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Centrifugal Pumps- Introduction
HYDRONICS SYSTEMDESIGN AND
APPLICATION SEMINARPump Curves
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Introduction and Definitions
Hydronics:
The science and art of providing thermal
comfort by using water as an intermediateheat transfer medium.
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Gravity Hot Water System
Open Expansion Tank
Overflow
to drain
Boiler Manual fill valve
Large radiators
pitch
Large pipes
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0
20
40
60
80
100
120
140
160
160 170 180 190 200
Supply Temperature
(F)
Head(mils/ft)
Return Temperature 150 160 170
Gravity Head
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Forced Circulation Systems
Compression Tank
Circulator Small Radiators and Piping
Boiler
PRV
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Centrifugal Pumps- Pump Basics
HYDRONICS SYSTEMDESIGN AND
APPLICATION SEMINARPump Curves
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Topics
Pump Definitions
Bernoulli's Theorem
Pump Components Impeller Types
Velocity Concept
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Pump Definition- Kinetic
Hydraulic Institute Standards
Pumps
Positive
Displacement
Kinetic
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Pump Definition - Kinetic
Kinetic
-- of or due to motion
-- (K. energy) -- body’s ability to do work by virtue
of its motion.
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Pump Definition- Centrifugal
Hydraulic Institute Standards
Kinetic
Special
Peripheral
Centrifugal
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Bernoulli’s Theorem
Daniel Bernoulli FRS; (8
February 1700 – 17 March
1782) was a Swiss
mathematician and physicistand was one of the many
prominent mathematicians
in the Bernoulli family
Conservation of Energy
Fluid Flow
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Bernoulli’s Theorema
b
P
W Z
V
g
P
W Z
V
g
a
a
a b
b
b
2 2
2 2
The total head of a fluid at “a” is equal to the total
head at “b”, provided that there’s no loss due tofriction or work, and no gain due to the application of
work.
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Centrifugal Acceleration
Low
Velocity
At rest Rotating
High Velocity
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Pump Definition - Centrifugal
A pump is a mechanism used to push a liquid with a specific force,
to overcome system friction loss and any existing difference in elevation
(static pressure).
A centrifugal pump is a mechanism that adds energy in the form of velocity
to a flowing liquid. The pump produces this velocity through the means of a
motor or driver which consumes energy in the process.
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Pump Definition - Centrifugal
Pressure is produced as a result of the
“centrifugal effect”
The velocity produced by the “centrifugal
effect” represents kinetic energy that has been
imparted to the fluid
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Pump Major Components
Casing Tongue
Volute Casing
Impeller Vanes Impeller
Impeller Eye
Rotation
Pump Suction
Area increases constantly
Discharge
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Pump Impeller
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Typical Single Suction Impeller
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Single Suction Impeller
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Open
Semi-open
Closed
Single suction
Double suction
Non-clogging
Axial flow
Mixed flow
Impeller Types
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Why so Many Impellers…?
Impeller “specific speed”, NS Correlates capacity, head, and rpm at optimum
efficiency.
NS = nQ.5/H.75, where NS, specific speed, dimensions not used
n, rpm
Q, gpm at best efficiency
H, head, feet
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Specific Speed
“… the revolutions per minute at which a
geometrically similar impeller would run if
it were of such a size as to discharge onegallon per minute against one foot of
head.”
Hydraulic Institute Standard 1.1-1.2 2000Section 1.1.4.1
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Impeller Profiles
Specific Speed
HI Standard
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Specific Speed
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Generally
Maximum efficiency lies in the range:
2000
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Typical Impellers
Single Suction Double Suction
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Typical Impellers- Application
End Suction- Single Suction Impeller Split Case- Double Suction Impeller
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Full Diameter Impeller
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Trimmed Impeller
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Impeller and Volute
Arrows represent the
direction of water flow
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Velocity Through the Pump
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Impeller- Velocity Concept
The water is“Whipped”away from theeye by thevanes.
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