2. WHAT IS THE PUMPWHAT IS THE PUMP??
The hydraulic machine which converts the mechanical energy into hydraulic
energy are called pumps. The hydraulic energy is in the form of pressure
energy.
Function of pump-
1. Flow from a region or low pressure to one of high pressure.
2. Flow from a low level to a higher level.
3. Flow at a faster rate.
4. RECIPROCATING PUMPRECIPROCATING PUMP
In pump mechanical energy is converted into hydraulic energy. The
hydraulic energy is in the form of pressure energy
If the mechanical energy is converted into pressure energy by sucking
the liquid into a cylinder where piston is reciprocating which exerts
thrust and increases its hydraulic energy is called reciprocating
pump.
For industrial purposes, they have become obsolete due to their high
pumping initial and maintenance costs
5. MAIN COMPONENTS OF RECIPROCATING PUMPMAIN COMPONENTS OF RECIPROCATING PUMP
The following are the main parts of a reciprocating pump as shown in figThe following are the main parts of a reciprocating pump as shown in fig::
1(A cylinder with a
piston, piston
rod, connecting
rod and a crank
2(Suction pipe
3(Delivery pipe
4(Suction valve
5(Delivery valve.
7. WORKING OF RECIPROCATING PUMPWORKING OF RECIPROCATING PUMP
When the crank rotates, piston moves to & fro.When the crank is at A,
the piston is at extreme left. As the crank rotates from A to C( =0ฦ o
to =180ฦ o
( piston moves towards right.
The movement of the piston creates a vacuum less than the atmospheric
pressure. Hence the suction valve open & the liquid moves up in suction
pipe.
When crank rotates for C to A ( =180ฦ o
to =360ฦ o
( piston moves from
right to left. This movement increases the pressure on the liquid which is
more than the atmospheric pressure.
Hence, suction valve closes and the delivery valve opens. The liquid is
forced into the delivery pipe.
8. CLASSIFICATION OF RECIPROCATING PUMPCLASSIFICATION OF RECIPROCATING PUMP
Follow are the three fields in which the reciprocating are classified:
1.According to the contact between water and plunger
2. According to the number of cylinders
3.According to the air vessel
4.According to the external power
9. According to the contact between water and plungerAccording to the contact between water and plunger
Single Acting Pump- This type of pump has one suction valve, delivery
valve and one suction and delivery pipe. It suck up the fluid only in one
direction, in single stroke and deliver it in single stroke.
Double acting pump-Double acting pump has two suction valves,
delivery valves .Liquid is receiving on both sides of the piston in the
cylinder and is delivered into the delivery pipes and two suction and
delivery pipes.
11. According to the number of cylindersAccording to the number of cylinders
Single Cylinder Pump- Single cylinder pump is one in which their is
only cylinder connected to a single shaft. It could be a single acting or
double acting pump.
Double Cylinder Pump- Double cylinder pump is one which have two
cylinder attached to a single shaft. Separate suction and delivery valve is
provided to each cylinder.
Triple Cylinder Pump- When the pump has three cylinders attached to a
single shaft then the pump is called triple cylinder pump.
13. According to the air vesselAccording to the air vessel
With Air Vessel-Some reciprocating pump are provided with a separate air
vessel attached to the suction and delivery valve. Its main function is
to accumulate excess quantity of water by compressing the air in the vessel.
With Out Air Vessel- Some pump lack the air vessel because of the nature
of their work. for example the reciprocating boiler feed pumps does not have
air vessel because they may introduce air into the deaerated water.
14. According to the external powerAccording to the external power
Direct Acting- In this case the pump is directly driven by steam/power.
This type of pump are mostly use in industrial applications sector.
Power pump- In this case the pump is driven by another pump. This
type of pumps are very costly to run and handle during itโs operation.
15. DISCHARGE THROUGH SINGLE ACTINGDISCHARGE THROUGH SINGLE ACTING
PUMPPUMP
Let
A = cross sectional area of cylinder
r = crank radius
N = r.p.m of the crank
L = stroke length (2r(
Discharge through pump per second= Area x stroke length x r.p.m /
60
Qth= A x L x N
60
This will be the discharge when the pump is single acting reciprocating
pump.
16. DISCHARGE THROUGH DOUBLE ACTINGDISCHARGE THROUGH DOUBLE ACTING
PUMPPUMP
Discharge in case of double acting pump.
Discharge/Second=
Where, Ap= Area of cross-section of piston rod
However, if area of the piston rod is neglected
Discharge/Second=
๏ฃบ
๏ฃป
๏ฃน
๏ฃฏ
๏ฃฐ
๏ฃฎ โ
+=
60
((
60
LNAAALN
Q P
th
60
(2( LNAA
Q P
th
โ
=
60
2ALN
17. SLIP OF RECIPROCATING PUMPSLIP OF RECIPROCATING PUMP
Slip of a reciprocating pump is defined as the difference between the
theoretical and the actual discharge.
Slip =Theoretical discharge - Actual discharge
Slip= Qth - Qa
Slip can also be expressed in terms of % age and given by
Where Cd is known as co-efficient of discharge (ratio of the actual
discharge to the theoretical discharge(.
Cd=Qa/ Qth.
( )10011001
100%
d
th
act
th
actth
C
Q
Q
Q
QQ
slip
โ=๏ฃท๏ฃท
๏ฃธ
๏ฃถ
๏ฃฌ๏ฃฌ
๏ฃญ
๏ฃซ
โ=
ร
โ
=
18. POWERPOWER
Consider a reciprocating pump.
Let hs=Suction head.
hd =Delivery head
Hst=Total static head
=hs + hd
Theoretical work done(Single Acting( by the pump
=
Theoretical work done(Double Acting( by the pump
=
Power input to (Single acting( pump KW
Power required for (Double Acting( pump= KW
( )ds hhg
ALN
+๏ฃท
๏ฃธ
๏ฃถ
๏ฃฌ
๏ฃญ
๏ฃซ
=
1000*60
ฯ
( )ds hhg
ALN
+๏ฃท
๏ฃธ
๏ฃถ
๏ฃฌ
๏ฃญ
๏ฃซ
ร
1000*60
2 ฯ
( )ds hhg
ALN
+๏ฃท
๏ฃธ
๏ฃถ
๏ฃฌ
๏ฃญ
๏ฃซ
ร
60
2 ฯ
( )d
h
s
hg
ALN
+๏ฃท
๏ฃธ
๏ฃถ
๏ฃฌ
๏ฃญ
๏ฃซ
60
ฯ
19. ADVANTAGE & DISADVANTAGEADVANTAGE & DISADVANTAGE
Advantages
๏ No priming is needed
๏ Can deliver water at high pressure
๏ Can work in wide pressure range
๏ Continuous rate of discharge
Disadvantages
๏ High maintenance cost
๏ More parts mean high initial cost
๏ Low discharging capacity
๏ Difficult to pump viscous fluid
๏ High wear in parts
21. VALVES
A valve is a device that regulates, directs or regulates the flow of fluid by
opening, closing or partially obstructing passageway.
VALVE FUNCTION.
Stopping or starting fluid flow-
Controlling direction of fluid
Varying(throttling( the amount of fluid flow.
Allowing flow in one direction.
22. SWING VALVE
It is a check valve which prevents flow reversal.
It consists of flapper hinged at the top by hinge pin
The disk swings freely in the form of arc.
The valve opens during upstream flow and closes during reverse fluid
flow.
25. INNER VIEW OF SWING VALVEINNER VIEW OF SWING VALVE
.
26. RECOMMENDED USE
Swing valve is used where pressure difference (โP )is minimal
It is used when the flow velocity is low
Swing valves are used when fluid flow reversal in infrequent.
Low installation space.
SELECTION CRITERIA.
Factors considered when selecting a check valve are:
Material compatibility with the medium
Valve rating
Application data (flow, design/operating conditions);
Installation (horizontal, vertical flow up or down);
End connection and cleaning
27. ADVANTAGES & DISADVANTAGES.ADVANTAGES & DISADVANTAGES.
AdvantagesAdvantages
๏ It can be used at a very low velocity
๏ They open and close automatically. They do not need exterior force to
open or close. They move quickly.
๏ Swing valve maintain slow pressure inside the valve
Disadvantages
๏ It is hard to determine if the valve is open or closed, because all the
moving parts of the valve are placed in a closed area.
๏ Check valves have restrictions during assembly.
๏ ย Valve disc can get stuck in open position.
