If you're using Darwin Calibrator's leakage detection feature, it will basically calculate the emitter coefficient for you, such that the model results match the field measurements. The larger the emitter, the bigger the leak. When the solution is exported, you'll see the emitter coefficient and you can compute the model to see the resulting outflow. You could perhaps take the resulting emitter coefficient (or pair of pressure and flow seen when running the exported solution) and use the orifice equation to estimate the size of the leak. If you're referring to modeling a known leak, you could again perhaps use the orifice equation to compute the emitter coefficient and find some reference material for typical coefficients for the break/leak in question.
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Forum Post: RE: Leakage Detection
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Forum Post: RE: Leakage Detection
When used to find leaks, Darwin assigns emitter coefficients to nodes where the observed pressure seems too low for the assigned flow. Nodes with higher emitter coefficients are likely areas where leakage or theft may be occurring. There is no rigid rule for differentiating between leak and non-leak nodes. Remember that for Darwin to detect leakage, the additional head loss additional head loss generated by the leak must be significant. It won't find small leaks. Use of Darwin requires judgment by the user. It doesn’t pinpoint leaks but indicates areas where detailed leakage surveys should be conducted.
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Forum Post: RE: Darwin Designer
Dear Tom What I've got of your opinion is software designing HAS TO be studied and modified by engineer and Dar. Designer can not offers the best solution ALWAYES. Am I right? About the particular model, both less cost AND satisfying the constraints can be got with smaller pipe that 400mm, which means smaller pipe is the best optimization NOT 400 diameter pipe. This behavior admits the first idea (Dar. Designer can not offers the best solution ALWAYES). Is my opinion true?
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Forum Post: Message ID 40005 "Network Unbalanced".
I have a looped system, with 2 points of connection to an existing water main that are modeled as reservoirs. Each reservoir has a GPV. When I run the model I receive an error (Message ID 40005) and flow is showing through the reservoir at 500gpm even though there is no demand proposed for any of the junctions. I don't receive this error when I only have 1 reservoir. Why is the network considered "unbalanced" when there are 2 reservoirs?
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Forum Post: RE: Leakage Detection
Dear Craig: Thank You for the Fast Reply, But I have this Example Already. I was asking about how to judge on the resulting Emitter Coefficients to decide that it is a Leak , Semi-Break or Break. So my Question is. Are there any limits or Ranges for the Emitter Coefficient that I Can refer to so I can Judge on this Type of leak? I know that the Darwin-Calibrator will help to calculate the Coefficients but what I need is how to judge on them? Thanks & best regards Joseph Atef
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Forum Post: RE: LNG pipeline surge analysis
Hi, Thanks for your reply. I agree with your feedback that HAMMER is designed for water service & for single phase fluids. For LNG service, specific gravity would be around 0.45 to 0.5 Request you to share your opinion regarding "Reliability" of results of the transient analysis generated by HAMMER especially for process fluids such as LNG. Pl note that I am considering negligible heat leak in piping by providing proper insulation so that LNG shall remain in liquid form without significant phase change. Your feedback shall help me to give confidence to my clients. Thanking you. Best regards,
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Forum Post: RE: Leakage Detection
Dear Jesse: Thank You for the Fast Reply. I know that the Darwin-Calibrator will help to calculate the Coefficients but what I need is how to judge on them? Also, I know that I can calculate the amount of the flow even by computing the Orifice Equation or by substitute the obtained Emitter coefficient into the Model and compute to see the flow. But,I was asking about how to judge on the resulting Emitter Coefficients to decide the Leak Type and if it is a Leak , Semi-Break or Break. And my Question is. Are there any limits or Ranges for the Emitter Coefficient that I Can refer to so I can Judge on this Type of leak? Thanks & best regards Joseph Atef
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Forum Post: RE: Leakage Detection
Dear Tom: Thank You for the Fast Reply. Yes, I was asking about how to judge on the resulting Emitter Coefficients to decide the Leak Type and if it is a Leak, Semi-Break or Break. So my Question is. Are there any limits or Ranges for the Emitter Coefficient that I Can refer to so I can Judge on this Type of leak? Thanks & best regards Joseph Atef
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Wiki Page: "COM Error Not Documented" when opening Haestad product
Applies To Product(s): Bentley SewerGEMS, Bentley SewerCAD, Bentley StormCAD, Bentley CivilStorm, Bentley WaterGEMS, Bentley WaterCAD, Bentley HAMMER Version(s): 08.11.03.83 and 08.11.03.77 (for Storm and Sewer products); build 08.11.03.19, 08.11.03.17, and 08.11.03.16 (for Water products) Environment: Windows 7 64 bit Area: Installation Original Author: Scott Kampa, Bentley Technical Support Group Error or Warning Message When opening SELECTseries 3 version of a Haestad Methods product (or earlier), the following error message is generated: Haestad.Domain.DaoInterop.DAOException: COM error not documented at Haestad.Domain.DaoInterop.InteropLibrary.ThrowCOMException(_com_error* e) at Haestad.Domain.DaoInterop.DaoDatabase.CreateDatabase(String fileName, CultureInfo locale) at Haestad.Domain.LibraryObjects.JetAppSettings.OpenRegistryDatabase(String fileName) at Haestad.Domain.LibraryObjects.EngineeringLibraryService.OpenImpl() at Haestad.Domain.LibraryObjects.EngineeringLibraryService.EngineeringLibraryTypeNames(HmiProductBeta product) This is sometimes followed by the following message: ------------------------------------------------------------ Database format not recognized. It could not be opened. ------------------------------------------------------------ OK ------------------------------------------------------------ Explanation This error may occur if the 64-bit version of the Haestad product has been installed along with a conflicting version of Microsoft Office. When installing the software on a 64-bit operating system, the program should detect the presence of the 32-bit version of Microsoft Office and force the software to install as a 32-bit application. The reason for is a Microsoft Office component called Access Database Engine. The 32-bit version of Microsoft Office will have the 32-bit version of the Access Database Engine. On rare occasions, the 32-bit version of the Access Database Engine is not properly idenified. When this occurs, the 64-bit version of the product is installed and used in the Desktop shortcut. Since the 64-bit version will conflict with the 32-bit version of the Access Database Engine, the error message is generated. This is a rare issue that will only occur the the SELECTseries 3 versions of the Haestad products and only on a 64-bit operating system with 32-bit Microsoft Office installed. Note that this problem will no longer occur, as of the SELECTseries 4 versions of WaterCAD, WaterGEMS and HAMMER (or later). The reason is because a SQLite database is now used instead of an Access Database, eliminating the dependency on the Access Database Engine for opening a file. This also applies to the SELECTseries 4 release of StormCAD, SewerCAD, SewerGEMS and CivilStorm. How to Avoid Primary Option: Upgrade to the latest version of the program The SELECTseries 4 and later versions of the Water products and the Storm and Sewer products will not see this issue. Upgrading to the latest version of the software will eliminate this error completely and provide you with all of the latest updates and tools the programs have to offer. You can find the steps to upgrade to the latest version at the following link: http://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/8175.how-do-i-download-watergems-watercad-hammer-sewergems-sewercad-civilstorm-stormcad-pondpack-flowmaster-culvertmaster Secondary Option: Creating new shortcut to 32-bit version of the product If you cannot upgrade, the next best workaround is as follows: 1) Open My Computer and navigate to installation directory, typically similar to C:\Program Files (x86)\Bentley\(product name) 2) Open the .exe file (SewerGEMS.exe for SewerGEMS.) This is 32-bit version. 3) If the program opens without any error, right-click on the .exe and click on Copy. 4) Go to the Desktop, right-click, and select "Paste shortcut". Another variation of the above is described below: 1) Locate the programs icon on your desktop and right click on it. 2) Select "Properties" and click on the Shortcut tab. 3) Locate the target file path the program is pointing to and change it from: "C:\Program Files (x86)\Bentley\ \x64\ .exe" to "C:\Program Files (x86)\Bentley\ \ .exe" . All you are doing is removing the "/x64" from the file path so the icon now points to the 32 bit executable. If 32-bit version of the Haestad product could not open from the program files directory, try reinstalling it. If you must use the 64-bit version of your Haestad product (such as for integrating with the 64-bit version of AutoCAD), then this workaround will not work. Other Options Also, you have the following other options, the above steps are not feasible: 1) Upgrade to the SELECTseries 4 version of the product. A SELECTseries 4 release of all Water, Storm, and Sewer products is now available. This is option is highly recommended since the SELECTseries 4 release of the products will install as a 64-bit application on any 64-bit Windows machine. 2) Uninstall 32-bit Office 3) Upgrade to 64-bit Office 4) Install the 64-bit version on a Virtual Machine (such as Windows 7's "XP Mode") 5) Try forcing the Haestad product installer to only install the 32-bit version. Details can be seen here . This option won’t work if you need the 64-bit version for some reason, such as for AutoCAD integration. 6) Try uninstalling the 64-bit Access Database Engine, then change the Haestad product shortcuts to point to the 32-bit version (the .exe under the root folder, not the x64 folder). Again, this won’t help if you need to integrate with 64-bit AutoCAD. 7) Try uninstalling Microsoft Office completely (including the 32-bit Access DB engine), then reinstall the Haestad product, then reinstall Office. The conflict happens when the 64-bit MS Access database engine is installed second, so this may work. IMPORTANT: this workaround is not tested so we cannot guarantee it will work. See Also Sometimes the error could be occurring because of unregistered DAO. Please see the link below: http://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/error-message-when-opening-up-watergems-watercad-hammer-sewergems-civilstorm-stormcad-pondpack-flowmaster-culvertmaster.aspx
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Forum Post: RE: Leakage Detection
Since Darwin is simply finding emitter coefficients that cause the model results to match field observations, it doesn't know anything about the type of break, only the amount of flow leaving it at the given pressure. Different types of leaks could all potentially have the same emitter coefficient - for example a small, long crack vs. a larger circular crack vs a loose joint, etc. So, my initial thought is that, from a practical standpoint, you would do a few runs in Darwin to find leakage "hotspots", then perhaps perform an inspection of these areas to identify the type of leak and what may need to be done to repair it.
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Forum Post: RE: Message ID 40005 "Network Unbalanced".
Hello Jaclyn, Try increasing the number of trials in the calculation options. To do this, open the calculation options from the Analysis menu. Double-click the active calculation option to view the properties. Find the Trials property and increase the value. For instance, if this is set to 40, change it too 100. Sometimes a few more trials are needed for some models. If that doesn't help, check the properties of the GPV. Make sure the curve is accurate and make sure that the orientation is correct (basically that the correct pipe is the downstream pipe). The following link has other steps that you can try as well: communities.bentley.com/.../8769.troubleshooting-network-unbalanced-or-cannot-solve-network-hydraulic-equations . If none of this helps, we will need to see a copy of the model files. The following link has information on sending the model to us: communities.bentley.com/.../32255.sharing-hydraulic-model-files-on-the-haestad-forum . If you upload the model to Sharefile, please post here with the name of the file so that we know it is available. Regards, Scott
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Wiki Page: Top filled tank head and flow values go up from zero
Product(s): Bentley WaterGEMS, WaterCAD Version(s): 08.11.04.50 +, 10.XX.XX.XX Problem I have a tank that fills from the top in my model. When I run the system head curve for the model the results seem to be wrong because the head and flow values go straight up from the 0 point. Why is this and how can I fix it? Problem ID#: 90678 Solution In the background of the software the top fill tank is actually modelled (from upstream to downstream) as a PSV going to a short pipe with a large diameter then going to the tank. The PSV is set to an active status with the hydraulic grade set equal to the base elevation of the tank plus the level (calculated) result field. The significance of this is better understood after understanding how the system head curve works in the background. The system head curve is calculated by removing the pump from the model and placing junctions at the upstream and downstream ends of the pipe. The junctions then get iteratively assigned a positive demand on the downstream junction and a negative demand on the upstream junction until the system head curve for the network is created. The tank head and flow values going directly up from zero occurs because at the 0 flow condition the PSV is set to a closed status and there is no headloss the PSV has to induce. Since the PSV is closed the network is in a disconnected stated and cannot be solved because there is no boundary element, which would normally be the tank which provides the hydraulic grade line. The network, therefore, essentially ends at the PSV because of the closed state and the results being displayed in in the millions is the output when a network is in a disconnected (unsolvable) state. To fix the system head curve in order to view it use the steps below: 1) Run the system head curve to open the graph 2) Click on the chart icon located next to the green compute icon. This will open the chart options. 3) Locate the Axes tab and click it. Make sure the Left Axix is highlighted in blue on the left side of this dialog. 4) Click the "Change..." button on the minimum tab and set the value to 0 and click OK to close this window. 5) Click on the maximum tab and click the change button. Set the value of it to 100 and click OK to close this window. 6) ON the scales tab just above the minimum and maximum tabs change the increment to something like 5 and click Ok to close the window. Once you've done this you should see your system head curve. There has been a enhancement request submitted to fix the system head curve feature for top fill tanks and other cases where networks have a disconnect. See Also Understanding System Head curves in WaterCAD, WaterGEMS, and SewerCAD
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Wiki Page: Using Extreme Flow Factors
Applies To Product(s): Bentley SewerCAD, Bentley SewerGEMS Version(s): 10.00.xx.xx, 08.11.xx.xx Area: Modeling Original Author: Scott Kampa, Bentley Technical Support Group Background Extreme flow factors are generally used for computing peak discharges, and therefore are typically referred to as peaking factors or peaking equations. However, since they can also be used to compute minimum discharges, the term extreme flow factor is more accurate and will be used throughout the program and documentation. This article applies to Bentley SewerCAD as well as Bentley SewerGEMS, when the numerical solver is set to "GVF-Convex". Steps to Accomplish Loading in SewerCAD is done through the Sanitary Load Control Center. Patterns can be applied are generally used for Extended Period Simulations (EPS). With Steady State runs using Unit Loading, a user will want to look at the peak flow to get a conservative analysis of system. That is where Extreme Flow Factors come in. To begin, you need to set up the Extreme Flow. To do this, go to Components > Extreme Flow Setups. To create a new Extreme Flow Setup, click the New button in the upper left. When you do this, a row will be added for each Unit Load associated with the model. You have the option to use a given load by placing a check box in the Use column. The other columns include the Extreme Flow Method and a couple of multipler options. There are a couple of options available to the extreme flow method. If you leave the Extreme Flow Method column set to "None" you can enter a constant. This is the multipler that will be used on the loading derive from the Unit Load in the Sanitary Loading Control Center. However, you also have the ability to use one of several Extreme Flow Methods. To create these, go to Components > Extreme Flows, or click the ellipsis button in the Extreme Flow Method cell in the Extreme Flow Setups dialog. Click the New button and choose from one of the four methods available. If you choose the Table methods, you will have to manually enter the base load value or the population and the extreme flow factor associated with it. Note that the keyboard shortcuts work with this table, so if you have the table values in a format like Excel, you can copy and paste the data into the table. If you choose the Equation methods, you will need to enter the coefficients for the equation. For convenience, the equation used to calculate the Extreme Flow Factor can be found at the bottom of the Extreme Flows dialog. NOTE: When choosing the method, be sure that it matches with your unit loads. For instance, if your unit loading is based on population, you should use a population-based extreme flow factor method. Once you have created the Extreme Flows, you must apply it to the Unit Load. Return to the Extreme Flow Setups dialog. In the Extreme Flow Method, select the table- or equation-based method you wish to use. If there is an extra adjustment you need to apply, you can enter a value for the Adjustment Multiplier. If you do not need to apply any extra adjustment, simply set the values in this column on 1.0. Now that the Extreme Flow Setups are completed, you need to apply them to the Calculation Option of the model. Go to Analysis > Calculation Options and double-click the active calculation option to view the properties. Find the properties field Extreme Flow Setup and set this to the Extreme Flow Setup you wish to use. Now when you compute the model, the extreme flow setup will be applied to the loading of an element. Please note : Extreme flow setups are only used for steady state simulations. They are not used for EPS runs. This is because a peak flow analysis is only valid in a steady state (snapshot of time). See Also Troubleshooting Extreme Flow Results with Count based Unit loads
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Wiki Page: User Notification: "GPV curve is undefined"
Applies To Product(s): Bentley WaterGEMS, Bentley WaterCAD, Bentley HAMMER Version(s): 08.11.XX.XX Area: Output and Reporting Original Author: Craig Calvin, Bentley Technical Support Group Problem When computing the model the following user notification appears: "GPV curve is undefined" Background The General Purpose Valve allows simulation of unique headloss/flow relationships using a headloss curve relationship that is always applied. Solution Click on the input field for General Purpose Valve Headloss Curve. Click the down arrow and then select "Edit GPV Headloss Curves". Enter a GPV headloss curve. See Also WaterGEMS Help Article: "Valves", section "Defining Headloss Curves for GPVs".
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Wiki Page: Zero flow at all the junctions in the Fire flow Available column
Applies To Product(s): Bentley WaterGEMS, Bentley WaterCAD Version(s): 08.11.xx.xx Area: Output and Reporting Original Author: Nancy Mahmoud, Bentley Technical Support Group Problem After a Fire Flow analysis run, I get zero flow at all the junctions in the Fire flow Available column. Area: Modeling, Problem ID#: 37211 Solution This most often occurs when either the residual pressure or zone pressure is less than the minimum pressure constraints included in the Fire Flow alternative. Both the residual pressure and zone pressure lower limit must be satisfied before the fire flow can be applied. This can occur for elements near a tank or reservoir, or on the suction side of a pump. If the issue is occurring because of a zone pressure, one possible solution is to move junctions like this to a different zone. In some cases, other constraints may be used as well. The automated fire flow has the option to assign pressure constraints for the whole system, as well as velocity constraints. Go to your Fire Flow alternative to confirm if you are using these. If so, also check the fields "Pressure (Calculated System Lower Limit)" and "Velocity of Maximum Pipe". See Also Understanding Automated Fire Flow Results
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Forum Post: RE: Darwin Designer
There are really several levels of answers to your question. 1. Darwin Designer uses Genetic Algorithms (GA) to find a solution from the overall solution space. You may not be letting it run long enough and if you let it run longer, you may get better solutions. 2. GA does not guarantee global optimality. That is why experts in GA encourage users to make multiple runs with just slightly different data. In encourage you to do some reading on GA. 3. The solutions from any optimization, including GA, are only as good as the data you provide. Are you 100% certain that your cost functions, demand forecasts, scenarios to consider, component failures, etc. are perfectly accurate? At Bentley we often use the term "optioneering" instead of optimization because what things like Darwin do is enable you to screen many solutions/options very quickly. No optimization can give you the best solution always. If someone tells you they can, don't believe them. An optimal solution is the solution that minimizes the objective function subject to the constraints. You need to provide the data that goes into the object function and the constraints. How do you define the "best" solution? You as an engineer still need to make decisions, account for that uncertainty in an imperfect world.
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Wiki Page: How much pressure is available exactly at the total needed fire flow? Do I need to set the upper limit equal to the needed fire flow?
Applies To Product(s): Bentley WaterGEMS, Bentley WaterCAD Version(s): 08.11.XX.XX Original Author: Mark Pachlhofer, Bentley Technical Support Group Problem What if I want to see how much pressure is available exactly at the total needed fire flow? Do I need to set the upper limit equal to the needed fire flow? Solution No, you don't. Click the yellow edit button at the top of the fire flow flextable and add the fields "Pressure (Calculated residual @ total flow needed)" and "Pressure (Calculated zone lower limit @ total flow needed)". These fields display the exact residual pressures at the total needed fire flow, instead of showing at the total available.
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Forum Post: RE: Darwin Designer
Yes, Darwin will often get you a very good initial design (dependent on how well the Designer run was configured), after which engineering judgment will need to be used. There are some further tips on this in the Help topic called "Advanced Darwin Designer Tips" and at the bottom of this wiki article: Using Darwin Designer
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Wiki Page: What is the upsurge ratio?
Applies To Product(s): Bentley HAMMER Version(s): 08.11.04.57 +, 10.XX.XX.XX Area: Output and Reporting Original Author: Jesse Dringoli, Bentley Technical Support Group Problem What is the upsurge ratio? Solution The upsurge ratio is the maximum transient pressure divided by the initial conditions pressure. 1.0 would mean that the maximum pressure is the same as steady state. The higher the number the higher the upsurge, relative to the steady state pressure. It's basically a reference value to see where the highest surges are occurring.
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Wiki Page: Modeling large amounts of vapor or air volume
Applies To Product(s): Bentley HAMMER Version(s): 08.11.XX.XX Area: Output and Reporting Original Author: Jesse Dringoli, Bentley Technical Support Group Problem Is there a rule of thumb for deciding if the volume of vapor or number of collapses is within the scope of what can accurately be simulated in HAMMER? I'm seeing large vapor pockets forming - how do I know if HAMMER can accurately simulate this? Problem ID#: 72094 Solution The literature on the Discrete Vapor Cavity Model references a rule of thumb: "the ratio of maximum cavity size to reach volume should stay below 10%". Given that HAMMER uses the Discrete vapor cavity model and that the literature supports this 10% rule of thumb, this is a reasonable rule if you are comfortable with it. However, generally speaking it is probably best to avoid recommending any rule of thumb with regards to acceptable vapor pocket size or number of collapses. Due to the chaotic behaviour of liquids in a cavitating system, it is very difficult to measure the high-frequency pressure spikes with any kind of accuracy; moreover, operators of such systems are generally reluctant to subject their pipe networks to these potentially damaging conditions. Meaning, the presence of large vapor pockets or multiple collapses usually tells you that you need to add some protection strategy. Unfortunately, it is equally hard to formulate rules of thumb for determining acceptable sizes for vapor pockets in the context of a HAMMER run. The 10% rule of thumb referenced above seems quite conservative, but we just don't have enough physical evidence or case studies to say that it will always be ok. Therefore, we ultimately concluded that you'll need to apply your own judgement in this case. It is OK to push the software to its limits, but we feel that if you do that, you'll need to assume the risk. Note that in the presence of multiple vapor pockets the Wave Speed Reduction Factor may be appropriate. In real systems it is understood that entrained air is released at low pressures slightly above vapor pressure. This phenomenon has the effect of reducing the wave speed during the period of time that the pressure is low. A reduced wave speed will normally mitigate the severity of upsurges upon collapse of cavities versus the basic cavitation model (full wave speed). By neglecting the decline in wave speed (the default factor of 1.0), the extreme pressures generated by vapor pocket collapses are conservatively overestimated. For more information on this, please see the help topic for wave speed reduction. Also note that the "reach volume" referenced in this rule-of-thumb would be the full volume of the pipe in which the pocket formed. Find the pipe length (consider including any "length adjustment" if that is significant, which you can view in the pipe flextable) and multiply by the pipe cross sectional area to get the reach volume. The "Vapor Volume (Maximum Transient)" or "Air Volume (Maximum Transient)" fields in the Transient results section of the properties of pipes should give the max volume in that reach. So you can typically divide this number by the reach volume. If a vapor pocket forms at a high point at the intersection of two pipes, or in the case of an air valve, you would need to treat it as two sepearate reaches/checks since there may be vapour/air in each pipe (on each side of the high point.) The one problem with using the "Vapor Volume (Maximum Transient)" or "Air Volume (Maximum Transient)" fields is they won't tell you much if you have multiple vapor/air pockets along a pipe. If that appears to be the case after inspecting the profiles it may be necessary to check the "*** LIST OF SORTED VAPOUR AND AIR POCKETS ***" section in the Transient Summary report (Reports > Transient Analysis Reports > Transient Analysis Output Log) to see the max vapor/air volumes along the pipe. You may wish to add these volumes up and check that they don't exceed the 10% rule of thumb (it is possible that these maximums don't all occur at the same time, but we don't provide results of volume versus time at interior points along a pipe).
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