Mechanical pumps properties

Substitute (substitution) Use mechanical pump seals vs. packing Use welded pipe vs. flanged Use solvents that are less toxic Use mechanical gauges vs. mercury Use chemicals with higher flash points, boiling points, and other less hazardous properties Use water as a heat transfer fluid instead of hot oil... 

The six major categories of diffusion pump fluids are explained in Table 7.9 (based on information from Laurenson32). Diffusion pump oils, like mechanical pump oils, need to be protected to maintain their properties. Sudden exposure to the atmosphere can destroy hot hydrocarbon pump oils (or even cause them to flash or explode) and damage others oils. Silicone oils, on the other hand, can easily survive contact with oxygen while hot, but their vapors can damage electronic equipment. Occasionally, undesirable vapors can speed the disintegration process of diffusion pump oils. 

The type of nasal device employed in delivering a drug formulation plays a major role in the efficacy of the treatment. In general, two types of delivery systems are used mechanical pumps and pressurized aerosol containers. The properties of the drug to be used influence the selection of the system. The various types of delivery devices are described in the following sections. 

Stability. When using this type of oil, the mechanical pump may have a sump heater to decrease the viscosity of the oil, particularly for startup. These pump oils have inferior lubricating properties compared to the hydrocarbon oils. The oil in the mechanical pump may be filtered, treated, and cooled if a circulation system is included. 

In the jet vapor deposition (JVDtm) process, evaporated atoms/molecules are seeded into a supersonic jet flow of inert carrier gas that expands into a rapidly pumped vacuum chamber. The jet transports the atoms/molecules to the substrate surface where they are deposited. The vapor source can be in the form of thermal evaporation or sputtering and is located in the jet nozzle. The deposition chamber pressure is about 1 Torr and is pumped using high capacity mechanical pumps. The JVD process can be combined with high current ion bombardment for in situ control of the film properties. 

Initial or primary oil recovery is accomplished primarily by use of the inherent energy of the oil reservoir—that is, the pressure of the gases and volatile hydrocarbons trapped under high pressures and temperatures in the rock formation. For shallow wells, mechanical pumping may be used. Additional recovery may be accomplished by the injection of water or steam into the rock to maintain a high pressure in the system and force additional oil to the surface through production wells. The use of such mechanisms can normally result in the recovery of about 40% of the potential oil in the formation. Beyond that point, more drastic (and more expensive) measures must be employed. Such measures may involve the use of surfactants and polymers for the alteration of the interfacial and rheological properties of the oil deposit and the fluids injected to facilitate movement of the crude toward production wells. 

The guarded hot-plate method can be modified to perform dry and wet heat transfer testing (sweating skin model). Some plates contain simulated sweat glands and use a pumping mechanism to deUver water to the plate surface. Thermal comfort properties that can be deterrnined from this test are do, permeabihty index (/ ), and comfort limits. PermeabiUty index indicates moisture—heat permeabiUty through the fabric on a scale of 0 (completely impermeable) to 1 (completely permeable). This parameter indicates the effect of skin moisture on heat loss. Comfort limits are the predicted metaboHc activity levels that may be sustained while maintaining body thermal comfort in the test environment. 

The surface mud system is designed to restore the mud to the required properties before it is pumped downhole. Most of the equipment is used for solids removal only a small part of the surface mud system is designed to treat chemical contamination of the mud. There are three basic means of removing drilled solids from the mud dilution-discard, chemical treatment, and mechanical removal. 

Scheiner-Bobis G (2002) The sodium pump. Its molecular properties and mechanics of ion transport. Eur J Biochem. 269 2424—2433... 

Siloxane-urethane segmented copolymers, which have very good mechanical, fatigue and surface properties 370,377 or their blends with conventional polyurethane-(ureas) have been successfully used in the production of blood pumps, intra-aortic balloons and artificial hearts 200,332,370,376,377). 

Other uses of thickening agents include pharmaceutical preparations, paper production, and oil well drilling fluids. This latter use is necessary because oil is obtained from rock that is porous. In order to remove the oil without altering the mechanical properties of the porous rock, viscous liquids ( drilling fluids ) are pumped into the rock to replace the oil. Among the substances that can be used for this purpose are thickened aqueous solutions of polymers such as poly(acrylic acid) or poly(acrylonitrile). 

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