Pump Intake Design9.8 Pump intake design . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19.8.1 Design objectives . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . 19.8.2 Intake structuresfor clear liquids . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . 19.8.3 Intake structures for solids-bearing liquids . . .. . . . . . . . . . . . . . . . . . . 159.8.4 Pump suction piping .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . 209.8.5 Model tests of intake structures . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . 229.8.6 Inlet bell designdiameter (D) . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . 289.8.7 Required submergence for minimizing surfacevortices . . . . . . . . . . . . 299.8.8 Glossary and nomenclature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Pump Intake Design ANSI HI 9.8: 1998.pdf
Figures9.8.1 Recommended intake structure layout . . . . . . . .. . . . . . . . . . . . . . . . . . 39.8.2 Filler wall details forproper bay width . . . . . . . . . . . . . . . . . . . . . . . . .. 39.8.3 Type 10 formed suction intake . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . 69.8.4A Wet pit duplex sumpwith pumps offset . . . . . . . . . . . . . . . . . . . . . . . .79.8.4B Wet pit duplex sump with pumps centerline. . . . . . . . .. . . . . . . . . . . . 79.8.4C Dry pit/wet pit duplex sump . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79.8.5AWet pit triplex sump, pumps in line . . . . . . . . . . . . . . . .. . . . . . . . . . . 89.8.5B Wet pit triplex sump, compact . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . 89.8.5C Drypit/wet pit triplex sump. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 89.8.6 Trench-type wet well . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89.8.7 Trench-type wet well with formed suction inlet . . . . . . .. . . . . . . . . . . . . 99.8.8 Datum for calculation ofsubmergence. . . . . . . . . . . . . . . . . . . . . . . . .109.8.9 Definitions of V and D for calculation of submergence. . .. . . . . . . . . . 119.8.10 Open bottom can intakes (pumps lessthan 315 l/s [5000 gpm]) . . . . 129.8.11 Closed bottom can . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 139.8.12 Submersible vertical turbine pump . . . . . . . . . . .. . . . . . . . . . . . . . . . 149.8.13 Open trench-type wet well. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169.8.14 Open trench-type wet well for pumps sensitive to loss ofprime. . . . . 169.8.15 Circular wet pit with sloping walls andminimized horizontalfloor area (submersible pumps shown forillustration) . . . . . . . . . . . . . . . . . . . . 189.8.16Circular wet pit with sloping walls and minimized horizontalfloorarea (dry pit pumps) . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 199.8.17 Confined wet walldesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . 209.8.18 Common intakes for suction piping showingsubmergencedatum references . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 219.8.19Recommended suction piping near pump, all pump types(D = pipediameter) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 229.8.20 Examples of suction pipefittings near pump that requireapproval of the pump manufacturer .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
9.8.21 Recommended suction piping for double suction pumpswiththe elbow in the same plane as the impeller shaft . . . . . . . . .. . . . . . . . . . 229.8.22 Suction header design options . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . 239.8.23Classification of free surface and sub-surface vortices . . . . . .. . . . . 269.8.24 Typical swirl meter . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . 279.8.25ARecommended inlet bell design diameter (OD) . . . . . . . . . . . .. . . . 309.8.25B Recommended inlet bell design diameter (OD) (USunits) . . . . . . . 319.8.26A Recommended minimum submergence tominimize freesurface vortices . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .339.8.26B Recommended minimum submergence to minimize freesurfacevortices (US units) . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 34A.1 Examples of approach flowconditions at intake structures andthe resulting effect onvelocity, all pumps operating . . . . . . . . . . . . . . . . . . .. . 43A.2 Examples of pump approach flow patterns forvariouscombinations of operating pumps . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . 44A.3 Comparison of flowpatterns in open and partitioned sumps . . . . . . . . . 45A.4Effect of trash rack design and location on velocitydistributionentering pump bay . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 46A.5Flow-guiding devices at entrance to individual pump bays . . . . .. . . . . . 46A.6 Concentrated influent configuration, with andwithout flowdistribution devices. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47A.7Baffling to improve flow pattern downstream from dual flow screen .. . . 47A.8 Typical flow pattern through a dual flow screen . . . .. . . . . . . . . . . . . . . 48A.9 Improvements to approach flowwithout diverging sump walls . . . . . . . . 49A.10 Elevation viewof a curtain wall for minimizing surface vortices . . . . . .49A.11 Methods to reduce sub-surface vortices (examples AI) . . . .. . . . . . . 51A.12 Anti-vortex devices . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . 52B.1Operational sequences . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . 56B.2 Pump and system head curves. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
RevisionsThe Standards of the Hydraulic Institute are subject toconstant review, and revi-sions are undertaken whenever it is foundnecessary because of new develop-ments and progress in the art. Ifno revisions are made for five years, thestandards are reaffirmedusing the ANSI canvas procedure.Over the past several decades,long-term performance results for many differentcentrifugal andaxial flow pumping facilities have become available. Based onsomeless than satisfactory results, the industry has recognized a needfor updat-ing the standard approaches to designing pump intakestructures and suction pip-ing. In response to this evolving need,the Hydraulic Institute has improved andexpanded itsrecommendations for designing intake structures for centrifugal,ver-tical turbine, mixed-flow, and axial-flow pumps and addedintake designs for solids-bearing liquids.This standard is a resultof the combined efforts of a balanced committee that wasformed toreflect the perspectives of sump designers, hydraulic researchers,pumpmanufacturers, and end users. It replaces ANSI/HI 1.1-1.5-1994Section 1.3.3.6and ANSI/HI 2.1-2.5-1994 Section 2.3.5.The intent ofthis current edition of the pump intake design standard is toprovidedesigners, owners and users of pumping facilities afoundation upon which todevelop functional and economical pumpingfacility designs. The material hasbeen prepared with the deliberategoals of both increasing understanding of thesubject andestablishing firm design requirements.
ScopeThis standard provides intake design recommendations forboth suction pipes andall types of wet pits. While specific intakedesign is beyond the scope of the pumpmanufacturers responsibility,their comments may be helpful to the intakedesigner.
ConsensusConsensus for this standard was achieved by use of thecanvas method. The fol-lowing organizations, recognized as havinginterest in the pump intake designswere contacted prior to theapproval of this revision of the standard. Inclusion inthis listdoes not necessarily imply that the organization concurred with thesub-mittal of the proposed standard to ANSI.Ahlstrom Pumps,LLCAlden Research Laboratory, Inc.Bechtel CorporationBlack &VeatchBrown & CaldwellCamp Dresser & McKee
Major RevisionsPast Hydraulic Institute intake design standardshave been based on the ratedflow rate of the pump, while severalother pump intake guidelines are based ondimensions determined frommultiples of the inlet bell diameter.Recognizing that a balancebetween these concepts may optimize the intakedesign, this editionis based upon:
Rectangular IntakesThe dimensioning for rectangular plan intakeshas been changed from a flow-based design to one based on D, asdetermined by the inlet bell velocity. A parti-tioned intake designis recommended over an open intake design.Reference sections(9.8.2.1 and 9.8.3.4)
Solids-Bearing Liquids ApplicationsIn past editions of thisstandard, discussions of solids-bearing liquids were limitedtoadvising designers to obtain specific recommendations from pumpmanufactur-ers. This standard provides recommendations for pumpsump designs intendedfor solids-bearing liquids. It addresses thespecial considerations of keeping wetwells clean and maintainingminimum velocities. Specific recommendations forwet well geometriesare provided.Reference section (9.8.3)
Pump Intake Design9.8 Pump intake designMetric units ofmeasurement are used; and corre-sponding US units appear inbrackets. Charts, graphsand sample calculations are also shown inboth metricand US units.
The negative impact of each of these phenomena onpumpperformance depends on pump specific speedand size, as well asother design features of the pumpthat are specific to a given pumpmanufacturer. In gen-eral, large pumps and axial flow pumps (highspecificspeed) are more sensitive to adverse flow phenomenathansmall pumps or radial flow pumps (low specificspeed). A morequantitative assessment of whichpump types may be expected towithstand a givenlevel of adverse phenomena with no ill effects hasnotbeen performed. Typical symptoms of adverse hydrau-licconditions are reduced flow rate, head, effects onpower, andincreased vibration and noise. 2ff7e9595c
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