Module 5 Notes
Contents
1. Elev 60 m ad Lj 700m Figure 11 Three Reservoir System Schematic Here we will first convert the image into a bitmap bmp file so EPA NET can import the background image and we can use it to help draw the network The remainder of the problem is reasonably simple and is an extension of the previous problem The steps to model the situation are 1 o ND a A WO N Convert the image into a bitmap place the bitmap into a directory where the model input file will be stored Start EPA NET Set defaults Import the background Select the reservoir tool Put three reservoirs on the map Select the node tool put the node on the map Select the link pipe tool connect the three reservoirs to the node Set the total head each reservoir Page 12 of 28 CE 3372 Water Systems Design FALL 2013 9 Set the pipe length roughness height and diameter in each pipe 10 Save the input file 11 Run the program Figure 12 is the result of the above steps In this case the default units were changed to LPS liters per second The roughness height is about 0 26 millimeters if converted from the 0 85 millifeet unit EPANET 2 example 3 net File Edit View Project Report Window Help OSHS BXm F Mee k HKP NJE OHBBHCNHT a tt Network Map Data Map Nodes Head Elev 80 m Links Flow Time Single Period v Elev 60 m Era 3154 19 AA Le 700m Auto Lenath Off LPS maj 1002. XY 2796 46 9663 72 Figure 12 Solution for Example 3 The pipes were originally straight segments but a drawing tool in EPA NET is used to follow the shape of the underlying basemap The training video shows the pipes as the straight lines The flowrates are in liters per second divide by 1000 to obtain cubic meters per second 1 3 5 Example 4 A Simple Network Expanding the examples we will next consider a looped network As before we will use a prior exercise as the motivating example Page 13 of 28 CE 3372 Water Systems Design FALL 2013 The water supply network shown in Figure 13 has constant head elevated storage tanks at A and C with inflow and outflow at B and D The network is on flat terrain with node elevations all equal to 50 meters If all pipes are ductile iron compute the inflows outflows to the storage tanks Assume that flow in all pipes are fully turbulent Elev 75 m L 700m D 250mm C lt 0 2 m s L 800m D 300mm L 1000m D 400mm Elev 70 m 0 2 m3 s L 1200m D 350mm Figure 13 Two Tank Distribution System Schematic As before we will follow the modeling protocol but add demand at the nodes The steps to model the situation are 1 Convert the image into a bitmap place the bitmap into a directory where the model input file will be stored 2 Start EPA NET 3 Set defaults 3This problem is similar to Chin Problem 2 31 Pg 92 Page 14 of 28 CE 3372 Water Syst
3. Pumps are treated as special links that add head Valves are also treated as special links depending on the valve types All models must have a reservoir or storage tank The next example presents an analysis for a system where a valve is used to maintain a set pressure 1 5 1 Example 6 Gravity Supplied Water Distribution Network Consider a hypothetical water distribution system for Eagle Pass Texas The real system takes water from the Rio Grande and lifts it into an at grade storage reservoir From there the water is more or less gravity driven to the customers Figure 21 is a map not to scale of the elevations of demand nodes in the Eagle Pass system Figure 22 is a map of the customer population that needs to be served by the system Figure 23 is a map not to scale of the individual pipeline diameter for each pipe in the major distribution network Figure 24 is a map not to scale of the individual pipeline lengths for each pipe in the major distribution network To analyze such a system one would take the following steps 1 Estimate the average and peak node demands in cubic feet per second for each node in the Eagle Pass system Cite your source of data and provide representative compu tations for demand at each node 2 Classify the system i e branch grid loop or hybrid 3 Prepare a table of the demands for average daily peak hourly and peak day demand for eventual inclusion in an engineering report 4 Prepare a
4. the pipe and reverse the start and end node connections Page 3 of 28 CE 3372 Water Systems Design FALL 2013 EPANET 2 File Edit View Project Report Window Help OSS XM g Meme k eta TE Network Map ea 5 e X Data Map Junctions 5 Auto Lenath Of CFS wl 100 XY 1933 09 9646 84 Figure 3 Place the reservoir and the demand node EPANET 2 File Edit View Project Report Window Help OSHS aXe FeO k KP QA HOH e eCNMT H Network Map DOR iims x k Data Map Pipes AA r mo Auto Length Off CFS 100 X Y 5929 37 8661 71 Figure 4 Link the reservoir and demand node with a pipe Page 4 of 28 CE 3372 Water Systems Design FALL 2013 Now we can go back to each hydraulic element in the model and edit the properties We supply pipe properties diameter length roughness height as in Figure 5 EPANET 2 Edit View Project Report Window Help File DehSexms kas Network Map REP QQUR OBAMAT O X amp Browser X Pipe 1 Property Pipe ID Start Node End Node Description Tag Length Diameter Roughness Loss Coeff Initial Status Unit Headloss Friction Factor Reaction Rate Quality Status XY 724 91 9721 19 AutoLenghot CFS gy 100 Figure 5 Set the pipe length diameter and roughness height Page 5 of 28 CE 3372 Water Systems Design FALL 2013 We supply the reservoir t
5. CE 3372 Water Systems Design FALL 2013 1 Hydraulic Modeling with EPA NET 1 1 Introduction EPA NET is a computer program that performs hydraulics computations in pressure pipe systems Most of the problems in the preceding chapters can be solved or well approximated using EPA NET The remainder of this chapter shows how to use EPA NET by a series of representative examples These examples are at best a subset of the capabilities of the program but should be enough to get one started The program requires some hydraulic insight to interpret the results as well as detect data entry or conceptualization errors hence the practical hydraulics review in Chapters 2 and 3 1 2 Installing EPA NET The QuickTime movie shows how to download and install EPA NET onto your computer EPA NET will run fine on a laptop computer and even a Macintosh that has a guest Windows OS WM Ware Parallels or BootCamp There may also be native Macintosh versions available search the Internet be surprised what one can find EPA NET can also be installed onto a flash drive and run directly from the drive 1 3 EPA NET Modeling by Example Examples 1 through 4 EPA NET models are comprised of nodes links and reservoirs Pumps are treated as special links that add head Valves are also treated as special links depending on the valve types All models must have a reservoir or storage tank 1 3 1 Defaults The program has certain defaults that should b
6. Pa UH OH GHENT Network Map 4 AE Browser Daa Map Curves Curve Editor Curve ID Description SE ee Curve Type Equation PUMP X Heada 15 00 0 1 Flow 2 00 lt Auto Lenath Off LPS wl 100 XY 12290 15 9233 58 Figure 19 Example 5 pump curve entry dialog box Three points are entered and the curve equation is created by the program Figure 19 is a screen capture of the pump curve data entry dialog box Three points on the curve were selected and entered into the tabular entry area on the left of the dialog box then the curve is created by the program The equation created by the program is the same as that of the problem hence we have the anticipated pump curve Page 22 of 28 CE 3372 Water Systems Design FALL 2013 Next the engineer associates the pump curve with the pump as shown in Figure 20 EPANET 2 Fi di DSES xe Grieg AA KEAa UH OH BHCMT Network Map a Data Map Pumps Pump ID Start Node End Node Description Tag Pump Curve Power Speed Pattern Initial Status Effic Curve Energy Price Price Pattern Flow Headloss Quality Status Auto Lenath Off ups 100 XY 9844 89 7372 26 Figure 20 Setting the pump curve Upon completion of this step the program is run to estimate the flow rate in the system Page 23 of 28 CE 3372 Water Systems Design FALL 2013 1 5 EPA NET Modeling by Example Valves EPA NET models are comprised of nodes links and reservoirs
7. am starts as a blank slate and we will select a reservoir and a node from the tool bar at the top and place these onto the design canvas EPANET 2 ile Edt View Project Report Window Help Ose S BX g HRMS FOES Q UH OH BH OMT AutoLength Of CFS 100 X 2100 37 7137 55 Figure 1 Start EPA NET program Page 2 of 28 CE 3372 Water Systems Design FALL 2013 Figure 1 is a screen capture of the EPA NET program after setting defaults for the simulation Failure to set correct units for your problem are sometimes hard to detect if the model runs so best to make it a habit to set defaults for all new projects Next we add the reservoir and DERS BX g MHS k HURRAA ON RHOMT St Network Map E AutoLenath Of CFS gt 100 X Y 2026 02 9907 06 Figure 2 Set program defaults In this case units are cubic feet per second and loss model is Darcy Weisbach the node Figure 3 is a screen capture after the reservoir and node is placed We will specify a total head at the reservoir value is unimportant as long as it is big enough to overcome the head loss and not result in a negative pressure at the node We will specify the demand at the node equal to the desired flow in the pipe Next we will add the pipe Figure 4 is a screen capture after the pipe is placed The sense of flow in this example is from reservoir to node but if we had it backwards we could either accept a negative flow in the pipe or right click
8. am will start If the nodal connectivity is OK and there are no computed negative pressures the program will run Figure 8 is the appearance of the program after the run is complete the annotations are mine A successful run means the program found EPANET 2 example 1 net RNePaQHrloHe cmNT Network Map E x BI x 3 Data Map Reservoirs F Run Status Run was successful Fall Nice outcome don t always get a sucessful run first time Sucessful does not mean correct just means the program functioned normally Auto Lenath Off CFS ma 100 XY 929 37 9981 41 Figure 8 Running the program an answer to the problem you provided whether it is the correct answer to your problem requires the engineer to interpret results and decide if they make sense The more common conceptualization errors are incorrect units and head loss equation for the supplied roughness values missed connections and forgetting demand somewhere With practice these kind of errors are straightforward to detect In the present example we select the pipe and the solution values are reported at the bottom of a dialog box Page 8 of 28 CE 3372 Water Systems Design FALL 2013 EPANET 2 example 1 net File Edit View Project Report Window Help DSGESaBxXem g eee kM E QQnoOHB eNT Network Map E gt X Browser X Data Map Nodes Head bd Links Flow ad Time Single Period ov ET Start Node En
9. ckground drawing BMP file Figure 16 is a screen capture of loading the background image After the image is loaded Page 18 of 28 CE 3372 Water Systems Design FALL 2013 we can then build the hydraulic model The next step is to place the reservoirs Page 19 of 28 CE 3372 Water Systems Design FALL 2013 File Edit View Project Report Window Help Deke eaxmh g kmar kk KCtQuno rr a a iz t Network Map E E3 e Browser Data Map Reservoirs v a Auto Length Off CFS m 100 XY 8804 74 4981 75 Figure 17 Example 5 place the lower and upper reservoir Figure 17 is a screen capture of the reservoirs after they have been placed The upper reservoir will be assigned a total head 10 meters larger than the lower reservoir a reasonable conceptual model is to use the lower reservoir as the datum Page 20 of 28 CE 3372 Water Systems Design FALL 2013 EPANET 2 File Edit View Project Report Window Help Ose axmd 2m PAPANE OHS CHT Network Map a ed 22 Browser Es Data Map Pumps Zz Auto Lenath Off CFS m 100 XY 9023 72 3266 42 Figure 18 Example 5 place the nodes pipes and the pump link Figure 18 is a screen capture of model just after the pump is added The next steps are to set the pipe lengths not shown and the reservoir elevations not shown Finally the engineer must specify the pump curve Page 21 of 28 CE 3372 Water Systems Design FALL 2013 EPANET 2 DSHS aXe GHEE kh K
10. d Node Friction Factor Reaction Rate Figure 9 Solution dialog box for the pipe Figure 9 is the result of turning on the computed head values at the node and reservoir and the flow value for the pipe The dialog box reports about 7 2 feet of head loss per 1000 feet of pipe for a total of 72 feet of head loss in the system The total head at the demnad node is about 28 feet so the head loss plus remaining head at the node is equal to the 100 feet of head at the reservoir the anticipated result The computed friction factor is 0 010 which we could check against the Moody chart if we wished to adjust the model to agree with some other known friction factor Page 9 of 28 CE 3372 Water Systems Design FALL 2013 1 3 3 Example 2 Flow Between Two Reservoirs This example represents the situation where the total head is known at two points on a pipeline and one wishes to determine the flow rate or specify a flow rate and solve for a pipe diameter Like the prior example it is contrived but follows the same general modeling process As in the prior example we will use EPA NET to solve a problem we have already solved by hand Using the Moody chart and the energy equation estimate the diameter of a cast iron pipe needed to carry 60 F water at a discharge of 10 cubic feet per second cfs between two reservoirs 2 miles apart The elevation difference between the water surfaces in the two reservoirs is 20 feet As in the
11. e set at the beginning of a simulation The main defaults of importance are the head loss equations Darcy Weisbach Hazen Williams or Chezy Manning and the units CFS LPS etc 1A useful trick on a networked system be sure you set up the flash drive to be writeable Page 1 of 28 CE 3372 Water Systems Design FALL 2013 1 3 2 Example 1 Flow in a Single Pipe The simplest model to consider is from an earlier exercise in this workbook A 5 foot diameter enamel coated steel pipe carries 60 F water at a discharge of 295 cubic feet per second cfs Using the Moody chart estimate the head loss in a 10 000 foot length of this pipe In EPA NET we will start the program build a tank pipe system and find the head loss in a 10 000 foot length of the pipe The program will compute the friction factor for us and we can check on the Moody chart if we wish The main trick in EPA NET is going to be the friction coefficient in the EPA NET manual on page 30 and 31 the author indicates that the program expects a roughness coefficient based on the head loss equation The units of the roughness coefficient for a steel pipe are 0 15 x 1078 feet On page 71 of the user manual the author states that roughness coefficients are in millifeet millimeters when the Darcy Weisbach head loss model is used So keeping that in mind we proceed with the example Figure 1 is a screen capture of the EPA NET program after installing the program The progr
12. ems Design FALL 2013 Import the background Select the reservoir tool Put two reservoirs on the map Select the node tool put 4 nodes on the map N DOD Oh A Select the link pipe tool connect the reservoirs to their nearest nodes Connect the nodes to each other oe Set the total head each reservoir 9 Set the pipe length roughness height and diameter in each pipe The pipes that connect to the reservoirs should be set as short and large diameter we want negligible head loss in these pipes so that the reservoir head represents the node heads at these locations 10 Save the input file 11 Run the program In this case the key issues are the units liters per second and roughness height 0 26 millimeters Figure 14 is a screen capture of a completed model 1 3 6 Summary EPA NET Examples 1 4 These examples did not have pumps or valves and as such are comparatively simple yet represent the kind of problems that EPA NET can model Videos of the four examples are available on the server To view these videos the reader will need the Apple Quick Time viewer available for free from Apple The WIndows Media Viewer usually can show the movies but if not download the Apple Viewer and proceed These videos have voice over so if you don t have speakers you wont be able to hear the voice over 1 4 EPA NET Modeling by Example Pumps The next example illustrates how to model a pump in EPA NET A pump is a s
13. le Pass water distribution pipe lengths Length is in feet Page 26 of 28 CE 3372 Water Systems Design FALL 2013 References Chin D A 2006 Water Resources Engineering Prentice Hall Gironas J L A Roesner and J Davis 2009 Storm Water Management Model appli cations manual Technical Report EPA 600 R 09 077 U S Environmental Protection Agency National Risk Management Research Laboratory Cincinnati OH 45268 NCEES 2008 Fundamentals of Engineering Supplied Reference Handbook 8th ed 280 Seneca Creek Road Clemson SC 29631 National Council of Examiners for Engineering and Surveying ISBN 978 1 932613 37 7 Rossman L 2000 EPANET 2 users manual Technical Report EPA 600 R 00 057 U S Environmental Protection Agency National Risk Management Research Laboratory Cincinnati OH 45268 Rossman L 2009 Storm Water Management Model user s manual version 5 0 Tech nical Report EPA 600 R 05 040 U S Environmental Protection Agency National Risk Management Research Laboratory Cincinnati OH 45268 Page 27 of 28
14. neer follows the modeling protocol already outlined only adding the special link 1 Convert the image into a bitmap place the bitmap into a directory where the model input file will be stored 2 Start EPA NET 3 Set defaults hydraulics D W units LPS 4 Import the background Page 17 of 28 CE 3372 Water Systems Design FALL 2013 5 6 10 11 12 13 14 Select the reservoir tool Put two reservoirs on the map Select the node tool put 2 nodes on the map these represent the suction and discharge side of the pump Select the link pipe tool connect the reservoirs to their nearest nodes Select the pump tool Connect the nodes to each other using the pump link Set the total head each reservoir Set the pipe length roughness height and diameter in each pipe On the Data menu select Curves Here is where we create the pump curve This problem gives the curve as an equation we will need three points to define the curve Shutoff Q 0 and simple to compute points make the most sense Save the input file Run the program DHS BX g wT kK KPQ FOB RHCHMT Open a Backdrop Map Look in C example 2 39 ef Ee 6324450 B P2 39 bng My Recent Documents e Desktop My Computer My Network File name Places Files of type All bmp emf wmf lt Auto Lenath Off CFS ma 100 XY 374 09 10000 00 Figure 16 Example 5 select the ba
15. otal head as in Figure 6 EPANET 2 example 1 net File Edit View Project Report Window Help Deh So Bx Fee NEP QU OHaHCNMT v x e Browser X Data Map Reservoirs Ne T Network Map Reservoir 1 1078 07 8587 36 Total Head jie Head Pattern Initial Quality Source Quality Figure 6 Set the reservoir total head 100 feet should be enough in this example Page 6 of 28 CE 3372 Water Systems Design FALL 2013 We set the demand node elevation and the actual desired flow rate as in Figure 7 EPANET 2 example 1 net File Edit View Project Report Window Help Ase Sexe g Cem kK UKPQaQHOHRGHoMT FTA a X Browser X Data Map Network Map Junctions a La Junction 2 EJ Junction ID X Coordinate Y Coordinate Description Tag Elevation Base Demand Demand Pattern Demand Categories Auto Length Off CFS A 100 XY 520 45 9962 83 Figure 7 Set the node elevation and demand In this case the elevation is set to zero the datum and the demand is set to 295 cfs as per the problem statement The program is now ready to run next step would be to save the input file File Save Name thes run the program Page 7 of 28 CE 3372 Water Systems Design FALL 2013 Run the program by selecting the lighting bolt looking thing kind of channeling Zeus here and the progr
16. pecial link in EPA NET This link causes a negative head loss adds head according to a pump curve In addition to a pump curve there are three other ways to model added head these are discussed in the user manual and are left for the reader to explore on their own Page 15 of 28 CE 3372 Water Systems Design FALL 2013 IF aE Ae Browser x T Network Map Nodes Head ue Links Flow B Time Single Period v P No 136 5500 L 1000m D 400mm Elev 70 m 70 00 15 33 70 00 121 44 L 1200m D 350mm Auto Lenath Off LPS Ps 100 X Y 2016 42 8996 35 Figure 14 Solution for Example 4 The flowrates are in liters per second divide by 1000 to obtain cubic meters per second Page 16 of 28 CE 3372 Water Systems Design FALL 2013 1 4 1 Example 5 Pumping Water Uphill Figure 15 is a conceptual model of a pump lifting water through a 100 mm diameter 100 meter long ductile iron pipe from a lower to an upper reservoir The suction side of the pump is a 100 mm diameter 4 meter long ductile iron pipe The difference in reservoir free surface elevations is 10 meters The pump performance curve is given as hy 15 0 1Q 1 where the added head is in meters and the flow rate is in liters per second Lps The analysis goal is to estimate the flow rate in the system 10m 100 m Figure 15 Example 5 conceptual model The pipes are 100 mm ductile iron To model this situation the engi
17. prior example we will need to specify the pipe roughness terms then solve by trial and error for the diameter required to carry the water at the desired flowrate Page 31 of the EPA NET manual suggests that the roughness height for cast iron is 0 85 millifeet As before the steps to model the situation are 1 Start EPA NET 2 Set defaults 3 Select the reservoir tool Put two reservoirs on the map 4 Select the node tool put a node on the map EPA NET needs one node 5 Select the link pipe tool connect the two reservoirs to the node One link is the 2 mile pipe the other is a short large diameter pipe negligible head loss Set the total head each reservoir Set the pipe length and roughness height in the 2 mile pipe Guess a diameter ce o N OH Save the input file 10 Run the program Query the pipe and find the computed flow If the flow is too large reduce the pipe diameter if too small increase the pipe diameter Stop when within a few percent of the desired flow rate Use commercially available diameters in the trial and error process so exact match is not anticipated Figure 10 is a screen capture after the model is built and some trial and error diameter selection Of importance is the node and the short pipe that connects the second reser Page 10 of 28 CE 3372 Water Systems Design FALL 2013 voir By changing the diameter inches in the dialog box and re running the program we can find a
18. solution diameter that produces 10 cfs in the system for the given elevation differences EPANET 2 File Edit View Project Report Window Help CehS BxXe 7 Re KOK QUT OHRACHT Pipe ID Start Node Lenath Diameter Roughness Loss Coeff Initial Status Unit Headloss Friction Factor Reaction Rate Quality Status Auto Length Off CFS ma 100 X Y 2371 68 7398 23 Figure 10 Solution dialog box for the pipe for Example 2 We would conclude from this use of EPA NET that a 22 75 inch ID cast iron pipe would convey 10 cfs between the two reservoirs Compare this solution to the by hand soluton to see if they are close 1 3 4 Example 3 Three Reservoir Problem This example repeats another prior problem but introduces the concept of a basemap im age to help draw the network First the problem statement Reservoirs A B and C are connected as shown in Figure 11 The water ele vations in reservoirs A B and C are 100 m 80 m and 60 m The three pipes connecting the reservoirs meet at junction J with pipe AJ being 900 m long BJ 2This problem is identical to Chin Problem 2 30 Pg 92 Page 11 of 28 CE 3372 Water Systems Design FALL 2013 being 800 m long and CJ being 700 m long The diameters of all the pipes are 850 mm If all the pipes are ductile iron and the water temperature is 293 K find the direction and magnitude of flow in each pipe Elev 100 m Elev 80m La 800 m
19. table of the node elevations for each node in the Eagle Pass system 5 Prepare a table of the pipe dimensions for each pipe in the current system Include in this table appropriate Hazen Williams loss coefficients for the pipes indicate likely pipe materials 6 Locate the lowest pressure node Is the lowest pressure above the minimum Texas pressure for a water distribution system 7 Locate the maximum pressure in the system is the pressure reasonable or too large for typical customer connections 8 Suggest a system modification bigger pipes new pipe etc that could satisfy the low pressure issue in the system Demonstrate by modeling that your suggested modifica tion indeed meets minimum maximum pressure requirements Page 24 of 28 CE 3372 Water Systems Design FALL 2013 9 Employ extended period simulation different demand patterns to assess loading con ditions on meeting pressure requirements Supply Node Elevations Figure 21 Eagle Pass water distribution node elevations Elevations are feet above mean sea level Supply Population Served by Node Figure 22 Eagle Pass water distribution node population served Population is individuals served Page 25 of 28 CE 3372 Water Systems Design FALL 2013 Supply Pipe Diameter inches 800 ft 775 ft 750 ft 725 ft Figure 23 Eagle Pass water distribution pipe diameters Diameter is in inches Supply Pipe Length feet Figure 24 Eag
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