Applies To Product(s): Bentley WaterGEMS, Bentley WaterCAD, Bentley SewerGEMS, Bentley SewerCAD, Bentley StormCAD, Bentley CivilStorm, Bentley HAMMER, Bentley PondPack Version(s): 08.11.xx.xx Environment: N\A Area: Calculations Subarea: N\A Original Author: Terry Foster, Bentley Technical Support Group Problem The following error is generated when saving or validating a model file: Attempted to read or write protected memory. Press Ctrl-C to copy details to clipboard: System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt. at memcpy(Void* , Void* , UInt32 ) at Haestad.DrawingStorage.GenericMemoryCollection`1.ToArray() at Haestad.Drawing.DrawingObjectTableModuleBase.Write(IStorageWriteStream astream) at Haestad.Drawing.PointDrawingObjectTableModule.Write(IStorageWriteStream astream) at Haestad.Drawing.TextDrawingObjectTableModule.Write(IStorageWriteStream astream) at Haestad.Drawing.MultiLineTextTableModule.Write(IStorageWriteStream astream) at Haestad.Drawing.AnnotationData.Write(IStorageWriteStream astream) at Haestad.Drawing.LayerDefinition.Write(IStorageWriteStream astream) at Haestad.Drawing.Domain.DrawingStorageElement.Write(IStorageWriteStream astream) at Haestad.Support.Storage.StorageFileBase.WriteElement(IStorageElement aelement) at Haestad.Support.Storage.BinaryStorageFileBase.WriteElement(IStorageElement aelement) at Haestad.Support.Storage.StorageFileBase.Write(IStorageElement aelement) at Haestad.Support.Storage.StorageManagerBase.Write(IStorageWriteContext acontext) at Haestad.Framework.Application.StorageProjectFileBase.Write() at Haestad.Drawing.Domain.DrawingFile.SaveAs(ProjectProperties app) at Haestad.Drawing.Domain.DrawingFile.Save(ProjectProperties app) at Haestad.Framework.Application.ProjectBase.Save(ProjectProperties app) at Haestad.Framework.Windows.Forms.Forms.HaestadParentForm.SaveProject(IProject aiproject) at Haestad.Framework.Windows.Forms.Forms.HaestadParentForm.SaveCurrentFile() at Haestad.Drawing.Control.Forms.GraphicalDrawingParentForm.menuButtonItemFileSave_Activate(Object sender, EventArgs e) at TD.SandBar.ToolbarItemBase.OnActivate() at TD.SandBar.ButtonItemBase.OnActivate() at TD.SandBar.ButtonItem.OnActivate() at TD.SandBar.ToolBar.OnItemRelease(ToolbarItemBase item, Point position) at TD.SandBar.ToolBar.OnMouseUp(MouseEventArgs e) at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks) at System.Windows.Forms.Control.WndProc(Message& m) at TD.SandBar.ToolBar.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) Solution First, try compacting the database. To do this, close the model but leave the product open. Go to Tools > Database Utilities > Compact Database. Select the database file and choose the option to purge the model to save space. Once completed, open the model and see if the issue still occurs. This is an indication that the output files are too large or numerous. Try creating a new folder and moving just the starter file and the database file (.wtg and .wtg.sqlite for the water products, .stsw and .stsw.sqlite for the storm and sewer products) to the new folder. Once done, open the model from the new folder location. If that doesn't help, try importing the database into a new drawing. This is done by going to File > Import > (product name) database. Lastly, you can also try deleting the engineering library database. Go to c:\users\ \AppData\Roaming\Bentley\EngineeringLibraries and delete EngineeringLibraries.mdb and EngineeringLibraries.sqlite. Make sure the program is closed when you do this. When you open the program again, the files will get re-created. Note: Custom items in the engineering library will be lost if you do this. If that doesn't help, review the model for missing or incorrect data. This could include references to deleted elements, such as the downstream pipe for a valve or pump or to the control node for a variable speed pump. Also check for missing or incorrect data like pipe lengths or pipe diameters. In one case, an updated AMD driver caused this issue. Once the update was removed, the error went away.
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Wiki Page: Error when saving or validating: System.AccessViolationException: Attempted to read or write protected memory.
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Forum Post: Why SewerCad Model Not Apply all Design Constraints
Dear All; Greetings i am modelling sewer network and i found that CO-12 & CO-13 does not meet the minimum required velocity? The model should increase the slope of theses pipes to be 4 m/km and then the minimum velocity will be achieved and the other constraints ( Cover ...etc) will not be violated also? I think Bentley should consider if the all constraints can be achieved why not???? I have attached the model Regards Sayed Elhagar (Please visit the site to view this file)
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Forum Post: WaterGEMS-Modeling a Hydropneumatic Tank with a Water Booster Pump
Colleagues, I am a relatively new user to WaterGEMS. I am working in Select series 6 and looking for assistance with how to model a hydropneumatic tank with a booster pump as a small "high" pressure district of a municipal water system. Does anyone know of a Bentley on-line course, or offer some guidance, etc?
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Comment on Bentley SewerGEMS V8i SELECTseries 5 自述文件
Bernadi, This File is the Readme.PDF for SewerGEMS. The English version of this can be found in the SewerGEMS installation folder - Readme.PDF. You can also read more about what's new in this release here: communities.bentley.com/.../21498.what-s-new-in-sewergems-v8i-selectseries-5
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Forum Post: VSP Target Pressure - Pump Output Higher
The VSP's in my system do not reduce speed to meet the target head assigned. I have a large model with many facilities, including 7 ON constant speed pumps, 7 VSP pumps, and 4 VSP Batteries. Some of the variable speed pumps/batteries reduce speed to meet the input target head, and some do not. In previous versions of the model all pumps functioned as expected. The conversion of some VSP's to VSPB's seemed to cause some un-modified VSP's to have trouble converging. Are there any known data input situations where this could occur? How should I go about troubleshooting if the model does not seem to obey input data? Thanks for any guidance.
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Forum Post: RE: WaterGEMS-Modeling a Hydropneumatic Tank with a Water Booster Pump
You can download a presentation about hydropneumatic tanks from this link communities.bentley.com/.../270151 There have been a lot of discussions on hydropneumatic tanks on Communities but most have to do with their use in transients. There is material in our On Demand training notes. I believe it is in the EPS session. As you get more specific questions, feel free to post them here. Good luck.
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Wiki Page: How can I easily add a color coding for a property like "Zone" to all my elements so I can visualize them separately?
Applies To Product(s): Bentley WaterGEMS, Bentley SewerGEMS, Bentley CivilStorm, Bentley StormCAD, Bentley PondPack, Bentley SewerCAD, Bentley HAMMER, Bentley WaterCAD Version(s): 08.11.XX.XX Environment: N/A Area: Original Author: Mark Pachlhofer, Bentley Technical Support Group Problem How can I easily add a color coding for a property like "Zone" to all my elements so I can visualize them separately? Solution Just create a color coding for one of the elements using the directions in this wiki and then use the directions in this wiki to copy and paste the color coding to the other elements.
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Forum Post: RE: WaterGEMS-Modeling a Hydropneumatic Tank with a Water Booster Pump
Here's a good resource on modeling hydropneumatic tanks in WaterGEMS or WaterCAD: communities.bentley.com/.../17625.how-are-hydropneumatic-tanks-hydro-tank-used-in-watergems-and-watercad-models I found a very simple example model I had put together some time ago (2008) and have attached it to the above article.
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Wiki Page: How are hydropneumatic tanks (hydro tanks) used in WaterGEMs and WaterCAD models?
Applies To Product(s): Bentley WaterGEMS, Bentley WaterCAD Version(s): 08.11.xx.xx Environment: N/A Area: Layout and Data Input Subarea: Original Author: Jesse Dringoli and Mark Pachlhofer, Bentley Technical Support Group Problem How are hydropneumatic tanks (hydro tank) used in WaterGEMs and WaterCAD models? Tips and What you Need to Know A hydropneumatic tank uses compressed air or gas to provide a relatively small amount of water storage volume while keeping the hydraulic grade much higher than the physical top of the tank. Hydro tanks can be set to either follow the traditional gas law or use the "constant area approximation" method to calculate a change in pressure/HGL and volume. The constant area approximation uses a linear relationship; the user must specify minimum/maximum HGL and the corresponding volume between. The gas law model is non-linear and follows the gas law--as gas is compressed, it becomes harder to compress it more. Unless you have a specific need to use the constant area method, you should use the Gas Law. The Constant Area method is primarily left in place for legacy purposes, to provide a way for users to achieve equivalent results compared to the method that was used before this element type was available in the product. Meaning, before the hydro tank element, it was common to model a hydro tank using a normal tank node element configured to be very tall with the appropriate constant diameter. With the hydro tank node element, an older model (or one from another product such as EPANET) could have a hydro tank inserted instead of the regular tank and configured with the constant area method to achieve comparable results. The two model are described in more detail below: Constant area approximation : This method approximates a hydropneumatic tank by using a tall, thin tank whose water surface elevation approximates the HGL in a hydropneumatic tank. The HGL on and HGL off fields represent the maximum and minimum hydraulic grade lines within the hydropneumatic tank (i.e. when an associated booster pump would turn on or off). An approximate diameter is computed based on the effective volume of the hydropneumatic tank so that the tank cross sectional area multiplied by the distance between HGL on and HGL off gives the same volume as the hydropneumatic tank. Gas Law : This method uses the ideal gas law, PV=nRT, to compute new hydraulic grades as liquid volume changes in the EPS simulation (nRT is assumed to be constant). The initial liquid volume is subtracted from the total tank volume to find the gas volume. The physical "elevation" is subtracted from the initial HGL to find the gauge pressure. The atmospheric pressure is added to the gauge pressure to get absolute pressure, which is used in the ideal gas law equation. *Both methods typically yield similar results within the "effective" control range, but the gas law is technically more accurate. If the hydropneumatic tank is just being used for transient protection and it 'floats" on the system, meaning that it stays at the system HGL and neither fills nor drains until a transient event, then you can just model junction by setting the property of the hydro tank for "Treat as Junction?" equal to 'True'. In some small scale systems you may want to model the tank filling or draining. If this is the case then you will need to make sure that you have the hydraulic time step, which is found in the calculation options (Analysis > Calculation Options), set small enough to capture all the quick changes these type of tanks can exhibit. You will want to make sure the time is small enough, so that if intermediate time steps are necessary to include for the controls they don't skip over the controls. Intermediate time steps are calculation time steps that are inserted between regular interval time steps to account for control changes to element statuses. These time steps are inserted at 1/10th of the normal hydraulic time step. You will know if you need a smaller hydraulic time step because the HGL in the tank will shoot past the control elevation in 1/10 of a calculation hydraulic time step.This helps to ensure that the controls do not end up overshooting the fast level changes that can occur. Example Model Click the below link to download a small example model with a reservoir > pump > hydropneumatic tank > demand. The gas law is used with pump controls based on the tank HGL, with a suitably small timestep. (Please visit the site to view this file) See Also Why are there so many extra elements listed for WaterGEMS and WaterCAD such as surge tanks, rupture disks, or periodic head-flow elements? How does the gas law model work for a hydropneumatic tank in WaterGEMS or WaterCAD? Hydropneumatic tanks modeling reference for HAMMER
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Wiki Page: User Notification about negative pressures at pumps, junctions, & other node elements.
Applies To Product(s): WaterGEMS, SewerCAD, HAMMER, WaterCAD Version(s): 08.11.XX.XX Environment: N/A Area: Modeling Subarea: Original Author: Dan Iannicelli, Bentley Technical Support Group What does it mean when a node reports a negative pressure? A negative pressure occurs when the hydraulic grade is below the physical elevation of a node. If WaterCAD/GEMS says the pressures will be negative, then in all likelyhood you will have problems. Assuming all data input has been checked, there are usually two general causes of negative pressure: 1. Trying to serve a customer at too high of an elevation. This will show up as low/negative pressure at any demand. You need to increase pump head or adjust pressure zone boundaries. 2. Some restriction in the system. This will show up as good pressure during low demand and poor pressure at high demand. You need to look at the model results and see if the pipes are too small causing excess head loss or the pumps are inadequate such that they are running far off to the right of the curve. You need to upsize the pipes or pumps accordingly. You should also check your demands for errors. Since your demands are likely based on historic averages, a significant decrease in pressure may skew the results, since the demands would likely be decreased in that condition. You may consider using pressure dependent demands or flow emitters. You may also consider conducting a transient analysis using Bentley HAMMER, if the problem occurs at a transmission main. What does the user notification, "Pressures below the lowest physically possible pressure in system at one or more time steps. Set up Alerts for details." mean? As of WaterCAD/WaterGEMS Select Series 6, this is a new user notification that was designed because sometimes small negative pressures aren't that bad. This user notification helps to reduce the number of negative pressure user notifications that used to be generated for each node where it occurred. If you'd still like to see those user notifications you can set up custom alerts described in the wiki link below: By double clicking on the user notification the properties window for the calculation options will open and you can adjust the minimum possible pressure (default value -14) if desired. Changing this will change the pressure at which the user notification will be generated. What are the best ways to visually locate negative pressures? 1. By creating an annotation based on pressures for your node elements. 2. By creating color coding based on pressures for your node elements. 3. Using a network navigator (View > Network Navigator) query for negative pressures (see the screen shot below) 4. Creating a custom alert for negative pressures. 5. By using the flextable to view the pressures sorted descending to ascending. Why do I get a negative pressure at a high point in my system? Shouldn't the pump add enough head to push the water over the hill? By default, pumps only consider the boundary conditions (reservoirs and tank elevations) in your system. So, the pump will add enough head to lift the water to the downstream known hydraulic grade. It does not consider junction elevations in between. If you are using WaterCAD or WaterGEMS V8i, you should add an Air Valve element at the high point to properly model this situation. By placing an air valve at the high point, the pump sees the air valve elevation as its downstream boundary condition for instances in which pressure would have otherwise been negative at the high point. For any air valve that is expected to be open in this way, ensure that you select "false" for the "Treat air valve as junction?" attribute. For more on this, see this technote . Another alternative to resolving negative pressures to take into consideration is installing a PSV at the downstream end of the system with a hydraulic grade equal to the highest point in the system. What will I need to do if I have negative pressures at high point in my system that does not have air valves installed? If you get a negative pressure at a high point that means the system is a siphon at that location. It is best to put an active air valve at that point (Treat as Junction? = False). If I find that pressure at any point in my system drops below vapor pressure what do I need to do? If the pressure drops below the vapor pressure, the siphon will not work. You definitely need to install an active air valve there (Treat as Junction? = False). This will also help provide protection against a vapor pocket collapse that would cause a transient to occur. Why do I get a user notification about negative pressure at a pump? This commonly occurs in cases where the user models the pump station (or connection to an existing system) using a reservoir and pump, with short pipe between them. Typically, the same elevation is used for both the pump and reservoir nodes. Since the reservoir elevation defines the boundary hydraulic grade and since there will always be some amount of headloss through a pipe, this means that the hydraulic grade at the pump node location will be slightly below the physical elevation. The suction pressure of the pump is derived from the difference between the hydraulic grade and the physical elevation, so that is why the pressure ends up being negative. You can simply ignore this informational message, but if you'd like to remove it, the solution is to simply raise the elevation of the reservoir by a small amount. Make sure the pipe has a very large diameter and smooth roughness coefficient, too (to minimize headlosses.) If the upstream hydraulic grade or reservoir elevation is correct, then this negative pressure message is accurate. To better understand what is happening, create a profile of the hydraulic grade and physical elevation for this segment of piping - you will see that the hydraulic grade is below the pump elevation. If this is an existing system, you may need to check your NPSH to ensure that cavitation will not occur at the pump. You can also investigate ways to increase the hydraulic grade upstream of the pump. Discussion: A negative pressure means that the calculated hydraulic grade is below the physical elevation of the element. You should closely examine your node elevations and boundary conditions (reservoir/tank hydraulic grades) to make sure they are correct. It is common for this to occur on the suction side of the pump, due to the elevation that you entered for the nearby reservoir. If the pump is off, then it is likely that the reservoir elevation is set to be lower than the pump elevation. Creating a profile of the area in question (physical elevations and hydraulic grades) should give you a good visual idea of what is going on. Note that negative pressures will not prevent the model from computing - the messages that you get about these are just informational. WaterCAD/GEMS still assumes that the pipes are pressurized and no vapor pockets will form. It basically just computes the hydraulic grade based on the system conditions and other data input, and then reports the pressure as the difference in head between that and the physical elevation. If the negative pressures occur at high points in the system, you probably would have an air valve at that point so you can fill the pipeline. However, once the pipeline is running, only those air valves that would have a pressure below 0 need to be modeled as active air valves (Treat as Junction? = False). The others can be set to 'True'.
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Forum Post: RE: Flow from A Wet well to A Gravity sewer System
By "DU" are you referring to a unit load? Population? The conservative approach would be to design the downstream gravity pipes using the pumped flow (204.95 gpm). The calculated flow that you see in the pipe is what the program is routing through the pipe. If you're using the automated design feature, it will be using that.
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Wiki Page: Creating a timer control to execute after a specific time period has elapsed
Applies To Product(s): Bentley WaterCAD, Bentley WaterGEMS, Bentley HAMMER Version(s): 08.11.04.58 Environment: N/A Area: Modeling Subarea: Original Author: Mark Pachlhofer, Bentley Technical Support Group Problem Description Is it possible to have a control that works based on a specifc elapsed time period? Can I have a control that makes an FCV close 30 minutes after a tanks becomes full? Solution This is possible, but it's easier explained when looking at the attached sample model. (Please visit the site to view this file) In the upper part of this model surrounded by a box you will see there is a timer built from 2 reserviors, a tank, and junction with a demand on it. Now open the controls so you can follow along with what is going on here (Components > Controls) and understand how this works as I explain it. The timer control: Pipes P-1 and P-3 is initally open so you don’t get the system disconnected user notification. This is because J-1 needs flow to satisfy the demand on it all the time and T-1 needs another boundary element to be connected to it. This is all set up in the properties of the elements. When the timer starts pipes P-1 and P-3 are closed and P-2 opens. This is done by the control with the ID LC140 that states: IF T-215 Hydraulic Grade > 925.00 ft And FCV-1 Status = Inactive THEN P-1 Pipe Status = Closed , P-3 Pipe Status = Closed , P-2 Pipe Status = Open We can see based on this control that the timer starts when the real tank in the model, T-215, is greater than an HGL of 925 ft. This would probably be the same way you wanted to set it up for your model. When the timer stops it resets everything so it can be used over again based on this control: IF T-1 Hydraulic Grade <= 50.00 ft THEN FCV-1 FCV Setting = 50.00 gpm, P-3 Pipe Status = Open , P-1 Pipe Status = Open , P-2 Pipe Status = Closed This allows tanks T-1 to refill (this is the timer tank) and allows us to reuse this timer. The part that you need to work out is the timer portion (i.e. the size of the tank). What you want to do is set the tank diameter based on the total active volume to demand (in junction J-1) relationship. You have to set it so that it will drain in the exact amount of time needed to turn on your pump or in the case of the example to trigger the FCV to engage. For example, if you want to drain your tank in 30 minutes you could have a tank with a volume of 30 gallons that drains at 1 gpm per minute. If you wanted to do this you would then add a 1 gpm demand on J-1. In the model you can see there is a 10 minute timer, so the total active volume is 10 gallons. The tank starts at the top with an HGL (or elevation) of 60 ft. and drains down 10 feet to an HGL of 50 ft. At this point this control kicks in IF T-1 Hydraulic Grade <= 50.00 ft THEN FCV-1 FCV Setting = 50.00 gpm, P-3 Pipe Status = Open , P-1 Pipe Status = Open , P-2 Pipe Status = Closed and stops the draining and triggers the action you want to initiate.
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Forum Post: RE: Time duration assist pump
Hello Busher, It should be possible, but you may have to get a bit creative. See below wiki article for an example of how to set up a "timer" device: Creating a timer control to execute after a specific time period has elapsed There is also the option of manually controlling the pumps by way of a pump Pattern. This is done by selecting "True" for "Is Variable Speed Pump", "Pattern Based" as the "VSP Type", then set up and select the pattern (1.0 = on, 0.0 = off). You can also set up pump controls based on clock time: How to model timed pump starts, such as a certain on-and-off cycles per hour
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Wiki Page: Using Fit To Page Printing In The Standalone Platform [TN]
Applies To Product(s): Bentley WaterCAD V8i, Bentley WaterGEMS V8i, Bentley HAMMER V8i, Bentley Pondpack V8i, Bentley CivilStorm V8i, Bentley SewerGEMS V8i, Bentley StormCAD V8i, Bentley SewerCAD V8i Version(s): 08.11.XX.XX Environment: N/A Area: Output and Reporting Subarea: N/A Original Author: Jesse Dringoli, Bentley Technical Support Group Overview This Technote explains how to adjust your layout in order to achieve the best results for a Fit-To-Page printout/plot in the standalone platform of WaterGEMS. These concepts apply to other programs such as WaterCAD, HAMMER, CivilStorm, SewerGEMS, StormCAD, SewerCAD, and PondPack V8i. Background Sometimes you may want the plan view of the model network to be fit to one single page when printing. The "Fit to Page" option under File > Print Preview or File > Print will do this, but can sometimes cause unexpected results. For example, consider the following network layout and corresponding fit-to-page print preview: Notice that the network is small and doesn't take up the whole page. Extra blank space is left on all 4 sides of the model. What Causes The Extra Space? The extra blank space on the sides of the network in a fit-to-page printout or print preview is caused by two main factors: 1. The entire contents of the drawing pane will be fit to the page. Basically, a "what you see is what you get" approach is taken. In the above example case, notice how the drawing pane (the area where the model is displayed) has a lot of extra white/blank space on the left and right of the network. This is because the shape of the network is much different from the shape of the drawing pane. The model network is tall, but the drawing pane is wide, due in part to the monitor resolution and location of docked windows (the EPS results browser takes up a lot of space at the bottom.) The below screenshot shows a similar case. Although the drawing pane appears to match the shape of the model, the same problem will occur, because the surrounding windows are not docked. Therefore, the drawing pane actually extends to both sides of the entire WaterGEMS window, behind those 'floating' managers. The red box indicates the true size of the drawing pane, all of which will be fit to the page when printing: 2. The aspect ratio of the drawing does not change . Basically WaterGEMS will not stretch the model vertically or horizontally to get a better fit - it is scaled up at the same ratio. So, when using zoom extents, the model network 'bumps' into the top and bottom before it can fill the space on the sides. This is basically as far in as the model can zoom while still being able to see the entire extents. However, even if the model shape closely matches the drawing pane shape (leaving no extra space space on the sides), it may differ from the shape of the paper you need to print it on. So, extra space may still show up in the print preview if the paper size is not in agreement with the drawing pane size. How do I Fix it? The first thing you will need to do is get your drawing pane shape to match the model shape as closely as possible. This can be done by docking and resizing windows on the sides, bottom, and/or top of the model. Using the example case from the first screenshot in this technote, you could close the EPS results browser at the bottom to make the drawing pane extents taller. You could also dock windows on the left and right sides of the drawing pane, then click and drag the inside edges of those docked windows inward to make the drawing pane size taller. Now, when you use the fit-to-page print preview, WaterGEMS will no longer be trying to fit extra white space from the drawing pane. So, it will be able to scale the model up more before hitting the sides of the sheet. Therefore, the model will appear larger and more like you might expect: To get the model to appear even larger, you can remove items from the header/footer and reduce margin size, under the Report menu > Report Options: Note that even with this optimized layout, a small amount of extra white space is seen in the print preview, on the left and right side of the model. This is because the paper size is slightly wider than the drawing pane. WaterGEMS will not stretch the model horizontally to fill both sides, since the aspect ratio is maintained. Basically as the model is scaled up to fit the page, it's 'bumping' into the top and bottom before it hits the sides. Logically, the only way to fix this would be to choose a different paper size. In general, the other option you have is to take advantage of one of the other platforms. For example with WaterGEMS, in addition to using the standalone user interface, you can work inside a compatible version of AutoCAD, Microstation, or ArcGIS. When integrated with any of those three applications, you can take advantage of their enhanced printing/plotting capabilities to get the printout you desire. See Also Product TechNotes and FAQs Haestad Methods Product Tech Notes And FAQs External Links Hydraulics and Hydrology Forum Bentley SELECTservices Bentley LEARN Server
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Wiki Page: Modeling a valve opening in HAMMER
Applies To Product(s): Bentley HAMMER Version(s): 08.11.XX.XX Environment: N/A Area: Original Author: Mark Pachlhofer, Bentley Technical Support Group Problem Modeling a valve opening in HAMMER Solution To model this start the valve as initially open by setting the "Status(Initial)" property to 'Active' and set the Headloss Coefficient, discharge coefficient, valve characteristics curve, pressure, flow setting, or hydraulic grade appropriately (what is set depending on the value type and information that you have). Next slowly close the valve with the pattern in order to try to induce as little transient as possible. To do this set the "Transient Analysis Behavior" to 'Valve' then click the option in the Transient analysis behavior dropdown. This will open the patterns manager where you will create an Operational (Transient, Valve) pattern. The 'Starting Relative Closure' of the pattern should be set to 0%. In order to close the valve slowly over a period of time with a pattern you might start the valve closure at 10 seconds and then have it close over a period of 60 seconds as shown below: After you're done you would click "Close' at the bottom of the Patterns manager then select the new pattern that you created in the cell next to the 'Operating Rule' property. Now run the model and check the results in the transient results viewer to make sure the transient has fully settled. If you need to adjust your pattern to elminiate the transient wave you should do that now. We also have information that might be useful for determining the exact time period you need to close a valve in to eliminate or reduce you transient wave under the "Wave Propagation and Characteristic Time " help document found within the software.
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Forum Post: Zero Flow after PRV valve in watergems
Hi I have a large water distribution network modelling in watergems. in order to reduce pressures in a proper value, I have to place some PRV valves in the network. But when I put a PRV valve, and set the pressure, the flow in that pipe gets zero, resulting in changing the flow direction in other pipes, and also the pressure doesn't reduce. I don't know the reason why flow gets zero when I pace the PRV valves?
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Forum Post: RE: Zero Flow after PRV valve in watergems
It's likely that you have provided a way for water to bypass a PRV and the flow is taking that route. When you have a boundary between pressure zones, all of the water from a higher zone to lower must pass through the PRV(s) between the zones. If not, then the water will go around them. Check your pressure zones boundaries. Try using the pressure zone manager.
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Forum Post: RE: Zero Flow after PRV valve in watergems
Yes, you are exactly right. I have more than one way (pipe) in order to cross the flow. But I am not sure about my maps, maybe there is a closed valve or the PRV existeddoes not work. Because it is a real region and in fact, my purpose is to do the pressure management in the city. Is there any useful link to help me in pressure management and new pressure zoning? And thanks Tom for your useful help.
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Forum Post: RE: Zero Flow after PRV valve in watergems
Select a scenario Pick Analysis > Pressure zone Select the same scenario in Pressure Zone Manager Pick compute Select the zone results tab Color code the zones using the 7th button Compare what you see with what you think the pressure zones should look like This will show you where you need to close a pipe or valve in the model (and possibly in the system) You can also pick Flow Balance (5th button) and see what the range of pressure is in each zone Best wishes
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Wiki Page: Unable to meet minimum or maximum velocity constraint
Applies To Product(s): Bentley StormCAD,Bentley SewerCAD, Bentley CivilStorm, Bentley SewerGEMS Version(s): 08.11.03.XX Environment: N/A Area: Output and Reporting Subarea: Original Author: Mark Pachlhofer, Bentley Technical Support Group Problem Description No matter what I do I can't get the design run to be within the minimum or maximum velocity constraint that I have set. Why is this? Solution The automated design feature attempts to minimize excavation, so constraints like the minimum and maximum velocity are at the bottom in terms of priority (see article in "See Also" section below.) For example in order to meet a minimum velocity constraint, it may be necessary to bury at least one end of the pipe deeper to increase the slope, which increases excavation costs. If a design priority is violated a user notification alert for the element that violates it will be generated and you might need to make a need an engineering decision on whether this is going to be ok for your project or not. The automated design tool can give you a good starting design but you will still need to use your engineering judgment to refine further. See Also What is the order of the design Priorities used in StormCAD and SewerCAD?
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