Rotary pumps Selection

From the definition of specific speed (eqs. 9 and 10), it follows that reciprocating pumps operate at high pressures and low flow rates. Conversely, centrifugal pumps are appHed at lower pressures and higher flow rates. Many rotary pumps are selected for viscous Hquids having pressures equal to or less than, and capacities lower than, centrifugal pumps. However, these limits are relative and a gray area exists as some pump types cross boundaries into the domain of other types. 

Suction and discharge heads are determined the same as for centrifugal pumps. Total head and capacity are used in selecting the proper rotary pump from a manufacturer s data or curves. Since viscosity is quite important in the... 

There are several important calculations which are needed to properly evaluate and select the appropriate rotary pump [17]. These calculations are used in conjunction with Equations 3-32-3-37. 

Resistance, equivalent feet, design, 86-89 Chart, 87, 88 Reynolds number, 55, 67 Calculations, 68 Chart, 110 Rotary pumps, 206 Selection, 214 Type, 213... 

In this region the vrater vapor pressure exceeds the admissible partial pressure at the inlet. The gas ballast pump must, therefore, have a condenser inserted at the inlet, which is so rated that the water vapor partial pressure at the inlet port of the rotary pump does not exceed the admissible value. The correct dimensions of the condenser are selected depending on the quantity of water vapor involved. For further details, see... 

The selection of materials of construction for rotary pumps is critical. The materials must be corrosion-resistant, compatible when one part is running against another, and capable of some abrasion resistance. 

All handling problems are aggravated by the use of 73% NaOH. All systems must be insulated, and pipelines should be traced. Handling temperatures are higher because of the high viscosity and freezing point (63°C). The selection of materials of construction reflects the temperature and concentration of the solution, in accord with Fig. 9.60. Rotary pumps become a more frequent choice with 73% NaOH. 

The main analytical instrumentation in the vehicle is a benchtop GC/MS by Hewlett Packard, HP 5890 GC/5970 MSB (mass selective detector). A basic configuration for analyzing liquid samples includes a heated injection port and a capillary fused-silica column interfaced directly to the MS via a heated transfer line. The MS is a quadrupole design operated under vacuum provided by a diffusion pump and backed by a mechanical rotary pump. System operation and data analysis are performed by a Pentium-level personal computer loaded with proprietary software and a NBS spectral library to aid with identification of unknowns. Depending on the mission, a simpler installation may consist of a GC equipped with an appropriate detector such as the electron capture detector (ECD). 

If a centrifugal is not suitable, select a rotary positive displacement pump. The design usually selects itself. 

A slurry pump operating at 1 atm must be selected to transport a coal slurry from an open storage tank to a rotary drum filter, at a rate of 250 gpm. The slurry is 40% solids by volume and has an SG of 1.2. The level in the filter is 10 ft above that in the tank, and the line contains 400 ft of 3 in. sch 40 pipe, two gate valves, and six 90° elbows. A lab test shows that the slurry can be described as a Bingham plastic with v = 50 cP and t0 = 80dyn/cm2. 

The nomenclature selected for the Dimensional Data Group (Grotq> C) was adcqjted fiom the Hydraulic Institute Standards for Centrifugal, Rotary, and Reciprocating Pumps. For example, the field number COOl, "Width of base srqrport", has the field name definition of "HIS A . This corresponds to dimension "A" in the Hydraulic Institute Standards. 

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