Page 101 - Centrifugal Pumps Design and Application

82 Centrifugal Pumps: Design and Application

Suction Layout (End View)

See Figure 1-2 for a diagram of the layout.

1. Draw a circle DI at point O.
2. Locate Sections 1 through 7 from Table 7-1.
3. Locate Section A-B perpendicular to flow, approximately D s di-
mension from O. For length of A-B use Table 7-1.
4. Locate nozzle dimensions L and S and mark off nozzle diameter.
Dimension L should be only long enough for gradual area progres-
sion and clearance behind the flange bolting. This clearance be-
comes more critical on horizontally split pumps, where nozzle bolt-
ing may interfere with the parting flange,
5. Connect all points freehand.
6. Locate Section C-D somewhere between A-B and nozzle.
7. Layout volute metal line.
8. Lay in chords PI, Pa, and P 3 to mid point of A-B, C-D, and nozzle
respectively.

Suction Layout (Profile)

See Figure 7-3 for a diagram of the profile.

!. Layout impeller shape, including shaft and sleeve.
2. Layout volute shape and metal line at intersection of chord Pa-
3. Layout volute shape in dotted lines at location X to observe maxi-
mum blockage.
4. Curve metal line around volute sections into the impeller eye,
maintaining minimum metal thickness.
5. Mark off chord lengths PI, ?2, and P 3.
6. Locate nozzle diameter.
7. Approximate width of A' - B' and C' - D' to satisfy area pro-
gression from Figure 7-4.
8. Connect outer wall points freehand with ample curvature into im-
peller eye.
9. Lay in Sections 1 through 7. In this example only Section 1 is
shown.
10. Develop Sections A-B and C-D as surfaces of revolution (Figure
7-5). Sections can be divided into any number of increments (e.g.,
PA and PB). Transfer these chords from the end view to the pro-
file, measure dimensions P' - A' P' - B' and transfer to section
layout.