PumpTech Customer Education · 2016-07-14 · Bernoulli’s theorem states that, during steady...
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PumpTech Customer Education Bellevue Moses Lake Canby http://www.Pumptechnw.com
Transcript of PumpTech Customer Education · 2016-07-14 · Bernoulli’s theorem states that, during steady...
PumpTech Customer Education
Bellevue Moses Lake Canby
http://www.Pumptechnw.com
PumpTech Product Lines UL Listed
Packaged Systems
Two full time Mechanical Engineers Licensed in OR, WA & ID
SolidWorks & E-Drawings Viewer
AutoCad Compatible Drawings
All Systems UL QCZJ Listed
Designed to HI Standards
Manufacturing Facility Canby, OR
Installation, Maintenance & Repair 9 Full Time Service Technicians 3 Full Service Shops 6 Service Trucks 23 Ton Crane Truck 8 Ton Crane Truck 3 Ton Crane Truck 2 Ton Flatbed & Trailer 1 Ton Flatbed & Trailer
Pump Ed 101
Joe Evans, Ph.D
http://www.PumpEd101.com
http://www.Pump-Zone.com
Velocity Head
Centrifugal Pump Dynamics
Discharge
Volute
Impeller
Suction
What Type of Energy is Added by the Impeller ?
Pump ED 101
Hint *
Dynamics
Centrifugal
Cutwater
Pump ED 101
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Dynamics
Centrifugal Force
It is defined as “center fleeing”
Pump ED 101
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Dynamics
Centrifugal Force
When an object is traveling in a circle, it is actually moving in a straight line at any single point in time.
Instead it actually moves in the same direction it was traveling at the exact instant it is released.
Pump ED 101
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Dynamics
So, How Does It Work ?
1 Rotation of the impeller forces water from its entry point, at the eye, into its vanes.
2 Water moving through the vanes creates a partial vacuum at the eye allowing atmospheric, or some other outside pressure, to force more water into the eye.
3 As water travels through the vanes, it gains rotational velocity (kinetic energy) and reaches its maximum velocity just as it exits the vanes.
4 Upon exiting the vanes, water enters the volute where its kinetic energy of motion is transformed into pressure energy.
Linear versus Rotational Motion
Speed = d / t
Rotational Speed (w) = rotations / t
Linear Speed (v) ∝ radius (r) x w
Pump ED 101
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Dynamics
Pump ED 101
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Dynamics
On the disc to the right there are two points, one at 6” from its center and one at 12”. The circle described at 6” has a circumference of 37.7” and the one at 12” a circumference of 75.4”.
12” 6”
Linear Velocity in a Rotational Frame of Reference
v = C x w
At a speed of one rotation per second a point 12” from the center will travel twice the distance of a point that is 6” from the center. Therefore its velocity is twice as great.
Pump ED 101
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Dynamics
Water Energy
Water Can Possess Three Forms of Hydraulic Energy
Potential Energy – Due to Elevation
Kinetic Energy – Due to Velocity
Pressure Energy – Due to Weight (force)
These Three Forms of Energy Must Live In Harmony
Conservation of Energy
Conservation of Energy
50 PSI 50 PSI 48 PSI
100 GPM
Pump ED 101
Bernoulli’s theorem states that, during steady flow, the energy at any point in a conduit is the sum of the velocity head, pressure
head, and elevation head. It also states that this sum will remain constant if there are no losses. Daniel Bernoulli 1700-1782
H = v + p + z = Constant
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Dynamics
Pump ED 101
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Dynamics
Energy = v + P + z = Constant
Daniel Bernoulli Hydrodynamica - 1738
Pump ED 101
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Dynamics
Piezometer Measurement
Energy = v + P + z = Constant
Pump ED 101
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Dynamics
Piezometer & Pitot Tube Measurement
Energy = v + P + z = Constant
Pump ED 101
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Dynamics
Energy = v + P + z = Constant
What is the Total Head produced by a centrifugal pump?
Pump ED 101 Total Head
Total Dynamic Head
Pump ED 101 Total Head
Total Suction Head
hs = ± hgs + hvs ± Zs
Total Discharge Head
hd = hgd + hvd ± Zd
Total Dynamic Head
H = hd - hs
Total Dynamic Head
Where:
hg = gauge head
hv = velocity head
Z = gauge distance above or below datum
Where:
hd = discharge head
hs = suction head
Falling Body Equation V2 = 2gh
Pump ED 101 Total Head
Velocity Head
Velocity Head Equation h = V2 / 2g
At a Velocity of 8 ft/sec h = 1’
KE = 1/2mv2
What is the effect of velocity?
The Performance Curve
Pump ED 101
BEP BEBOP
3X4 End Suction - 650 GPM
Pump ED 101 Total Head
Pump Testing
hv = V2 / 2g
258.3 ’ 247.2 ’
Actual 3” Pressure = 112.4 PSI (259.6 ft) .
Actual 5” Pressure = 112.5 PSI (260 ft)
TDH Error 4.7%
TDH Error 0.6%
Velocity 3” = 28.2 ft/sec Velocity 5” = 10.4 ft/sec
3” Section hv = 12.4 ft 5” Section hv = 1.7 ft
Pump ED 101
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Dynamics
Lift Station Pump
650 GPM @ 25’ (10.8 PSI)
4” Discharge Piping 10 ft
Gauge Reading at Valve Box = 6.6’ (2.8 PSI)
Corrected for Friction = 10.8’ (4.7 PSI)
Corrected for Elevation = 20.8’ (9 PSI)
Pump Testing
Corrected for Velocity Head (v = 16.4 ft/sec) = 25’ (10.8 PSI)
TDH Error Ignoring Velocity Head = 19%
Pump ED 101
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Dynamics
Pump ED 101
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Dynamics
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Dynamics
Pump ED 101
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Dynamics
Pump ED 101
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Dynamics
Pump Ed 101
Joe Evans, Ph.D
http://www.PumpTechnw.com
http://www.PumpEd101.com
http://www.Pump-Zone.com
Velocity Head
