Fuel and Ventilation
The quantity of
combustibles in a space and their location (e.g., high elevations, stacked
against walls, etc.) also play roles in determining preferred fire-protection
designs. For rack storage or other spaces with obstructions that could impede
the effective application of water from ceiling-mounted sprinklers, spray
nozzles at different elevations may be necessary. The supply of fresh air into a
space by natural and mechanical means also impacts design choices.
Different extinguishing agents are well suited for different
occupancies and commodities. Liquid water is the most common extinguishing
agent, but steam, carbon dioxide, dry chemicals (e.g., bicarbonate of soda), wet
chemicals (e.g., aqueous solution of potassium carbonate and/or potassium
acetate) and other materials may be preferred for some hazards.
Detector, Nozzle and Pipe Variables
water is selected as the extinguishing agent, a number of nozzle styles are
available (sprinkler, water spray, water mist and steam). Choices also exist for
piping and valve design (e.g., wet pipe, dry pipe, deluge, circulating,
preaction and antifreeze). Detectors can be mechanical (fusible links) or
electrical (temperature switch or fused contacts).
solutions are often implemented for special hazards. The interior of processing
equipment may be incompatible with conventional sprinklers due to chemicals or
extreme temperatures and pressures. Such locations could be best served by inert
gas or other extinguishing agents. Ducts that convey combustible particulate
matter may require spark-detection and rapid extinguishing-agent discharge to
prevent a deflagration and explosion. Non-metal, product-conveying ducts and
plenums should be manufactured with fire-retardant material or protected by
Obviously, the design of an effective fire-suppression
system involves numerous subsystems and many choices for the plant owner. In
Part 3, some specific fire-protection examples will be discussed along with
reasons to select or avoid many of these design choices.