Pumps

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Pumps

• Outline
• Where are pumps used
• Pumps, fans, compressor differences
• General HP and mechanical efficiency
• Types of Pumps
• Displacement
• Dynamic
• Reading
• Handouts
• Chapter 4 Principles of Process Engineering
• Fluide Design Inc. Centrifugal Pump Fundamentals
  (download)

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Pumps, Fans, Compressors--Turbomachines

• Turbomachines change energy level of flowing
  fluid by means of momentum exchange
• 2nd only to electric motors in number
• Wide spread in ALL industries
• Power units cars/trucks, tractors
• Computers
• Grain elevators
• Oilfield
• Water supply/treatment
• Food processing
• And.

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Pumps, Fans, Compressors--Turbomachines

• Differences between pumps, fans, compressors
• Pumps move liquids
• Fans move gases with little increase in
  pressure
• Compressors move gases with greater increase in
  pressure

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Mechanical Efficiency

• Ratio
• Power Output
• English Units, HP
• Efficiency

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Pump example 1

• A pump provides 0.009 m3/s of water and total
  head of 10.6 m. Determine the power output of
  the pump. If the power input is 1310 W,
  determine the mechanical efficiency of the pump.

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Pumps

• Two types

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Displacement Pumps
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Displacement Pumps

• Reciprocating and Piston Pumps
• Crank
• Connecting rods
• Pistons or plungers
• Vol. efficiencies gt 97, Mech. eff. approx. 90
• For more stable flow, increase number of cylinders

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Displacement Pumps

• Rotary Pumps (gear, lobe, screw, vane)
• Most popular gear pumps
• 90 mechanical eff.
• Relatively constant output

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Dynamic Pumps

• Centrifugal
• Relative simplicity
• Mech. eff. as high as 90
• Can handle fluids containing suspended solids
• Ease of maintenancegood for food products
• 2 parts impeller and casing
• Radial, mixed, axial flow

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Performance Curves
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Performance Curves
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Centrifugal Pump Affinity Laws
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Centrifugal Pump Affinity Laws
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Centrifugal Pump Fundamentals

• Static head the height of a column of liquid
• Units feet or meters
• Pump imparts velocity to liquidvelocity energy
  becomes pressure energy leaving the pump. Head
  developed vel. energy at the impeller tips.
• Why do we use feet or head instead of psi
  or pressure?
• Pump with impeller D will raise a liquid to a
  certain height regardless of weight of liquid

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Converting pressure to head in feet
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Suction Lift
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Suction Head
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Static Discharge Head

• Static Discharge Head vertical distance from
  pump centerline to the point of free discharge or
  the surface of the liquid in the discharge tank.

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Total Static Head

• Vertical distance between the free level of the
  source of supply and the point of free discharge
  or the free surface of the discharge liquid.

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Total Dynamic Suction Lift or Head

• (fluid below suction) Static suction lift -
  velocity head at suction total friction head in
  suction line
• (fluid above suction) Static suction head
  velocity head at pump suction flange total
  friction head in suction line
• Velocity head energy of liquid due to motion,
  Usually insignificant

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Total Dynamic Discharge Head

• Static discharge head velocity head at pump
  discharge flange plus discharge line friction

Total Dynamic Discharge Head (TH or TDH) (this is
what we design for!!!)

• Total dynamic discharge head total dynamic
  suction head (tank above suction). Or.
• Total dynamic discharge head total dynamic
  suction lift (tank below suction)

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Total Dynamic Discharge Head (TH or TDH) (this is
what we design for!!!)
TDH includes friction losses due to piping and
velocity
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One last item to considerNPSH (net positive
suction head)
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NPSHR
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NPSHA
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NPSHA
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Capacity, Power, Efficiency

• Capacity Q, gpm 449 x A, ft2 x V, ft/sec
• Where A cross-sectional area of the pipe in ft2
  V velocity of flow in feet per second
• Bhp actual power delivered to pump shaft by
  driver
• Whp pump output or hydraulic horsepower

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Pump Efficiency
Ratio of whp to bhp
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System Example 80 ft of 4 ID galv. iron pipe
with 3 elbows, 75 lift, pumps from an open tank,
discharges through a pipe to a tank at atm.
Pressure (find rate, imp. dia., eff., motor size,
rpm)
Ratio of whp to bhp
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Homework Handouthttp//biosystems.okstate.edu/Hom
e/jcarol/Class_Notes/BAE2023_Spring2011/pump
hw.pdf
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Questions???
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