The illustrated exhibitor: a tribute to the world's industrial jubilee (London, 1851)

242

:he illustrated exhibitor.

THE CENTRIFUGAL PUMP.

they are derived

V

p>-

\

Fig. 1.
is a yertical section, and fig. 3 a front view.

Few objects in the department devoted to machinery in motion more speedily arrest the attention of the visitor
:han Appold's Centrifugal Pump. The following particulars, therefore, will he interesting, the more especially as
from a perfectly competent authority—the " Architects' and Civil Engineers' Journal:"—

Mr. Appold's pump consists of a hollow disc or cylinder as
shown in the annexed engraving, (fig. 1), 12 inches diameter
and 3 inches wide on the rim, with a circular openino- in t}10
centre of 6 inches diameter. This cylinder is inclosed^onboth
sides, excepting the central opening, and is entirely open all
round the rim. The disc is placed vertically on a shaft passing
through its centre, and on the end of this shaft is fixed a
pulley 12 inches diameter, for driving it by a strap from the
gearing of an oscillating steam-engine, having a cylinder 8-i-
inches diameter and 2 ft. 2 in. stroke ; and at the time we saw
it at work the steam-gauge in the machine-room near the
pump showed a pressure of steam of 28 lbs. on the square
inch, and the engine was making 58 revolutions per minute
which will give the velocity of he piston at 250 feet per
minute.!

In order to raise the water, the disc is placed near the tot-
tom of a vertical trunk, as shown in the engravings. Pie. 2

The trunk is 7 ft. 6 in. long, 1 foot wide, and about 22 feet high, and at

the bottom of this trunk is

a tank to receive the water

as it flows out of the upper

valves.- On the face of the

trunk are three outlet-
valves, one placed about a

foot above the surface of

the water in the tank; a

second one at 10 feet, and

a third one at 17 feet above.

The lower part is a tank

with a vertical pipe to carry

off the water into a lower

tank; and when the vertical

valve is closed the other

valve at Ihe bottom is

opened, and the water can

then be drawn up from the

lower tank, giving an ad-
ditional lift of 7 or 8 feet.
The remarks we are now

about to make will refer to

a lift of 10 feet. At the

time of making our ob-
servations, the water was

issuing out of the valve at

this lift at the rate of 1,600

to 1,800 gallons per minute,

and the disc was making

800 revolutions in that

time. At this speed the

velocity of the rim would

be equal to 2,512 feet per

minute, which, if multiplied

by 3 inches (the width of the

disc), would give a superfi-
cial area of 628 feet for the

delivering orifice. The ca-
pacity of the disc is equal

to 339 cubic inches, or

|%l| 1*224 gallon—say 1^- gal-
lon. If this be multiplied
by 800, the number of re-
volutions, it would only jr^, 3.
give 1,000 gallons per mi-
nute, whereas the delivery is, according to Mr. Appold's statement, equal to 1,800 gallons. This may be easily ac-
counted for when we consider the large superficial area of the outlet per minute.

If we take Mr. Appold's statement as the work done at 1,800 gallons per minute, it will be equal to 1,800X
10 lbs. X 10 ft.=180,000 lbs. lifted 1 foot high per minute ; and which, if divided by 33,000 lb. (1-horse power), will
give as the result about 5^-horse power. The power of the engine at the time it was doing this work was equal to
8-52 x -7854 x 28 lb. X 250 ft. the velocity of the piston=397,000 lbs lifted 1 foot high per minute, which, if divided by
33,000 lbs. will give 12-horse power.

The following observations are extracted from Mr. Appold's prospectus:— ,

" From the results of various experiments, it has been found that the loss 0 power would not be more tnan
30 per cent. It will be observed the centrifugal force is not so much in the large diameter, on account 01