Methanol flammability limits

Fire Hazards - Flash Point (deg. F) 182 CC (based on solution of 37 % fonnaldehyde and Methanol free), 122 CC (based on solution with 15 % Methanol) Flammable Limits in Air (%) 7.0 - 73 Fire Extinguishing Ageras Water, diy chemical, carbon dioxide, or alcohol foam Fire Extinguishing Agents Not To Be Used No data or recommendations found Special Hazards of Combustion Products Toxic vapors form Behavior in Fire Not pertinent Ignition Temperature (deg. F) 806 Electrical Hazard Not pertinent Burning Rate Not pertinent. 

Some organic compounds can be in solution with water and the mixture may still be a flammable mixture. The vapors above these mixtures such as ethanol, methanol, or acetone can form flammable mixtures with air. Bodurtha [39] and Albaugh and Pratt [47] discuss the use of Raoult s law (activity coefficients) in evaluating the effects. Figures 7-52A and B illustrate the vapor-liquid data for ethyl alcohol and the flash point of various concentrations, the shaded area of flammability limits, and the UEL. Note that some of the plots are calculated and bear experimental data verification. 

Flammability Limits of Methanol-Air Mixtures The Effect of Water Vapor On, is discussed by K. Dvorak A. Reiser in ChemLisry 49, 467-72(1955) CA 49, 9927(1955) (A static app suitable for liquid foels is described. Results for water-median e-air mixts are given. A simple correlation method on (he basis of heat balances is attempted)... 

T. Urbanski, Influence of Non-Explosive liquids on the Detonation Rate of Solid Explosives , ArchProcesouSpalania 3 (2), 117—32 (1972) CA 78, 99944 (1973) [The author discusses the effect on the deton rate of adding w to PETN, RDX, p-Nitrotoluene or TNT in concns of from 5 to 40%. He reports that at low w concns the deton rate is minimized. As the w content increases the deton rate curve passes thru a maximum to reach a second minimum at the higher ( V 40%) level of w concn. The author concludes that the increase in deton rate can be attributed to three factors, the existence of a covolume, a phlegmatizing factor, and the result of mixing of two components, at least one of which is expl] 9) T.V. Ferris, Expansion of Methanol-Air Mixtures at Above Atmospheric Conditions , LossPrevn 8,15—19 (1974) CA 82, 45989 (1975) [Upper flammability limits were detd for various mixts of methanol with air, or a 30/70 02—N2 mixt with and without w. A rise of 12 vol % in the flammability limit above the nominal value of 36 vol % methanol in w-free air mixts is reported in the presence of liq w]... 

Flammability limits of methanol-air mixtures, the effect of water-vapor on 6 F60... 

Highly poisonous, odorless, colorless, tasteless gas. Very flammable, burns in air with a bright blue flame. Ignition pt in air 700. mp-205.0. bp-191.5°. d - M (liq) 0.814. d (gas) 0.968 (air — 1.000). dg at 760 mm 1.250 g/liter. The top pressure is 1500 psi. Flammable limits in air 12 to 75 vol %. Crit press 35 atm, crit temp — 139. Heat capacity at 20° 6.95 cal/mole/ C. Heal value per m3 3033 keal. Heat of formation — 26.39 kcal/mol. Dec into carbon and carhon dioxide between 400 and 700°, at lower temp when in contact with catalytic surfaces. Above 800° the equilibrium reaction favors CO formation. Hopcalite, a mixture of the oxides of manganese and copper, catalyzes the decompn at room temp, as does Pd on silica gel. Sparingly sol in water 3.3 ml /100 ml HjO at O 2.3 ml/100 ml HjO at 2(T freely absorbed by a coned soln of cuprous chloride in HC1 or in NHjOH. Appreciably sol in some organic solvents, such as ethyl acetate. CHCI. acetic acid- The soly in methanol and ethanol is about 7 times as great as the soly in water. 

The lower flammability limits for benzene, methanol and methane are 1.4, 6.0 and... 

The synthesis of formaldehyde from selective oxidation of methanol over a thin layer of electrolytic silver catalyst is a well-known industrial process that occurs in the temperature range of 850-923 K at atmospheric pressure. Since the total reaction is highly exothermic and fast, requiring very short contact time (0.01 s or less), the use of a silicon MSR was demonstrated to improve conversion up to 75% and 90% selectivity at safe conditions within the flammability limits [29]. 

Air is compressed and preheated, fresh and recycled methanol is pumped and preheated, and these two streams are mixed to provide reactor feed. The feed mixture is about 39 mole % methanol in air, which is greater than the upper flammability limit for methanol. (For methanol, UFL = 36 mole % LFL = 6 mole %.) In the reactor, the following two reactions occur. 

This process is typically operated at 600700°C (873973 K) using a methanol-air ratio that is higher than stoichiometric (stoichiometric ratio 0.4) and outside the upper flammability limit (36.5 vol% of methanol in air). In this range of temperature, both the oxidaive [Eq. (11)] and the nonoxidative [Eq. (12)] dehydrogenation process are operative. The carbon-containing by-products are primarily carbon oxides formed by the following reactions ... 

This oxide-catalyzed process operates at a much lower temperature of 270400°C than the silver-catalyzed process, and its feed has a lower methanol-air ratio, which is below the lower flammability limit (6.7 vol% methanol in air). The methanol concentration can be increased without danger of explosion if the oxygen concentration is reduced to below 10 mol% by diluting with recycled off-gas [24]. The amount of air used is in excess of the stoichiometric ratio. Methanol is produced by the highly exothermic oxidative dehydrogenation reaction [Eq. 

As an aside, we might ask why both of the commercial formaldehyde processes operate with feeds where the ratio of air to methanol is far removed from the stoichiometric ratio. The answer is safety, specifically the need to avoid the possibility of an explosion. In both processes, the feed compositions are outside the flammability limits of methanol/air mixtures, so that an explosion is not possible, even if an ignition source is present. In the silver catalyst process, the methanol/air ratio is above the upper flammability limit. In the iron molybdate process, the methanol/air ratio is below the lower flammability limit. 

The low toxicity of DME is comparable to that of liquid propane. Comparatively, methanol is toxic upon skin contact and ingestion. Dimethyl ether has a higher autoignition temperature and lower flammability limit than gasoline [61], however. 

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