Pumps CM4120 D. Caspary February, 2004
Outline • Intro to Pumping • Classifications of pumps • Positive Displacement Pump – Examples and Applications • Centrifugal Pumps – Examples and Applications • Pump Curves
History of Pumps • First pumps were driven by water wheels or animal powered • Water was lifted w/ paddles and dumped at a higher elevation • Over 2200 years ago in Greece, Persia, the Orient , some still in use today • Electric motor is most common machine in use today, the pump is second most common • Agriculture Automobile Construction Chemical Manufacturing Household Hydraulic Systems Submarines Space Station Zeeland to Zimbabwe
Pump Applications Used to increase the potential and/or kinetic energy state of a fluid • Liquid – water, chemical, fuels, coolants, refrigerants, hydraulic fluids, boiler feed, condensate return, etc. • Vapor/gas – foams, air, other gases • Slurries – concrete, quarry slurries, mud for drilling, precipitates, sewage, pulp stock, etc.
Two Primary Classifications of Pumps • Dynamic (or Centrifugal) – Use a spinning impeller to induce centrifugal forces, increasing pressure at the discharge side of the housing. • Positive Displacement – Transfers a fixed volume of fluid thru the pump housing with each cycle of operation.
Classifications of Pumps Overwhelming majority of all pumps are some type of Centrifugal Pump. • Lower initial cost • Reduced maintenance costs Positive Displacement Pumps are widely used but for specific applications.
Comparison betweenPositive Displacement and Centrifugal Pumps
Head vs. Flow Comparison between Positive Displacement and Centrifugal Pumps
Effect of Increasing Viscosity on Flow for Positive Displacement and Centrifugal Pumps
Comparison of Efficiency vs. Head between Positive Displacement and Centrifugal Pumps
Positive Displacement Pump “Family Tree”
Types of PD Pumps – Gear Pumps • External Gear Pump • High speed • Quiet operation • Fuel, lubricants, hydraulic fluid power systems, metering • No solids • Internal Gear Pump • Non-pulsating discharge pressure • Low NPSHR • Low to moderate speed • High viscosity fluids
Other Common Types of PD Pumps • Lobe Pump • No metal to metal contact • Can handle solids without damaging them • Applications are found in food processing, pharmaceutical, personal care, etc. • Diaphragm Pump
Pumps Positive Displacement Centrifugal Multi-Stage Vertical Single Stage Horizontal Open Impeller Closed Impeller Centrifugal Pump “Family Tree”
How a Centrifugal Pump Works • Pump housing must be primed • Impeller rotates, imparting an outward velocity to the fluid – kinetic energy • Fluid velocity reaches maximum at the outside diameter of the impeller • Fluid enters the volute where it is channeled to the discharge • Resistance to flow, starting at the volute, reduces velocity creating pressure energy • Vapor pressure of fluid causes new fluid to be drawn into the eye of the impeller
A Centrifugal Pump/Driver Installation Discharge line Electric Motor Pump Housing Coupling Bearing Support Suction line External Cooling Stuffing Box and Packing Gland
Single Stage, Horizontal Shaft, Closed ImpellerFlowserve Pump Co.
Horizontal, Split Case, Single Stage Fire PumpPatterson Pump, Div. of Gorman-Rupp
Vertical PumpsCarver Pump Co.
Horizontal, Multi-Stage Pump Cut-away
Types of Impellers • Closed vane • Open vane • Open vane, cut impeller
Pump Curve for a Goulds Model HSC centrifugal pump at 3500 rpm When selecting new pump or changing capacity of existing pumps: • Capacity for 6 impeller sizes • NPSHR • Req’d horsepower • Efficiency
Pumping Affinity Laws Used for estimating pump performance when changing impeller size or RPM • Q1/Q2=N1/N2 • H1/H2=(N1/N2)2 • P1/P2=(N1/N2)3
Pump EfficiencyOverall Efficiency PP, Pump Input power, BHP PW, Pump Output Power PMOT, Driver Input Power
Pump Maintenance • Seals • Shaft packing vs. mechanical seals • Monitor for leaks • Bearings • Overhung vs. double support • Monitor vibration • Wetted parts corrosion • Cavitation • monitor suction-side pressure • listen for rattling
References • Viking Pump product literature • Gorman-Rupp product literature • Goulds Pump product literature • Flowserve product literature • Carver Pump product literature • Pump Handbook, Karassik, Krutzsch, Fraser, Messina, McGraw-Hill, 1976 • www.pumpschool.com, Viking Pump, Feb. 2004. • www.engineeringtoolbox.com, The Engineering Toolbox, March 2004.
Pumping Terminology • Head • Gauge head (hg) • Velocity head (hv) • Elevation head (Z) • Atmospheric head (hatm) • Total suction head or suction lift (hs) • Total discharge head (hd) • Total head (H) • NPSHA • NPSHR
