PI 2001 & IP 19 along with a lot of other international codes provide specific parameters that are to be followed in preventing the occurrence of fires and other calamities in a refinery area. Fuel, oxygen which is present in the atmosphere and heat mixed in the right proportions are the necessary ingredients that are required to begin and sustain a fire. (API 2001, 2005, p.3) Cutting off the supply of any one parameter shall assist in controlling the fire.
Vapor pressure, Flash point, Flame point & boiling point are some of the reference parameters that are used in defining a hazard posed by a particular flammable liquid. Petroleum products which have a certain degree of volatility always releases small amount of vapors at ambient temperature. This release increase’s as the temperature rises. Vapor pressure is thus defined as the pressure exerted by the vapor of the substance when both the vapor and the substance are in equilibrium. Flash point is the lowest temperature at which a liquid gives off enough vapor to produce a flammable mixture. These vapors will ignite but will not continue to burn. At a
Based on the flash point, fuels are classified into flammable liquids and combustible liquids. Flammable liquids have flash points below 100º F and vapor pressure not exceeding 40 psia while Combustible liquids have a flash point at or above 100º F. (API 2001, 2005, p.3) Further flammable liquids are subdivided into 3 classes (in decreasing hazard) based on flash point and
Class C: Fires involving electrical equipment are treated in this category. Class C fires are essentially a manifestation of Class A and Class B fires. Once the electric circuitry is de-energized and the source of electric rupture contained these fires are treated as Class A or Class B fires since these fires would then essentially progress via the combustible solid or liquid source lying in the vicinity of the fire.
For fires to begin and propagate Oxygen, Heat and the flammable fuel may