Applies To Product(s): WaterGEMS, HAMMER, WaterCAD Version(s): 08.11.XX.XX Original Author: Mark Pachlhofer, Bentley Technical Support Group Problem My fireflow report shows fire flow nodes failing due to low pressure at the suction side of a pump. What can I do about this? Solution Create a zone for the low pressure nodes If you are not concerned about this, you can create a special "low pressure" zone and select that as the zone for the node in question. This way it will not be considered in the automated fire flow analysis (unless you select to have a minimum system pressure constraint.) However, you may want to make sure the reservoir elevation upstream of the pump is correct and that the pump intake pressure meets the minimum NPSH requirements. Create a selection set for nodes excluding the low pressure nodes 1) Create a selection set for all the junctions in the low pressure zone. There are a few different ways to do this that are described in the wiki linked to below. 2) With that selection set active in the drawing pane go to "Edit" > Invert Selection to select all the other elements. Right click in the drawing pane and choose "Create Selection Set". 3) Open the Fire Flow Alternative manager and chose the selection set created from step 2. This excludes all the low pressure junctions from the fire flow alternative. 4) Close the fire flow manager and compute the scenario See Also WaterGEMS Automated Fire Flow FAQ
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Wiki Page: My fire flow report shows fire flow nodes failing due to low pressure at the suction side of a pump. What can I do about this?
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Forum Post: RE: Fire Flow with a Selection Set / PRV / Contours
Just a few additional notes: 1) (fireflow issue) - When you say that you're seeing "N/A" results, are you referring to the results in the fire flow flextable? In that case, are those the nodes that are not included in your selection set? Or, if you're referring to looking at results of other elements in the model during a specific fireflow run (clicking a fire flow node in the fire flow results browser), you'll need to make sure the auxiliary results section of the fireflow alternative is set up correctly to store those results. You can read more about this here: Results show as "N/A" when clicking a node in the Fire Flow Results Browser 2) (PRVs) As seen in the material Sushma sent, the PRV monitors the downstream pressure and throttles (adjusts the headloss, essentially) as needed to achieve the desired pressure setting. That pressure setting can be changed with controls or a pattern ("Pattern (Valve Settings)", if needed.
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Wiki Page: User notification "Pump exceeds the maximum operating point specified for the pump curve"
Applies To Product(s): WaterGEMS, HAMMER, WaterCAD Version(s): 08.11.XX.XX, 10.XX.XX.XX Original Author: Mark Pachlhofer, Bentley Technical Support Group Problem My pumps are operating at a much higher rate than the design point. How do I fix this? OR What does the user notification "Pump exceeds the maximum operating point specified for the pump curve" mean? Solution The first step to solving this problem starts with understanding how pumps function in the hydraulics and hydrology products. You can find that explanation in this wiki . The second step is to check the pump curves for the pumps that are adding too much flow and make sure the curves are correct. Next check the demands in your model for the junctions, hydrants, tanks, and the HGL on your reservoirs that are downstream of the pump. The best way to check your demands on downstream elements is to make a selection set of all those nodes and then open your flextable based on that selection set. There are directions in the wiki found here that explain how to do this. With the flextable open add the column called "Demand" if it's not already. This wiki article will explain how to do that. Once that column is added you can right click on the column header and choose statistics to see the total sum of the demand and other important information. At this point you can also sort that column by right clicking on it and choosing Sort > Descending because you are likely looking for values in the column that are to high. After doing this you should scan all the demands to make sure they are correct. Note that for the reservoir there is no "demand" column. You should be checking the hydraulic grade in reservoirs to make sure that it is set correctly. Finally, if you are checking the demands for an EPS simulation you should use the time browser to choose the time step where the pumps are operating higher than the design point and then use the steps above to check the appropriate tables for the demands. What does the user notification "Pump exceeds the maximum operating point specified for the pump curve" mean? Pumps in water and storm water product line operate by adding enough head to system to balance the hydraulic grade in the system, namely by overcoming the losses and elevation differences between your upstream and downstream boundary conditions. The head and flow rate is defined on your pump definition curve. In the water products, like WaterGEMS and WaterCAD, the pumps need to also add enough flow to be able to fulfill the demand. This warning message usually indicates that the pump is operating beyond the user-entered pump characteristic curve (pump definition). This will happen when the pump definition is not defined all the way out to zero head. WaterCAD and WaterGEMS will use extrapolation on the pump curve, so that it extends all the way to zero head. The pump can operate past the user entered range if the system conditions warrant it. The pump curve that you see in the system head curve viewer is an extrapolated pump curve. The warning message may indicate that the real pump may not be able to operate correctly in this condition. Basically, the system conditions are such that the head the pump needs to add is less than the lowest head value in your pump curve. You can always check the operating point and extrapolated pump curve by right clicking the pump and selecting "Pump Curve". You should compare the operating point to the actual pump curve that you have defined under Components > Pump Definitions, and not to the system head curve window. Sometimes you may also get this message if you are using a multiple point pump curve with large gaps between flow values. If this is the situation you're facing, the issue can usually be resolved by adding one or two flow values with its corresponding head value to make the gaps between consecutive values smaller. See Also Pump cannot deliver flow or head user notification
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Wiki Page: User notification: Constant flow VSPs (or VSPBs) and fixed head VSPs (or VSPBs) are not both allowed in the same scenario
Product(s): WaterGEMS, WaterCAD Version(s): 10.00.xx.xx, 08.11.xx.xx Area: Modeling Original Author: Scott Kampa, Bentley Technical Support Problem When validating a model, the following user notification is generated: Constant flow VSPs (or VSPBs) and fixed head VSPs (or VSPBs) are not both allowed in the same scenario. Problem ID#: 81585 Solution The inclusion of both fixed head and fixed flow variable speed pumps can have adverse effects on the model calculation. For this reason, the use of both methods in the same scenario is not allowed. As a workaround, either try to correlate the fixed flow value to a head value or use the Pattern-Based VSP type. A fixed head is correlated through a trial-and-error process. The pattern for pattern-based VSP can be set up as time from the start of the simulation going to 24 hours with the multiplier that will control the relative speed factor for the pump. If you know your pump at a relative speed factor of 1.0 at a certain flow you should be able to figure out what relative speed factor the pump will need to be set to in order to run at whatever flow settings you need. See Also How to I model parallel fixed head (target head) variable speed pumps that are controlled by flow in a downstream pipe
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Wiki Page: Transient maximum result is different from the highest value seen in a time history graph
Applies To Product(s): HAMMER Version(s): V8i, CONNECT Edition Area: Output and Reporting Original Author: Scott Kampa, Bentley Technical Support Group Problem The maximum transient pressure value in the Properties display, the Transient Analysis Detailed Report and the Transient Results Viewer profile are different from what is reported in the Time History graph at the same location. Meaning, the graph peaks at a value less than the reported maximum Problem ID#: 91593 Solution This is likely occurring because of the report period set in the Transient Calculation Options. If you have a fast-moving transient occurring (such as an air pocket collapse in an air valve) and your report period is set too high, then the peak could be occuring between the report timesteps, in which case it would not show in the time history or profile animation. For example if your report period is set to "10" and your maximum HGL occurs between timestep 105 and only lasts two timesteps, then it will be missed since the results will report at timestep 100 and 110. Go to Analysis > Calculation Options and double click the active transient calculation option to view the information in the properties. Find the field "Report Times". Change this to "At All Times" and compute the model again. When you graph the time history at the check valve, the results will coincide with the Transient Analysis Output Log and the properties. You may also see a user notification stating that the report period was increased. For more on how to resolve this, see the first article further below. Note: check your user notifications after computing the model and make sure you do not see one that mentions the report period was increased by a certain factor. This can happen if there are too many report points in the model. In this case, reduce the number of Report Points, choose to report "only if on path" and/or consider skeletonizing the model. To see the true / calculated max/min transient results, see the transient statistical results section of the properties, or in flextables. To see the maximum/minimum at each point along the length of a pipe (since the Method of Characteristics calculates at intermediate points), use the “extreme pressures and heads” table. See more in the second article below. See Also "The period between path histories has been increased by a factor of X to limit the number of path records to Y. " How can you find the minimum and maximum transient pressure or hydraulic grade results in a HAMMER model? Results from the Extreme Pressure and Heads table are different from results found in the transient profiles
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Wiki Page: Pump efficiency impact on transient results
Product(s): HAMMER Version(s): V8i, CONNECT Edition Area: Calculations Problem How / why does the motor efficiency effect the Transient results for a pump that is shut down? Solution The motor efficient of the pump impacts the overall efficiency of the pump, which is a factor in the transient representation of the pump, specifically when changing the electrical torque of the pump. The pump’s electrical torque is changed during a transient simulation when using either the “shut after time delay” transient pump type, or when using the “variable speed” transient pump type with “torque” as the control variable. The “shut after time delay” transient pump type simulates the electrical torque instantly dropping from the initial value to zero. Similarly with torque selected as the control variable with the “variable speed” type, you are controlling the electrical torque over time. The efficiency of the pump is a factor in the initial torque of the pump (see related article below), which is in turn a factor when that torque changes. Using the example of shut after time delay, changing the pump efficiency changes the initial torque and thus the magnitude of the drop in torque that occurs when the pump “trips”. See Also Calculating Nominal Torque for a Transient Pump Startup or Variable speed User notification: "Pump Efficiency must be between X% and Y% inclusive."
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Wiki Page: Calculating Nominal Torque for a Transient Pump Startup or Variable speed
Product(s): HAMMER Version(s): V8i, CONNECT Edition Area: Modeling Problem When using "Torque" as the "Control Variable" for a pump whose Transient Pump Type is set to "Variable Speed/Torque", what should be entered for the "Torque (Nominal)"? How can this be calculated? Solution When using Torque as the Control Variable, the nominal torque value must be entered. This is the value that the multipliers in the pump's Operating Rule pattern will multiple against. So, when the pattern has a 1.0, it will use an applied electrical torque of 1.0 X the nominal torque. So, the nominal torque should normally be equal to the torque when the pump is on, so that a pattern multiplier of 1.0 will reflect the full torque applied. If you are not sure how to calculate the nominal torque to enter, it can be calculated with the below spreadsheet (be sure to log in first before using the link). Use the "Pump Power and Torque calculator" section, entering the flow, head, efficiency, fluid weight (keep that the same if using the default fluid properties in HAMMER) and rotational speed, and use the computed Shaft Torque as the nominal torque. Pump flow and head: run a steady state simulation with the pump on and check the head and flow in the correct units Efficiency: with the above steady state, right click on the pump and choose Pump Curve. Enable the option to display the efficiency curve. Pump rotational speed: this is entered in the Transient tab of the pump definition Pump Power and Torque (from the Haestad | Hydraulics and Hydrology File Gallery) Here are the steps of the calculation: 1) First, calculate the Hydraulic Power of the pump based on the initial head and flow 2) Calculate the shaft power based on the hydraulic power and efficiency. 3) Calculate the Shaft Torque based on shaft power and rotational speed References: Fluid Transients in Systems, Wylie, 1993, pg. 146 http://www.engineeringtoolbox.com/pumps-power-d_505.html http://www.engineeringtoolbox.com/pumps-speed-torque-d_1114.html See Also Pump efficiency impact on transient results Pump Startup occurs too quickly / initial upsurge too severe Calculating initial electrical torque for use with the Load Rejection turbine Operating Case
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Wiki Page: ACAD alert: Unhandled exception has occurred
Applies To Product(s): WaterCAD, WaterGEMS Version(s): 08.09.XX.XX, 08.11.XX.XX Area: Other Original Author: Bentley Technical Support Group Problem "AutoCAD alert: Unhandled exception has occurred" when working with WaterCAD in the AutoCAD interface. Version: 08.09.XX.XX Problem number:31380 Solution Please try the following steps after closing all the programs: Note: if you're using version 08.11.01.32 or greater of WaterCAD/GEMS, stop after step 1. 1. Go to Control Panel > Add/remove programs > Select WaterCAD/WaterGEMS > Select Change/Remove > Repair Registry 2. Open WaterCAD for AutoCAD and type in "options" as the command. Go to the "profile" tab and delete the WaterCAD profile 3. Uninstall WaterCAD 4. Go to the program files and search for acad.exe.config and rename it to acad.exe.config.old 5. Open plain AutoCAD and close it to rewrite the profile. 6. Install WaterCAD. 7. Go to Start > All programs > WaterCAD V8 XM > Integrate WaterCAD and AutoCAD.
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Forum Post: Absolute or gauge pressure in hydropneumatic tank results?
Hi all, Am I right in supposing that the values of "Gas Pressure (Maximum Transient)" and "Gas Pressure (Minimum Transient)" under the "Results (Transient)" menu of the properties table for a Hydropneumatic Tank are expressed as absolute pressure? I know that in Hammer (right...that's the software I'm talking about) pressure values are generally expressed as gauge pressure, but I think this is an exception. Otherwise I can't explain some results I got...
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Wiki Page: What are the differences between HEC-22 3rd edition and HEC-22 2nd edition headloss methods?
Applies To Product(s): SewerGEMS, CivilStorm, StormCAD, SewerCAD Version(s): V8i, CONNECT Edition Area: Calculations Original Author: Mark Pachlhofer, Bentley Technical Support Group Problem What are the differences between HEC-22 3rd edition and HEC-22 2nd edition regarding structure losses? Solution HEC-22 documentation can be found at this location: Calculations for the 3rd edition are done exclusively with energy grade (EG), not hydraulic grade (HG). For the HEC-22 2nd edition it's fine to use either the HG or the EG option, although technically speaking the EG option is more correct. This is because the head loss by definition is the energy loss. When using the HEC-22 3rd edition, however, an engineer should only use the EG option for a structure loss method because HEC-22 specifically states that only the EG should be used when computing structure loss. Plunging Flow In 2 nd ed., the largest incoming invert is considered. In 3 rd ed. it’s done based on each pipe. The 2 nd ed. refers to center line of the outflow pipe whereas the 3 rd edition ignores the outflow pipe In the 2 nd ed., plunging coefficient is statically declared, in 3 rd edition it is a proportion of plunging flow to all incoming flow. In the 3 rd ed., there is a ceiling put on maximum plunging depth of 10 * diameter. In the 2 nd ed. there’s a comparison of incoming pipe invert to structure invert, in the 3 rd it is compare of incoming pipe invert and structure energy level. Benching New benching classification titled “Improved” (both 2 nd and 3 rd editions) Benching is interpolated in the 3 rd edition and not in the 2 nd An “IsSubmerged” condition is defined for a lower threshold in the 3 rd Bend Loss In the 2 nd ed. it is folded into an initial headloss term In the 3 rd ed. it is a weighted composite loss from each incoming pipe Initial Headloss In the 2 nd ed. it is computed with bend angle and structure equivalent diameter In the 3 rd ed. it is an inlet or outlet control that governs this Entrance and Exit Losses (most significant component of 3 rd ed. junction losses) These are transitions between the node structure and the outflow pipe Exit losses are only computed in the 3 rd edition 3rd ed. computes each exit loss for each incoming pipe. 2 nd ed. lumps entrance, structure, and exit loss considerations into one structure loss result and uniformly applies it as tailwater for all incoming pipes. Profile Enhancements Addition of Exit, additional, and entrance losses is displayed from pipe to pipe As of the CONNECT Edition (10.00.00.40), with the Explicit (SWMM) solver, there is a separate result field for the Entrance loss component, and all other losses are included in the field "Total additional structure energy losses", along with the total structure energy loss result. These can be seen in the "Results (HEC-22, Third edition)" section of the manhole properties, or in the manhole flextable. With the GVF-Convex and GVF-Rational solvers, there are additional result fields, for all the different components. See Also What is the difference between the hydraulic grade and energy grade structure loss calculation option?
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Wiki Page: Inlet flooding with the HEC-22 Third Edition headloss method, but not with HEC-22 Second Edition headloss method
Applies To Product(s): Bentley StormCAD Version(s): 10.00.xx.xx, 08.11.04.54 + Area: Calculations Original Author: Terry Foster, Bentley Technical Support Group Defect Description I'm getting flooding at an inlet, but when I run as a culvert, no flooding. Why? In my StormCAD model, a single lateral conduit has an incredible exit loss at a manhole connection. Explanation This is a rare, known limitation with our current implementation of the HEC-22 3rd edition structure loss method. This can occur in a specific condition where the downstream node is using the 3rd edition structure loss method and is considered "plunging", but the plunging depth is very small (difference between the upstream pipe's outgoing invert and the structure's HGL). The velocity used in the exit loss calculation is based on the area created by this difference along with the respective flow. So, you can see that with a very small plunging depth, the velocity used is very high, leading to a high exit loss. To illustrate further, in the case with the manhole, you can set the "bolted" option for this manhole to "false". This causes the HGL to be effectively "capped" at the rim, allowing you to see more clearly the small plunging depth mentioned above (the manhole in question is on the right side) The conduit/manhole situation being very close to non-plunging makes the model sensitive. For example when you lower the invert of the node by enough of a distance so that the upstream pipe's stop invert is above the node's HGL, it is enough to cause a non-plunging condition. Workaround Our developers have implemented an enhancement to check for this condition and handle it more appropriately. You can get this enhancement by downloading the Select Series 4 cumulative patch or installing the latest version of the software. Directions for how to do that can be found here: https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/8175.downloading-haestad-hydraulics-and-hydrology-software If you are unable to apply the Select Series 4 cumulative patch or install the latest version of the software, there are a number of potential workarounds. You could: 1) Set the structure loss method to HEC-22 2nd edition for that node; 2) Lower the invert to prevent the plunging condition 3) Calculate the desired structure loss externally and input that as an "absolute" loss for the node (or estimate a K for the standard method). See Also What are the differences between the HEC-22 3rd edition and the HEC-22 2nd edition? Flat hydraulic grade line over nodes for the HEC-22 3rd edition energy method
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Wiki Page: Zero headloss through node when using the HEC-22 2nd Edition headloss method
Applies To Product(s): StormCAD, CivilStorm, SewerGEMS, SewerCAD Version(s): 10.00.xx.xx, 08.11.xx.xx Area: Calculations Original Author: Scott Kampa, Bentley Technical Support Group Problem Why are the computed headlosses shown to be zero in some inlets when using the HEC-22 headloss method? (2nd edition) Problem ID#: 58020 Solution This is occurring because the HEC-22 method does not apply to an inlet without conduits coming into and out of the inlet. For instance, the upstream-most inlet will always have a headloss of zero with this method since there is no conduit coming into it. In such cases, it is recommended to use the Standard method with a headloss coefficient of 0.5, which is typical for entrance headlosses to a structure. See Also What are the differences between the HEC-22 3rd Edition and HEC-22 2nd Edition headloss methods? Inlet flooding with the HEC-22 Third Edition headloss method, but not with the HEC-22 Second Edition headloss method
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Wiki Page: Why are the junctions not showing any pressure for flushing event?
Applies To Product(s): WaterGEMS, WaterCAD Version(s): 10.00.xx.xx, 08.11.xx.xx Area: Calculations Original Author: Terry Foster, Bentley Technical Support Group Problem Why are the junctions not showing any pressure after I click on the flushing event in the Flushing Results Browser? Problem ID#: 71277 Solution After clicking on the flushing event, you will only see pressure on the nodes that have a pressure that fell below the pressure set up in the flushing alternative in the Auxiliary Output Settings. See Also Flushing in WaterGEMS/WaterCAD CONNECT Edition and V8i SELECTseries 6
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Wiki Page: Source of the default Specific Speed for pumps and turbines
Applies To Product(s): HAMMER Version(s): 10.00.xx.xx, 08.11.xx.xx Area: Modeling Original Author: Jesse Dringoli, Bentley Technical Support Group Problem In the Transient tab of a pump definition, there are several default selections available for Specific Speed. What is the source of the 4-quadrant characteristic curves behind these specific speeds? Also - what is the source of the curves behind the default Specific Speeds for turbines Solution Pumps For Pumps, the specific speeds 25, 94 and 145 (SI units) were derived from data published by Stepanoff (1957), as well as personal correspondance, in terms of relative Q and N along lines of constant head and torque throughout the entire operating range. The other default specific speeds are from Thorley, A.R.D and A. Chaudry., "Pump Characteristics for Transient Flow Analysis", Department of Mechnical Engineering & Aeronautics, City University, London ECIV OHB Turbines For turbines, the specific speeds 115, 170 and 230 (SI units) are from published data from the US Bureau of Reclamation (USBR). See Also Estimating the Specific Speed of a Pump or Turbine
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Wiki Page: Transient simulation for a hydrant closure or opening
Product(s): HAMMER Version(s): V8i, CONNECT Edition Area: Modeling Problem How can I model a transient simulation of a hydrant closing or opening too quickly? Solution A hydrant closure or opening transient event can be modeled in HAMMER using one of two approaches: Discharge To Atmosphere A Discharge to Atmosphere (D2A) element can be used to model a hydrant closure, if you are comfortable with assuming a simple linear closure. First, lay out a D2A node element at the hydrant location. Set "discharge element type" to "Valve", and the "Valve Initial Status" appropriately. If you're modeling a hydrant closing, set it to "open". If you're modeling a hydrant opening, set it to "closed". The characteristics of the opening are modeled by way of the "typical flow" and "typical pressure drop". See more on this in the relevant section of the article linked to at the bottom of this article. For a hydrant, you might enter the typical pressure and flow as the flow and pressure observed in a field test when the hydrant was opened. You are basically defining an orifice size by way of the "typical" flow and pressure drop fields. By supplying one pair of pressure and flow, HAMMER can figure out the relationship based on the orifice equation that gives the pressure drop for any flow value. So, if unsure, you can use the orifice equation along with the size of your opening and an estimate of the "head" (pressure head drop) to solve for the typical flow. Selecting a pressure head drop close to a typical value you might see under normal operating conditions will yield the most accurate pressure/flow relationship during both the initial conditions and transient simulation. Note: a standard 2.5 in. (100 mm) hydrant outlet would have a pressure drop of roughly 10 psi at 500 gpm. For an example of this, see the hydrant scenarios in the example model "Discharge_To_Atmosphere_Example.wtg", included in your HAMMER installation. It is located in the "Samples" folder within the installation folder. Valve If you need more control over the closure of the valve itself, you can use the Throttle Control Valve (TCV) element, with a pipe downstream of it followed by a demand or a D2A. The demand would be set up to model the hydrant flow. If the hydrant should be initially closed, use a D2A node downstream of the valve instead, as its outflow is pressure dependent even in the initial conditions and therefore it will have zero outflow when the valve is initially closed, yet will have outflow when it starts to open during the transient simulation. If using a D2A downstream of the TCV, configure its "Discharge element type" as "orifice" and enter the typical flow and pressure drop fields (see above and in the link below for more information on that). For the TCV, you can then configure the coefficient type, initial position, valve characteristics, and operating rule pattern. This gives you full control over what the hydrant is doing including how fast it is opened or closed. You can even model a closure and opening in the same simulation using an appropriate operating rule. See more in the link below for modeling the TCV. See Also Modeling Reference - Discharge To Atmosphere Modeling Reference - Valves Modeling An Initially Partially Closed Valve
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Wiki Page: Surge mitigation for systems with intermediate high points experiencing negative pressure
Applies To Product(s): HAMMER Version(s): V8i, CONNECT Edition Area: Modeling Original Author: Jesse Dringoli, Bentley Technical Support Group Problem Description When computing a transient simulation with an emergency pump shutdown, no matter what surge protection I try to put in place, it does not seem to help with negative pressures. Reason Take a close look at the profile of your system. If you're pumping over a hill and the boundary conditions on either end of the system are lower, than it may not be possible to maintain a positive pressure, so long as the pump(s) remain off. Basically when the pump turns off and the HGL drops, even if you had multiple tanks along the pipeline, they may help protect the system at first, but will eventually drain out and cause the HGL to drop to low levels. This can cause vapor pocket formation. When vapor pockets collapse, they can cause severe pressure spikes (or "upsurges"). If you only have air valves as protection, it's important to note that they can only limit the pressure from dropping below zero in the immediate vicinity of the air valve. Pressure can still become subatmospheric some distance to either side of the air valve. There are a number of factors that come into play, including the physical topology and angle of the surge wave as it approaches the air valve location. In some cases, other protective measures may be necessary, such as a tank or pump flywheel (increased inertia). Another factor to consider is what happens when air is released back out of the air valves. If a controlled air release does not occur (such as with a triple acting air valve or smaller outflow orifice diameter with a double acting air valve) then the adjacent water columns can rejoin too quickly, causing a severe upsurge, which can reflect and combine with other waves, causing severe a downsurge. The best way to visualize and understand if this is happening is to animate a profile path of the area in question. In your transient solver Calculation Options, make sure you have selected "True" for "Generate Animation data", then open the Profile of "Hydraulic Grade and Air/Vapor Volume" for a profile covering the area of interest. Click the play button at the top or move the time bar to animate the transient simulation and get a better understanding of exactly what's happening. You may notice an air or vapor pocket forming (top graph) and later collapsing with subsequent severe surges forming, reflecting and interacting with each other. You may need to consider how long the pumps will be off and size the surge protection device(s) based on that. You can use the "variable speed" transient pump type to simulate the pump turning off and then back on, or consider two runs (one for shutdown and the other for start up). For example, if the pump is shut down for 10 minutes the surge protection device would need to mitigate the transient wave for at least that long. In the case of a surge tank (hydropneumatic tank) the tank will need to be sized appropriately for the water to supply the demands and dampen the transient wave for at least the minimum time the pump is off. There may be concerns with how fast any trapped air is released upon startup. (Please visit the site to view this video)
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Wiki Page: Graphs under View > Graphs aren't showing transient results
Applies To Product(s): HAMMER Version(s): V8i, CONNECT Edition Area: Output and Reporting Original Author: Mark Pachlhofer, Bentley Technical Support Group Problem When I create a graph under View > Graphs, this seems to only show the initial conditions. Where can I view detailed graphical results of the transient simulation? Solution The transient results are viewed in the Transient Results Viewer, located under the Analysis menu. The amount of results included in here is determined by the report period, report points and "generate animation data" settings, under Analysis > Calculation Options > Transient calculation option The Transient Results Viewer displays transient results in graph form and also can animate hydraulic grade in a profile. The "Paths (Profiles)" pulldown at the top allows you to select a profile (defined in the main user interface under View > Profiles) and then either plot or animate it. The "plot" will provide the minimum/maximum transient envelope. The "animate" button will allow you to see the hydraulic grade profile as it changes over time. This is useful to understand how certain transient inducing events affect the system as a whole. If the animate button is grayed out, make sure "generate animate data" is set to "true", in your transient calculation options. To reduce the amount of profiles available, go to View > Profiles, right click on the ones you'd like to omit from the transient results viewer and deselect "transient report path". The "Time Histories" pulldown at the bottom of the Transient Results Viewer displays end points that are available to graph. The amount of endpoints listed are determined by the "report points" option in the transient calculation options. Note that transient simulation results are available at the ends of the pipes where they meet a node element. For example, the upstream side of a pipe or the downstream side of a pump. For time histories, you can plot the head, pressure, flow, air/vapor volume and force (if you've chosen to compute transient force.) (Please visit the site to view this video)
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Wiki Page: How to view and graph extended transient results such as gas volume for hydropneumatic tanks, pump or turbine speed, air valve extended data, etc.
Applies To Product(s): Bentley HAMMER Version(s): V8i and CONNECT Edition Area: Output and Reporting Original Author: Scott Kampa, Bentley Technical Support Group How To: How can I generate a graph of the various extended results not available in the Time History tab of the Transient Results Viewer? For example gas volume/pressure in a hydropneumatic tank or rotational speed of a pump? Steps to Accomplish The steps to view this information depend on your HAMMER version and what type of element/results you want to graph. If you have an older version of HAMMER, see the section further below. Version: V8i SELECTseries 5 (08.11.05.61) or higher Certain element types, such as hydropneumatic tanks, pumps, and turbines, now have select data available directly from the Transient Results Viewer. Hydropneumatic tanks include data on gas volume, gas pressure, and water inflow. Pumps include information on pump speed. Turbines include in formation on wicket gate position and speed. The steps below describe how to access this information. 1) Enter a number for the Report Period field in the properties of the element of interest (for example "10" means the results will be reported at every 10 time steps) 2) Compute the model and open the Transient Results Viewer 3) Click the Extended Node Data tab 4) Select the element and graph type, then click Plot to view the graph NOTE: If the element or result type is not currently available, see the steps below, which are also still valid. As of the current release of HAMMER, air valve and surge tank extended data is not available in the Transient Results Viewer. (Please visit the site to view this video) Version: 08.11.04.58 and earlier The steps below assume you are using Microsoft Office 2007 edition or later. The process may be different for older versions of Office. 1) Enter a number for the Report Period field in the properties of the element of interest (for example "10" means the results will be reported at every 10 time steps) Note: this is not currently available for all element types. 2) In your transient Calculation Options, make sure "True" is selected for "Generate Detailed Reports" and "Generate Extended Output Log". 3) Compute the model, open the Transient Analysis Detailed Report under Reports > Transient Analysis Reports and scroll to the bottom until you see the table of extended results for the node of interest. 4) Copy/paste the text from this table into a separate .txt file in Notepad. 5) Open Microsoft Excel and start a new spreadsheet (the process is likely different with older versions of Excel) 6) Click the "Data" tab, choose "From Text" and select your file. 7) Choose "Fixed width", then "next" 8) Set up the field widths so that the columns of data are separated appropriately 9) Set up a line graph with the appropriate columns (Time, plus whatever attribute you would like to graph. For example, volume of air for a hydropneumatic tank) See Also General HAMMER FAQ Extended Node Data at odds with Time History graph for hydropneumatic tanks
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Forum Post: RE: How to Import Sub-model to Water-gems??
Hello Anan, Here is a video that might explain what is happening with the active topology in your model. (Please visit the site to view this video) The following article may help also. Elements turning inactive and reverting to default properties after submodel import
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Wiki Page: Elements turning inactive and reverting to default properties after submodel import
Applies To Product(s): WaterGEMS, WaterCAD, HAMMER, StormCAD, SewerCAD, CivilStorm, SewerGEMS Version(s): 08.11.XX.XX Area: Layout and Data Input Original Author: Mark Pachlhofer, Bentley Technical Support Group Problem When importing a submodel, why do my new elements turn inactive (gray color or disappear) and old elements change their attributes to the defaults in the new scenarios? Solution This will occur if your current scenario is one that did not exist in the model that the submodel was created from. Basically there is no way for the program to know which physical/topology information should be used for the new elements, in a scenario that was not present in the submodel. So, the default values are used for those new elements in those existing scenarios (the default value for "is active? is "false"). If you switch your active scenario to one from the submodel's original model, the submodel elements will become active, but then the elements from the original model will become inactive, for the same reason. When importing a submodel, you should first make sure the structure (parent/child relationship/hierarchy) and labels for both the alternatives and scenarios match, between the source and destination model. Otherwise, the above difficulties will occur, due to the program creating new alternatives/scenarios. If all the scenario/alternative labels/structures match, then the program will know where to place all of the data (which is stored in the alternatives) from the submodel, so the physical/topology information will be present in your scenarios. (Please visit the site to view this video) See Also Submodel Import/Export Pipes connecting to the wrong element after submodel import
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