Positive Displacement & Axial Pumps
Created by: Evan Croft, Chandler Croneigh & Jon Cronin
CIVE 401—Spring 2015
Axial Pumps Type of Centrifugal Pump
Applies a centrifugal force to the fluid moving through the impeller
Centrifugal force becomes greater than gravity force holding water in place
Fluid rises and flows out of the pipe
Conversion of energy using principles of angular momentum
Momentum is conserved along axis of the pump
Configuration & Operation
Axial Pump Consists of:
Rotating element known as the “impeller”
Closed housing to seal pressurized water inside
Vanes within housing guide and direct flow through pump
Motor connected to shaft supplies power to impeller
Hydraulic Operations
Impeller draws water in through the eye to a region of low pressure
Water is directed toward the outside of the housing to a region of high pressure
Energy is converted from velocity head at the eye of the impeller to pressure head at the outlet
Positive Displacement Pumps
Two Types Reciprocating
Plunger/Piston
Single Acting: Fills pump cylinder with fluid on suction stroke and forces fluid out on discharge stroke.
Diaphragm
Uses reciprocating action of diaphragm and valves to trap fluid and force it into discharge pipe
Work by drawing in a fixed amount of fluid and forcing it out of the pump at a constant rate.
Diaphragm pump in use at the water quality lab at CSU. Pumps water through electro-coagulation device and discharges it into small reservoir.
Positive Displacement Pumps: Types
Rotary Rotating mechanism
draws fluid in from region of low pressure and discharges to a region of high pressure
Self Priming
Typically located above the fluid source
i.e. A drinking straw in a glass of water
Advantages/DisadvantagesPDPs Advantages PDPs DisadvantagesFixed volume of fluid ejected each time Oscillating PDPs less suitable with high speeds
Continuous flow despite differential pressure and/or high pressure differentials
Safety issues can arise due to ability of pump to produce extremely high pressures requiring use of pressure-release mechanism
Handle high-viscosity liquids efficiently Larger number of parts prone to wear
Create suction lift Cannot achieve high flow rates necessary for industrial applications
Axial Pump Advantages Axial Pump Disadvantages
Wide range of pressure, flow & capacities Not well-suited for high-pressure applications
Fewer moving parts Do not handle high-viscosity fluids well
No excess pressure build-up No suction lift capabilities
Produce high flow rates necessary for industrial applications
Common ApplicationsPositive Displacement Pumps Axial Pumps
Rotary Reciprocating Single Suction
Metering Suction Lifti.e. wells
Sewage handling—Domestic, Industrial, Commercial
Pulsed Deliveryi.e. fuel injection for engines
Agriculture—Lift water for irrigation and drainage
Wastewater treatment plants
Governing Equation #1 –Pump HeadBernoulli’s Equation:
Where: = Pressure Head, = Velocity Head, = Elevation Head,
= Friction and Minor Losses Through Pipe, = Pump Head
Conditions:
0 ( at surface)
0 ( 0 at surface)
Yields:
∆
Governing Equation #2 –Pump PowerDefinition:
∗
or∗
∗ ∗ ∗ ∗ ∗
∗ ∗
Conversions:∗ ∗
550 fromEnglishunitstoHorsepower
∗ ∗745 fromEnglishunitstokiloWatts
Example #1The pipe system shown must provide a discharge rate of 10 ft3/s. Determine the power in HP required by the pump.
Using Governing Equation #1:
∆
∆ 5
Find :
. ∗ 1.8 , 0.04, 1.0 , 0.9
/∗
12.73 /.
∗ . /2.52
Example #1 (continued)
∗ 2 1.8 0.04 1.0 0.9 ∗ 2.52ft 9.41ft
∆ 5 9.41 14.41
Using Governing Equation #2:
∗ ∗62.4
∗ 14.41 ∗10
8,994∗
Conversion:∗ ∗
5508,994550 16.4
Example #2If the pipe system shown must provide a flow
rate of 4ft3/s, would a displacement pump as shown be be adequate to provide the needed power?
Using Governing Equation #1:
∆
∆ 2
Find :
. ∗.
1.6 , 0.5, 1.0
/∗ .
20.37 /.
∗ . /6.44
Example #2 (continued)
∗ 2 1.6 0.5 1.0 ∗ 6.44ft 19.98ft
∆ 2 20 22
4 ∗ 450 1,800
According to the pump classification chart,
the pump type should be “axial flow”.
Therefore, a linear displacement pump
is adequate for these conditions.
Axial Flow Pump Applications
Pumps used for high flow and low head
Flood Control
Agricultural Irrigation
Raw Water Intake at Water Treatment Plant
Raw Water Intake at Coal-Fired Power Plant
Flood Control
Flood control system in New Orleans, Louisiana
Storm water temporarily stored in a canal
Storm water pumped from a canal to a lake
Protects lives and property during floods
Agricultural Irrigation
Simple pump system is relatively inexpensive, easy to operate, and transportable
Moves large flows of water from nearby waterway to crops
Improves agricultural production which drives subsistence and economy
Displacement Pump Applications
Pumps used for constant flow of various fluids (e.g. air, water, oil, etc.)
Pump for water filtration system (Rotary Pump)
Pump water from well (Reciprocating Pump)
Water Treatment Plant –Membrane Filtration
Water Treatment Plant in Beijing, China
14 rotary pumps achieve a total output of up to 10,000 m3/h
Direction of flow is easily reversed to backwash filters
Low maintenance pumps may be serviced on-site by plant operators
Hand Pump for Well Water
Reciprocating pumps system is relatively inexpensive to install and easy to operate
Provides access to groundwater
Improves quality of life
Conclusion
Axial Pumps
Type of Centrifugal pump
Good for high flow rate, low pressure applications
Do not handle highly viscous fluids well
Used in industrial applications
Positive Displacement Pumps Two Types:
Reciprocating & Rotary
Good for applications with high pressure differentials requiring suction lift and fixed volumes
Used in many types of engines and well-pumps
References “Axial Flow Pumps.” Pump Scout. Pump Scout, 2014. Web. 22 Oct. 2015.
"Axial Flow Pumps Information." IHS Engineering 360. IHS Engineering 360, 2015. Web. 23 Oct. 2015.
Eisler, Peter. “Probe: New Orleans flood control pumps not reliable.” USA Today. USA Today, 29 Aug 2009. Web. 22 Oct. 2015.
"Positive Displacement Pumps." Engineering Toolbox. Engineering Toolbox, n.d. Web. 23 Oct. 2015.
“Positive Displacement Pumps.” Positive Displacement Pumps. Pump Scout, 2014. Web. 22 Oct. 2015.
"Pump School's Rotary Pump Family Tree." Pump School's Rotary Pump Family Tree. Viking Pump, 2014. Web. 23 Oct. 2015.
“Rotary Lobe Pumps: Membrane Filtration.” Boerger. Boerger, 2015. Web. 22 Oct. 2015
"Rotary Pumps." Rotary Pumps. Freelance Software, n.d. Web. 23 Oct. 2015.
"Rotating Machinery Design Basis – Pump." Harmadipedia. Harmadipedia, 27 June 2013. Web. 21 Oct. 2015.
Stuck, Dietmar. “Hand Pumps for Water Wells: Comparison.” New Solar Pump. New Solar Pump, n.d. Web 22 Oct. 2015