Flammable conditions

In another description of the flammability condition, the authors (7) introduced the average rate of heat liberation, q, defined by... 

Nevertheless, it has also been noticed that some interactions between nanoparticles and conventional FRs could occur, particularly reactions leading to new mineral species, such as metallic phosphates, depending on the flammability conditions. 

Most resinous materials used in epoxy adhesive are organic and will bum when sufficient heat and oxygen are supplied. A common measure of the flammability is the flash point temperature. This value indicates the minimum temperature at which flammable conditions are produced in controlled laboratory experiment at atmospheric pressure. Solvents, diluents, and other materials used with epoxy resins commonly increase the hazard of flammability and/or explosion. 

X 14,093) + (0.2513 X 51,623)) - 2,005.93 = 21,518.4. The maximum fluegas quantity or minimum flammability condition for methane is lb fluegas/lb fuel = 21,518/ (carbon fraction x 745) = 38.58 lb, where the carbon fraction represents active combustion carbon. Oxidized or partially oxidized carbon should be treated as inert in this equation. 

A factorial design of kinetic experiments utilizing Au/TS-1 was the first study of propylene epoxidation kinetics in the absence of catalyst deactivation [55]. The adoption of a factorial design allowed for the examination of the largest statistically significant number of reaction conditions centered around the standard reaction mixture of 10/10/10/70 vol% Fl2/02/propylene/diluent while avoiding flammable conditions. The experimental results [55] from the evaluation of three Au/TS-1 catalysts showed that PO production could be approximated using the power rate law expression rpo = k [Fl2] [O2] [CsHe]... 

American Oil Company s experience indicates that tall blown stacks are safe with no more than 6% oxygen 25 feet from the top. This oxygen level is roughly half that required for flammable mixtures with hydrocarbons. Hence, flammable conditions would be limited to less than the top 25 feet of stack. The gas rate required to establish the 6% level 25 feet from the stack top is therefore defined as the minimum safe purge rate. Minor increases in rate are required for the special application of short stacks and hydrogen-rich fuel gas. 

Tall blowdown stacks are safe with no more than 6% oxygen 25 feet from the top. This is roughly half the oxygen required for flammable mixtures with hydrocarbons. Hence, flammable conditions would by limited to less than the top 25 feet of stack. 

The relationship between oxygen concentration and temperature suggests that a stack can be kept nonflammable by temperature control. The steam rate to the stack would be controlled by a differential thermocouple with one junction in the isothermal zone and the other in the declining temperature zone. The latter junction could be placed at the elevation below which non-flammable conditions are to be maintained. 

Containment, venting and suppression are not usually applicable to the reactor itself, but are used to protect downstream equipment such as blenders, dryers, and filter cabinets. They are not dealt with in this guide, but information is available in References 112, 117 and 118. Reference 11 illustrates a basis of safe operation relating to a particular type of reaction (phenolic resin production). Avoidance of sources of ignition and flammable conditions is described in Reference 110 and an outline is given below. 

Keep water in drain traps, particularly for floor drains or sinks used infrequently. Vapors emitted from dry, unsealed drains may cause an explosive or flammable condition such vapors are also the most common source of unexplained laboratory odors. Running water into a drain for 20 to 30 seconds is usually sufficient to fill a drain trap. 

In BWRs, design consideration are made such that the inert gas inside the containment vessel and installation of flammable gas treatment facilities allow to suppress hydrogen concentration not reach the flammable conditions even after a LOCA. 

It has been also confirmed through a safely design evaluation that the design mentioned above does not allow hydrogen to reach the flammable condition even after a LOCA. 

On the other hand, another common aspect in most of the published results is the presence of steam in the process which seems to be essential in the feed mixture, either from an engineering or catal3dic point of view, as it i) favors no flammability conditions by decreasing the concentration of isobutane and O2, and ii) improves catalytic performance by favoring both surface reconstruction of the Keggin catalyst... 

Low pressure. Low pressures are not in general as hazardous as the other extreme operating conditions. However, one particular hazard that does exist in low-pressure plants handling flammable materials is the possible ingress of air with the consequent formation of a flammable mixture. 

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. 

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. 

In the absence of air, TEE disproportionates violently to give carbon and carbon tetrafluoride the same amount of energy is generated as in black powder explosions. This type of decomposition is initiated thermally and equipment hot spots must be avoided. The flammability limits of TEE are 14—43% it bums when mixed with air and forms explosive mixtures with air and oxygen. It can be stored in steel cylinders under controlled conditions inhibited with a suitable stabilizer. The oxygen content of the vapor phase should not exceed 10 ppm. Although TEE is nontoxic, it may be contaminated by highly toxic fluorocarbon compounds. 

Usually, organoboranes are sensitive to oxygen. Simple trialkylboranes are spontaneously flammable in contact with air. Nevertheless, under carefully controlled conditions the reaction of organoboranes with oxygen can be used for the preparation of alcohols or alkyl hydroperoxides (228,229). Aldehydes are produced by oxidation of primary alkylboranes with pyridinium chi orochrom ate (188). Chromic acid at pH < 3 transforms secondary alkyl and cycloalkylboranes into ketones pyridinium chi orochrom ate can also be used (230,231). A convenient procedure for the direct conversion of terminal alkenes into carboxyUc acids employs hydroboration with dibromoborane—dimethyl sulfide and oxidation of the intermediate alkyldibromoborane with chromium trioxide in 90% aqueous acetic acid (232,233). 

Safety is a critical aspect in the design of phenol plants. Oxidation of cumene to CHP occurs at conditions close to the flammable limits. Furthermore, the CHP is a potentially unstable material which can violendy decompose under certain conditions. Thus, phenol plants must be carefully designed and provided with weU-designed control and safety systems. 

Commercially, phosphinic acid and its salts are manufactured by treatment of white phosphoms with a boiling slurry of lime. The desired product, calcium phosphinite [7789-79-9], remains ia solution andiasoluble calcium phosphite [21056-98-4] is precipitated. Hydrogen and phosphine are also formed, the latter containing sufficient diphosphine to make it spontaneously flammable. The details of this compHcated reaction, however, are imperfectly understood. Under some conditions, equal amounts of phosphoms appear as phosphine and phosphite, and the volume of the hydrogen Hberated is nearly proportional to the hypophosphite that forms. 

Fire and Explosion Prevention. Prevention of fire and explosion takes place in the design of chemical plants. Such prevention involves the study of material characteristics, such as those in Table 1, and processing conditions to determine appropriate ha2ard avoidance methods. Engineering techniques are available for preventing fires and explosions. Containment of flammable and combustible materials and control of processes which could develop high pressures are also important aspects of fire and explosion prevention. 

Flammability. Most nylons ate classified V-2 by the Underwriters Laboratory UL-94 test, which means that these nylons are self-extinguishing within a certain time-scale under the conditions of the test. They achieve this performance by means of giving off burning drips. 

PTMEG is a polymeric ether susceptible to both thermal and oxidative degradation. It usually contains 300—1000 ppm of an antioxidant such as 2,6-di-/ f2 -butyl-4-hydroxytoluene (BHT) to prevent oxidation under normal storage and handling conditions. Thermal decomposition in an inert atmosphere starts at 210—220°C (410—430°E) with the formation of highly flammable THE. In the presence of acidic impurities, the decomposition temperature can be significantly reduced contact with acids should therefore be avoided, and storage temperatures have to be controlled to prevent decomposition to THF (261). 

Propylene is a colorless gas under normal conditions, has anesthetic properties at high concentrations, and can cause asphyxiation. It does not irritate the eyes and its odor is characteristic of olefins. Propjiene is a flammable gas under normal atmospheric conditions. Vapor-cloud formation from Hquid or vapor leaks is the main ha2ard that can lead to explosion. The autoignition temperature is 731 K in air and 696 K in oxygen (80). Evaporation of Hquid propylene can cause skin bums. Propylene also reacts vigorously with oxidising materials. Under unusual conditions, eg, 96.8 MPa (995 atm) and 600 K, it explodes. It reacts violentiy with NO2, N2O4, and N2O (81). Explosions have been reported when Hquid propylene contacts water at 315—348 K (82). Table 8 shows the ratio TJTp where is the initial water temperature, and T is the superheat limit temperature of the hydrocarbon. 

Styrene is mildly toxic, flammable, and can be made to polymerize violently under certain conditions. However, handled according to proper procedures, it is a relatively safe organic chemical. Styrene vapor has an odor threshold of 50—150 ppm (72,73). 

The results of small-scale flammability tests are not intended to reflect the hazards of this or any other material under actual fire conditions. 

Butadiene is a noncorrosive, colorless, flammable gas at room temperature and atmospheric pressure. It has a mildly aromatic odor. It is sparingly soluble in water, slightly soluble in methanol and ethanol, and soluble in organic solvents like diethyl ether, ben2ene, and carbon tetrachloride. Its important physical properties are summarized in Table 1 (see also references 11, 12). 1,2-Butadiene is much less studied. It is a flammable gas at ambient conditions. Some of its properties are summarized in Table 2. 

Flammability = 4, ie, very flammable gas, very volatile, and materials that in the form of dusts or mists form explosive mixtures when dispersed in air Health = 2, ie, hazardous to health, but may be entered freely with self-contained breathing apparatus Reactivity = 0, ie, is normally stable when under fire-exposure conditions and is not reactive with water... 

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