544 Molesworth’s pocket-book.
Centrifugal Pumfs.
(D. Thomson, ‘Trans. Inst. Civ. Eng.,’ vol. xxxii.)
DIAGRAM OF FORM OF VANES.
Divide the quarter circumference into four equal parts with
radial lines; then draw concentric circles with radii = -559K,
• 696 R, • 81 K, and • 91K respectively ; then the intersection of
these circles with the radial lines gives points in the curve
of the vane.
The number of vanea is generally 6.
Duty of vanes of this form = -6s ; if radial vanes — '46.
An 18-inch pump will work well with 20 ft. lift.
36-inch „ „ „ 30 ft. „
I) =. I fiumeter of fan in feet.
H = Head of water in feet, including head corresponding
with friction of pipes, &c.
S = Speed of periphery of fan, feet per second.
Q = Quantity of water lifted, feet per minute.
S = 8 rj H in small fans ; = 9 • 5 V H in large fans.
_ S2 _ S2
H~64 ” ” 5 “ 9^25 ” ”
D = c\/~~^; the value of c varying from *12 to '18
VH
(Unwin),
Diam. of fan, inches 12 16 18 21 24 30 36 |
Discharge, gals, per min.. 1200 1800 2700 3600 4800 7500 10800|