Pentanes flash points

Pentanes are only slightly toxic. Because of their high volatihties and, consequently, their low flash points, they are highly flammable. Pentanes are classified as nonreactive, ie, they do not react with fire-fighting agents. The fire ha2ard properties for pentanes are Hsted in Table 8 (38). 

Pentane Bp, °C Flash point, °C Ignition temperature, °C Lower Upper... 

A commercial solution of f-BuLi in pentane may be substituted for t-BuLi in heptane. However, the lower volatility and higher flash-point of the heptane solvent makes t-BuLi in heptane much easier and safer to handle than this alternative. 

Ignitability-flammability. A liquid that has a flash point of less than 60°C (140°F) is considered ignitable. Some examples are benzene, hexane, heptane, benzene, pentane, petroleum ether (low boiling), toluene, and xylene(s). 

Expandable PS beads are a material devised to accommodate the transportation drawbacks of foams. Foams take up a lot of room, but not much weight, so a truck or boxcar cannot be used very efficiently. Expandable PS beads can be readily turned into foam at their destination. The beads are impregnated with a volatile liquid like pentane as they are extruded, chopped, and cooled. Later, on site, the beads are heated in small batches with steam. The vaporization temperature of the pentane is just below the melting point of the PS beads. As the beads soften, the pentane flashes (volatilizes) and causes the PS to foam. The polymer is then ready for molding. Coffee cups, ice chests, life preservers, buoys, and floats are often fabricated this way. 

The solvents in the black category are there for a number of reasons pentane and diethyl ether because of their low flash points the chlorinated solvents, pyridine and benzene because they are carcinogens and the polar aprotic solvents dimethylamine (DMA), A,A-dimethylformamide (DMF) and A-methyl pyrolidin-2-one (NMP) because they are toxic. Alternatives for many of these are readily available in most laboratories and some of them are listed in Table 1.8. 

Class IA - Liquids with flash points below 73°F and boiling points below 100 F. An example of a Class lA flammable liquid is n-pentane (NFPA Diamond 4). 

METHYL PENTANE (107-83-5) Forms explosive mixture with air (flash point —20°F/—9°C). Violent reaction with strong oxidizers. Incompatible with nitric acid, sulfuric acid. Flow or agitation of substance may generate electrostatic charges due to low conductivity,... 

PENTAN-2,4-DIONE (123-54-6) Forms explosive mixture with air (flash point 93°F/ 34°C). May form unstable peroxides on prolonged storage in air may undergo explosive polymerization. Reacts violently with strong oxidizers. Incompatible with aliphatic amines, alkanolamines, organic acids, isocyanates. 

Hexane is a six-carbon alkane and has a boiling point of 156°F, a flash point of -7°F, a flammable range of 1.1 to 7.5%, and an ignition temperature of 437°F. The structure and molecular formula for pentane are shown in Figure 5.29. 

F]), cyclohexane (245 C [473°F]), re-pentane (260°C [500°F]), ethanol (365°C [689°F]), methanol (385 C [725 F]), and isopropanol (399°C [750 F]). Table IX.l provides flash point and autoignition temperature data for some common flammable compounds. The flammability data for these compounds, as well as those of other flammable and combustible substances, are presented throughout this book. 

Arkema recommends a small quantity of /ra 5-l,2-dichloroethylene to reduce the flammability of pentanes. It has a boiling point of 48 C, a flash point of 2 °C and a good environmental profile in terms of global warming and ozone depletion. 

Again, there is no hard line between what is safe and what is not, but solvents with flash point of less than -18°C are not used. A solvent with a flash point above -18°C can be used but special precautions must be taken such as grounding of all drums and reactors to prevent buildup of electrostatic electricity and excluding all other sources of ignition. All other solvents (toxic or flash point <-18°C) must be replaced. For example, chlorinated solvents (chloroform, carbon tetrachloride), which are carcinogenic, can be replaced with ethyl acetate. Solvents such as pentane (flammable) or hexane (forms electrostatic charges) are replaced with heptanes. Benzene (a carcinogen) is replaced with toluene or xylene. Diethyl ether is replaced with t-butyl methyl ether and dioxane with tetrahydrofiiran. 

Feed analyses in terms of component concentrations are usually not available for complex hydrocarbon mixtures with a final normal boihng point above about 38°C (100°F) (/i-pentane). One method of haudhug such a feed is to break it down into pseudo components (narrow-boihng fractions) and then estimate the mole fraction and value for each such component. Edmister [2nd. Eng. Chem., 47,1685 (1955)] and Maxwell (Data Book on Hydrocarbons, Van Nostrand, Princeton, N.J., 1958) give charts that are useful for this estimation. Once values are available, the calculation proceeds as described above for multicomponent mixtures. Another approach to complex mixtures is to obtain an American Society for Testing and Materials (ASTM) or true-boihng point (TBP) cui ve for the mixture and then use empirical correlations to con-strucl the atmospheric-pressure eqiiihbrium-flash cui ve (EF 0, which can then be corrected to the desired operating pressure. A discussion of this method and the necessary charts are presented in a later subsection entitled Tetroleum and Complex-Mixture Distillation. ... 

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