Chemicals fluid categories

The three principal Viton categories are (1) Viton A dipolymers composed of vinylidene fluoride (VF2) and hexafluoropropylene (HFP) to produce a polymer with 66% (% wt) fluorine content, (2) Viton B ter-polymers of VFg + HFP -I- tetrafluoroethylene (TFE) to produce a polymer with 68% fluorine, and (3) Viton F terpolymers composed of VF2 + HFP + TFE to produce a polymer with 70% fluorine. The three categories are based on their resistance to fluids and chemicals. Fluid resistance generally increases but low-temperature flexibility decreases with higher fluorine content. Specialty Viton grades are made with additional or different principal monomers in order to achieve specialty performance properties. An example of a specialty property is low-temperature flexibility. 

Clinical chemistry analy2ets ate automated instmments used for measuring concentrations of the various chemical constituents of blood or other body fluids. For a discussion of the related category of instmments used for the measurement of blood cell parameters, see Automated instruments, HEMATOLOGY. 

Most plate heat exchanger designs fall into the viscous flow range. Considering only Newtonian fluids since most chemical duties fall into this category, in laminar ducted flow the flow can be said to be one of three types ... 

Manufacturers and specialist materials development associations publish extensive corrosion data in the form of monographs, and this form of presentation is also used in national standards. The most recent comprehensive text in this category is perhaps the publication by the Zinc Development Association . The work is important in that the section on chemicals also deals with common, though complex, chemical formulations, e.g. Are-extinguisher fluids, soaps and syndets, agricultural chemicals such as pesticides and fertilisers. This publication also demonstrates the mammoth task of recording all the available data for just one material. A comparable book for mild steel would probably be much larger, whereas for many other materials the information has not yet been determined. Thus at best, only very incomplete data are available in this form. 

Mineral Oil Hydraulic Fluids and Polyalphaolefin Hydraulic Fluids. No literature was identified dealing with the bioavailability of chemicals in this category of hydraulic fluids. Because of this wide variation and the lack of any information in mammalian species, it is difficult to estimate bioavailability to humans. Additional research on the bioavailability of this category of hydraulic fluids would be valuable but may not be as high a priority as research on bioavailability issues for the phosphate ester-based hydraulic fluids. 

Nitrite substitutes can be divided into seven chemical categories (1) amine benzoates (2) fatty acid amines (3) phosphate or carbonate silicates (4) organophosphates (5) amine borates (6) alkanolamines and (7) quaternary ammonium compounds ("quats"). Thus, the technology already exists for replacing nitrite with no loss in rust protection. However, most replacements for nitrite are more expensive, less effective, less likely to be compatible with other additives, and work by a different mechanism (12). It is therefore not surprising that fluids containing nitrite are still relatively com mon. 

In the category of silicone coatings used for surface modification of the specific substrates, functional silicone fluids are often used, which can selectively interact with the chemical groups of the substrate, thus modifying its surface properties. The use of functional silicones in the textile industry has been discussed in a number of recent publications.5 421 422 The use of different types of high-performace silicone-coated textiles, which include elastomers and resins, has recently been reviewed.423 The use of functional silicones in personal-care products, for example, in shampoos and hair conditioners, mentioned before,381 provides another well-known example. 

A second category of respiratory toxicity is that characterized by damage to the cells anywhere along the respiratory tract. Such damage can cause the release of fluid to the open spaces of the tract, and result in accumulation of that fluid, or edema, in several areas. These edematous reactions can occur after acute exposure to some chemicals, although the production of edema can be delayed, and arise after subchronic and chronic exposures. 

The possible alternatives to ozone-depleting or otherwise environmentally challenging organic solvents for chemical processes are abundant. We can begin a review by looking at five broad categories aqueous, ionic liquids, supercritical fluids, fluori-nated solvents, or solventless processes (llhnan, 1993). 

The design of heterogeneous chemical reactors falls into a special category because an additional complexity enters into the problem. We must now concern ourselves with the transfer of matter between phases, as well as considering the fluid dynamics and chemistry of the system. Thus, in addition to an equation describing the rate at which the chemical reaction proceeds, one must also provide a relationship or algorithm to account for the various physical processes which occur. For this purpose it is convenient to classify the reactions as gas-solid, gas-liquid and gas-liquid-solid processes. The present chapter will be concerned with gas-solid reactions, especially those for which the solid is a catalyst for the reaction. 

Besides the stress of state in the polymer, environmental stress cracking in polymers involves both solubility and absorption rate phenomena. Sensitizing media that cause ESC can be divided into two categories those that swell or wet the polymer and those that chemically react with the polymer. The medium may be gaseous or liquid. The former mechanism has been the subject of numerous studies and is commonly recognized as the primary cause of the majority of chemically induced failures of polymers. Although both amorphous and semicrystalline polymers are susceptible to ESC, it is well known that amorphous polymers tend to be more at risk. The close packing of chains in the crystalline domains of semicrystalline polymers acts as a barrier to fluid. 

A wide range of fluids with similar physical and chemical properties, including linear and cyclic perfluoroalkanes, linear and cyclic perfluoroethers and polyethers, perfluorotertiary amines and, in a few instances, perfluoroalkylhalides, may be considered to be perfluorinated or fluorous . Solvents within these categories are marketed around the world under a series of brandnames (Table 1). In certain instances, the commercial fluids represent mixtures of similar compounds with... 

Chemicals whose vapors or gases can be intentionally inhaled to give the user a high are called inhalants. The use of inhalants produces psychoactive or mind-altering effects on the user. Inhalants are usually solvent fluids, a category that includes thousands of diverse chemicals. A few such chemicals and products that are abused are lighter fluid, markers, spray paint, and glue. 

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