atmospheric pressure alone has to raise the water against the
force of gravity and has to overcome the friction, whereas in
the former these are effected by the power used to work the
pump.
Water may be raised by means of pumps by manual labour,
by labour of some animal, horse, pony, ox, mule or ass, by aid
of the wind or falling water, or by steam, hot-air, gas, or oil
engines.
For small and intermittent supplies, where the water has
only to be raised to an inconsiderable height, human labour
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PUMPS AND PUMPING MACHINERY 339
must often be depended upon ; but both human and animal
labour is often used when wind or water power could be pro-
fitably utilised, and even where some form of gas or oil engine
would be more economical
Hand labour may be employed in pumping, either in work-
ing a pump handle or in the continuous turning of a crank
and handle. In the ordinary pump the leverage is usually
about 6 to 1, i.e. the distance from the fulcrum to the
free end of the handle is about six times that of the fulcrum to
the point of attachment of the handle to the piston rod.
With a crank and handle the leverage varies from 3 to 1 to 4
to 1, according to the length of the stroke and the diameter
of the circle described by the handle. Whilst the latter is
pleasanter to work, it is evident that a man exercises more
power with the former. With the pump, the whole or nearly
the whole of the force is exerted in depressing the handle,
whereas with a crank and fly-wheel the work is more equalised.
With a single-barrel pump the pump handle or the fly-wheel
can be so weighted as to render the work in the up-stroke and
down-stroke more nearly equal. If the well frame be provided
with a wheel and pinion the power required to raise water a
given distance can be diminished in any ratio ; but the amount
of water raised by each revolution of the handle is diminished
in the same proportion, or, in other words, what is gained in
power is lost in time. It is easier to raise a given quantity
of water with a double -barrel pump than with a single-
barrel pump of a capacity equal to the two barrels, since
with the former half the water is raised with each half
turn, whereas, with the latter the whole is raised at one half
turn.
The resistance to be overcome in raising water any given
height will be the weight of a column of water of that height
and of cross section equal to that of the pump piston, plus
the resistance due to friction and the weight of the pump
rods. The following table admits of the water pressure being
readily calculated : —
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WATER SUPPLIES
Diameter of Pump Cylinder.
2 inches
24
3
3i
4
5
6
Weight of corresponding Column
of Water 10 feet high.
13 6 lbs.
21-2 „
30*6 „
416 „
54-4 „
85-0 „
122-4 „
Example. — Required the water pressure upon a piston of
3 inches diameter raising water to a height of 80 feet.
Since from the table a column of water 3 inches in diameter
and 10 feet long weighs 30*6 lbs., the pressure of a column
80 feet long will be 244 8 lbs. The above weight includes
that of the column of water raised by the atmospheric pressure,
since the piston is raised against this pressure. With an
ordinary pump, having a handle with leverage of 6 to 1, a force
of ^- 8 = 40*8 lbs. would have to be applied to raise the water
alone without allowing for friction, etc. By the use of a wheel
and pinion this power could be reduced so as to enable one man
to raise the water, the power which an ordinary labourer is able
continuously to employ for such a purpose being only 25 lbs.
From the above table the height to which one or more men
can raise water by means of a pump worked either by a
handle or crank can be determined approximately, if the
effect due to friction be not excessive.
The following table, by Molesworth, gives the theoretical
power required to raise water from deep wells, or to raise
water a given height. In using it an allowance must be
made for friction in the gearing and pipes, for it should be
remembered that the fluid friction of water traversing a pipe
varies directly as the length of the pipe and as the square of
the velocity. Doubling the length of a pipe therefore will
double the friction, whereas, diminishing the internal area by
half will increase it four-fold.
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PUMPS AND PUMPING MACHINERY
341
Mjaiiuuoi H*vlit to which Water can be rai***L
Quantity of
Water 1
rained per By one Man
Hour. taming a I
Crank.
By (fof,
wirkiiig
a Gin.
Gin. , Eu » nue '
It is assumed that a good class double or treble barrel pump
is used.
JPwuf as a motive power for driving pumps is again receiv-
ing considerable attention in consequence of the introduction
of improvements rendering the wind engine more reliable,
more uniform in action, less liable to damage by storms, etc.
For pumping water to supply farms, groujw of cottages, and
mansions, the wind can often be utilised. Beyond the first cost
of the engine there is practically no ex|>ense, and in the most
modern mills self-regulating gearing reduces the |>ersonal
attention required to a minimum. Naturally they are moHt
efficient in exposed situations, but they can be utilised any-
where if placed at such an elevation as to receive the full
force of any wind which blows. The mill will work from 30
to 35 per cent of the possible time, but to provide for the
periods of calm it is necessary to have the mill amply large
and a storage reservoir capable of holding from four to seven
days' supply of water. Unless these precautions are taken in
the first instance, occasional failures in the supply are certain
to occur, necessitating the provision of a steam or other engine,
or gearing for animal power, to work the pumps during the
intervals of calm.
The wind engine may be fitted with a crank, to which
the piston rod of the pump is directly attached. This form,
however, is only adapted for raising very limited supplies of
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342 WATER SUPPLIES
water; for larger quantities, or where the water has to be
drawn from a- considerable depth or forced to a height, it is
better to connect with gearing from which a double or treble-
barrel pump can be worked. Mills with annular sails are
now almost exclusively employed for pumping purposes, and
the sails may be either "solid" or "sectional." In the
" solid " form each sail is pivoted at both ends, and coupled
together with rods, and so adjusted as to develop the
maximum of power when working. An automatic regulator
causes the sails to furl when the wind pressure becomes too
high, and so ensures the safety of the mill. The head also
revolves, and is kept facing the wind either by a large tail
vane or a tail-steering wheel. By aid of levers the engine can
be started or stopped and its speed regulated. In the
" sectional " wheel the individual sails are not pivoted into
any framework, but are fixed at a definite angle and connected
together into a series of sections which vary in number with
the size of the wheel. Each section carries a weight or
counterpoise so hung that when the wind is very high the
wheel opens and assumes a tubular form, allowing the wind
to pass through. When the wind falls the sails resume their
normal position and the mill is again in action. It is claimed
that this form is safer in a storm, is more easily regulated to
work at a uniform speed, and is more sensitive to light breezes.
Either form can be fitted with an automatic appliance for
keeping the water in the supply tank or reservoir at a definite
height. Where water has only to be raised a few feet, the
wind engine may work an Archimedean screw, or a dash
wheel, or a " Noria " pump (an endless chain carrying a series
of small buckets), instead of the ordinary force or lift pump.
Such contrivances, however, are only adapted for raising water
for irrigation and similar purposes.
The amount of power developed by these engines varies
with the diameter of the wheel, its construction, and the
velocity of the wind. If built on correct principles the
wind will produce the same effect upon the wheel of one
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PUMPS AND PUMPING MACHINERY
343
maker as upon another, but a difference may arise from loss
of power by friction, leverage, gearage, etc. Where the mill
has to be fixed at some distance from the pumps, the trans-
mission of the power causes further loss. Whilst some
makers claim that, with a wind of 18 miles an hour, their
machines, with wheel of 13 feet diameter, have 2 horse-power,
other makers, more modest, claim only to give 1 horse-power
with such a wheel. Roughly stated, the power of a wind
engine varies directly as the square of the diameter of the
wheel, that is, a 20-foot wheel will do twice the work of one
15 feet, and four times that of one 10 feet in diameter. As an
approximate guide to the amount of water which a wind engine
of modern construction will raise, the following estimates may
be useful. The water raised is given in gallons per hour, and
the wind is assumed to be blowing at a rate of from 14 to 18
miles an hour. It must also be remembered that the average
day's work corresponds to about eight hours.
Diameter
of Sail.
Gallons raised
per Hour.
Height raised.
Daily Supply.
Feet.
Feet.
Gallons.
Maker A.
10
200
100
1600
ft
12
250
150
2000
Maker B.
10
250
100
2000
12
250
150
2000
12
400
100
3200
Maker C.
10
240
50
1920
jj
12
240
100
1920
Maker D.
10
210 to 300
100
1680 to 2400
10
300 to 450
50 to 60
2400 to 3600
12
300 to 500
100
2400 to 4000
»»
30
7000?
150
Expressed in terms of h.p., a 10-foot mill will give J-l h.p., a 12-
foot mill 1-1J h.p., a 14-foot mill 1J-2 h.p., a 16-foot mill 2-2J h.p.,
an 18-foot mill 2J-3 h.p., and a 20-foot mill 3-4 h.p.
Estimates by different makers for pumping engines of
various kinds can readily be obtained, but in consider-
ing those for wind engines it must be remembered that the
storage capacity required is much larger than with any other
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344 WATER SUPPLIES
form of engine, and therefore increases the initial expense.
Where a larger supply than 20,000 gallons per day is required,
a steam or gas engine is probably in all cases preferable, but
for raising smaller supplies the possibility of utilising the wind
as the motive power is always worthy of serious consideration.
Water Power. — Running water, when available in sufficient
quantity, is one of the cheapest and most manageable sources
of power for pumping purposes. It may be utilised by means
of water-wheels, turbines, or rams, the choice often depending
on the fall which can be utilised, the amount of water to be
supplied, and the height to which it has to be raised ; but in
some cases, where any form is applicable, the selection will be
influenced by minor considerations. Whilst water-wheels
and turbines are occasionally used for pumping large
quantities of water, rams are rarely used when more than
10,000 gallons a day have to be raised. As the hydraulic
ram, where it can be utilised, is probably the simplest and
cheapest, it may be considered first.
Its construction will be rendered intelligible by the follow-
ing section and description (Fig. 22).
In this ram it is obvious that the water working the ram
is the same as that which enters the rising main, and as the
proportion of water raised to that wasted is invariably
small, its utility is somewhat limited. Recently, however, a
double-acting ram has been devised, whereby an impure water
by its fall is caused to pump water from a purer source. As
yet these are not in general use.
These self-acting pumps work day and night, and if by a
good maker, and properly adapted for the work they have to
perform, the amount of attention and repair required during
the year is remarkably little, as there are no parts requiring
packing or lubricating. With a reservoir holding sufficient to
meet one or two days' demand, repairs, when necessary, can
be effected without interfering with the supply. Where
large quantities of water are being pumped, a duplicate ram is
desirable.
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PUMPS AND PUMPING MACHINERY 345
The smallest fall which can be utilised is about 18 inches ;
the greater the fall the larger the proportion of water, and
the greater the height to which it can be raised. Although
falls of 40 feet are sometimes used, the wear and tear conse-
quent upon the friction and shock necessitates the use of
specially-constructed rams. Special rams are also made
which will lift water a height of 800 feet, and the water so
Fig. 22. — A is the feed pipe communicating with the reservoir supplying the
water, B the escape valve, C the valve leading to the air-vessel, D, E is the rising main.
When water is admitted to A, it at first escapes through the valve B, which opens
downwards, but as the maximum velocity is reached the force is sufficient to close
the valve. The flow being suddenly stopped, the pressure rises, and lifts the
valve C, which opens upwards, a certain amount of water entering the air-vessel
D. The pressure being relieved by the recoil, both valves fall. The water again
escapes at B, and the action described is repeated. The intermittent flow into G is
converted by the compressed air into a constant flow through the rising main E.
raised may be caused to act upon a second ram and raise a
portion of the water to a height of 1500 feet. Rams,
however, are rarely used to lift water to more than 150 to
200 feet, as the amount of water wasted compared to that
supplied increases with the elevation, but more rapidly than
the elevation on account of the increased friction. A ram of
best construction will raise water thirty times the height of
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346
WATER SUPPLIES
the fall, but it is not safe to depend upon delivering it at
more than twenty-five times the height. Where the water
supply is not sufficient to work a ram continuously, it may
often be dammed up and discharged at intervals by a
syphon arrangement, the ram then working intermittently.
Theoretically, disregarding friction, the product of the
amount of water falling in a given time into the fall should
be equal to the product of the amount raised into the height.
Thus 100 gallons falling 10 feet would raise 10 gallons 100
feet, 20 gallons 50 feet, or 100 gallons 10 feet, etc. Friction
and imperfections in construction, however, render such a
degree of efficiency unattainable; but some of the best of
most modern rams have reached over 80 per cent of
efficiency, even with a rising main of considerable length
and when the water was being lifted over 100 feet. The
smaller the fraction expressed by the ratio of the fall to the
height raised, the less the efficiency. Tables giving the
efficiency for different ratios have been published, but they
are quite useless. Thus in a table recently issued the
efficiency of a ram with a ratio of fall to height of -fa is given
as 37 per cent, whilst more than one English maker will
guarantee at least 50 per cent, and 69 per cent has been
attained. Allowing for the friction in a moderate length of
rising main, a good ram properly fixed should supply not less
than the following percentages of the theoretical amount : —
Fall.
Degree
Efficiency attained by
Height
raised.
of Efficiency.
Blake's Rams.
i
86 per cent.
i
76 „
78 per cent.
i
70 „
83
i
66 „
72
i
63 „
\
60 ,.
75 '"„
i
58 ,;
i
56 ,,
tV
54 „
a
52 „
69 '"„
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PUMPS AND PUMPING MACHINERY 347
Example. — It is required to know what amount of water
can be raised to a height of 100 feet, by a ram working
with a fall of 10 feet, the amount of water available being
20,000 gallons per day.
Here the ratio J fa should give an efficiency of at least
54 per cent. With perfect efficiency the amount raised
would be 2000, since
2000x100 = 20,000x10
and 2000x^=1080, which is the number of gallons per
day the ram should be guaranteed to raise to the required
height.
The efficiency decreases very rapidly when the ratio of
the fall to the height raised exceeds ^ so that when -£ s is
reached the proportion of water pumped to that wasted
becomes a very small fraction indeed. In such cases other
forms of water motors are preferable ; moreover, with a fall of
over 10 feet the wear and tear becomes so very considerable
that it is not desirable to attempt to utilise much greater
falls with a ram. These conditions, therefore, limit the general
usefulness of the ram to situations where the fall of water
available is from 1 J to 10 feet, and where the supply has not
to be raised more than 250 feet.
A turbine can often be used where a ram is inadmissible.
In the ram the pump is a part of the machine, whereas a
turbine is merely a machine for utilising a fall of water to
supply the power to work a pump or set of pumps. It
follows, therefore, that a turbine worked by a falling stream
may be used for pumping water from any source, as from a
deep well, and the pumps may be placed at any convenient
distance from the source of power, the connection being
made by suitable gearing. Any fall from 1 to 1000 feet can
be taken advantage of, and there is practically no limit to
the depth from which the supply can be raised, or to the height
to which it can be propelled. Moreover, they can be so
constructed as to work with fluctuating falls and a constant
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348 WATER SUPPLIES
efficiency of 75 per cent attained. In experimental trials the
best turbines have yielded 87 per cent of the actual power
of the water, but even with the best makers it is not
safe to rely upon more than 75 per cent.
The numerous varieties of turbines may be divided into
two classes. In the first or " pressure " turbine the falling
water is conducted through one or more pipes and allowed to
impinge upon the vanes of a wheel, which revolves upon a
pivot and is included in a metal case. The impact of the
water causes the wheel to revolve with a velocity depending
chiefly upon the fall. After expending its energy, the water
escapes around the centre of the case. The turbine may be
fixed horizontally or vertically, and the vanes may' be fixed
or movable, the latter only being necessary where the power
required or the water available is variable. In the second
class of turbines or "impulse" turbines, the falling water
(conducted by suitable guides) impinges against a series of
"buckets," arranged around the periphery of the wheel.
This turbine, therefore, need not be acted upon by the water
all round, neither need the wheel be submerged. It must
always be fixed at the bottom of the fall, whereas the
" pressure " turbine may be placed as much as 20 feet above,
the water escaping from the centre passing down a suction
pipe and so contributing to the available power. The first
form is most generally applicable for low and medium falls,
and the latter for high falls. When the supply of water is
abundant and a high degree of efficiency is not necessary,
cheap forms of the turbine may be employed ; but where it is
required to fully utilise the power a machine should be
obtained, the high efficiency of which is guaranteed. As
large turbines are more efficient than small ones, it is often
advisable to store the water during the night and give the
whole out during the day to a large turbine, rather than
work a smaller machine with the constant flow.
On the Continent turbines are much more used than in
this country, the largest installation probably being at St.
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350 WATER SUPPLIES
Maur, where four sets of turbines, each with a diameter of 40
feet, raise over 8,000,000 gallons of water per day to an
elevation of 250 feet for the supply of the city of Paris.
The fall of water utilised is only 3 feet The turbines are
fixed with the axes horizontal, and are of the "impulse"
class. The turbines pumping water for the city of Geneva
are of the same description, but work with a fall of 165
feet.
Probably the greatest height to which water is raised by
any machine is by the turbines pumping water to supply the
town of La Chaux de Fonds (population 30,000). These
turbines, made by Mons. Escher of Zurich, work with a fall
of about 100 feet of water, derived from the Gorges de
PAreuse, and throw that supplying the town to a height of
over 1600 feet.
As an example of a village supply the works recently
executed at West Lulworth (Dorset) may be cited. The
water from a spring on the hillside is piped to a tank placed
on a tower immediately over the turbine. The vortex
(pressure) horizontal turbine is fixed in a pit 20 feet below
the level of the water in the tank. The water falls to the
turbine by means of a vertical pipe, the waste water being
conveyed away from the bottom by a 12-inch drain and
discharged into the sea. From the turbine, which runs
about 600 revolutions a minute, the power is communicated
by a 10-inch pulley to a larger pulley on the overhead
shafting, and thence the power is transferred to a set of
three-throw plunger pumps. The machine is estimated to
be of 5 h.p., and will lift continuously 1200 gallons per
hour into the service reservoir, which is on the hillside, 300
feet above the source of the water. The reservoir has a
capacity of 60,000 gallons, and as the population to be
supplied is only about 400, it is obvious that the reserve is
ample to admit of the pumping being intermittent, and to
give time for repairs, etc., to the turbine when such are
needed.
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PUMPS AND PUMPING MACHINERY
351
The efficiency of turbines decreases with the size ; hence for
small supplies (of from 1000 to 4000 gallons per 24 hours) a
small water-wheel, which can be used without gearing, is often
more economical, both in first cost and in amount of water
used. Water-wheels are too well known to need any descrip-
tion. Recently, however, the substitution of light iron wheels
for the cumbersome wooden ones previously used has greatly
increased the utility of this machine. An " overshot " water-
wheel receives the water near the top and has a higher degree
of efficiency than either the " high breast," which receives the
water above the centre, or the undershot wheel, which receives
the water below the centre. Where sufficient fall is available,
therefore, the overshot wheel should always be selected. A
fall of 1 foot may be utilised for driving an undershot
wheel, but not less than 3 feet is required for the over-
shot. They are quite as reliable as rams, and as the wheels
revolve at a slow speed the shaft can be directly connected
with the piston rods of the pumps. Where the water avail-
able for working the wheel is variable, an adjustable disc
crank can and should be provided, so as to enable the stroke
of the pump to be correspondingly varied. The following
table gives approximately the amount of water which can be
raised per day to a height of 100 feet, with wheels of different
diameter and with different supplies of water : —
Diameter of Wheel.
Water Supply
per Minute.
Quantity raised 100 Feet
in 24 Hours.
4 feet.
60 galls.
1,000 galls.
4 „
100 ,,
1,850 „
4 „
500 „
9,250 ,,
5 „
50 „
1,000 ,,
5 „
100 „
2,000 „
5 „
250 „
5,000 „
6 „
100 ,,
2,750 „
6 „
500 „
13,750 ,,
These figures refer to an "overshot" wheel. A "high-
breast" wheel would raise about 5 per cent less, and an
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352 WATER SUPPLIES
" undershot " about 15 per cent less, assuming the fall utilised
to be the same. As these wheels run night and day, rarely
require any attention, are very inexpensive both to purchase
and fix, and can be worked by impure water, whilst raising a
pure water from a well, spring, or other source, it is obvious
that under many circumstances they are preferable to a ram,
whilst under others they can be used when the ordinary ram
is inadmissible.
Fuel Engines. — Where neither wind nor water are avail-
able an engine, deriving its energy from the combustion