Fire hazard degree

For dammable and combustible hquids, dash point is the primary basis for classifying the degree of fire hazardousness. NFPA Classifications 1, 2, and 3 designate the most to the least fire hazard hquids, respectively. In essence, low dash point hquids ate high fire hazard hquids. 

It is important to identify areas in accordance with the expected degree of fire hazard to facilitate an appropriate and economical selection of electric motors. These areas, according to lEC 60079-10, are classified into three categories as follows. 

A normal enclosure is meant for a reasonably clean atmosphere and a relative humidity not more than 50% for LT and 95% for FIT indoor enclosures. Where the atmosphere is laden with fumes or steam, saline or oil vapours, heat and humidity, excessive dust and water or contaminated with explosive and fire hazardous gases, vapours or volatile liquids (Section 7.11) a special enclosure with a higher degree of protection is required as in lEC 60529 or lEC 60079-14. For non-hazardous areas, the enclosure can be generally one of those discussed in Tables 1. 10 and 1. 11, and when required can be provided with special treatment to the metallic surfaces. For hazardous areas, however, special enclosures will be essential as discussed in Section 7.11. 

Here again there is a classification system with five degrees, already mentioned for fire hazard and reactivity risks. The definition of these five degrees is qualitative.They run from 4 to 1 ie ... 

Liquid resoles, chemical shifts of methylene carbons in, 18 775t Liquid rocket propellants, 10 726-727 Liquid rubber technology, 9 563-566 Liquid runaround systems, 10 144 Liquids. See also Nonideal liquid mixtures boiling points of, 24 2841 bulk handling of, 18 5 combustion of, 13 174 degree of fire hazardousness of, 24 284 density of, 24 282... 

The inherent flammability and low melting point of sulfur impose some limitations of SC use. Flammability can be controlled to some extent by the use of additives, and it is fortunate that the DCPD types of additives used to improve the durability of SC also impart a degree of fire resistance. Sulfur concretes are in any case considerably less of a fire hazard than wood. Because of the low thermal conductivity, heat penetration is slow, and SC can survive short exposures to fire without serious damage. Sulfur concretes do not support combustion, and flame spread is essentially zero. 

At this point a differentiation should be made between a nonflammable and a fire-retardant film. On the one hand, the coating is designed to be applied on a nonflammable substrate and, in this case, the film itself should be as near nonflammable as possible. On the other hand, a fire-retardant film is designed to retard the spread of flame through a flammable substrate. Most commercial paints are fire-retardant to a degree an unpainted wood or wall board surface will burn much more freely if unpainted than if coated with an ordinary flat wall paint such as TT-P-47. There has been a widespread misconception that the dried paint film is a fire hazard, when actually a wood or cellulosic wallboard surface is considerably more readily combustible uncoated than when coated with the average wali paint. 

Fire gas toxicity is an essential component of any fire hazard analysis. However, fire toxicity, like flammability, is both scenario and material dependent. Bench-scale assessment of fire gas toxicity either adopts an integrative approach, where the material is burnt in a fixed volume of air, allowing the initially well-ventilated fire condition to become under-ventilated to an unknown degree, or the ventilation is controlled, so that individual fire stages may be replicated. 

Cleveland Open Cup (COC) and Pensky-Martens (PM). The dosed cup flash point value is usually several degrees lower (more flammable) than the open cup, as the test in the former case is made on a saturated vapor-air mixture, whereas in the latter case the vapor has free access to air and thus is slightly less concentrated, For tliis reason, open cup values more nearly simulate actual conditions (see below), Fire Point (fire pt). Tliis is the lowest temperature at which a mixture of air and vapor continue to burn in an open container when ignited. It is usually above the flash point. Where the flash point is available, only it is given if it is not, the fire point may be given. It is at least as significant as the flash point as an indication of the fire hazard of... 

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