Lecture 12 Pumps Flashcards

1
Q

definition of a pump

A

machine : move liquid: raise pressure

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2
Q

four reasons for pumping

A

pressure
velocity
friction
elevation

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3
Q

3 types of pumps

A

gravity
positive displacement
kinetic

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4
Q

positive displacement cpump description and 4 examples

A

part of liquid is trapped and displaced by applicatrion of a force

diaphragm
reciprocating hand pump
rotary (da vinci wheel)
rope pump

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5
Q

when to use PD

A

high viscosity
high presure
low velocity
fragile solids

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6
Q

three types of centrifugal pumps (which are kinetic pumps)

A

radial
axial
mixed

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7
Q

how does cavitation occur

A

absolute presure at pump inlet falls below vapour pressure of fluid
bubbles form
they reach impeller , increased pressure, collapse, large localised pressure

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8
Q

three types of efficencies

A

hydraulic
mechanical
volumetric

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9
Q

hydraulic efficeincy based on

A

friction
accel/deccel
change in directions

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10
Q

what is mechanical efficiency

A

power gained by fluid compared to power upplied by shaft

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11
Q

volumetric efficiency

A

leakage and backflow

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