=========+==========+==========+===================+===========+=============
Diameter |Capacity, |Elevations|Size Steam Cylinder| Size | Size
Discharge| Gallons | in Feet +---------+---------+Steam Pipe,|Exhaust Pipe,
Opening |per Minute| up to |Diameter | Stroke | Inches | Inches
---------+----------+----------+---------+---------+-----------+-------------
2 | 120 | 25 | 3 | 3 | 3/4 | 1
2-1/2 | 180 | 25 | 3 | 3 | 3/4 | 1
3 | 260 | 25 | 3 | 3 | 3/4 | 1
4 | 470 | 25 | 4 | 4 | 3/4 | 1
5 | 735 | 25 | 5 | 5 | 1 | 1-1/4
6 | 1050 | 30 | 5 | 5 | 1 | 1-1/4
8 | 2000 | 30 | 8 | 8 | 1-1/2 | 2-1/2
10 | 3000 | 10 | 6 | 6 | 1-1/4 | 1-1/2
10# | 3000 | 40 | 12 | 10 | 2-1/2 | 3
12 | 4200 | 20 | 9 | 9 | 2 | 3
12 | 4200 | 30 | 12 | 10 | 2-1/2 | 3
12# | 4200 | 40 | 14 | 12 | 3 | 3-1/2
15 | 7000 | 30 | 14 | 14 | 3 | 4
15* | 7000 | 22 | 12 | 10 | 2-1/2 | 3
18 | 10000 | 30 | 15 | 10 | 4 | 5
18* | 10000 | 20 | 12 | 12 | | 3-1/2
20 | 12000 | 20 | 14 | 14 | 3 |
---------+----------+----------+---------+---------+-----------+-------------
* Low-Lift Pumps. # Special High-Lift Pumps.
The steam shovel, bucket or elevator dredge will do efficient service
in raising material, but none are capable of delivering the material
except within a very short radius of the dredging operation. The
centrifugal dredge not only raises the material, but also delivers it
at the place wanted, at one operation. _Besides, it is practically
impossible to build any other type_ with the enormous capacity that
some hydraulic dredges have.
[Illustration: FIG. 499.]
Fig. 499 is a perspective view of a centrifugal vertical pump of
_the submerged type_. This pump is used largely by contractors in
excavations and coffer dam work and for keeping pits drained.
A double suction centrifugal pump, _driven directly by a steam engine_,
is shown in Fig. 497; these are generally and very satisfactorily used
for circulating water through surface condensers and the cooling pipes
in refrigerating systems. The engine and pump thus combined occupy
small floor space and consequently little masonry is required for a
foundation.
[Illustration: FIG. 500.]
_The Buffalo centrifugal pump_ is shown in Fig. 500. These are built
by the Buffalo Forge Co. in two types, viz., the submerged and the
suction; the latter is the one shown in the cut. The suction type is
employed for pumping from mines, pits, etc., and all places where the
supply will not allow of a horizontal pump to be used, or in others
where the supply is either below the pump, _or sometimes above and
at other times below_. This type possesses merit above the submerged
design in that it will work equally well, when set either above or
below the liquid to be pumped.
_Multi-stage centrifugal pumps._ Experience has demonstrated that by
placing several pumps together and discharging from one into the other,
water can be delivered to almost any height. For a long time after the
introduction of centrifugal pumps, it was supposed that about sixty
feet was the limit for their economical working, owing to the high
speed at which they had to be run to accomplish the results desired.
It was a discovery of importance, that _by coupling two or more pumps
in series_, so that each pump worked against only a part of the total
delivery head, water could easily be raised to even two thousand
feet or any reasonably high head with satisfactory efficiency. Pumps
connected in this way will throw more water at a given speed than when
operated separately, and are therefore attended by less wear and tear.
[Illustration: FIG. 501.]
Pumps worked in series are built compound, triple or quadruple as
required by service either belt driven or directly connected to
engines. Owing to the fact that they have no valves or absolutely
close-parts, they are able to pump muddy or gritty water with sand in
suspension, and are, therefore, especially in the vertical type, the
only ones that can be successfully used for draining deep mines.
Fig. 501 is designed to illustrate _a four stage centrifugal pump_, or
a quadruple compound pump capable of lifting water 250 feet.
[Illustration: FIG. 502.]
_Explanation of diagram page 225._ In determining the requirements best
suited as regards rotation of shaft and connection with the suction and
discharge pipes, in installing a pump, the figure 502, will be found
a convenience. It is important to run the most direct pipes with the
least number of elbows or bends.
The diagram relates particularly to the centrifugal pumps made by
the Morris Machine Works of Baldwinsville, N. Y.; the principle is,
however, of general application. In making use of the diagram each
number represents a particular design. See Note.
_How to determine right-or left-hand pumps._ If, when standing at the
suction end of pump, looking over the pump shell toward the pulley, the
top of the shaft revolves from right to left, or _against the hands of
clock_, the pump is _right-hand_, and from left to right, or _with the
hands of clock_, it is _left-hand_.
_Directions for erecting and running centrifugal pumps._ Place the pump
as near suction water as possible, and limit suction lift to 20 feet or
25 feet.
Erect the pump so that the pump shaft is level; in bolting to
foundation be careful that the frame is not sprung. See that the
bearings are clean and well oiled. The suction pipe and stuffing-boxes
must be air-tight.
Never use pipes smaller than those represented by the flanges on the
pump; avoid elbows or bends as much as possible; if discharging long
distances, use pipes one or two sizes larger than ordinary.
Whether a foot valve is used or not, a strainer should be attached
to the suction pipe to prevent large substances from entering, that
might choke or clog the pump, but be careful that suction area is not
contracted.
NOTE.—In viewing diagrams on page 225 you are supposed to stand at
the outer half of pump shell looking over pump towards the pulley or
engine, if directly connected. _The pump can be swiveled around the
frame_, so that, for instance, if you order pump per diagram No. 50,
it can after receipt be made Nos. 51, 52 or 53.
_Run the pump in proper direction, as indicated by arrows cast on the
pump shell._
If the combined length of suction and discharge pipe is more than 50
feet, the speed must be increased to overcome friction.
Before starting, prime the pump so that suction pipe and pump are
filled with water.
Warm water can only be raised by suction to moderate heights, and if
very hot it must flow to the pump. To prevent freezing in cold weather,
drain by unscrewing plug provided in the bottom of the pump shell.
Sometimes a pump when first started will deliver a good stream of
water, which gradually diminishes in volume until it stops entirely.
One reason for this is a leak in suction pipes or stuffing-box of
pump, or, when suction primer is used, in the hand pump stuffing-box.
Another reason might be that the pump lowers the suction supply,
thus increasing the lift until there is not sufficient speed for
the elevation. If the pump works indifferently, delivering a stream
obviously too small, it is generally because the pump was not properly
primed and some air remains in the top part of pump shell. Unless
primed by steam ejector, the pet cock or plug found on top of pump
shell should always be open while priming, and the pump must not be
started until water flows out of same.
NOTE.—“One feature or fact in centrifugal pumping that is overlooked
or not known to many makers, is that water will not enter a pump when
the impeller vanes sweep over the inlet way and are driven at high
speed. To illustrate this, one can not thrust a cane or lath through
the spokes of a rapidly revolving wheel. European centrifugal pumps
with their small impellers and consequent high speed of rotation, are
especially liable to this repelling action, and very often are wholly
inefficient from this cause. One maker who claims a high duty for
his pumps, attaches a screw at the sides of the impeller to coax the
water into the pump, and the idea is a good one if the difficulty is
not otherwise provided for. In this way a pump can be made of smaller
diameter for a given duty, but it is commonly inferior to a larger
one for the same work.”—_Industries._
A pump with horizontal top discharge and short length of discharge
pipe is sometimes difficult to start, especially if suction lift is
high, owing to the fact that the water is thrown out of the pump shell
before the water in the suction pipe has got fairly started, thus
allowing air to rush back into the pump. If the pump is to work under
this condition, it is better to use a pump with a vertical discharge
and deliver through an elbow, or else lead the discharge pipe upward
for a short distance so as to keep a slight pressure, or head on the
pump, and after priming as high as possible start quickly.
Generally nothing is gained by running a pump above the proper speed
required for a given elevation.
In addition to what is said in connection with the priming device
illustrated on page 218, numerous other methods have been adopted to
suit pumps of various designs. The accompanying engravings represent
those largely used.
Fig. 1 illustrates a multi-stage turbine pump with ejector for priming.
The ejector is connected to the highest point on the pump casing, and
either steam, air or water under pressure may be employed in it to
produce a vacuum.
Fig. 2 shows an auxiliary hand pump mounted on top of the discharge
casing. When the pump is ready to start, the gate valve on the
discharge is closed, and by operating the hand pump a vacuum is
produced and water drawn in, filling the suction pipe and casing.
The method of priming shown in Fig. 3 may be resorted to where a foot
valve is used on the suction pipe. Water is allowed to run into the
pump until it reaches the discharge flange, when the supply is shut
off, and the pump may be started.
After the pump has been properly primed, it should be started before
the gate valve on the discharge is opened. When full speed is reached,
the discharge gate may be slowly opened, and the pump will perform its
work.
NOTE.—_The Worthington centrifugal pumps_ are divided into three
classes, viz.: _Conoidal_, _Volute_ _and Turbine_.
_The Conoidal Centrifugals_ (_named from the cone-shaped impeller_)
are designed especially for low lifts and large deliveries and are
adapted to irrigation work, the handling of sewage and similar
purposes. They are comparatively inexpensive and operate at high
rotative speeds, making possible direct connection to electric
motors. _For heads up to 30 feet_ they are unexcelled in the pumping
field.
_The Volute Centrifugals_ (illustrated on page 232) are built for
medium lifts, but for all capacities. Since they run at moderate
speeds, diffusion vanes are not needed, but the volute casing has
been carefully designed to obtain high efficiency and 86% has been
shown under test. These pumps are recommended _for heads up to 70
feet_, although they will safely withstand 150 feet.
It is always best to use a foot valve in connection with centrifugal
pumps where the lift is more than three to four feet, and even under
these low lifts where long suction pipes are used to conduct water
long distances, foot valves should always be used to keep the pump and
suction pipe charged.
[Illustration: FIGS. 1, 2 AND 3.]
[Illustration: FIG. 503.]