Small capacity pumps

Small capacity pumps commonly referred to as "jockey" pumps are provided on a firewater system to compensate for small leakages and incidental usage without the main pump(s) startup. They are set to start 0.70 to 1.05 kg/sq. cm. (10 to 15 psi) above the start up pressure of main firewater pumps. In some cases a cross-over from the utility water system can be used in place of a jockey pump, however a check valve is installed to prevent drain down of the firewater by the utility water system. Jockey pumps do not require the... 

Holding pump (vacuum technology) A small-capacity pump used to maintain the foreline pressure of certain types of high vacuum pumps when the use of the main backing pump is not justified. See also Backing pumps. 

Water above 250° F. Single or double suction. This is usually boiler feed service at high pressures requiring multistage pumps. Closed except for very small capacities... 

Coarse abrasives Single suction. Not available for full range of ratings, that is, small capacities not too easily obtained. Often have very large impellers operated at slow speeds for use when solids larger than 1" diameter are the standard diet. This would be of the type called dredge pumps handling sizeable rocks. Closed. 

Figure 3-57. Viscosity performance correction chart for small centrifugal pumps with capacity at best efficiency point of less than 100 GPM (water performance). Note Do not extrapolate. For small centrifugal pumps only, not for axial or mixed flow. NPSH must be adequate. For Newtonian fluids only. For multistage pumps, use head per stage. (By permission. Hydraulic Institute Standards for Centrifugal, Rotary, and Reciprocating Pumps, 13th ed.. Hydraulic Institute, 1975.)...

Rotary pumps with volume capacities up to 50 gal/min are considered to be small-volume capacity pumps. Pumps with volume capacities from 50 to 500 gal/min are moderate-volume capacity pumps. And pumps with volume capacities beyond 500 gal/min are large-volume capacity pumps. 

TWo-Teeth Difference. In this type of pump an abutment on one side plate is used to fill the clearance between the external and internal gear. This construction reduces leakage but involves the use of an overhung internal gear. Such a gear arrangement limits the application of these pumps to small and moderate-volume capacity pumps. 

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. 

Turbine pumps [Figs. 7.9(f), 7.12(i), and 7.4(a)] also are called regenerative or peripheral. They are primarily for small capacity and high pressure service. In some ranges they are more efficient than centrifugals. Because of their high suction lifts they are suited to handling volatile liquids. They are not suited to viscous liquids or abrasive slurries. 

Figure 2.38 shows that a volume of 1000 L (chamber and condenser) will be evacuated to 0.01 mbar in -8 min by a pump with the capacity of 100 m3/h. For a volume of 100 L, a pump with a capacity of 10 m3/h is sufficient. The pump for evacuation only can be relatively small. A pump with 100 m3/h has this capacity also at a pressure of 0.05 mbar however, at this low pressure 100 m3/h represents only 1.4 mbar L/s or 1.1 x 10 3 g/s. This pumping capacity is more than sufficient if the leak rate is smaller than 0.01 mbar L/s, which can be expected for most plants. The critical dimension for the pump size can be the gas from the product. In a chamber of 700 L (plus 300 L condenser volume), there may be, e.g., 10 kg of product, which may have a minimum of 10 g (but often 100 g) of air dissolved within, which may become free... 

It is important to note that most of the cost plots have an exponent that differs somewhat from the 0.6 value. Some of the plots actually show a curvature in the log-log slope, which indicates that the cost exponent for these process units varies with capacity. Variations in the log-log slope (cost exponent) range from about 0.5 for small-capacity units up to almost 1.0 for very large units. This curvature, which is not indicated in the previously published cost curves, is due to paralleling equipment in large units and to disproportionately higher costs of very large equipment in large units, such as vessels, valves, and pumps. The curvature in the log-log slope of cost plots has been recently described by Chase [4],... 

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