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on the pump sump design Determining the best pump sump for a site therefore requires engineering and exper tise We will provide general guidance for the design of pump sumps using large centrifugal pumps Methods and procedures are given for handling various inflow conditions avoiding solids buildup and arranging multiple pumping
Engineering Expertise,Total solution engineering,increases operational efficiency. Achieving lowest total cost of ownership, Introduction When providing pumping solutions Flygt prefers to. take the total cost of ownership into consideration. The proper design of the pump sump is criti,cal in order to optimize pump inflow and. thereby pump station efficiency The number,Investment. type and arrangement of pumps variable,flow conditions in the approach area the. geometry of the structure itself and other Unplanned. site specific factors must be evaluated on a Operational. case by case basis to identify their influence,on the pump sump design. Determining the best pump sump for a site,therefore requires engineering and exper. tise We will provide general guidance for the, design of pump sumps using large centrifugal Investment costs. pumps Methods and procedures are given for Costs associated with design excavation civil work. handling various inflow conditions avoiding product purchases installation and commissioning. solids buildup and arranging multiple pumping, units in order to achieve an efficient well de Operational costs. signed pump sump Over time energy usage and maintenance costs are. often the major contributors to the overall costs along. For more detailed information and design with the cost of labor required to run the system. requirements please read our engineering, brochure Design recommenda tions for pump Unplanned costs. stations with large centrifugal Flygt wastewater When things go wrong such as pump failures stem. pumps ming from problematic station design costs can. sky rocket Unexpected downtime can cause sewer,backups overflows basement flooding and untreated. effluent On top of that you have to repair pumps and. take corrective measures regarding the station design. Engineering Expertise,Thanks to our engineering expertise we can lower. your total cost of ownership We can analyze your,system using state of the art computational pro. grams We can test your pump station using scale,models if required We can also provide you with. reference installations that are similar to your proj. ect All of this together with our premium products. provides you with an optimized design,Reference installations. Engineering Expertise,Introduction,Reliable pump station designs. Flygt large centrifugal pumps with self cleaning pumps operate in various appli. technology are highly effective compact pumps cations such as. that can be submersed directly into the liquid to be. pumped or dry installed Wastewater pumping,Raw water pumping. Because the motor and hydraulics are integrated Cooling water. into one compact unit these pumps have a much Stormwater. smaller installation footprint than their non sub Flood control. mersible counterparts This enables the design of Seawater pumping. more compact easier to build pump stations Key Industrial effluent. features are handling,Irrigation,Sustained high efficiency Process water. Self cleaning capabilities, Compact modular design General performance range We offer a broad range of pumps. No separate lubrication system,Low noise and vibration levels 100. Flood proof pump stations,Quick and easy installation. Minimal station superstructure 3312 3531,Reliabilty easy to service 20. Flygt large centrifugal submersible 3800,50 100 200 500 1 000 2 000 3 000. Achieving lowest total cost of ownership, Correctly designed stations will ensure minimal sed. imentation and or accumulation of debris thereby,reducing planned services and maintenance A well. designed pump station optimizes hydraulic condi,tions for the pumps thus ensuring reliable pump. operation and specified performance We assure,optimal sump size making it as small as feasibly. possible without compromising on reliability or,efficiency. Design conditions,Adverse hydraulic, According to the Hydraulic Institute Ideally the Uneven velocity distribution at the pump intake. flow of water into any pump should be uniform Uneven velocity distribution can result from differ. steady and free from swirl and entrained air Lack ent types of phenomena and disturbances While. of uniformity can cause the pump to operate away some unevenness in velocity distribution is inevi. from the optimum design condition and at a table and does not harm the pump variations that. lower hydraulic efficiency Unsteady flow causes are greater than 10 at the pump intake can have. the load on the impeller to fluctuate which can severe consequences and should be avoided A. lead to noise vibration bearing problems and fa large variation results in an uneven load on the im. tigue failures of pump shafts peller and bearings Unsteady flow causes the load. on the impeller to fluctuate which leads to noise vi. To ensure the expected pump performance and bration bearing loads and increased risk of fatigue. long service intervals it is important to design the failures. pump sump to prevent adverse flow conditions,Excessive pre swirl. Pre swirl changes the flow conditions at the pump, inlet which results in a change in the relative impel. ler speed This in turn causes a change in pump,performance which can lead to overloading the. motor or reduced pump performance Excessive, pre swirl can also result in bearing wear and cavi. tation across the impeller area Pre swirl usually,originates from an asymmetric velocity distribu. tion in the approach channel which evolves into a, pre swirl at the pump inlet The Hydraulic Institute. recommends a pre swirl angle that does not exceed, 5 calculated from the ratio between the tangential. velocity and the axial velocity, CFD simulation of the flow distribution at the impeller plane. A non uniform approach inflow leads to pre swirl which can Uneven velocity into the pump inlet leads to noise vibration. overload the motor or reduce pump performance and bearing wear. Entrained air Vortices, It is widely known that even minor air entrainment Unlike excessive pre swirl vortices appear locally. of some 3 4 of the volume will lead to a clear with higher intensity and are a major hindrance. reduction in pump performance and loss of effi to proper pump operation resulting in cavitation. ciency the severity depends upon the quantity of uneven load noise and vibration There are several. air entrained and the pump type The expansion of different types of vortices. ingested air bubbles within the impeller may result. in mechanical imbalance vibration and accelera The most commonly known type is the free surface. tion of mechanical wear Normal design practices vortex which can have varying degrees of intensity. recommend the exclusion of any air entrainment in from weak surface vortices to fully developed vor. the approach flow to the pump intake In addition tices with a continuous air core that extends from. entrained air leads to increased corrosion the surface into the pump. While air bubbles may be present in the liquid for a Less well known but just as common is the vortex. variety of reasons their presence is usually due to that originates under the surface from the sump. cascading of the water as it enters the sump from bottom walls or between two pumps and extends. a weir culvert or incoming pipe located above the to the pump inlet This type of vortex can achieve. surface water level in the sump high rotational speeds with high subpressures and. cavitations, Entrained air and vortex shown in scale model test Strong surface vortex with an air core will result in cavitation. uneven load noise and vibration, Entrained air can cause reduction in discharge and loss of Strong submerged vortex. efficiency,Design conditions,Sediment floating debris. and clogging problems, In addition to preventing the occurrence of adverse Floating debris. hydraulic phenomena it is also important to design Low velocity regions also create floating debris on. the station to minimize build up of sediment at the the surface of the sump Again cleaning is costly. bottom of the sump and accumulation of floating and time consuming. Floating debris can be avoided with good station, Bottom sediments design by ensuring that the velocities in sump are. Too low a velocity will result in low shear stresses maintained and by not making the sump too large. on the bottom floor and build up of sediments It is also important to use a wastewater control. Cleaning bottom sediments is a costly and time philosophy and ensure functions such as alternation. consuming between all pumps and automatic cleaning cycles to. process In addition problems with odors are likely minimize floating debris. to occur when sediments build up,During a cleaning cycle the water level is pumped. When designing a sump it is important to avoid any down to a lower level until the pumps are snoring. low velocity regions within the sump This can be All floating debris will then be removed from the. achieved through the use of benching and a slop sump by the pumps. ing floor to direct the bottom sediments toward, the pump inlet If the bottom sediments are evenly Clogging. distributed over time into the pump no clogging If large mats of floating debris accumulate on the. problems will arise in the pumps surface in the sump significant increases in the flow. rate can release huge portions of the mats which,may clog the pump or system components. Bottom sediment buildup shown in a scale model test Pump station with accumulation of floating debris. PUMP STATION DESIGN,Verified design,We have designed developed and verified stan. dard Flygt branded pump stations Extensive physi, cal tests applications expertise and years of experi. ence have been utilized to optimize the design of,Flygt pump stations. Proven installations,Today there are thousands of pump stations in ac. cordance to the Flygt standard in operation all over. the world These have a proven track record of pre,venting sedimentation clogging floating debris. and adverse hydraulics Experience from existing, Flygt pump stations is also a critical success factor Centrifugal pump sump design verified by a scale model test. when designing new pump stations, Scale model testing Flygt pioneered the use of CFD to verify sump. When there is little or no prior experience we use design and we have been using CFD for many years. physical model testing to ensure the reliability in Depending on the complexity of the installation CFD. the design A model is built to scale typically at a can complement physical model testing or replace it. 1 10 scale on the basis of Froude number similarity entirely. to preserve the laws of physics and operated as a, real installation Analysis from the physical tests will We have a number of standard Flygt sump designs all. show if the design is reliable and effective and pro of which have been tested extensively through physi. vides a solution to ensure safe pumping operation cal model testing verified through CFD and proven. through installations in use around the world These. Computational fluid dynamics sump designs have proven to minimize accumulation. Another method we use to verify design is computa of sediments and debris and prevent adverse hydrau. tional fluid dynamics CFD a mathematical mod lic conditions When using standard Flygt designs. eling of the design where the flow pattern can be within the limits of our recommendations there is no. need for additional physical model testing or CFD, Centrifugal pump sump design verified through computational fluid dynamics CFD. Pump station design,Reliable cost,effective pumping. Our engineering expertise and vast experience Optimal sump sizing criteria. contributes to pump station designs that together Other important factors to consider are the dimen. with Flygt equipment ensure reliable and cost sions and capacity of a sump Designing a sump. effective pumping Because the pump station is a that is too small carries a low risk of sedimentation. complex system it is important to consider every problems but a high risk of poor inflow In contrast. critical aspect during the design phase Pumping designing a sump that is too large will create low flow. system efficiency depends not only on the effi regions which implies a high risk of sedimentation. ciency of the pumping units but also on the pre problems while at the same time a low risk of poor. vention of adverse hydraulic phenomena as well inflow These criteria must be taken into consider. as sedimentation floating debris and clogging ation to determine the optimal sump size. Objectives, Ideally the design of a pump station aims to achieve. Poor Sedimentation, Smallest possible footprint with the lowest inflow problem. possible cost,Elimination of sedimentation and buildup of. other debris,Reliable handling of variable inflow,Necessary operating conditions for optimal. Ease of installation maintenance and repair,When designing a station it is also important to. consider other factors that can have an impact on Optimal sump size depends on criteria such as poor inflow and. operations such as site conditions type of media sedimentation problems. and local regulations and practices,Methods of installation. To reduce installation costs standard Flygt pump packages with key pump station components are avail. able to facilitate site specific installation We have all the accessories and components required to meet. your specific needs, Semi permanent wet well Semi permanent free Vertically mounted Horizontally mounted. installation standing installation Permanent dry well or in Permanent dry well or in. Twin guide bars on a dis Transportable with pipe or line installation line installation. charge connection hose connection Flange connections for Flange connections for. suction and discharge suction and discharge,pipework pipework. The proper design of the pump sump is crucial in These standard wet well sump designs have been. order to achieve an optimal inflow to the pumps verified by computational fluid dynamics CFD. We can provide you with standard solutions for and physical scale model testing and have been. sump design based on our engineering expertise applied in thousands of pump stations around the. and experience world,Distributes and redirects uni. form flow with minimal mass,flow rotation into the sump. BAFFLE WALL,Minimizes air entrainment,due to cascading water. GUIDE VANES,Directs flow to the pumps,Distributes and redirects uni. form flow with minimal pre,swirl into the pump inlets. BACK WALL FILLING Flow splitter INTERMEDIATE BENCHING SLOPING FLOOR. Prevents sedimentation Prevents pre swirl and en Prevents pre swirl and Prevents sedimentation. mass flow rotation and re sures safe inflow at pump sedimentation. duces vortices intake,Standard sump design, Standard sump designs recommended by Flygt may design should therefore consider all critical aspects. be used as is or with appropriate variations to meet of operation correct operating levels and efficient. the requirements of most installations These design pumping cycles for reliable pumping. recommendations are valid for use with two three or. four pumps installed either in a semi permanent wet For more information on basic principles dimen. well or permanent dry well sioning and installation tips please read our publi. cation Design recommendations for pump stations, A sump designed in accordance with our recom with large centrifugal Flygt wastewater pumps. mendations is smaller than a conventional sump,naturally the pump capacity must match the ex. treme inflows to minimize the risk of flooding The. Pump station design,Standard wet well designs, Basically we have three standard pump station designs that are. applicable for use with either submersible or dry installed Flygt. pumps These designs are capable of being adapted to meet most. installation requirements,Rectangular sump with high front entry inlet. The standard rectangular front entry sump is the most common. sump design A specially designed inlet chamber with baffle wall. minimizes air entrainment due to cascading water, The flow from the inlet pipe strikes the baffle wall and then flows. down into the inlet chamber through the slot in the baffle floor The. slot distributes the flow toward all pump inlets The baffle wall is suf. ficiently high to prevent flow from surging over it Although the flow. in the inlet chamber is highly turbulent various materials can collect. there In such cases side overflow weirs or side gaps may be used. to carry away debris to prevent debris accumulation The top of the. baffle wall or portions of it should be below the highest start level Rectangular sump with high front entry inlet. of the pumps to allow transport of floating debris into the pump shown with submersible pumps. chamber which is then evacuated by the pumps,Rectangular sump with high side entry inlet. If the piping system and the sump location do not allow for a front. entry inlet a side entry inlet with a modified baffle wall with ports. may be used Lateral inlet naturally induces mass flow rotation into. the pump sump here the baffle wall redirects the incoming flow and. uniformly distributes the flow towards the pumps through the baffle. wall ports With a high inlet it is recommended that ports be posi. tioned along the inlet baffle chamber floor to dissipate the energy of. the cascading inflow when the water level in,the station is low Correct location. Rectangular sump with high side entry inlet and size of these ports are also. shown with dry installed pumps important,Rectangular sump with low side entry inlet. If the sewer is below the normal water level in the sump or if. an open channel supplies the sump a rectangular sump with a. straight baffle wall is recommended In the absence of cascading. flow in the approach no intense entrainment of air takes place. As a result the inlet chamber can be greatly simplified because. its only task is to distribute flow uniformly to the pumps In a dry. installed pump installation vertical baffles between the suction Rectangular sump with low side entry inlet. pipes are recommended to prevent mass rotation in the wet well shown with submersible pumps. Alternative wet well designs, When the three standard sump designs prove to be inappropri. ate to the site conditions we have alternative sump arrangements. that can also be adapted to the specific requirements. Circular sump, For deep sumps the use of a circular outer structure offers dis. tinct advantages Inside such a structure individual pump sump. modules similar to those used for compact sumps can be accom. modated This smaller installation footprint significantly reduces. construction costs,Circular sump shown with high front entry inlet. Double sump,When there are more than four pumps required in a. sump it can be difficult to achieve uniform flow dis. tribution to all pumps across the width of a sump In. such cases a double sump may be used to ensure, uniform flow distribution Another advantage is that. the station is split into two enabling one part of the. station to continue to function while the other part. is shut off thereby simplifying maintenance, Double sump shown with high side entry inlet and submersible. Large circular sump, For large structures it is often beneficial to install. the pumps in a circular formation rather than in a. linear manner This makes it easier to direct the flow. and obtain a more compact station The discharg,es can also be oriented either towards the center. or towards the periphery depending on the site,constraints and discharge conditions Location and. correct sizing of the distribution ports are of impor. tance as well as the infill forms in the vicinity of the. pumps this generally requires a specific study, Large circular sump distribution chamber shown with pump. discharges towards the center,Reference installations. Proven worldwide,Flygt has designed pump stations for thousands. of installations around the world Engineering,expertise and years of experience have resulted. in the success of these installations Three such,installations are described below. United States Wastewater lift station France Circular stormwater pump station. Challenge Challenge, A 54 000 acre service area in a major city in Texas One of the largest airports serving France required. required assistance to handle a projected 50 in a stormwater treatment plant to handle the inflow. crease in population and subsequent increase in from a large gravity sewer collecting water from the. wastewater processing demands runways,Solution Solution. With engineering expertise from Flygt the city built The pump station is set in a circular deep caisson and. the largest submersible pump station in the world includes both the dry weather inflow and stormwa. with 14 constant speed Flygt submersible pumps ter sumps The storm sump includes a circular inlet. in operation Prior to installation and commission baffle chamber for the stabilization and de aeration. ing the lift station design underwent physical scale of incoming storm flows and is equipped with 12. model testing to assure satisfactory flow condi large Flygt CP 3602 935 submersible pumps that are. tions The circular lift station design accommodates capable of discharging a total of 16 m s 254 000 US. the entire facility within the confines of the re gpm. stricted site and enables the use of sunken caisson. construction The pumped effluent is discharged to a grit chamber. and then to a dual lagoon collecting system before. This circular wastewater lift station provided esti it is treated through large sand filters and cleaned. mated cost savings of approximately 37 saving water is then transferred to the nearby river. millions of dollars City engineering staff reports. that the multiple pump facility operates reliably and. cost effectively under variable conditions,United Kingdom Transfer pump station. At one of the largest wastewater treatment plants in The second sump house is equipped with four. the Midlands a strategic pump station was at risk of Flygt CP 3531 835 variable speed pumps rated at. complete failure and required fast and efficient re 0 9 m3 s 14 000 US gpm These pumps operate. placement within the shortest possible timeframe on a three duty one standby basis Should inflow. exceed the capacity of these pumps the sump, Solution water level will increase and bring storm pumps. Flygt engineers contributed to designing and com that are mounted at a higher level in the sump into. missioning a 1300 kilowatt pump station with a ca operation The storm pumps are four fixed speed. pacity of 6 0 m3 s 95 000 US gpm within a 12 month Flygt CP 3531 805 units rated at 0 8 m s 12 700. period at costs well below the project budget The US gpm that operate on a three duty one standby. station includes two wet wells to handle inflow and basis This multiple pump installation provides a. maintain solids in suspension and valve chambers nominal combined output of 6 7 m3 s 106 000 US. suspended over the wet wells to minimize installation gpm for the pump station. The first sump house has six fixed speed pumps,operating on a six duty basis The pumps are Flygt. NP 3300 181LT units each rated at a flow of 0 2 m3 s. 3 200 US gpm When the inflow exceeds the capac, ity of the NP 3300 pumps the water level will increase. and eventually spill over into the second sump,Services AND support. Engineering Expertise, To ensure reliable and highly efficient operation Theoretical analysis. we offer comprehensive support and service for, pump station design system analysis installation Computational fluid dynamics CFD can provide far. commissioning operation and maintenance more detailed information about the flow field in a. fraction of the time required to get the same infor. mation through physical hydraulic scale model test. Design tools ing Using CFD in combination with computer aided. design CAD tools it is possible to obtain a more, When you design pump stations we can offer efficient method of numerical simulation for pump. advanced engineering tools to generate sump station design. designs Our design recommendations give you, essential information regarding dimensions and To obtain a reliable energy efficient pumping. layout In short we assist you every step of the system it is important to analyze all modes of op. way to make sure you optimize performance and eration To analyze the transient effects at pump. achieve energy efficient operations start and stop with respect to flow and head as. well as the electrical parameters such as current, and torque it is also important to have an accurate. mathematical description of the pump and motor,which is gained in part from extensive testing in. our laboratories,Physical testing Reference installations. Physical hydraulic scale model testing can provide We have conducted system analysis and designed. reliable cost effective solutions to complex hydraulic pump stations for thousands of installations around. problems This is particularly true for pump stations the world Engineering expertise and years of experi. in which the geometry departs from recommended ence gained from the design and operation of these. standards or where no prior experience with the installations have been a critical success factor when. application exists Scale model testing can also be analyzing testing and commissioning new pump. employed to identify solutions for existing installa installations. tions and has proven to be a far less expensive way. to determine the viability of possible solutions than. through trial and error at full scale,When our standard design recommendations are. not met we can assist in determining the need for, physical testing as well as planning and arranging. the testing and evaluating the results,Reference installations. Engineering Expertise, Model test photos courtesy of Hydrotec Consultants Ltd 15.