Uses. Essentially all polymer-grade terephthalic acid and dimethyl terephthalate are used to make saturated polyesters, the great majority being poly(ethylene terephthalate). Poly(ethylene terephthalate) is employed to make fiber and is the largest-volume synthetic fiber in the world. Fiber use makes up 73% of worldwide poly(ethylene terephthalate) production (92). It is used for woven and knitted fabrics for clothing, draperies, upholstery, and carpeting. In clothing appHcations, it is usually blended with other fibers, primarily cotton (qv). AppHcations for high strength polyester continuous fibers are reinforcing cord for tires, V-belts, conveyor belts, and hoses (see Fibers, polyester).  [c.492]

Chloroprene Elastomers. Polychloroprene is a polymer of 2-chloro-l,3-butadiene. The elastomer is largely composed of the trans isomer. There are two basic polymer types the W-type and the G-type. G-types are made by using a sulfur-modified process W-types use no sulfur modification. As a result, G-types possess excellent processing and dynamic properties, and tend to be used in V-belts. However, they have poorer aging properties than W-types. The W-types tend to be used in appHcations requiring better aging, such as roUs and mechanical goods (see Elastomers, SYNTHETIC-POLYCm.OROPRENE).  [c.233]

Fan Drivers Electric motors or steam turbines are most commonly used. These connect with gears or V belts. (Gas engines connected through gears and hydraulic motors either direct-connected or connected through gears are in use. Fans may be driven by a prime mover such as a compressor with a V-belt takeoff from the flywheel to a jack shaft and then through a gear or V belt to the fan. Direc t motor drive is generally limited to small-diameter fans.  [c.1079]

Since it is good practice to maintain a selected inventory of spare parts for drives, economy can be achieved by standardizing conveyor drives throughout the plant. For example, intermediate speed reduction by means of V belts, sheaves or chains, and sprockets can frequently permit using the same speed-reducer size for several drives. Thus, it may be necessary to keep only one repair-stock speed reducer for a number of conveyors.  [c.1913]

Mechanical adjustable-speed drives are used when a high degree of regulation is not required. One drive consists of a constant-speed ac motor driving the load through V belts and variable-pitch pulleys. The speed range can be as high as 8 1. It is available up to 18.6 kW (25 hp). Speed adjustment is either manual or remote with a motor drive for the adjustment. Speed regulation from no load to full load is normally 3 to 6 percent. Efficiency is high over the entire speed range since there are no slip losses.  [c.2487]

Pipe-hne and marine installations are frequently arranged so that the engine drives all its auxiharies from the crankshaft by means of chains and V belts. But process-plant practice is to have all the auxiliaries independently driven, using standby pumps to minimize engine downtime.  [c.2494]

A centrifugal compressor driven through V-belts at a speed of 4500 r.p.m. having the torque curve as shown in Figure 2.18 and a moment of inertia /WK of 2.50 kgm employs a squirrel cage motor with the following parameters  [c.46]

The selection of flat belts is made along similar lines to that for V-belts (discussed later in more detail). The load-transmission capacity of a flat belt can be defined by  [c.204]

These are short centre drives unlike flat belt drives. The belt slip in such drives is negligible. The recommended maximum power that can be transmitted through such belts of different cross-sectional areas is provided by the belt manufacturer. The normal cross-sections of V belts in practice are given in Table 8.3. The cross-section of a belt depends upon the power to be transmitted and its speed. To select the appropriate section of the belt for the required transfer of load refer to Figure 8.11 also provided by the manufacturer. It is recommended that  [c.206]

Table 8.3 Nominal cross-sections of V-belts and their code numbers Table 8.3 Nominal cross-sections of V-belts and their code numbers
The load-transmitting capacities of a single V-belt, at 180° arc of contact, are provided by the belt manufacturer as standard selection data for the user for different areas of belt cross-sections and speed of the faster shaft. We have provided this data for a leading manufacturer, for belts of section D, in Table 8.4, to illustrate the selection of V-belts for the drive of Example 8.2.  [c.206]

Consider a reciprocating compressor operating in a process plant and using a motor of 110 kW, 980 r.p.m. The compressor is required to operate at 825 r.p.m. through V-belts. The approximate centre distance between the motor and the compressor may be considered as 1 m.  [c.206]

Figure 8.11 Selection of cross-section for V-belts Figure 8.11 Selection of cross-section for V-belts
Table 8.4 Power ratings for section D V-belts, with 180° arc of contact with the smaller pulley Table 8.4 Power ratings for section D V-belts, with 180° arc of contact with the smaller pulley
Indusirial Power Engineering and Applications Handbook Table 8.5 Service Factors for flat and V-belts  [c.210]

Industrial Power Engineering and Applications Handbook Table 8.7 Arc of contact correction factors [flat and V-belts]  [c.212]

K = belt factor, 2 to 2.5 for V-belts and 2.5 to 2 for flat belts. Sometimes it may be higher (up to 4 to 5). (The higher values must be considered when the distance between shafts is short or belt tension is high).  [c.212]

Transmission of load and suitability of bearings 8/213 Table 8.9 Nominal inside lengths, pitch lengths L for all standard sizes of multiple V-belts  [c.213]

V BELTS Pulleys - V grooved for endless V-belts sections Z, A, B, C, D and E and endless wedge belt Sections SPZ, SPA, SPB and SPC - Specifications 3142/1993 3790/1995 4183  [c.216]

Endless V-belts for industrial purposes - Industrial V-belt drives - calculation of power ratings Pulley and V ribbed belts for industrial applications-PH, PJ, PK. PL and PM profiles 2494-1/1994 3790/1995 4184 5292/1980 9982/1998  [c.216]

To determine the pitch length of V-belts  [c.217]

Effluent air temperature should be limited to 200°F, to prevent potential damage to fan blades, bearings, V-belts, or other mechanical components in the hot air stream.  [c.43]

Most of the drivers used with the sliding vane compressor are electric motors. Variable speed operation is possible within the limits of vane speed requirements. The vanes must travel fast enough to seal against the cylinder wall but not so fast that they cause excessive wear. For the smaller units, under 100 hp, V-belts are widely used. Direct connection to a motor, however, is possible for most compressors and is used through out the size range.  [c.129]

Whenever there is an inherent speed mismatch between a compressor and driver, several solutions are available. For small sizes, V-belts offer advantages in flexibility. For compressors where the power levels approach 100 hp, a more positive drive should be considered. Depending on the application, this value may move up or down by 25 hp.  [c.328]

General features same as steam, except drive ahvays through crankshaft speed gear increasers or reducers V-belts, or direct coupling connection to drive shaft.  [c.217]

For V-helt drive, the type of helt section and maximum number of belts may be specified, as well as the minimum number —usually 3. B-sections are most common. V-belts are not considered for drives over about 50-60 hp, and a minimum service factor of 1.4 should be specified for continuous duty. Belts should not be used in any conditions where the surrounding temperature is greater than 160°F, with or without fens operating. This is of particular importance in induced draft conditions where belts might be in the exit air stream.  [c.254]

V-belts using electric motors are the most common drive for process applications. Belts should be selected to be  [c.542]

Power Belting and V Belts 420. Chains 429.  [c.391]

Power Belting and V Belts  [c.420]

Ribbed, or Joined V Belts  [c.421]

V belts were developed from the older rope drive systems. The grooved sheaves required for ropes became V shaped, and the belt itself was contoured to put the groove. There are. several different configurations of V belts for power transmission applications. Standard sections for V belts are shown in Figure 3-19. The important difference between flat belts and V belts is that they are able to transmit higher torque at smaller widths and tensions than flat belts. The reason for this is the wedging action of the V belts is the sheave groove. Figure 3-20 shows this wedging action of the belt in its sheave groove (Figure 3-21 show s typical sheave designs for single and multiple V belts) [11].  [c.421]

In addition to the standard types of V belts (see Figure 3-19), many manufacturers make V belts that arc specifically designed to have a higher horsepower capacity. 4 hese V belts are shown and compared to standard V-belt cross-sections. These superpower V belts allow shorter center distances and narrow er sheaves without imposing any extra total bearing stresses. Such belts are able to reduce the drive by 30-. )0% and less for horsepow er capacity. In addition, speeds can be increased up to 6000 ft/ min without dynamic balancing of the sheaves because the sheaves arc smaller.  [c.421]

Figure 3-21. Types of sheaves for V belts [11]. Figure 3-21. Types of sheaves for V belts [11].
Modern V belts are nearly all of the closed-loop continuous type which come in standard lengths.  [c.423]

Figure 3-23 shows the constant speed forces in the V belts with drive sheave transferring power via the V belt to the large driven sheave [11]. If centrifugal forces and slippage are neglected, then taut side tension force Fj (lb) is  [c.425]

Principal uses include automotive V-belts, industrial and hydraulic hose, specialty roofing, heels and soles in footwear, wine coveting, and a wide variety of coated fabric uses, eg, rafts. Chloroprene elastomers are also used extensively in adhesives (qv). It is estimated that about 77,000 t of chloroprene are used each year in the United States. The two main suppHers of chloroprene elastomers in the United States are DuPont and Bayer. In addition, Distiguil (France) sells polymers through the A. Schulman Company.  [c.233]

Thermal black is a large particle size, low stmcture carbon black made by the thermal decomposition of natural gas, coke oven gas, or Hquid hydrocarbons in the absence of air or flames. Its use in the United States in 1989 was estimated at about 54—68 million kg or about 4% of total consumption. Although at one time, based on cheap natural gas, thermal black was the least expensive of the regular mbber-grade blacks, it is today the most expensive. It is used in mbber and plastics appHcations for its unique properties of low hardness, high extensibiUty, low compression set, low hysteresis, and excellent processing. Its main uses are in O-rings and seals, hose, tire innediners, V-belts, other mechanical goods, and in cross-hnked polyethylene for electrical cables.  [c.547]

Open-Bottom Basket Centrifuges These centrifuges are made in top-suspended and link-suspended configurations. In both, the bottom bowl nead consists of three functional components contained in a single fabrication (1) the central nave by which the basket is attached to the driveshaft, (2) an outer ring to which the cyhndrical shell is attached and whose inside diameter is less than that of the liquid ring weir on the opposite end of the basket, and (3) spokes connecting the nave to the outer ring. A typical cycle follows that shown in Fig. 18-145. The control of the cycle may be manual, semiautomatic, or fidly automatic. The drive may be a variable-speed elec tric motor, either direct or through V-belts a high-pressure, fixed-volume hydraiilic motor receiving its energy from a constant-speed variable-volume pump or, infrequently in modern practice, a steam or water turbine.  [c.1735]

Cooling tower fans can be directly coupled to the motor, or, cormected via gear boxes or V-belts. Direct drives are limited to small diameter fans. Otherwise, tip speeds would be too great- even with 900rpm motors. Direct drives are, therefore, generally found on small cooling towers or, medium size towers with numerous motors. V-belts are used on the full range of factory assembled towers- from less than 10 tons to over 1,000 tons. They allow the manufacturer to easily tailor the speed of fans through the judicious selection of sheave (pulley) diameters. Fixed pitch prop fans can be used. V-belt drives do not require precise alignment and work fine after the rigors of shipment and rigging. Belts and sheaves come from numerous manufacturers.  [c.84]

For V-bell applications D and d are sheave pilch diameters. From the geometry ol Figure 3-22, 6 is always less than or equal to 180° or n radians. The lower guideline for 6 is approximately 150°. Below this value there will be increasing tension and slip, which will result in decretised life of the V belts. This limit on 6 imposes a lower limit on the center distance and thus a practical limit on the speed ratio attainable is a given V-belt design.  [c.423]

See pages that mention the term V-belts : [c.550]    [c.195]    [c.203]    [c.206]    [c.216]    [c.212]    [c.420]   
Industrial power engineering and applications handbook (2001) -- [ c.0 , c.216 , c.217 ]

Plant Engineer's Handbook (2001) -- [ c.0 ]