Oxygen grades

Fire resistance is naturally weak. For general-purpose grades, oxygen indices are roughly 25 up to 27 with a V2 UL94 rating. 

Aviator s breathing grade oxygen, used because of its low moisture content, was delivered to the ozonator through a pressure regulator, an iron case meter, and an orifice manometer. Suitable connections were provided for measuring the frost point, pressure, and temperature. 

After passage through a rotometer, molecular gas entered the reaction system through a capillary orifice, A. Pressure was monitored by a McCloud gauge attached to side arm E, located 50 cm. beyond the gas inlet. Pressure was maintained at 1.2 torr and flow rates at 150 cc. per minute, S.T.P. U.S.P. grade oxygen and instrument grade carbon dioxide were used. 

As outlined in a previous paper (3), the original four-compartment autoclave was replaced with a five-compartment autoclave in 1997. Technical grade oxygen is sparged into the first four compartments, and return acid is added to all compartments. With the new autoclave, the concentrate feed rate has increased from 18.5 t/h to 23 t/h. 

A) Part of the standard grade oxygen can be reacted over a palladium or another suitable noble metal catalyst at 500°C, converting the hydrocarbons and some of the oxygen to carbon dioxide and water ... 

B) Part of the standard grade oxygen can be fed to a standard three-component distillation process (requiring two additional distillation columns) to remove both the light and heavy impurities (King, 1980). 

When industrial-grade oxygen is combusted with either gaseous, liquid or solid fuels in a furnace, it generally optimises thermal efficiency and fuel burnout. Thanks to the higher partial pressure of O2 and the exclusion of nitrogen ballast, reactivity in furnaces improves and flue gas volume decreases (see Fig. 2.41). 

Although acetic acid and water are not beheved to form an azeotrope, acetic acid is hard to separate from aqueous mixtures. Because a number of common hydrocarbons such as heptane or isooctane form azeotropes with formic acid, one of these hydrocarbons can be added to the reactor oxidate permitting separation of formic acid. Water is decanted in a separator from the condensate. Much greater quantities of formic acid are produced from naphtha than from butane, hence formic acid recovery is more extensive in such plants. Through judicious recycling of the less desirable oxygenates, nearly all major impurities can be oxidized to acetic acid. Final acetic acid purification follows much the same treatments as are used in acetaldehyde oxidation. Acid quahty equivalent to the best analytical grade can be produced in tank car quantities without difficulties. 

In normal practice, inhibitors such as hydroquinone (HQ) [123-31 -9] or the monomethyl ether of hydroquinone (MEHQ) [150-76-5] are added to acrylic monomers to stabilize them during shipment and storage. Uninhibited acrylic monomers should be used prompdy or stored at 10°C or below for no longer than a few weeks. Improperly iahibited monomers have the potential for violent polymerizations. HQ and MEHQ require the presence of oxygen to be effective inhibitors therefore, these monomers should be stored in contact with air and not under inert atmosphere. Because of the low concentration of inhibitors present in most commercial grades of acrylic monomers (generally less than 100 ppm), removal before use is not normally required. However, procedures for removal of inhibitors are available (67). 

Acid Oxidation. Reactions of lead with acid and alkaUes are varied. Nitric acid, the best solvent for lead, forms lead nitrate acetic acid forms soluble lead acetate in the presence of oxygen sulfuric acid forms insoluble lead sulfate. Sulfuric acid is stored in containers with chemical or acid-grade lead. Lead dissolves slowly in HCl, but in the presence of aqueous alkaUes forms soluble plumbites and plumbates. 

Depending on their stmctural type, PEPE oils are stable up to 300—400°C ia air. Pure oxygen ia a test bomb at 13 MPa (1886 psi) at temperatures up to 400°C was tolerated with no ignition (43). Densities at 20°C vary from 1.82 to 1.89 g/mL, and viscosities from 10 to 1600 mm /s. The pour poiat for low temperature operation usually ranges from —30 to —70° C, and the viscosity iadex varies from about 50 for low viscosity grades up to 150 for more viscous oils and considerably higher for fully linear polymers (43). 

Ura.nium, The hydrometallurgical treatment of uranium ores is a concentration and purification process. Typical ore grade is 0.1—0.5% U Og, and pregnant solutions contain ca 1 kg/m of U Og. The dissolution requires the presence of an oxidant, either oxygen or a ferric salt. 

In the United States, the Compressed Gas Association Hsts nine grades of nitrogen, differentiated by oxygen content, dew point, total hydrocarbon content, and other contaminant levels (25). These grades, more often specified in government than commercial contracts, are shown in Table 3. 

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