Compressed air for pumping

Colburn equation, flat plates 434 Colorimetric methcxls for humidity determination 759 Comings, E. W, 745, 786 Compact heat exchangers 550 Compressed air for pumping 358 Compressibility factor 34, 35,161 Compressible fluids 30, 48... 

Pumps can be used for both loading and unloading nitric acid. Standard chemical pumps may be used for nitric acid concentrations up to 70% if they are made of suitable materials (for example, DIN/EN 1.4408 = UNS I 92900 (ASTM A 296 Grade C78M). Magnetically coupled, side-channel pumps made from Antinite (DIN/EN 1.4361 = UNS S 30601) or compressed-air diaphragm pumps made of PTFE/TFM composite are recommended for highly concentrated nitric acids above 70%97. 

For some tasks very cheap and simple fish tank-type diaphragm pumps are useful. These will produce a vacuum of about SOOmmHg and can also be used to provide compressed air for pressurizing chromatography columns (see Chapter 11). 

Figure 24-2 The Frasch process for mining sulfur. Three concentric pipes are used. Water at about 170°C and a pressure of 100 Ib/in (7 kg/cm ) is forced down the outermost pipe to melt the sulfur. Hot compressed air is pumped down the innermost pipe. It mixes with the molten sulfur to form a froth, which rises through the third pipe.

Compressor - A device used to compress air for mechanical or electrical power production, and in air conditioners, heat pumps, and refrigerators to pressurize the refrigerant and enabling it to flow through the system. 

The combined airmix process operates at a lower paint pressure (2-8 MPa). Additional low-pressure air jets (0.02-0.25 MPa) from the air-cap bores impinge on the spray jet to mix and homogenize it. In addition to the atomizer and a compressed air generator (airless pump), the airmix unit therefore also requires compressed air for postatomization. Advantages over the airless method are the less sharply defined spray jet and the smaller droplet size. Compared with compressed air atomization, a low-mist coating is possible. 

In the 1980s a Bulgarian merchant ship sank in the Black Sea near the town of Odessa. It was proposed to use adhesive to havil it up. For this purpose the breach, holes, and all the sites of leakage in the hull were thoroughly sealed with VAK adhesive, whereupon compressed air was pumped into the hull. Once all the water had been expelled from the ship, it floated to the surface. 

The so-called hyperbar vacuum filtration is a combination of vacuum and pressure filtration in a pull—push arrangement, whereby a vacuum pump of a fan generates vacuum downstream of the filter medium, while a compressor maintains higher-than-atmospheric pressure upstream. If, for example, the vacuum produced is 80 kPa, ie, absolute pressure of 20 kPa, and the absolute pressure before the filter is 150 kPa, the total pressure drop of 130 kPa is created across the filter medium. This is a new idea in principle but in practice requires three primary movers a Hquid pump to pump in the suspension, a vacuum pump to produce the vacuum, and a compressor to supply the compressed air. The cost of having to provide, install, and maintain one additional primary mover has deterred the development of hyperbar vacuum filtration only Andrit2 in Austria offers a system commercially. 

Industrial separations are conducted in gravity or bath separators for a coarse feed, and in centrifugal separators for a fine feed (2,6,10). In gravity-type separators the feed and medium are introduced to the surface of a large quiescent pool of the medium. The float material overflows or is scraped from the pool surface. The heavy particles sink to the bottom of the separator and are removed using a pump or compressed air. The dmm separator (Fig. 13), up to 4.6 m dia and 7 m long, processes approximately 800 t/h, and treats feed of size up to 30 cm dia, operates in the gravity or the... 

Pnettmatically Actuated Diaphragm Pumps (Fig. 10-53) These pumps require no power source other than plant compressed air. They must have a flooded suction, and the pressure is, of course, limited to the available air pressure. Because of their slow speed and large valves, they are well suited to the gentle handling of liquids for which degradation of suspended solids should be avoided. 

An acid egg, or blowcase, consists of an egg-shaped container which can be filled with a charge of liquid that is to be pumped. This container is fitted with an inlet pipe for the charge, an outlet pipe for the discharge, and a pipe for the admission of compressed air or gas, as illustrated in Fig. 10-58. Pressure of air or gas on the surface of the liquid forces it out of the discharge pipe. Such pumps can be hand-operated or arranged for semiautomatic or automatic operation. 

The cost of the filter station includes not only the installed cost of the filter itself but also that of all the accessories dedicated to the filtration operation. Examples are feed pumps and storage facihties, precoat tanks, vacuum systems (often a major cost factor for a vacuum filter station), and compressed-air systems. The dehvered cost of the accessories plus the cost of installation of filter and accessories generally is of the same order of magnitude as the dehvered filter cost and commonly is several times as large. Installation costs, of course, must be estimated with reference to local labor costs and site-specific considerations. 

The operational test of the lube system is, as the name implies, a functional test to check as many of the features as practical under running conditions. The first and last step is a demonstration of the cleanliness of the system. This is followed by a running test of a four-hour duration. The test should simulate the field operation with the compressor in every way practical. All equipment to be furnished with the lube system should be used in the test, including the standby pump start and trip switches. All other instruments should be used to demonstrate their operation. Prior to starting the four-hour run, the system should be thoroughly inspected for leaks and the leaks corrected. If no steam is available for a steam turbine (if one is used), the four-hour run can be made on the electric pump. However, every effort should be made to use an alternate source of energy such as compressed air, to operate the steam turbine. 

In air drilling operation, large compressors and usually a booster compressor are used to compress atmospheric air and supply the required volumetric flowrate to the standpipe in much the same way that mud pumps supply mud for drilling. The volumetric flowrate of compressed air needed (which is usually stated in SCFM of air) depends upon the drilling rate, the geometry of the borehole to be drilled and the geometry of the drill string to be used to drill the hole [64,65]. 

Although not widely used for gears, oil-mist lubrication is nevertheless worth mentioning here. It is a total loss technique in which the oil is supplied in the form of fine droplets carried by compressed air. Two virtues are that the lubricant can be carried long distances through pipes without severe frictional losses, and that no oil pumps are needed since the motive power is provided by factory compressed-air lines. However, unless such systems are totally enclosed, the exhaust can create a build-up of oil-mist in the atmosphere. In order to maintain good standards of industrial hygiene, it is recommended that... 

Solenoid valves are used in refrigeration and air-conditioning systems for refrigerant lines, oil pressure pipes (to control oil return and capacity reducers), and water and compressed air lines. Four-port changeover valves (Figure 9Ab) are used to reverse flow in defrosting and heat pump circuits. A de-energized expansion valve will act as a solenoid valve. 

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