Liquids, ignitable, classification

Table 1 Ignitable liquid classification scheme (adapted from ASTM E1618) ...

Lu, Y., Harrington, P.B., Forensic applications of gas chromatography-differential mobility spectrometry with two-way classification of ignitable liquids from fire debris. 

The most frequently encountered accelerants are readily available petroleum distillates such as gasoline, jet fuel, and kerosene. ASTM has published a classification for ignitable liquids that is widely used as part of the forensic analysis of fire debris a summary is presented in Table 10.1. Each class is further... 

Table 10.1 Classification of Ignitable Liquids (after ASTM) ... 

The classification of gases, vapour and volatile liquids according to their ignition temperatures has been given in Table 7.4. The basic requirements of these enclosures,... 

Predictive hazard evaluation procedures may be required when new and different processes, designs, equipment, or procedures are being contemplated. The Dow Fire and Explosion Index provides a direct method to estimate the risks in a chemical process based upon flammability and reactivity characteristics of the chemicals, general process hazards (as exothermic reactions, indoor storage of flammable liquids, etc.) and special hazards (as operation above the flash point, operation above the auto-ignition point, quantity of flammable liquid, etc.). Proper description of this index is best found in the 57-page Dows Fire and Explosion Index, Hazard Classification Guide, 5 th ed., AIChE, New York, 1981. 

A flammable chemical substance is a solid, liquid, vapor, or gas that ignites easily and burns rapidly in air. Many of the flammable chemicals used in laboratories are flammable liquids and organic solvents. The vapors of these chemical substances form ignitable mixtures with air. Based on the flash points of these chemicals, classifications are made. The flash point of a chemical substance is defined as the lowest temperature at which a fuel-air mixture present above the surface of a liquid will ignite, if an ignition source is present. The common flammable chemical substances include, but are not restricted to, acetone, benzene, cyclohexane, ethanol, ethyl acetate, ethyl ether, gasoline, hexane, isopropyl alcohol, methanol, propanol, tetrahydro-furan and toluene, and xylene. 

Flammability classifications of solvents (and other chemicals) are based on flash point (fl.p.) measurements. Flash point is the lowest temperature at which a liquid has sufficient vapour pressure to form an ignitable mixture with air near the surface of the liquid. The following criteria currently apply (CHIP Regulations 2009) ... 

DOT CLASSIFICATION 4.3 Label Danger When Wet, Corrosive, Flammable Liquid SAFETY PROFILE Moderately toxic by inhaladon. Corrosive. A severe irritant to skin, eyes, and mucous membranes. Ignites spontaneously in ait. A very dangerous fire hazard when exposed to heat or flame. Forms impact-sensitive explosive mixtures with potassium permanganate, lead(II) oxide, lead(TV) oxide, copper oxide, silver oxide. To fight fire, use water, foam, CO2, mist. When heated to decomposition it emits toxic fumes of CL. See also CHLOROSILANE. 

The classification procedure for pyrophoric liquids need not be applied when experience in production or handling shows that the substance or mixture does not ignite spontaneously on coming into contact with air at normal temperatures (i.e. the substance is known to be stable at room temperature for prolonged periods of time (days)). 

The NFPA 430 classification system, the fire hazard behavior of liquid and solid oxidizers that can increase the burning rate or cause spontaneous ignition of a combustible material. Also, the reactivity behavior of liquid and solid oxidizers includes those that can undergo a self-sustained decomposition or an explosive reaction. The definitions used to define liquid and solid oxidizer classes can be subject to interpretation. The NFPA 430 classification system is based on the Technical Committee s evaluation of available scientific and technical data, actual experience, and it s considered opinion. A listing of typical liquid and solid oxidizers by class can be found in the Appendix of NFPA 430. The oxidizers listed are assumed to be pure materials unless otherwise specified. 

Depending on the ignitability of their vapors, liquids are classified as flammable or combustible. These two classes differ in their flash point range. A liquid that ignites spontanteously when in contact with dry or moist air, a pyrophoric liquid, is classified as a flammahle liquid. The criteria for these hazard classifications (49CFR 173.115) are as follows ... 

Area classification is employed to identify locations where electrical equipment could provide a source of ignition to flammable liquids and gases/vapours that may be present. It is also used to prevent dust explosions. Area classification is necessary for selecting and installing safer electrical and instrumentation equipment, and its review is very important for revamp projects as it may influence site selection and also project cost. In some cases it may require a change in electrical area classification for existing facilities and hence require replacement of some electrical and instrumentation equipment. 

Auto ignition temperature Upper flammability limit Lower flammability limit Viscosity Refractive index Solubility in water Solubility of water Solubility parameter Hydrogen bond index Fractional polarity Nitro cellulose dil ratio Nitro cellulose dil ratio Surface tension Specific heat liquid Latent heat Dielectric constant Antoine constant A Antoine constant B Antoine constant C Heat of combustion UN number IMO classification ADR/RID classification UK exposure limits USA exposure limits German exposure limits EU classification EU risk phrases EU safety phrases... 

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