Pumps, centrifugal double-suction

Figure 7.9. Some types of centrifugal pumps, (a) Single-stage, single suction volute pump, (b) Flow path in a volute pump, (c) Double suction for minimizing axial thrust, (d) Horizontally split casing for ease of maintenance, (e) Diffuser pump vanes V are fixed, impellers P rotate, (f) A related type, Ihe turbine pump.

Fig. 12.—Single-stage centrifugal pump with double-suction impellers.

Use a double. suction impeller. Convert an end suetion centrifugal pump into a split ease horizontal design. 

Figure 3-4. Centrifugal Pump, double suction single-stage impeller. (Courtesy Allls-Chalmers Mfg. Co.)...

Figure 3-50. Typical centrifugal pump characteristic curve vrith auxiliary specific speed curve. Double-suction, single-stage, 6-in. pump, operating at 1760 rpm constant speed. (By permission, Karassik, I. and Carter, B., Centrifugal Pumps, McGraw-Hill Book Co., inc., 1360, p. 197.)...

Figure 3-65 gives the upper limits of specific speeds of single-stage, single and double-suction centrifugal pumps handling clear water at 85°F at sea level [22]. 

Table 3-26 gives the specific speeds for various centrifugal pump types. Table 3-27 gives the suction specific speed ratings for single-suction and double-suction centrifugal pumps. These tables are for pumps handling clear water. 

Don t use cast iron for flammable or hazardous service unless there is no other choice. In very few cases, only cast iron is available. This is true for large double-suction water pumps used by municipalities where types other than cast iron are not readily available. The minimum metallurgy for centrifugal pumps for hazardous or flammable materials is cast ductile iron, type ASTM A 395, having an ultimate tensile strength of 60,000 psi. This metal is not brittle at ordinary temperatures. Often, special alloys are required because of corrosion. In no case should brittle materials be used for a pump if other choices are available. 

What is the upper limit of specific speed and capacity of a 1750-r/min single-stage double-suction centrifugal pump having a shaft that passes through the impeller eye if it handles clear water at 85°F (302 K) at sea level at a total head of 280 ft with a 10-ft suction lift What is the efficiency of the pump and its approximate impeller shape ... 

As a general guide, single-suction centrifugal pumps handle up to 50 gal/min (0.0032 m3/s) at total heads up to 50 ft (15 m) either single- or double-suction pumps are used for the flow rates to 1000 gal/min (0.063 m3/s) and total heads to 300 ft (91 m) beyond these capacities and heads, double-suction or multistage pumps are generally used. 

Volute centrifugal pumps (a) single suction (fi) double suction. 

Centrifugal pumps constitute the most common type of pumping machinery in ordinary plant practice. They come in a number of types other than the simple volute machine shown in Fig. 8.8a. A common type uses a double-suction impeller, which accepts liquid from both sides, as shown in Fig. 8.8h. Also, the impeller itself may be a simple open spider, or it may be enclosed or shrouded. Handbooks, texts on pumps, and especially the catalogs of pump manufacturers show many types, sizes, and designs of centrifugal pumps. 

ProeeSB Pumps. Three 10,000-gpm 225-ft-head horizontal single-stage double-suction centrifugal pumps, each driven by a 700-hp motor, are... 

Heat transport pumps are centrifugal motor-driven pumps, mounted with the shaft vertical and with a single suction and double discharge. 

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