Pumps Liquids

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Pumps (Liquids)

• Important part of every chemical process design
• Many different kinds - application specific
• How to size a pump - nomenclature - required
  data - calculations necessary

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Pump web sites

• www.pumpschool.com mostly positive displacement
  pumps
• www.pumpworld.com dynamic and positive
  displacement

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Pump Types
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Centrifugal Pump
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Two transparencies cross section of centrifugal
pump pump and motor assembly
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Positive Displacement Pumps
Taken from www.pumpschool.com
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Pump Nomenclature

• Friction head the pressure expressed in psi or
  feet of liquid needed to overcome the resistance
  to the flow in the pipe and fittings
• suction head when the liquid source is above
  the center line of the pump
• static suction head the vertical distance from
  the center line of the pump up to the free level
  of the liquid source
• static discharge head the vertical distance
  from the center line of the pump to the point of
  free discharge

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Pump Nomenclature

• velocity head the head needed to accelerate the
  liquid hv (velocity)2/2g
• dynamic suction head static suction head minus
  friction head minus velocity head
• dynamic discharge head static discharge head
  plus friction head plus velocity head
• total dynamic head dynamic discharge head minus
  dynamic suction head

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Pump Nomenclature

• Net positive suction head (NPSHa) available the
  absolute pressure of the liquid at the inlet of
  the pump. Is a function of the elevation,
  temperature and pressure of the liquid (total
  suction head minus vapor pressure)
• Net positive suction head (NPSHr)
  required determined by the manufacturer through
  exhaustive testing of pump. Is a function of
  head, flow, rotational speed, impeller diameter
  and can change with wear and different liquids
• For proper operation of a pump NPSHa gt NPSHr

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Pump Nomenclature

• Viscosity terms - Absolute viscosity - Kinetic
  viscosity absolute viscosity/density -
  Centipoise 0.01 g/cm-s or 0.001 Pa-s -
  Seconds Saybolt Universal (SSU) time for a
  certain quantity of liquid to flow through a
  certain capillary tube

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Centrifugal Pumps

• For most applications

Where N rotational speed, RPM Q capacity,
GPM NPSHA net positive suction head available,
ft.
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Centrifugal Pump curve
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Rotary Pump - Internal gear
Taken from www.pumpworld.com
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Rotary Pump - External gear
Taken from www.pumpworld.com
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• Rotary Pump Performance at Constant
  Pressure Note Pressure, viscosity
• What viscosity to use for non-Newtonian
  fluid Note log-log scale
• Typical Performance curve for Moyno Pump

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Pump Selection

• Liquid properties pH, specific gravity,
  viscosity, temperature corrosive nature,
  aeration, solids in suspension, etc.
• Pump properties type of pump, flow rate, NPSH,
  capacity, materials of construction, economic
  life, etc.

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• Show data sheets for pump selection
• Show Quotation for Viking Pump

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Flow Measurement
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Flow meter web sites

• http//www.omega.com/techref/flowcontrol.html
• http//www.omega.com/techref/
• http//www.frco.com/brooks/UnitedStates/index.htm
  l

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Flow Measurement-Types of Meters

• Differential Pressure
• Electromagnetic Flowmeters
• Tubine Meters
• Vortex Meters
• Positive Displacement Meters
• Ultrasonic meters
• Metering Pumps
• Mass Flowmeters
• Others

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Pressure Losses for Various Flow meters
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Energy costs of Flow meters
C correction factor for units 1.65 for F in
GPM and dP in feet OT operating time of meter
1.0 if operated continuously dP the pressure
loss F the flow rate SpG specific gravity
(water 1.0) the efficiency of the pump,
expressed as fraction
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• Show orifice plate error
• show magnetic flow meter
• show turbine meter (2)

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