Index : PURPOSE, Classification of Pumps, FACTORS AFFECTING THE SELECTION OF A PARTICULAR TYPE OF PUMP, HEAD POWER AND EFFICIENCY OF PUMPS, ECONOMICAL DIAMETER OF THE RISING (PUMPING) MAIN, LEA FORMULA, RIGOROUS ANALYSIS

**PUMPS AND PUMPING STATIONS**

**PURPOSE**

I.
To
lift the water from source to the treatment plant which is at higher level
compared to the source

II.
To
lift the treated water to the elevated tanks

III.
To
increase the pressure in the distribution system.

IV. To lift the water at the treatment plant if
sufficient natural ground slope is not available as to cause gravitational flow
between different units of treatment plants.

**Classification of Pumps**

Based
on their Principal of power required

i.
Displacement pumps

ii.Centrifugal
pumps

iii.
Airlift pumps

iv.
Impulse pumpsiv.Diesel engine pumps

v.
Stand by pumps

Based
on the type service

i.Electrically
driven pumps

ii.
Gasoline pumps

iii.
Steam engine pumps

iv.
Boosters

Based
on the type of operation

i. Low lift pumps

ii.High
lift pumps

iii.Deep
well pumps

Under most of the situations in
water supply scheme, displacement and centrifugal pumps are commonly used.

Displacement pumps

i.
Reciprocating
pumps

ii.
Rotary
pumps

**PUMPING STATIONS**

The
location of a pumping station is primarily governed by the place where it is to
recerive water. The points to be kept in mind while selecting a suitable site
are.

i.
The
site should be away from all the sources of contamination or pollution

ii.
The
site should be above the HFL of the river.

iii.
Its
future growth and expansion is easily possible

iv.
Possibility
of fire hazards is also to be considered

**FACTORS AFFECTING THE SELECTION OF A PARTICULAR TYPE OF PUMP**

1. Capacity of pumps

2. Importance of WSS

3. Initial cost of pumping arrangement

4. Maintenance cost

5. Space requirements for locating the
pumps

6. Number of units required

7. Total life of water required

8. Quantity of water to be pumped.

**HEAD POWER AND EFFICIENCY OF PUMPS**

The total head against which a pump
works is made up of

i.
The
suction Head(H_{s})

ii.
The
Delivery Head(H_{d})

iii.
The
Head loss due to friction entrance and exit in the rising main(H_{f})

The suction HEAD is the difference
in elevation between the low water level and center line of pump.

Delivery HEAD is the difference in
elevation between the pump center line and point of discharge

Total HEAD (H) =H_{s}+H_{d}+H_{f}

The
work done by the pump in lifting „Q? cumecs of water by a head(H) =WQH kg-m/sec.
Where,

W = Specific weight of water, 1000
kg/m^{3} Q = discharge to be pumped, m^{3}/sec.

The water horse power of the pump is
given by

WHP(out put) = WQH/75

If „n? is the efficiency of the pump
then

**BRAKE HORSE POWER **of the pump is given by

BHP(INPUT) + WQH/75n

**ECONOMICAL DIAMETER OF THE RISING (PUMPING) MAIN**

The
economical diameter is a particular size of the pumping or rising main which
while passing a given discharge of water gives the total annual expense to be
minimum.

If the diameter chosen is more than
the economic dia, it will lead to higher cost of the pipe line on the other
hand, if the dia of the pipe is less than the economical dia, the increased
velocity will lead to higher friction headless and require more HP for the
required pumping and the cost of pumping shall be much more than the resultant
saving in the pipe cost.

**LEA FORMULA**

An empirical formula given by LEA

Connecting the dia and discharge is
given by

D
= 0.97 to 1.22 SqRt(*Q)*

Where

D = economical diain m

Q = Discharge to be pumped in cusecs

This relation gives optimum flow
velocity varying between 0.8 to 1.35m/sec

**FOR
RIGOROUS ANALYSIS **The
total cost of pipe and pumping should be woeked out at** **different assumed velocities (b/w 0.8 to 1.8m/sec) and a graph
plotted between the annual cost and the size of the pipe. The economical size
is one which gives the least annual cost.

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