Benzene flammability limits

Figure 16. Flammable limits for methane, ethylene, benzene, with nitrogen, carbon dioxide and water vapor.

Benzene Hexachloride — Rre Hazards Flash Point (deg. F) Not flammable Flammable Limits in Air (%) Not flammable Fire Extinguishing Agents Not pertinent Fire Extinguishing Agents Not To Be Used Not pertinent Special Hazards of Combustion Products Toxic gases are generated when... 

Most industrial installations have adopted the fixed bed technology. The concentration of the hydrocarbon is kept below the lower flammability limits (1.8%), for both inlet and outlet streams. A similar reactor design to that used in benzene oxidation is used to cope with the highly exothermic reaction and heat utilization is a major issue for the economic viability of the plant and its location. 

The temperature at which the vapor in equilibrium with the standard atmosphere above a pool of that liquid is at the lower flammability limit. Reported as open-cup or closed-cup. For materials that vaporize rapidly, the two values are about the same. For materials that vaporize slowly the closed-cup temperatures are always less than open-cup data because of the conditions of the test. Benzene -11.15°C toluene 4.0°C. 

The benzene concentration in the feed mixture with air must be set outside the flammability limits, which are 1.4 and 7.1 per cent volume at 25 C. Operations are conducted below the lower limit at 1.2 to 1.3 per cent volume. The catalyst, placed in a fixed bed, consists of vanadium pentoxide and molybdenum oxide, deposited on a low... 

What are the lower and upper flammability limits of benzene ... 

There are a few general rules which help in the estimation of flammability limits. In the case of hydrocarbons, the lower limit can be estimated from simple formula 6/number of carbon atoms in molecule for benzene and its derivatives the formula changes to 8/num-ber of carbon atoms. To calculate the upper limits, the number of hydrogen and carbon atoms is used in calculation. 

The traditional maleic anhydride manufacturing process involves reacting benzene with excess air. A low benzene concentration is used in order not to exceed the flammability limit of the mixture. The reaction gas mixture is passed over a multitubular, fixed bed catalyst reactor at a pressure of 0.15-0.25 MPa. In addition to maleic anhydride, the reaction produces two moles of CO2 and water. The reaction is highly exothermic, causing "hotspots" of 340-500°C. For each ton of benzene that is reacted, 27MJ of heat are generated. Molten eutectic salts circulate outside the reactor tubes to dissipate the heat. Steam is generated when the molten salts are cooled, which is used to drive air compressors (see Fig. 9.31). 

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

Since this concentration is inside the flammability limits (1.2% of benzene in air is the lower limit, while 8% is the upper limit), the benzene evaporator and reactor should be protected using appropriate safety devices. 

In addition to the chemicals included on the other lists, the CDC also included heavy metals such as arsenic, lead, and mercury volatile solvents such as benzene, chloroform, and bromoform decomposition products such as dioxins and furans polychlorinated biphenyls (PCBs) flammable industrial gases and liquids such as gasoline and propane explosives and oxidizers and all persistent and nonpersistent pesticides. Agents included in this volume are limited to those that are most likely to pose an acute toxicity hazard. 

The xylenes are flammable and are shipped under the same regulations and using the same methods as benzene and toluene rank cars, trucks, barges, and tankers. Pipeline movements are limited. Toxicological problems dictate handling in closed systems like benzene and toluene. 

Butadiene is a colorless, odorless, flammable gas, with a bp of -4.7°C. As of 2000 butadiene has been on the Known to Be a Human Carcinogen list of the Department of Health and Human Services. It has a time-weighted average threshold limit value (TLV) of 2 ppm. TLVs and carcinogens will be discussed more fully under benzene. Butadiene is expensive to store because it polymerizes easily and must be refrigerated. 

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