Flammability, of mixtures

The MIE of gas — air or vapour—air mixtures can be determined from the structural formula and the molar heat of combustion of the compounds studied, and equations for the calculation are presented. The method is stated to give more accurate results than conventional methods used to assess flammability of mixtures of gas or vapour with air [1], It is claimed that in oxygen MIEs are about a hundredfold lower than in air [2], A study of the ignition behaviour of dusts, including correlation of electrical and mechanical minimum ignition spark energies and ignition temperature is made [3],... 

Fig. 3. Test of flammability of mixtures containing 3.1% to 10% of Pxy-TFSI (a) lighter flame in contact with the soaked paper, (b) gentle burn.

The flash point measures the tendency of a petroleum material to form a flammable mixture with air. It is one of the properties to be considered when evaluating the flammability of a petroleum cut. 

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). 

Ethyl alcohol under ordinary conditions is a volatile, flammable, clear, colorless Hquid. Its odor is pleasant, familiar, and characteristic, as is its taste when suitably diluted with water. The most amazing property of ethanol is the volume shrinkage that occurs when it is mixed with water, or the volume expansion that occurs when it is mixed with gasoline. One volume of ethanol plus one volume of water results ia only 1.92 volumes of mixture. 

Flammability Limits There are both upper (or rich) and lower (or lean) limits of flammability of fuel-air or fuel-oxygen mixtures. Outside these hmits, a self-sustaining flame cannot form. Flammability limits for common fuels are listea in Table 27-18. 

Below atmospheric pressure there is no effect on the limits of flammability of natural gas-air mixtures and most other gas-air mixtures. Below about 25 mm absolute pressure, carbon monoxide-air mixtures are not flammable. 

Detonations can only take place within the detonable limits, which fall inside the flammable limits. Mixture composition may vary widely in some systems, and this can further depend on the number of connections feeding a manifolded header. There are few cases where it can be assumed that a nondetonating flammable mixture will be produced hence, most in-line flame arrester applications involve the use of detonation flame arresters. 

The quantity of mixture present in the propane-air jet can only be estimated if a simplifying assumption is made that the jet flow is not influenced by rigid objects. If not, according to the Yellow Book (1979), the volume of flammable mixture in the jet equals 215 m, which corresponds to a quantity of energy of... 

Figure 7-50. Effects of pressure on limits of flammability of ethane-nitrogen-air mixture at 26°C. By permission, U.S. Bureau of Mines, Bulletin 627 [43],...

Lx = distance between adjacent vents, meters or feet LEL = lower explosive, or lower flammable limit, percent of mixture of flammable gases only in air Lj, Lj, etc = lower flammability limits, vol % for each flammable gas in mixture... 

At this moment, the price of the used granular PCM exceeds 10 EURO/kg due to the test production stage. Our calculation showed the cost payback time can be less than 10 years when the PCM cost would be reduced to 4 EURO/kg under the electrical utility rate condition in Japan. Further cost reduction will be needed to promote the actual system. In addition we have to care of flammability of paraffin wax as PCM in use of inside the buildings. Fortunately, PCM is placed under the OA floor board made of fireproof cement-mortal and above the concrete slab in this system. It may not have any problems under the Fire Defense Law in Japan. However, further development of noninflammable PCM granules, for example micro encapsulation of mixture of inorganic and organic PCM, is required. 

When synthesizing a process, the occurrence of flammable gas mixtures should be avoided, rather than relying on the elimination of sources of ignition. 

MRH values calculated for 31 combinations with oxidisable materials are given [1]. Flammability limits and auto-ignition temperatures for a number of mixtures with organic fuels are measured and reviewed. All experimental work reported is in the vapour phase, detonation is common. Precautions for chlorination reactions are considered [2],... 

Checkel, M. D. et al., J. Loss Prevention, 1995, 8(4), 215 Flammability limits of mixtures of nitric oxide and ammonia were studied. The limits are 15-70% ammonia tenfold pressure rise and explosion are possible. Introduction of oxygen into flammable compositions will produce autoignition, via nitrogen dioxide formation, contamination with air might. 

Diethyl ether is a very low-boiling, highly flammable liquid => open flames or sparks from light switches can cause explosive combustion of mixture of diethyl ether and air. 

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