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Sunday
May082011

TFE-7

Tank Farm Firefighting Operations

     Section 12-3.1 thru 12-3.1.2 focuses its attention with the competencies for “Planning the Response”. The factors to be evaluated for tank farm firefighting or spill mitigation involving Foam as the initial tool is product specificity. While class “B” is the weapon of choice for flammable liquids, the modern additives of fuels determine what “type” of class “B” will perform efficiently to extinguish fire and suppress vapors. Percentage of non-petroleum additives for environmental emissions, grade of petroleum product and “cracking” bi-products must all be considered when choosing Foam and a system of application. We will restrict our factors to “portable application” to mitigate the three most common incidents found at tank farm

incidents. 1] Flammable liquid spills 2] Flammable liquid spills with a surface pool fire and 3] A flammable liquid storage tank fire.

     Defining the specific product spilled should be immediate from the tank farms emergency pre-plan. Foam choices vary and will be detailed in another post. Once your “type” of class “B” has been chosen and is presumably on-site, portable application can begin. Due to the incredible amount of nearby flammables on-site, primary strategy for spills is to isolate flammable vapors before they ignite. Secondary concerns should be to apply Foam vapor suppression to the spillage confined to the “bermed dike”. Tertiary concerns shall be to transfer the Foamed spillage to a containment tank. The quickest method may be pump transfer from confinement dike to fixed tank or mobile container.

     In the second most prevalent situation, ignited flammable liquid pool fires may afford you time just as a spill does. If the pool fire has been drawn away from tank walls by the natural slope of the dike area, and there is sufficient product volume within the exposed tank {to withstand a limited heating time} allowing the spilled product to burn off may be an option. Only tank farm “operators” can accurately assess this option. However, if the fire pool “IS” making contact with a loaded tank, immediate application with Foam must be implemented. Not only will this prevent tank heating, but also aid in eliminating corrosive contact between spill constituents and tank bottom walls. Transfer or production piping may be in close proximity to the pool fire and may not contain the product volume inside them to absorb heating. If these are exposed to fire, and burn through, a constant supply of fuel to your fire will be created.

     Thirdly, a full surface fire of a bulk storage tank is the most difficult to extinguish with portable equipment. Many factors contribute to its difficulty. Excessive heat from large fire load, re-ignition from hot tank walls, height of the tank itself, burn-back of Foam from the “rain-down “ application method are the greatest challenges. Tank product levels can work against you too. Remember, whatever you add to the surface of the fire causes the level to increase. Continuation of this tactic without lowering the level of the tank by pump transfer will cause an overflow of burning fuel on-top of you! Due to the Foams’ destruction occurring quickly from the “rain-down” method of ground monitors, larger volumes of water and Foam concentrate will be needed. The above factors work against a successful extinguishment.

     The biggest factor you have on your side is to pre-plan the amount of Foam needed, the number of monitors needed in operation at the same time, the pumping capabilities on-site, in position, and functioning, all at once. Because of Foam “burn-back”, it is critical not to begin application until all elements are positioned. Once all equipment and supplies are ready, begin the attack in unison at the same time. Any deviance will cause finished Foam burn-back; reduce your resources, possibly exhausting them before the fire is extinguished. The inability to get above the fire itself and apply a cohesive blanket is the largest drawback for portable ground monitors. Any Foam chambers still intact should be accessed with your pumping capabilities and tank farm Foam supplies. This immediate technique while assembling resources can positively influence your success in extinguishing a full surface tank fire.

                                                                           Haz Mat Mike

 

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