Hydraulic Engineering Prof. Zaher Kuhail Eng. Tamer Eshtawi Prof. Zaher Kuhail Eng. Tamer Eshtawi

Hydraulic EngineeringHydraulic

Engineering

Prof. Zaher Kuhail

Eng. Tamer Eshtawi

Prof. Zaher Kuhail

Eng. Tamer Eshtawi

Lecture 12

Water Pump

Safety systems on pipelines to avoid (water hummer)

• Pump Inertia

• Bypass Reflex Valve

• Surge Tanks

• Discharge Tanks

• Reflex Valve

Water Pump• Water pumps are devices

designed to convert mechanical energy to hydraulic energy. They are used to move water from lower points to higher points with a required discharge and pressure head. This chapter will deal with the basic hydraulic concepts of water pumps.

Pump Classification

• Turbo-hydraulic (kinetic) pumpsCentrifugal pumps (radial-flow pumps)Propeller pumps (axial-flow pumps)Jet pumps (mixed-flow pumps)

• Positive-displacement pumps Screw pumpsReciprocating pumps

Centrifugal pumps (radial-flow pumps)

Propeller pumps (axial-flow pumps)

Centrifugal Pump Impeller; which is the rotating part of

the centrifugal pump .

Casing; which is an air-tight passage surrounding the impeller

Suction Pipe with a Foot-valve and a Strainer

Delivery Pipe

The Shaft

The Motor

Hydraulic Analysis of Pumps and Piping Systems

H t

hd

H s

tat

h s

H m

s

H m

d

Datum pump center line

h fs

h f

d

Case 1

H s

tat

H m

dH

ms

hd

H t

h s

Datum pump center line

h f

d

h f

s

Case 2

• hs (static suction head): it is the difference in elevation between the suction liquid level and the centerline of the pump impeller.

• hd (static discharge head): it is the difference in elevation between the discharge liquid level and the centerline of the pump impeller.

• Hstat (static head): it is the difference (or sum) in elevation between the static discharge and the static suction heads, .

• Hms (manometric suction head): it is the suction gage reading (if a manometer is installed just at the inlet of the pump, then Hms is the height to which the water will rise in the manometer).

• Hmd (manometric discharge head): it is the discharge gage reading (if a manometer is installed just at the outlet of the pump, then Hmd is the height to which the water will rise in the manometer).

• Hm (manometric head): it is the increase of pressure head generated by the pump, .

• Ht (total dynamic head): it is the total head delivered by the pump:

)2

(2

22

g

VH

g

VHH s

msd

mdt

)2

(2

22

g

VH

g

VHH s

msd

mdt

Case 1

Case 2

g

V

g

VHHH sd

msmdt 22

22

2 Case ,2

1 Case ,2

2

2

g

VhhhH

g

VhhhH

hhhH

SmSSfSmS

SmSSfSmS

mddfdmd

HP V

gZ

P V

gZt

d dd

s ss

2 2

2 2Or From Bernoulli

Pump Efficiency

p

o

i

t

i

Power output

Power input

P

P

Q H

P

•Motor which has an the efficiency

PQ H

it

p

•Which is the power input delivered from the motor to the pump

m

im P

P

which is the power input delivered to the motor .

•The overall efficiency of the motor-pump system o p m

Example 1Pump with suction pipe diameter of 100mm and delivery pipe diameter of 75mm, Q in the system is 15L/s. the manometeric suction head is 198 mm of mercury, where the manometeric discharge pressure is 0.95 bar. Motor power is 3.2 KW

S

SSd

ddt Z

g

V

γ

PZ

g

V

γ

PH

22

22

m 69.910.1980.95 bar 95.0γ

Pheadwater

d

m 5.21)(13.6 198.0γ

Ps

m 588.02/V 2d gm/s 39.3Vd

m 186.02/V 2s gm/s 91.1Vs

m...-...H t 9911588052201860699

Solution

3200t

m

o ρgQH

P

Pη

percent ..

...η 55550

23

99110150819

Efficiency