Belt drive pumps

Band assignments, 274,285 Beam current, 164 Belt drive pumps, 118 Benzene, 15... 

The difference between the brake horsepower and the water or liquid horsepower is the pump efficiency. The requirement in either case is the horsepower input to the shaft of the pump. For that reason, the brake horsepower represents the power required by the pump, which must be transmitted from the driver through the drive shaft through any coupling, gear-box, and/or belt drive mechanism to ultimately reach the driven shaft of the pump. Therefore, the losses in transmission from the driver to the pump itself must be added to the input requirement of the driven pump and are not included in the pump s brake horsepower requirement. 

Plunger pumps are available with one, two, three, four, five, or even more cylinders. Simplex and duplex units are often built in a horizontal design. Those with three or more cylinders are usually of vertical design. The driver may be an electric motor, a steam or gas engine, or a steam turbine. This is the common type of power pump. An example, arranged for belt drive, is shown in Fig. 10-28 from which the action may be readily traced. 

For many years the connection between the pump and motor was made with a V-belt, but direct-drive pumps are becoming common. The latter are more compact, smoother running, and perhaps a bit quieter and more reliable. On the other hand, the semiflexible coupler between the motor and pump shaft can... 

Pumps can also be divided into direct-drive or belt-driven models. Direct-drive models run faster and quieter, and they are smaller and lighter for the same level of performance. For many years they were not considered able to withstand the workloads of belt-driven pumps because they tended to wear out prematurely. Fortunately, direct-drive pumps have improved considerably over the years. 

For general experimentation, large manifold systems, and industrial operations, direct-drive pumps are also strongly recommended. If, however, you are pumping a dirty environment, belt-driven mechanical pumps should be considered because their greater oil chambers can better tolerate contamination (see Sec. 7.3.7). They can easily be placed in pans (to catch any accidental oil leaks) on the floor, and they can be left on for days and/or weeks of continuous operation. 

In addition, mechanical pump oils can be specialized for use in specific environments such as those with high-oxygen contents. Some are blended for use in specific types of pumps such as direct-drive pumps, belt-driven pumps, and rotary-piston pumps. As with most things, no single product fits the bill for all circumstances. Thus, there are many varieties, grades, and types of mechanical pump oils. 

Cost of gear pumps. 100 psig discharge pressure. Cost includes pump, base p ate antj y belt drive, but no motor. 

Direct-drive pumps, with an ultimate vacuum that is typically 5 mTorr, are increasingly becoming the dominant design since they are more compact and quieter. However, they are somewhat less durable, since the rotor operates at significantly higher speed than that of a belt-driven pump. A wide variety of pumps with different capabilities are available from Hyvac, Welch, Balzers, Kurt Lesker, Edwards, and Kinney. 

The vacuum pumps initially used in freeze-dryers were of the belt-drive type and, as such, extremely bulky and noisy by current standards. At present, most research-scale freeze-dryers use direct-drive pumps, which are much quieter than the previous models and also, frequently, very small. Because they are constructed from corrosion-proof materials, they are highly flexible in operation. 

In addition to the size factor, the purchase cost of a reciprocating plunger pump depends on the material of construction. The f.o.b. purchase cost of a reciprocating plunger pump of ductile iron construction and a cost index for mid-2000 (CE = 394) (referred to here as the base cost, Cg), is plotted in Figure 16.6. The cost includes a V-belt drive, but not the electric motor. The cost curve in Figure 16.6 is given by flie equation ... 

Pump not turning] drive motor stopped/key sheared or missing/belt drive broken/pump shaft broken. 

Generalized vacuum pump including TEFC motor, base plate and belt drive. FOB cost = 50 000 at the ratio of the gas capacity (kg/h)/the absolute pressure (kPa) =... 

Pumps, rotary screw moyno cast iron with pump, base plate, V-belt drive but excluding motor. FOB cost 10000 at flow rate = 5.5 L/s with n = 0.5 for the range 1-5.5 and n = 0.6 for the range 5.5-25. L+M = 1.6-2.2. L/M = 0.15. Factor without motor, X 1.00 with TEFC motor, X 1.2. 

Pumps, Archimedes screw c/s with 38° inclination with shaft and flights, upper and lower bearing mounts, V belt drive and TEFC motor excluding concrete channel and influent and effluent basins. FOB cost 160 000 at drive power = 10 kW with n = 0.58 for the range 0.6-100. L+M = 1.7-2.1. L/M = 0.3-0.41. 

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. 

Industrial equipment is a continuing area of development for plastics. Pipes, pumps, valves and sight glasses, made from such materials as PVC, PTFE and poly-4-methylpent-l-ene, have become well established on account of their corrosion resistance. The nylons are used for such diverse applications as mine conveyor belts and main drive gears for knitting machines and paper-making equipment. These and other materials are widely used where such features as toughness, abrasion resistance, corrosion resistance, non-stick properties, electrical insulation capability and transparency are of importance. 

Today belts are used in automobiles to drive aux-iliaiy devices such as air conditioning, power brakes, power steering, the alternator, and the cooling fluid pump. Belts also can be found in household appliances such as vacuum sweepers, on lathes in machine shops, or inside copying machines. 

Normal electric motor speeds run from the standard induction speeds for direct connection of 3600, 1800 and 1200 rpm to the lower speed standards of the synchronous motors, and then to the somewhat arbitrary speeds established by V-belt or gear drives. For some cases, the pump speed is set by the type of drivers available, such as a gasoline engine. 

The driver horsepower must be greater than the calculated (or value read from curves) input BHP to the shaft of the pump. The mechanical losses in the coupling, V-belt, gear-box, or other drive plus the losses in the driver must be accounted for in order that the driver rated power output will be sufficient to handle the pump. 

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