Calculation centrifugal pump

API mandates that the pressure drop across a clean filter element be no more than 15% of the allowable pressure drop when dirty. An upper limit of 5 psi drop is set for clean filters. This is a reasonable criterion. If a little arithmetic is performed, the head rise for a centrifugal pump may be calculated. The specifications on both of these items must be coordinated and made compatible. 

The system of Figure 2-27 consists of 125 feet of unknown size schedule 40 steel pipe on the discharge side of a centrifugal pump. The flow rate is 500 gallons per minute at 7o°F. Although the tank is located above the pump, note that this elevation difference does not enter into the pipe size-friction drop calculations. How ever it will become a part of selection of the pump for the serrice (see Chapter 3). For quick estimate follow these steps ... 

Mdien dscous liquids are handled in centrifugal pumps, the brake horsepower is increased, the head is reduced, and the capacity is reduced as compared to the performance with water. The corrections may be negligible for viscosities in the same order of magnitude as water, but become significant above 10 centistokes (10 centipoise for SpGr = 1.0) for heavy materials. While the calculation m.ethods are accepta oly good, for exact performance charts test must be run using the pump in the service. 

The Operating System. Regardless of calculated centrifugal compressor performance, the machine will operate only on or along its operating curve to fit the system of which it is a part. This is quite similar to the system performance of a centrifugal pump. Friction, other pressure drops of the system, and how friction varies with operating conditions determine machine performance. 

There are important calculations that are needed to properly evaluate and select the appropriate centrifugal pump [20]. 

Figure 32.51 illustrates how system NPSH or NPSH-available is calculated for the usual suction systems outlined. For a centrifugal pump, the basic NPSH is calculated from ... 

Brake horsepower, centrifugal pumps, 200 Driver horsepower, 201 Burst pressure, 405, 456 Cartridge filters, 274-278 Capture mechanism, 279 Edge filler, 278 Filter media, table, 278 Micron ratings, 277 Reusable elements, 281 Sintered metal, 280 Types, 276, 277, 279 Wound vs. pleated, 276, 277 Centrifugal pumps, operating characteristics, 177-180 Calculations, see hydraulic performance Capacity, 180... 

Dusts, particle sizes, 225 Dusts, hazard class, 521-523 Explosion characteristics, 524 Efficiency, centrifugal pumps, 200 Ejector control, 380 Ejector systems, 343, 344, 351 Air inleakage, table, 366, 367 Applications, 345 Calculations, 359-366 Chilled water refrigeration, 350 Comparison guide, 357, 375 Evacuation lime, 380, 381 Charts, 382 Example, 381 Features, 345... 

Overall coefficients, 332 Vertical plate coil, 331 Hindered settling velocities, 231, 236 Horsepower, centrifugal pump driver, 201 Hydraulic performance, calculations, 180-188... 

Centrifugal pumps, 181 Discharge systems, 187 Example calculation, 186 Flow friction losses, 185. 186 Friction losses, pipe, see Chapter 2 Friction, 188 Pressure head, 184—186 Static head, 184-186 Suction head, 184, 185 Suction lift, 184, 185 Suction systems, 186 Hvdroclones, 265—267 Application system, 267 Ignition, flammable mixtures, 493 Impellers, centrifugal, reducing diameter, 203 Impellers,... 

Pressure-vacuum relief, 466 Manhours, calculation, 37-40 Material of construction, centrifugal pumps, 211 Pipes, 18, 27, 28... 

Rupture disk, 455 Safety relief valves, 454, 467, 481 Specifications, centrifugal pumps, 209 Spray nozzle particle size, 225 Standards and Codes, 31, 32, 33 Static electricity, 536 Static mixing, 332 Applications, 336 Calculations, 337, 338 Materials of construction, 337 Principles of operation, 335 Type of equipment 334-338... 

Total head, centrifugal pumps, 180, 183 Discharge, 205 Head curve, 198 Suction head, 184, 186 Suction lift, 184, 186 Type, 184 Tubing, 63, 64 Two-phase flow, 124 Calculations, 125-127 Flow patterns, chart, 124 System pressure drop, 125 Types of flow, 124, 125 Utilities check list, process design, 34 Vacuum,... 

The efficiency will depend on the type of pump used and the operating conditions. For preliminary design calculations, the efficiency of centrifugal pumps can be determined using Figure. 5.9. 

You have purchased a centrifugal pump to transport water at a maximum rate of 1000 gpm from one reservoir to another through an 8 in. sch 40 pipeline. The total pressure drop through the pipeline is 50 psi. If the pump has an efficiency of 65% at maximum flow conditions and there is no heat transferred across the pipe wall or the pump casing, calculate ... 

Figure 4.5 shows a typical relationship between the available NPSH in the system and the NPSH required by the pump as the volumetric flow rate of liquid or capacity Q is varied. The NPSH required by a centrifugal pump increases approximately with the square of the liquid throughput. The available NPSH in a system can be calculated from equation 4.9 having substituted for hfs... 

Kinetic Studies. Peracetic Ac id Decomposition. Studies with manganese catalyst were conducted by the capacity-flow method described by Caldin (9). The reactor consisted of a glass tube (5 inches long X 2 inches o.d.), a small centrifugal pump (for stirring by circulation), and a coil for temperature control (usually 1°C.) total liquid volume was 550 ml. Standardized peracetic acid solutions in acetic acid (0.1-0.4M) and catalyst solutions also in acetic acid were metered into the reactor with separate positive displacement pumps. Samples were quenched with aqueous potassium iodide. The liberated iodine was titrated with thiosulfate. Peracetic acid decomposition rates were calculated from the feed rate and the difference between peracetic acid concentration in the feed and exit streams. 

Step 6. Multiply the horsepower per pound of steam value calculated in step 5 by the turbine steam flow, in pounds per hour. This is the total shaft work that appears at the turbine s coupling. This is the amount of horsepower that is available to spin a centrifugal pump. 

Related Calculations. Use the similarity laws to extend or change the data obtained from centrifugal-pump characteristic curves. These laws are also useful in field calculations when the pump head, capacity, speed, or impeller diameter is changed. 

Related Calculations. Use the procedure given here for any type of centrifugal pump where the similarity laws apply. When the term model is used, it can apply to a production test pump or to a standard unit ready for installation. The procedure presented here is the work of R. P. Horwitz, as reported in Power magazine [2]. 

Related Calculations. Use the method given here for any type of pump whose variables are included in the Hydraulic Institute curves (Figs. 6.10 and 6.11) and in similar curves available from the same source. Operating specific speed, computed as above, is sometimes plotted on the performance curve of a centrifugal pump so that the characteristics of the unit can be better understood. Type specific speed is the operating specific speed giving maximum efficiency for a given pump and is a number used... 

Related Calculations. Use this procedure for any centrifugal pump handling any liquid in any service—power, process, marine, industrial, or commercial. Pump manufacturers can supply a temperature-rise curve for a given model pump if it is requested. This curve is superimposed on the pump characteristic curve and shows the temperature rise accompanying a specific flow through the pump. 

Related Calculations. Use the method given here for any uniform viscous liquid—oil, gasoline, kerosene, mercury, etc.—handled by a centrifugal pump. Be careful to use Fig. 6.32 only within its scale limits do not extrapolate. The method presented here is that developed by the Hydraulic Institute. For new developments in the method, be certain to consult the latest edition of the Hydraulic Institute—Standards. 

The latter equation can be used to calculate v or L as a function of time t, once the filtration mode is specified, e.g., constant-pressure filtration, with p constant constant-rate filtration, with constant or centrifugal-pump filtration, with q as a function of p. 

Constant-rate filtration is employed sometimes when an improperly used centrifugal pump may break down the slurry particles. In fact, however, centrifugal pumps are most often chosen for filtration operations. The following example shows the relevant calculations. 

TABLE 14.2 Data and Calculated Results for Centrifugal-Pump Filtration (Example 14.3)... 

Chapter 5 considered pump types and their evaluation and selection. After selecting a pump type, the next step is to size the pump. This requires calculating the flow rate and the pressure rise across the pump or the pump head. The net positive suction head (NPSH), is also important, particularly for centrifugal pumps. NPSH is the difference between the total pressure and the vapor pressure of the fluid at the pump inlet. NPSH will be discussed later. 

---