Flash point, flammability terms

KEY TERMS flash point flammable vapor pressure... 

No single parameter defines flammability. Commonly used terms are flash point, flammability limits, autoignition temperature, minimum ignition energy and burning velocity. 

Butylenes are not toxic. The effect of long-term exposure is not known, hence, they should be handled with care. Reference 96 Hsts air and water pollution factors and biological effects. They are volatile and asphyxiants. Care should be taken to avoid spills because they are extremely flammable. Physical handling requires adequate ventilation to prevent high concentrations of butylenes in the air. Explosive limits in air are 1.6 to 9.7% of butylenes. Their flash points range from —80 to —73° C. Their autoignition is around 324 to 465°C (Table 2). Water and carbon dioxide extinguishers can be used in case of fire. 

Combustible Eiquid A term used to classify certain liquids that will burn on the basis of flash points. The National Fire Protection Association (NFPA) defines a combustible liquid as having a flash point of 100°F (37.8°C) or higher. See also, Flammable Liquid. Class II liquids have flash points at or above 100°F, but below 140°F. Class III liquids are subdivided into two subclasses. 

Flammable Liquid A term used to classify certain liquids as defined by NFPA 30 as a liquid with a closed-cup flash point below 100°F (37.8°C) and Reid vapor pressures not exceeding 40 psia at 100°F (37.8°C). Flammable liquids are called Class I liquids and have three subdivisions as follows ... 

Combustible According to the DOT and NFPA, combustible liquids are those having a flash point at or above 100 degrees F (37.8 degrees C), or liquids that will burn. They do not ignite as easily as flammable liquids. However, combustible liquids can be ignited under certain circumstances, and must be handled with caution. Substances such as wood, paper, etc., are termed Ordinary Combustibles. ... 

As the temperature of a liquid increases, the partial pressure of the vapor above the liquid increases hence, the percentage vapor composition above the pool increases. Liquid boils when its partial vapor pressure reaches the external pressure and the percentage of vapor reaches 100%. Flash point is when the vapor pressure of a substance is such that the concentration of vapor in air above the substance corresponds to the lower flammable limit. For flammable liquids, the term flammable is typically used for liquids with a flash point below 100°F (37.8°C), and the term combustible is used for liquids with a flash point above 100°F (37.8°C) (NFPA, 1997), but this in no way reflects the intensity of an ensuing fire. 

A substance is usually termed flammable if its flash point is below 100°F (38°C). 

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