Class A combustible

The technical literature sometimes refers to the "fire point", which in most instances is just a few degrees above the flash point temperamre, and is the temperature the liquid must be before the released vapor is in sufficient quantity to continue to bum, once ignited. However, because a flash fire will normally ignite any Class "A" combustible present in the pafo of the flash, it is... 

Low Level Waste. The NRC 10CFR61 specifies the nature of the protection required for waste containers (20). Class A wastes must meet minimum standards, including no use of cardboard, wastes must be solidified, have less than 1% Hquid, and not be combustible, corrosive, or explosive. Class B wastes must meet the minimum standards but also have stabiHty, ie, these must retain size and shape under soil weight, and not be influenced by moisture or radiation. Class C wastes must be isolated from a potential inadvertent intmder, ie, one who uses unrestricted land for a home or farm. Institutional control of a disposal faciHty for 100 years after closure is requited. 

Portable fire extinguishers are classified according to appHcabiHty Class A for soHd combustibles Class B for flammable Hquids Class C for electrical fires that require a nonconducting agent and Class D for combustible metals. Water frequently is used for Class A extinguishers bicarbonates for Class B and Class BC carbon dioxide or Freon for Class C ammonium phosphate for Class ABC and powdered salt, sodium chloride, for Class D. 

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. 

CLASS A FIRE A fifc involving solids, normally organic, in which combustion generally occurs with the formation of glowing embers. 

Class A fire Wood, cloth, paper or similar combustible material Cooling by water most effective Most suitable Small fires only Small fires only Yes Small fires only No, except for personal clothing on fire No... 

I.P. Borovinskaya, A New Class of Combustion Processes , Combustion Science Technology 10 (1975), 195—201. See also A.G. Merxhanov, Regularities and Mechanism of Combustion of Pyrotechnic Titanium Boron Mixtures , 4th Symposium, see Ref 148, See also V. Maslov et al, On Gasless Combustion Mechanism , FizikaGoreniaiVziyva 12, No 5... 

Pool Fires. Flammable and combustible liquids processed at temperatures such that they remain in a liquid state with limited evaporation upon release will form a pool. These materials, which have the potential for pool fire upon ignition, include NFPA Class I flammable liquids, such as gasoline, and NFPA Class II and Class III combustible liquids. 

Substances applied to or incorporated in a combustible material (e.g. organic polymers, nylon, vinyl and rubber, etc.) to reduce flammability. Act by retarding ignition, control/douse burning, reduce smoke evolution. Slow down or interrupt the self-sustained combustion cycle when the heat-flux is limited. Flame retardants (FRs) improve the combustion behaviour and alter the combustion process (cool, shield, dilute, react) so that decomposition products will differ from nonflame retarded articles. FRs are usually divided into three classes ... 

Hydrogen chloride and chlorine gases form when chlorinated organic compounds in hazardous wastes are burned. If uncontrolled, this chlorine can become a human health risk and is a large component in the formation of acid rain. U.S. EPA has developed different requirements to control the emissions of chlorine from the different classes of combustion units. 

Substances that are water-reactive will nearly always be identified as such on their MSDSs or ICSCs. They may be identified as DOT/UN Hazard Class 4.3 materials for shipping purposes and labeled as dangerous when wet. However, some water-reactive materials are classified otherwise. Acetic anhydride is designated Class 8 it may also be identified as a combustible liquid. 

Ionization and condensation nuclei detectors alarm at the presence of invisible combustion products. Most industrial ionization smoke detectors are of the dual chamber type. One chamber is a sample chamber the other is a reference chamber. Combustion products enter an outer chamber of an ionization detector and disturb the balance between the ionization chambers and trigger a highly sensitive cold cathode tube that causes the alarm. The ionization of the air in the chambers is caused by a radioactive source. Smoke particles impede the ionization process and trigger the alarm. Condensation nuclei detectors operate on the cloud chamber principle, which allows invisible particles to be detected by optical techniques. They are most effective on Class A fires (ordinary combustibles) and Class C fires (electrical). 

While solid fires generally do not have the same impact as flammable material fires in process units, the hazards from solids are important in several respects. Class A materials may be the source of ignition for hazards having a greater combustible loading or posing a greater threat in terms of impact and Class A or D solids may pose a threat due to inherent reactivity or use in a process. For more information on solid fires, refer to SFPE Handbook (Beyer, 2002). Radiant heat from solid fires can be calculated similarly to that of pool fires. 

Water is not suitable for electrical (Class C) fires, but is effective on all combustible (Class A) and many flammable liquid (Class B) fires. Water can be applied by hose streams, monitors, sprinklers, water spray systems, or as water curtains for such purposes as ... 

Multipurpose dry chemical extinguishers (20-A 80B-C) should be provided in warehouses and shop buildings where wood, paper, plastics, and other flammable solids, as well as flammable liquids, may be stored. In grease manufacturing and compounding or similar operations where little or no wood, paper, and similar combustibles are stored, but where flammable liquids may be prevalent, potassium bicarbonate dry chemical extinguishers should be used. Extinguishers should be located not more than 75 ft (23 m) away from any potential Class A fire hazard and not more than 50 ft (15 m) from Class B fire hazards. 

Exposed ordinary combustibles (Class A) should not be permitted to accumulate in the control room area. Process data printouts, batch records, shipping documents, and other paper in the open should be minimized, preferably limited to one-day s output. Where longer-term storage of such paper files or storage of supplies is required, closed-door metal cabinets should be provided. Metal file cabinets should be provided to store drawings, electrical diagrams, manuals, equipment catalogs, etc. 

Laboratories are classified as Class A (High Fire Hazard), Class B (Moderate Fire Hazard), Class C (Low Fire Hazard), or Class D (Minimal Fire Hazard), according to the quantities of flammable and combustible liquids each is allowed to have. Table 8-16 and Table 8-17 (NFPA45) describe the flammable and combustible liquids limitations and the requirements involving automatic sprinkler protection and fire-resistive partition wall separations. The tables apply to laboratories less than 10,000 ft (929 m ) area and should be suitable for most labs in processing facilities. 

Fires are classified based on the type of fuel involved. Fuels are typically placed into three classes ordinary combustibles (like wood and paper), flammable liquids, and combustible metals. For firefighting, a fourth fire class, electrical fires, is also considered. The four main classifications of fire are shown in Table B-1. 

Class A Ordinary combustibles Fires in ordinary combustible materials, such as wood, cloth, paper, rubber, and many plastics. 

When black powder is used to propel rockets it is classed as a composite propellant (where the fuel and oxidiser are intimately mixed) and forms part of a rocket motor in which the powder is compressed to form a monolithic single grain inside a combustion chamber as shown in Figure 3.1. As well as gunpowder, the composite propellant mix will contain a binder which is used to improve the cohesion of the ingredients. Binders form a distinct phase and tend to reduce the sensitiveness of the propellant to shock and impact. When based on organic materials, as is normally the case, they will serve as part of the fuel component also. 

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