Course
ENGINEERING
ENGINEERING SCIENCE
N4
(15070434)
PROGRAMME:
CHEMICAL
ENGINEERING
LECTURER:
R SINGH
Berea Technology College
CHAPTER
HYDRAULICS
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TOPIC
LESSON 39
HYDRAULIC PUMPS
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OUTLINE
1. Learning outcomes
2. Introduction
3. Content
a) Concept
b) Examples
4. Activity
5. Additional Resources
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LEARNING OUTCOMES
Students should be able to:
1. Analytically solve practical problems to determine
 the volume of liquid delivered per stroke
The pressure in the liquid, plunger diameter and force on plunger
The power required and efficiency with input power in the case of
single, double and three cylinder single acting pumps
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INTRODUCTION
1. HYDRAULIC PUMPS
-
hydraulic pumps are used to transmit liquid
vertically, horizontally or against pressure
2. WORKING PRINCIPLE
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-
If the plunger moves upwards, valve A is
opened and liquid is sucked from reservoir,
while valve B is closed
-
When the plunger is moving down, valve A is
closed and valve B is opened and liquid is
delivered at pressure
CONCEPT
3. WORK DONE AGAINST PRESSURE
𝑺𝒕𝒂𝒕𝒊𝒄𝒉𝒆𝒂𝒅 = 𝑺𝒖𝒄𝒕𝒊𝒐𝒏𝒉𝒆𝒂𝒅 + 𝑫𝒆𝒍𝒊𝒗𝒆𝒓𝒚𝒉𝒆𝒂𝒅
WD = F x s
WD = mgh
WD = (Vρ) xgh
WD = Ph x V
WD – work done (J)
F – force (N)
m- mass(kg)
h- height (m)
V – volume 𝒎𝟑
Ph – pressure (Pa)
S – distance (m)
4. VOLUME DELIVERED
V = A x sl x n
5. Water
𝑽𝒅 = 𝑨𝑷 𝐱 𝐬𝐥 𝐱 𝐧 × 𝑪 × 𝑵 × ʯ
1000 l = 𝟏𝒎𝟑
𝑽𝒅 - volume delivered (𝒎𝟑 )
ρ = 1000 kg/𝒎𝟑
𝑨𝑷 -
area (𝒎𝟐
)
𝒔𝒍 - stroke length (m)
𝒏 – number of strokes
𝑪 – number of cylinders
𝑵 – rotational frequency
ʯ - efficiency
𝝅𝒅𝟐
𝑨𝑷 =
𝟒
1l = 1kg
EXAMPLES
1 The plunger of a three-cylinder pump has a diameter of 1.1 water delivered in 𝑙/𝑠
90 mm and a stroke length of 590 mm. The crankshaft
𝑽𝑷 = 𝑨𝑷 𝐱 𝐬𝐥 𝐱 𝐧 × 𝑪 × 𝑵 × ʯ
speed is 240 r/min.
𝜋(0,09)2
4
Calculate the quantity of water delivered in litres per
second if the slip is 1,8%.
=
Given
= 0,044𝑚3 x 1000
= 44 𝑙/𝑠
D = 90 mm ÷ 1000
Sl = 590 mm ÷ 1000 = 0,59 m
= 0,09 m
N = 240 r/min ÷ 60 = 4r/s
ʯ = 100 – 1,8
= 98,2%/100% = 0,982
C=3
x 0,59 x 1x 3 x 4 x 0,982
2 The plunger of a three-cylinder single-acting
pump has a diameter of 280 mm and a stroke
length of 390 mm. The crankshaft speed is
333,33 r/min.
Calculate the volume of water delivered per hour if
the slip is 4,8%.
Given
d = 280 mm ÷ 1000
Sl = 390 mm ÷ 1000 = 0,39 m
= 0,28 m
N = 333,33 r/min × 60 = 20000 r/h
ʯ = 100 – 4,8
= 95,2% /100% = 0,952
C=3
1.1 water delivered /ℎ𝑟
𝑽𝑷 = 𝑨𝑷 𝐱 𝐬𝐥 𝐱 𝐧 × 𝑪 × 𝑵 × ʯ
𝜋(0,28)2
4
=
x 0,39 x1 X 3 x 20000x 0,952
=1371,699 𝑚3 /hr x 1000
=1371699 𝑙/ℎ𝑟
ACTIVITY
1. The crankshaft of a single-acting 3-cylinder water pump has plungers each having a diameter of 200 mm and a stroke
length of 600 mm runs at
1 800 r/min.
Calculate the following:
1.1
1.2
The volume of water delivered in kℓ/h if there is a slip of 5%
The input power to drive the pump if the efficiency is 90% and the static head is 32 m
HINT: Use the density for water as 1 000 kg/m3
ADDITIONAL RESOURCES
ENGINEERING SCIENCE N4 MJJ VAN RENSBURG
PAGE 125
Activity 5.1
Qn 2
PAGE 122
EXAMPLE 5.3