservoir for Oil Tank Farm 2

[08M3Steve]

Need help finding information to size a water reservoir to supply fire protection of an oil tank farm (4 tanks (15 MM gals total)).

Each tank is approx. 190 ft. in diameter and 25 ft high.

 

[chicopee]

Is this a mandatory requirement?

 

[08M3Steve]

This site is remote without sufficient municipal water supply.

 

[chicopee]

Forget about water storage in your case. I would make sure that the local fire department is knowledgeable of the situation so that nearby properties can be protected while the fire burns to its end. If there is a military base, arrangement may be made to arrange for foam equipment.
Local fire department may also be able to set up a convoy of tanker trucks to fight this fire or at least protect nearby properties.

 

[b1ueshift]

In an application like yours, there is no life safety consideration, however there is economic and environmental protection. You may require exposure protection systems (in accordance with NPFA 15) to be fitted to all tanks so that if one catches fire, it will not spread to other tanks.

Sizing the water supply is difficult as oil tank fires can burn for days. You probably need at least 2 hours of water supply, but that could easily be exhausted.

 

[Duwe6]

Also put Foam Fisers on each tank. Then 2-hours of water will actually be enough to do something useful.

 

[chicopee]

I suppose that in addition to an automatic fixed foam fire extinguishing system as proposed above, you could install water storage tanks piped to fire pumps to protect adjacent tanks from a fire. Obviously, the diked tank farm should be increased in size not only to allow for a designed storm event but also for the water in the storage tanks.

 

[08M3Steve]

The main concerns are:Environmental Impact & Financial Liability.
Need to minimize both.
With a limited water supply and a remote location, foam application at each tank seems the most effective and environmentally sound.
I believe NFPA 11 addresses foam systems unless somebody can direct me otherwise.
From what I can find, NFPA 11 requires a minimum of 55-65 minutes of foam application but in reality an oil fire will require much more water/ foam than 55 minutes.

Does anyone have experience with these systems and recommendations for water supply capacity when being supplied from an onsite reservoir?

 

[chicopee]

If water is used for the protection of the tanks, could one agree that the diked area should contain the contaminated water and minimize the environmemtal impact

 

[08M3Steve]

Yes

 

[stookeyfpe]

What specification are these tanks constructed to?

 

[chicopee]

Steel.

On a recent observation of water availability to fight fires, Westover in Chicopee,MA had a fire drill whereby one or two helicopters fitted with water buckets were making filling passes over the Chicopee State Park pond, then emptying these buckets somewhere by the base. That may be an option, for the area mentioned on the OP.

 

[DavidCR]

As an example, looking for a minimum:

For a power plant with an oil tank farm the requirement following NFPA 850 would be based on:

- The duration of the fixed equipment involved in a worst water consuming reasonable design scenario (i.e. NFPA 15 spray cooling on walls of the involved tanks for 1 hr, the duration of the fixed NFPA 11 foam chambers (20 or 30 min)plus foam solution hoses for the diked area for an indicated time (I don´t remember it now). Plus 2hrs of 500gpm for hoses or monitors.

Depending on the particular design scenario, this would lead to capacities around 500m3 to 1000m3 for relatively small installations.

For tank farms in general, depending on the stored liquids and the geometry of the tanks arrays. The protection could be based on big monitors fighting fires for 2hrs or more, that, would lead to huge water demands.

If you dare to look for a minimum with fixed equipment like foam chambers, NFPA 15 spray cooling as the example above, and assuming that it is not your responsibility to provide enough water for manual operations for a brigade trying to solve a big problem, you may be looking for a design minimum and go for a less water design need as in the example. It is a difficult decision.

But of course I would not recommend to use engineering numbers to look for a minimum, especially if you have crude storage, and low flash point liquids, or a particular risky tank farm condition.

If you ask for it to industrial fire fighters, they would ask for fire pumps with the option to get water from a lake or the sea.