Flammability temperature

An application of this test method is ISO 4589-3,149 a method which assesses the LOI at a variety of temperatures (Figure 21.11). The combination of these results allows a prediction of the flammability temperature, at which the LOI has a predicted value of 21, and the percentage of ash remaining after the test. 

The lower and upper flammabihty limits are the boundary-line equilibrium mixtures of vapor or gas with air, which if ignited will just propagate a flame away from the ignition sonrce. Each of these limits has a temperature at which the flammabihty Emits are reached. The lower flammability limit temperature corresponds approximately to the flash point, but since the flash point is determined with downward flame propagation and nonnniform mixtnres and the lower flammability temperature is determined with npward flame propagation and nnifrom vapor mixtures, the measured lower flammability temperature is often somewhat lower than the flash point. 

Flammability temperatures are found by determining the temperature at which the vapor pressure equals the partial pressure corresponding to the LFL or UFL. 

Commercial aviation utilizes low volatility kerosene defined by a flash point minimum of 38 °C. The flammability temperature has been invoked as a safety factor for handling fuels aboard aircraft carriers Navy JP-5 is a low volatility kerosene of minimum flash point of 60°C, similar to other Navy fuels. 

Method 141 Determination of flammability by oxygen index Method 143 Determination of flammability temperature of materials... 

In 2002, Solvay Advanced Polymers introduced new grades of flame retardant Amodel PPA for use in E E applications such as cormectors, chip capacitors, cell phone components, circuit breakers, contactors, relays and switches. A special feature of the new products is their high conductive tracking index and glow wire flammability temperature performance. They are also more colour stable due to their thermal stability when processed at high temperatures. 

SIT significantly depends on fuel composition and its structure as well as on pressure, temperature, and fuel concentration in a fuel vapor/oxidizer system. For typical hydrocarbons SIT lies in the range between 600°C (methane) and 200°C (decane). The lower SIT level = 190°C is used for assessing the danger of aviation kerosene ability to explode. SIT is always much higher than the explosion temperature and significantly lower than the flammability temperature of a heated surface. 

Combustion of a flammable gas-air mixture occurs if the composition of the mixture lies in the flammable range and if there is a source of ignition. Alternatively, combustion of the mixture occurs without a source of ignition if the mixture is heated up to its autoignition temperature. 

Flammability limits are also affected by temperature. An increase in temperature usually widens the flammable range. 

The autoignition temperature is the minimum temperature required for self-sustained combustion in the absence of an external ignition source. The value depends on specified test conditions. Tht flammable (explosive) limits specify the range of concentration of the vapor in air (in percent by volume) for which a flame can propagate. Below the lower flammable limit, the gas mixture is too lean to burn above the flammable limit, the mixture is too rich. Additional compounds can be found in National Fire Protection Association, National Fire Protection Handbook, 14th ed., 1991. 

Substance Autoignition temperature, °C Flammable (explosive) limits, percent by volume of fuel (25°C, 760 mm) ... 

Many grades of acetal resins are Hsted in Underwriters Eaboratories (UL) Kecogni d Component Directory. UL assigns temperature index ratings indicating expected continuous-use retention of mechanical and electrical properties. UL also classifies materials on the basis of flammability characteristics homopolymer and copolymer are both classified 94HB. 

The catalytic vapor-phase oxidation of propylene is generally carried out in a fixed-bed multitube reactor at near atmospheric pressures and elevated temperatures (ca 350°C) molten salt is used for temperature control. Air is commonly used as the oxygen source and steam is added to suppress the formation of flammable gas mixtures. Operation can be single pass or a recycle stream may be employed. Recent interest has focused on improving process efficiency and minimizing process wastes by defining process improvements that use recycle of process gas streams and/or use of new reaction diluents (20-24). 

Storage tanks should have temperature monitoring with alarms to detect the onset of reactions. The design should comply with all appHcable industry, federal, and local codes for a class IB flammable Hquid. The storage temperature should be below 37.8°C. Storage should be under an atmosphere of dry nitrogen and should vent vapors from the tank to a scmbber or flare. 

Thermal Resistance and Flammability. Thermal analysis of PVA filament yam shows an endothermic curve that starts rising at around 220°C the endothermic peak (melting point) is 240°C, varying afitde depending on manufacture conditions. When exposed to temperatures exceeding 220°C, the fiber properties change irreversibly. 

Dehydration or Chemical Theory. In the dehydration or chemical theory, catalytic dehydration of ceUulose occurs. The decomposition path of ceUulose is altered so that flammable tars and gases are reduced and the amount of char is increased ie, upon combustion, ceUulose produces mainly carbon and water, rather than carbon dioxide and water. Because of catalytic dehydration, most fire-resistant cottons decompose at lower temperatures than do untreated cottons, eg, flame-resistant cottons decompose at 275—325°C compared with about 375°C for untreated cotton. Phosphoric acid and sulfuric acid [8014-95-7] are good examples of dehydrating agents that can act as efficient flame retardants (15—17). 

Viayl fluoride is flammable ia air between the limits of 2.6 and 22% by volume. Minimum ignition temperature for VF and air mixtures is 400°C. A small amount, <0.2%, of terpenes is added to VF to prevent spontaneous polymerization. The U.S. Department of Transportation has classified the inhibited VF as a flammable gas. 

Properties. VinyHdene fluoride is a colorless, flammable, and nearly odorless gas that boils at —82°C. Physical properties of VDF are shown in Table 1. It is usually polymerized above its critical temperature of 30.1°C and at pressures above 3 MPa (30 atm) the polymerization reaction is highly exothermic. 

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