Spill or pool fire

Spill or Pool Fire - Is a release of a flammable liquid and or condensed gas that accumulates on a surface forming a pool, where flammable vapors burn above the liquid surface of the accumulated liquid. 

Dry chemical agents currently used are a mixture of powders, primarily sodium bicarbonate (ordinary), potassium bicarbonate (Purple K), monoammmonium phosphate (multipurpose). When applied to a fire they cause extinguishment by smothering the fire process. They will not provide securement of a flammable liquid spill or pool fire and it can re-flash after it is initially suppressed if an ignition source is present (i.e., a hot surface). Dry chemical is still very effective for extinguishment of three dimensional flammable liquid or gas fires. It is nonconductive and therefore can be used on live electrical equipment. 

Fire damage to cable trays can be caused by exposure to flames and heat from spill or pool fires below, falling burning liquids from above, thermal radiation from an adjacent fire, or fire originating among the cables themselves. Cable trays and other grouped cable, wire, and nonmetallic tubing runs should be evaluated to determine the potential for fire exposure where warranted by their size and cost or safety-related importance of their service. 

In all of the cases where protection from a spill or pool fire is justified, the structural supports for the cable trays also require fire protection. Protection... 

Fires in processing facilities may include vessel and equipment fires (internal or external), ground level pool fires, multilevel and three-dimensional fires resulting from spills or releases at elevated levels, liquid or gas jet fires from leaks, gas fires from vaporizing liquefied gas releases, or combinations of these. 

Solid floors in multilevel process structures can provide a passive means of containing any spilled liquids or solids and preventing materials from falling onto lower levels. To maximize the effectiveness of solid floors, the floor design should include appropriately located drainage for spills and fire water runoff. Fire protection systems can be designed to effectively manage liquid pool fires. 

Liquid Pool Flames. Liquid fuel or flammable spills often lead to fires involving a flame at the surface of the liquid. This type of diffusion flame moves across the surface of the liquid driven by evaporation of the fuel through heat transfer ahead of the flame. If the liquid pool or spill is formed at ambient conditions sufficient to vaporize enough fuel to form a flammable air/fuel mixture, then a flame can propagate through the mixture above the spill as a premixed flame. 

An integral part of defining the fire-scenario envelope is determining the appropriate dimensions for use in planning fire protection. For liquid hydrocarbon fuels, a frequently used frame of reference is a fire-scenario envelope that extends 20-40 ft (6-12 m) horizontally, and 40 ft (12 m) vertically, from the source of liquid fuel. For pool or spill fires, the source is generally considered to be the extent of the fire as defined by containment such as dikes and curbs. 

When a flammable or toxic material is released, all the potential hazards, except for pool and jet fires, are associated with airborne concentrations of the material. The material is either released as a vapor, subsequently vaporizes from a pool of spilled material, or is entrained as an aerosol during the release and subsequently vaporizes. This section considers methods for suppressing aerosol entrainment and evaporation. 

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