VisualFlonet. User Guide

Transcription

1 VisualFlonet User Guide

2 VisualFlonet User Guide NOTICE The information in this document is subject to change without notice and should not be construed as a commitment by ABB. ABB assumes no responsibility for any errors that may appear in this document. In no event shall ABB be liable for direct, indirect, special, incidental or consequential damages of any nature or kind arising from the use of this document, nor shall ABB be liable for incidental or consequential damages arising from use of any software or hardware described in this document. This document and parts thereof must not be reproduced or copied without written permission from ABB, and the contents thereof must not be imparted to a third party nor used for any unauthorized purpose. The software described in this document is furnished under a license and may be used, copied, or disclosed only in accordance with the terms of such license. TRADEMARKS Microsoft, Windows, Excel and Visio are either registered trademarks or trademarks of Microsoft Corporation in the United States and/or other countries. All other trademarks are the property of their respective owners. COPYRIGHT Copyright ABB Limited. All Rights Reserved. Document: VisualFlonet User Guide Revision: 1.1 Published: September 2012 Software: VisualFlonet Version: SUPPORT INFORMATION This program is developed, maintained and supported by PEL Support Services, ABB. We run a Hotline telephone and service to answer any queries about VisualFlonet. Please let us have any suggestions on how you feel we could improve VisualFlonet. You can contact us by any of the following routes: By Telephone: By Fax: +44 (0) (0) By Post: PEL Support Services ABB Limited. Daresbury Park By pel.support@gb.abb.com Daresbury Warrington Cheshire WA4 4BT United Kingdom. ii

3 Contents Preface... 1 About this guide... 1 Who should read this guide... 1 What is in this guide... 1 How this guide is structured... 1 Conventions... 2 Chapter 1 Introduction... 3 Introduction to VisualFlonet... 3 VisualFlonet network properties... 3 VisualFlonet network configurations... 4 VisualFlonet calculation assumptions... 4 Overview of PEL... 5 Programs for fluid flow... 5 Chapter 2 Getting started... 7 Starting VisualFlonet... 7 Starting VisualFlonet with a Visio drawing file... 7 Quitting VisualFlonet... 7 User interface... 8 Accessing VisualFlonet features in Visio Editor (data entry) dialogs... 9 Standard calculator dialogs... 9 User assistance Online help Online documentation PEL Support Services Chapter 3 VisualFlonet Quick Tour Chapter 4 VisualFlonet basics Calculation overview Loading a CAD drawing Loading a drawing as a template Showing or hiding the CAD drawing layer Creating a VisualFlonet piping diagram Entering and editing data fields Entering data fields Converting units and values Saving your VisualFlonet diagram Chapter 5 Running a calculation Setting the calculation mode Entering node conditions for a flow calculation Entering data for all the nodes in the system Entering data for an individual inlet or outlet node Entering data for an individual internal node iii

4 VisualFlonet User Guide Entering node conditions for a pressure calculation Entering data for all the nodes in the system Entering data for an individual inlet or outlet node Entering data for an individual internal node Entering data for pipes Entering data for all the pipes in the system Entering data for an individual pipe Entering data for pumps Entering data for all pumps in the system Entering data for an individual pump Entering physical properties data Running the calculation and viewing the results Viewing pump results Viewing the results manually Saving and printing your results Printing results Saving results Viewing results data on your network diagram Finding items on a large network diagram Chapter 6 Standard calculators PPDS calculator Saving the current stream Pipe inner diameter calculator Pipe roughness calculator K-value calculator Adding tee junctions Adding bends Adding valves Adding expansions/contractions Adding User Defined (Process Equipment) items Chapter 7 VisualFlonet options Naming the calculation Changing units Creating your own set of units Changing decimal places Changing calculation options Changing iteration limits Changing applications options Quick reference Glossary Index iv

5 Preface About this guide Welcome to VisualFlonet, the calculation tool for fluid flow in networks. One of a suite of fluid flow programs for process engineers, VisualFlonet calculates the flows and pressure drops throughout your gas or liquid network. This guide is designed to assist you in becoming quickly familiar with the capabilities of VisualFlonet, its interface and how the program is used. Who should read this guide This guide is written for users of VisualFlonet to help you take full advantage of its calculation tools. If you are new to this product, we recommend that you first read The 60 Second Guide to VisualFlonet. The guide assumes you are familiar with the Windows operating system. If you are new to Windows, you can find help, tutorials and support information by clicking Start > Help and Support. What is in this guide The guide contains descriptions and step-by-step instructions for all the tasks involved in using VisualFlonet. How this guide is structured The chapters are organised as follows: 1. Introduction Introduces the product, outlining the database. 2. Getting started Shows how to start VisualFlonet, introducing the user interface for the application. 3. VisualFlonet Quick Tour Tutorial for a typical session using VisualFlonet, emphasising the commonly used features. 4. VisualFlonet basics Describes the overall process for running a calculation, shows how to create a basic piping diagram and how to enter data. 5. Running a calculation Shows how to enter data and calculate results for your piping diagram in VisualFlonet. 6. Standard Calculators Describes the standard PEL piping calculators. 1

6 VisualFlonet User Guide 7. VisualFlonet options Describes the various option settings in VisualFlonet. The guide also includes a quick reference section and a glossary. Conventions The following typographical conventions are used in this guide: Convention Bold Italic Monospace Monospace oblique Description To help with procedures, items that you click, select, or view may appear with the bold format (buttons, options, and window titles, for example). Proper names (software products, for example) and titles appear in the italic format. Represents any text that appears on the computer screen or text that you should type. It is also used for filenames, functions, and examples. Represents variable text where you would type in a specific value. > The chevron indicates a menu option in a procedure. For example, click File > Open, means on the File menu, click Open. 2

7 Chapter 1 Introduction Introduction to VisualFlonet VisualFlonet brings speed and reliability to the process of modelling liquid and gas distribution networks. The network is drawn with Microsoft Visio using a specially designed template for specifying nodes, pumps and pipes in the layout. It calculates single phase liquid or vapour flow rates and pressure drops in piping systems. These may consist or piping loops or be "tree-like" in form. Pumps and nonreturn valves can be included in the system. VisualFlonet performs two types of calculation: Pressure mode. Given the flows at the input and output nodes and one pressure in the system, VisualFlonet calculates all other flows and pressures. Flow mode. Given the pressures and flow direction at the input and output nodes, VisualFlonet calculates all the other flows and pressures. In this mode expert users can also use it to calculate systems given other valid combinations of flowrates and pressures. This guide explains how to use VisualFlonet to set up a VisualFlonet model. It provides an example of how to use the capabilities of the program while pointing out suggestions for best practice in both constructing and validating a model. VisualFlonet network properties A VisualFlonet network can contain: Compressible or incompressible fluids. Loops and tree-like structures. Pumps and non-return valves. Turbulent, transitional and laminar flow regimes. Pipes of any dimension and reasonable roughness. Pressure loss data due to fittings. Moderate temperature variations. Gravity heads due to sloping pipes. 3

8 VisualFlonet User Guide VisualFlonet network configurations A VisualFlonet network consists of nodes and pipes. Nodes are points where pipes begin or end: pipes run between nodes. In the VisualFlonet stencil, nodes are represented by red circles. As you add nodes or pumps to the drawing grid, straight pipes appear as the connecting lines between them. The following information is required to specify a VisualFlonet network: A name, length, bore, roughness, and mean temperature for each pipe. A label and height for each node. Details of pressure losses due to fittings in the form of K-values. Details of the capability of any pumps in the system in the form of Head (m) versus Flow (m 3 /s) characteristics. The pump curve can be defined using between 1 and 20 points (see the curve in the Quick tour for an example). Density and viscosity data for the fluid in the network (a value for Cp/Cv is required for gases). A datum pressure at some point in the network. VisualFlonet calculation assumptions The following assumptions are made in VisualFlonet calculations: 1) The flow/pressure equations in VisualFlonet work on an isothermal basis. 2) VisualFlonet calculations are only valid for low Mach numbers, that is, around 0.2 Ma. At high Mach numbers the internal energy changes become important and the isothermal model is less valid. 3) VisualFlonet fittings are modelled using a single K-value. This represents all the fittings and no provision is made for the order in which fittings occur. 4) The K-value calculator allows detailed information about the fittings in a pipe to be stored although a single value is used for calculations. The calculator stores the information that the K-value comprises, for example, three tight radius 90 bends, one long radius 180 bend and a 4 inch NB circular port plug valve. 5) The network description is not directed (unlike the VisualAdrian program). This means that, even though a particular pipe starts at node A and ends at node B, it does not follow that the fluid can only flow in the direction of A to B. 4

9 Overview of PEL Chapter 1 Introduction PEL is a collection of tools to enable process engineers to carry out their day-to-day tasks more quickly and reliably. The software includes purpose built programs to generate datasheets, perform engineering calculations of liquid and / or gas flow, investigate physical properties and create fault tree diagrams. Designed by engineers for engineers, the tools are intuitive and easy to use. They can be used to work out every day calculations, for troubleshooting issues such as bottlenecks, or when making plant modifications. This low cost solution will enable engineers to design processes more quickly and reliably with up-to-date and permanently available design data. Benefits Allows engineers to be more efficient and productive. With fewer manual calculations to do, tasks are carried out quicker; Improves QA and standardises procedures, through everyone using same set of data and calculations; Human errors in calculations are reduced; Improves production as bottlenecks can be identified quickly so a solution can be sought; Allows operators to get the best out of their existing assets by carrying out modifications rather than designing new ones. Programs for fluid flow VisualFlonet is one of a suite of fluid flow applications built on the drawing functionality of Microsoft Visio. Together with the calculations provided by PEW, these Visual applications allow you to quickly and reliably calculate the correct size of every part of pipelines, equipment and pressure relief systems. VisualFlonet for fluid flow in networks VisualFlonet calculates the flows and pressure drops throughout your gas or liquid network. 5

10 VisualFlonet User Guide VisualAdrian for pressure relief VisualAdrian calculates flows and pressures for high velocity, compressible gases allowing the capacity of relief streams and sizing of associated equipment to be assessed. VisualPiper for two-phase fluid flow VisualPiper calculates the pressure change or flowrate of a liquid, two-phase mixture, or gas through an unbranched closed conduit system. PEW PEW is a collection of validated chemical engineering calculations relating to fluid flow, heat transfer, mixing, and vessel calibration. 6

11 Chapter 2 Getting started This chapter shows you how to start VisualFlonet and introduces the user interface for the application. Starting VisualFlonet The most common way of starting VisualFlonet is from the Windows Start menu, but you can also run it from a desktop shortcut. VisualFlonet uses Microsoft Visio as a drawing tool to create a diagram of your piping network. To start VisualFlonet from the Start menu: Click Start > All Programs > PEL > VisualFlonet > VisualFlonet. If using the classic Start menu or earlier versions of Windows, click Start > Programs... The application launches Microsoft Visio using the VisualFlonet template. Starting VisualFlonet with a Visio drawing file Once you have saved your piping network diagram as a Visio drawing file, you can start VisualFlonet by double-clicking the drawing file in Windows Explorer, or in the most recent versions of Windows from the Documents Library. To start VisualFlonet with a Visio drawing file: Double-click your Visio drawing file in Windows Explorer or your Documents Library. Note In more recent versions of Windows if you point at VisualFlonet in the Start menu, you can select your drawing file from the list of recent files. You can also open a recent file from the File menu in Visio. Quitting VisualFlonet To quit VisualFlonet: 1) Do one of: On the File menu, click Exit. Click the Close (X) button. If you haven't saved any data on the current drawing, a message asks if you want to save your changes. 2) Click Save. 7

12 VisualFlonet User Guide User interface Once you have started VisualFlonet and Microsoft Visio has opened, you see the following, or similar, user interface. As VisualFlonet is installed as an Add-In for Microsoft Visio, the look of the user interface will depend on which version of Visio is installed on your computer. This is how it looks in Visio 2007 (or earlier). The following main features are apparent: Menu bar. The standard Microsoft Visio menu contains an added menu for VisualFlonet. Tool bar. Under the Visio toolbar (or toolbars) you see an added toolbar containing buttons for accessing the VisualFlonet tools. Move the mouse pointer over a button to see its name. Shapes window. This standard Microsoft Visio feature shows the loaded VisualFlonet stencil, which contains the various shapes you can drag onto the drawing page. Visio drawing page. The main area of the screen contains your piping networkdiagram. You can view this either as a floating window or maximised (as shown above). 8

13 Chapter 2 Getting started Accessing VisualFlonet features in Visio 2010 If you have Microsoft Office Visio 2010 installed on your computer, this uses the ribbon interface introduced for most of the other Office applications in Microsoft Office VisualFlonet opens Visio with an extra Add-Ins tab on the ribbon. This contains the VisualFlonet menu and the VisualFlonet toolbar. The functions are the same whether accessed from the ribbon or from the menu and toolbar. Editor (data entry) dialogs The various editor dialogs let you add or change the modelling data for your piping networkdiagram. The dialogs are called up from either the commands on the VisualFlonet menu or by clicking the buttons on the toolbar. The topological data (that is the various nodes, pipes and pumps) are automatically picked up from the Visio diagram. You use the forms to enter physical data, such as pipe lengths, and conditions, such as temperature and pressures. Many of the dialogs let you enter values for all the nodes, pipes and pumps on your diagram: other dialogs let you enter or change values for a single component. These are called either by the Edit command on the right-click context menu or by doubleclicking the component. Standard calculator dialogs Secondary to the editor dialogs are a number of standard piping calculator dialogs. These are standard tools provided in all the PEL programs to complete various piping 9

14 VisualFlonet User Guide parameters. The dialogs are generally called by right-clicking the field that will contain the value in the editor dialog. The editor dialogs for individual components have one or more buttons for calling the calculator next to the appropriate field. The calculator then returns a single resultant value to the field. User assistance There are standard calculators for pipe inner diameters, pipe roughness and for calculating the fittings loss (k-value). VisualFlonet has the following forms of user assistance: Online help Online documentation PEL Support Services Online help VisualFlonet has an integrated online help system, which provides clear reference information and step-by-step instructions for tasks. This is an online help version of this guide. To open the help system: On the VisualFlonet menu, click Help User Guide. The help opens in a separate window. 10

15 Chapter 2 Getting started Online documentation Documentation is provided for PEL products on the website. The documents are provided as PDF files for you to download and print. These include: 60 second guides Online user guides PEL Support Services This program is developed, maintained and supported by PEL Support Services, ABB. We run a Hotline telephone and service to answer any queries about VisualFlonet. Please let us have any suggestions on how you feel we could improve VisualFlonet. You can contact us by any of the following routes: By Telephone: +44 (0) By Fax: +44 (0) By By Post: pel.support@gb.abb.com PEL Support Services ABB Limited. Daresbury Park Daresbury Warrington Cheshire WA4 4BT United Kingdom. 11

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17 Head [m] Chapter 3 VisualFlonet Quick Tour This short self-paced tutorial will show you how to begin to use VisualFlonet to calculate pressure drops and flow rates for liquids or gases in piping networks. Within seconds from now you will have learned how to use VisualFlonet to calculate the pressures and flowrates in the network given the inlet and exit pressures shown on the right: Flow diagram N1 P1 1.0 bar pmp1 P2 N3 P3 P5 N2 P4 N4 0.4 bar 0.6 bar N5 P6 N6 Pipe data Pump curve Pipe Length Bore Fittings Temp 26 P1 50 m 2 4 x 90 bend, radius 500mm 40 C 25 P2 50 m 2 1 x T-junction type 2 40 C 24 P3 50 m 1 1 x 1 globe valve cast 40 C 23 P4 30 m x 90 bend, radius 300mm 30 C 22 P5 50 m 1 1 x 1 globe valve forged 40 C 21 P6 30 m x T-junction type 3 30 C All pipes are Schedule 40, mild steel and slightly corroded Flow [m3/s] Starting VisualFlonet 1) Click Start > All Programs > PEL > VisualFlonet > VisualFlonet. Click Enable Macros twice and the VisualFlonet splash screen appears briefly. The first thing to do is to specify we want to do a Flow Calculation from the pressures that we have been given. 2) Click the Options button on the VisualFlonet toolbar. On the Project tab under Calculation Mode, click Flow. While the VisualFlonet Options is open, let s check that automatic naming of nodes, pipes and pumps is switched on, and auto-connect is the default. 3) Click the Application tab. Clear the Prompt for Object Name on Drop check box, and select Switch on auto-connect by default. Then click OK. Now we are ready to draw the network. 4) Make sure the Connector tool on the Visio standard toolbar is selected. 5) Using the flow diagram, drag node N1, pump pmp1, and nodes N2, N3 and N4. VisualFlonet connects the items and automatically names them. Before adding node N5, click node N2 to make sure node N5 is connected to N2 and not N4. Complete the drawing by adding N6. That was easy wasn t it? Next we need to enter the process data. Let s begin by adding the inlet and outlet pressures using the Node Conditions Editor 13

18 VisualFlonet User Guide 6) Click the Edit Nodes button on the toolbar to open the Edit Nodes dialog. Enter the pressures as defined in the flow diagram: 1 bar at N1, 0.4 bar at N4, and 0.6 bar at N6. In the Height column, type 5 for the height above the datum point for each of the nodes N3, N4, N5 and N6. Click OK to save the data. The Edit Pipes dialog lets you specify the pipe data. VisualFlonet add the connections automatically. You can rename pipes but you can t add or delete them. Let s start by adding the data for the first pipe and find out about the various tools for helping us. There are calculators for Pipe Inner Diameters, Pipe Roughness, and K-Values. 7) Click the Edit Pipes button on the toolbar to open the Edit Pipes dialog. Click the Length cell for P1 and enter 50. Click the Inner Diameter cell for P1, right-click and click Pipe Inner Diameter Calculator. When the calculator appears select a 2 Schedule 40 / STD / 40S pipe and click OK to return the result to the cell. Click the Roughness cell, right-click and click Roughness Calculator. Select Mild Steel (slightly corroded) and click OK to return the value to the cell. Click the Fittings Loss Coefficient cell, right-click and click K-Value Calculator. When the calculator opens, click the Bends tab, type 500 in the radius box and 4 in the Quantity box and click Add. Click the Summary tab to see the K-Value summary and then click OK to return the result to the cell. Click the Temperature cell and type in 40. That s the first pipe done. Now add the data for the other five pipes using the information in the above table. Try using the special Cut & Paste commands on the shortcut menu to paste the Roughness into all the pipe roughness cells. Remember to double-click the valves in the K-Value Calculator to show the required options. Why not try adding the data for one of the pipes by doubleclicking the pipe in the drawing; you will still have access to all the calculators. We ve entered a lot of data now so it s a good idea to save the drawing at this stage. 8) Click the Save button on the toolbar and save the data in VisualFlonet.VSD on the C:\ drive Next we need to enter the Pump characteristics. We could use the Pump Editor on the VisualFlonet toolbar but there is only one pump so we will use the editor for a single pump. 9) Double-click the pump pmp1 in the drawing to open the Edit Pump dialog. Click the Characteristic Pump Curve tab and set the Number of points to 3. Using the graph above, type in the following three pairs of values for Head and Flow: 25.0, , , Finally, we need to add the physical properties. To do this we need the Physical Properties Editor dialog. 10) Click the Physical Properties button on the VisualFlonet toolbar to display the Physical Properties dialog. Select Liquid as the Fluid Type then enter the following 3 pairs of temperatures and pressures: 0.1bar & 10 C, 1bar & 20 C, 2bar & 40 C. Next click Calculate to calculate liquid density and viscosity. The Physical Property Calculator opens. 11) First select the components. (If some are already present, click Clear Worksheet to remove them.) Click Add Component and type W in the Search for Name box. Four components are found beginning with the letter W. Click Water and then click Add to Stream. Next, delete W from the Search box and type in ET for Ethanol. Select Ethanol from the results and click Add to Stream then Close. 14

19 Chapter 3 VisualFlonet Quick Tour The last thing we need to do for the physical properties is to specify the composition. You can use the spreadsheet to specify the stream composition, both in terms of moles or mass, and as quantities or fractions. 12) Click the Mass Fraction cell for Water to give it focus. Enter 0.5 for both Ethanol and Water. The Physical Property Calculator updates the spreadsheet. If you wish, the Calculator will also normalise the values if they do not add up to 1. All that s all the input we need to calculate the physical property data so 13) Click Calculate to calculate the liquid densities and viscosities at each of the 3 sets of pressure and temperature. Click OK to close the Physical property calculator and automatically transfer the results back to the Physical Properties Editor. Finally, click OK to close the Physical Properties window That s it for the input data for VisualFlonet. Now we re ready to run the calculation. 14) Click the Calculate button on the VisualFlonet toolbar. The hourglass appears until the calculations are complete when the hourglass disappears and the results appear in the Results window. You will see that the calculated flowrates are 2.55 kg/s at the inlet, and 1.33 kg/s and 1.22 kg/s at the outlets N4 and N6 respectively. And that s it! If you still have some time, try doing a Pressure calculation by specifying the inlet and outlet flows. 15

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21 Chapter 4 VisualFlonet basics This chapter describes the overall process in running a calculation, shows you how to create a basic piping network diagram and tells you how to enter data in VisualFlonet. Calculation overview The overall process in running a VisualFlonet calculation involves creating a piping diagram in Visio, entering data using the various editor dialogs and then clicking the Calculate button on the VisualFlonet toolbar to generate the results. The main steps in the process are as follows: Create the Visio diagram. Drag the various shapes from the stencil to form your piping diagram. See Creating a VisualFlonet piping diagram on page 18. Set Calculation mode. Use the options dialog to set the calculation mode as either Flow mode (default) or Pressure mode. See Setting the calculation mode on page 21. Enter node conditions. For a Flow calculation, you define the pressures at the inlet and outlet nodes, with the direction of flow taken from the diagram topology. For a Pressure calculation, you define the flow rates for the inlet and outlet nodes and one set pressure. See Entering node conditions for a flow calculation on page 22. Enter data for pipes. Enter physical data for each pipe, namely pipe length, inner diameter, roughness and fittings loss coefficient. Use the standard piping calculators to enter these values. Then specify the pipe temperatures. See Entering data for pipes on page 26. Enter data for pumps. For each pump in your system, enter the number of points on the manufacturer s pump curve, specifying the head and flow rate for each point. See Entering data for pumps on page 28. Enter physical properties data. Enter three separate temperature/pressures points to span the operating range of the pipe network. Use the PPDS calculator tool to compute the density and viscosity of the fluid in the network for each of these points. See Entering physical properties data on page 29. Calculate. Click the Calculate button on the toolbar to generate the results for the network. On completion, the results dialog opens automatically. See Running the calculation and viewing the results on page

22 VisualFlonet User Guide View the results. You can also open the results dialog manually. The dialog shows the computed inlet and outlet pressures and flow rates for each pipe and each pump in the network. Commands on the dialog let you print the results or save them as a tab delimited text file that can be input into any spreadsheet program. Loading a CAD drawing VisualFlonet lets you import a sketch or an engineering drawing to use as a template for creating your piping network diagram. The loaded image is held as a separate CAD drawing layer that you can show or hide as needed. Loading a drawing as a template To load a drawing as a template: 1) In the VisualFlonet menu, click Load CAD drawing. 2) Navigate to select the file and click Open. The image appears behind the Visio drawing layer. To replace the drawing image: 1) In the VisualFlonet menu, click Load CAD drawing. A prompt asks you if you want to replace the current CAD layer. 2) Click Yes. 3) Navigate to select the file and click Open. The image appears behind the Visio drawing layer. Showing or hiding the CAD drawing layer To hide the CAD drawing layer: In the VisualFlonet menu, click Toggle CAD layer. The image no longer appears. To show the CAD drawing layer: In the VisualFlonet menu, click Toggle CAD layer again. The image reappears behind the Visio drawing layer. Creating a VisualFlonet piping diagram Basic VisualFlonet diagrams show the primary pieces of your piping system and how those pieces are connected. This article describes how to quickly create a basic VisualFlonet diagram in Microsoft Office Visio. For full information on creating diagrams, press F1 to open the standard Visio Help. To create a piping network diagram: 1) In Visio open a new drawing file. 18

23 Chapter 4 VisualFlonet basics (In Visio 2007, click File > New > New Drawing.) 2) Make sure the Visio Connector tool on the Visio toolbar is selected. 3) Drag the first shape you want from the VisualFlonet stencil onto your drawing page. The shape will be selected in the drawing with selection handles around it. 4) With the shape still selected, drag a second shape onto your drawing page. The second shape is automatically connected to the first shape. 5) Continue to add shapes to complete your diagram. Entering and editing data fields The Editor dialogs contain a grid of small data fields. A few of these will be text fields, but most are for entering numeric values, with or without units. Entering data fields To enter text or a value: 1) Double-click the field you want to change. Type the new text or number and then click on another cell. An alert appears if numeric data is not entered in the correct format. Click OK and correct the entry. 2) Repeat for other fields as required. 3) When you have finished, click OK. Converting units and values The units for any field appear on the dialog. These are defined on the VisualFlonet options dialog. Sometimes the source data to be entered may be in different units. For example, if a pressure is shown in bar, while the source data is in psi. Rather than have to convert the value in another application, you can enter the value with the units and VisualFlonet will do the conversion inline. To convert a value inline: Enter the data in the format: Value <space> units 19

24 VisualFlonet User Guide and then press Enter (or click another field). The value is converted to the units shown on the dialog. Example: For a pressure in bar, entering 50 psi converts to Saving your VisualFlonet diagram When you have completed your VisualFlonet diagram, you will need to save your diagram as a Visio file. When you have added data to the diagram, you will need to save the file again to save the data. To save your diagram in Visio 2007 or earlier: Do one of: Click the Save button on the toolbar. On the File menu, click Save. Press Ctrl+S. To save your diagram in Visio 2010: Do one of: Click the Save button on the Quick Access toolbar. On the File ribbon, click Save. Press Ctrl+S. 20

25 Chapter 5 Running a calculation When you have created your piping network diagram in VisualFlonet, you are ready to enter modelling data to calculate pressure and flow data. Before you enter the data you have to set the calculation mode. This chapter shows you how to set the calculation mode, enter data and calculate the results. It also shows you how to save and print the results and how to view results data on your network diagram. Setting the calculation mode The VisualFlonet Options dialog contains a number of settings for determining how VisualFlonet runs. Most of these settings should only be changed by advanced users. The one option, which is suitable for all users, is setting the Calculation mode. This option determines the conditions data you need to enter. For Flow mode, you enter the inlet and outlet pressures. You can add estimated flowrates, though these are optional. For pressure mode, you enter the inlet and outlet flowrates and a single reference pressure for the system. To set the calculation mode: 1) Do one of: In the VisualFlonet menu, click Options. On the VisualFlonet toolbar click the Options button. The VisualFlonet Options dialog opens. 2) Under Calculation Mode click Flow or Pressure. 3) Click OK. 21

26 VisualFlonet User Guide Entering node conditions for a flow calculation Once you have set the calculation mode you have to define the conditions for all the nodes in the system. You can do this in either of two ways: use a single dialog to enter all the conditions, or double-click each node to define in turn. Entering data for all the nodes in the system The Edit Nodes dialog lets you define conditions for all the nodes in the system. For a Flow calculation, you define the pressures at the inlet and outlet nodes, with the direction of flow taken from the diagram topology. To enter node data: 1) Do one of: In the VisualFlonet menu, click Edit Nodes. On the VisualFlonet toolbar click the Edit Nodes button. The Edit Nodes dialog opens with the calculation mode on the title bar and listing the nodes from your piping diagram. 2) Specify the pressures for each inlet or outlet node. 3) For the Height, enter the height of each node above some known reference point. The best values to use are the elevation levels from the piping isometrics. Note. Remember that ground level may not be constant if using it as a datum. This is especially true with networks spread over a large area. 4) Click OK. Entering data for an individual inlet or outlet node The Edit Node dialog lets you define an individual node in the system.you enter the pressure at the node and the height above a fixed reference point. For an external node, that is a mode with inlet or outlet flow, you can also add an estimated flow in or out of the system. The direction of flow is picked up from the diagram topology. To enter or change node data: 1) Double-click the inlet or outlet node shape in the diagram. The Edit Node dialog opens. 22

27 Chapter 5 Running a calculation 2) Enter or change the Pressure, if required. 3) Enter or change the Height (above some known reference point). The best values to use are the elevation levels from the piping isometrics. 4) Click OK. Entering data for an individual internal node To enter or change node data: 1) Double-click the internal node shape in the diagram. The Edit Node dialog opens. 2) Enter or change the Height (above some known reference point). The best values to use are the elevation levels from the piping isometrics. 3) Click OK. 23

28 VisualFlonet User Guide Entering node conditions for a pressure calculation Once you have set the calculation mode you have to define the conditions for all the nodes in the system. You can do this in either of two ways: use a single dialog to enter all the conditions, or double-click each node to define in turn. Entering data for all the nodes in the system The Edit Nodes dialog lets you define conditions for all the nodes in the system. For a Pressure calculation, you define the flow rates for the inlet and outlet nodes and one set pressure. To enter node data: 1) Do one of: In the VisualFlonet menu, click Edit Nodes. On the VisualFlonet toolbar click the Edit Nodes button. The Edit Nodes dialog opens with the calculation mode on the title bar and listing the nodes from your piping diagram. 2) Specify the Flowrate for each inlet or outlet node. Note The total flowrate into the system must equal the total flowrate out. 3) Specify a single Pressure for one of the nodes. 4) For the Height, enter the height of each node above some known reference point. The best values to use are the elevation levels from the piping isometrics. Note. Remember that ground level may not be constant if using it as a datum. This is especially true with networks spread over a large area. 5) Click OK. Entering data for an individual inlet or outlet node The Edit Node dialog lets you define an individual node in the system.you enter the pressure at the node and the height above a fixed reference point. For an external node, that is a mode with inlet or outlet flow, you can also add an estimated flow in or out of the system. The direction of flow is picked up from the diagram topology. To enter or change node data: 1) Double-click the inlet or outlet node shape in the diagram. 24

29 Chapter 5 Running a calculation The Edit Node dialog opens. 2) Enter or change the Flowrate, if required. 3) Enter or change the Pressure, if required. Only enter one reference pressure. 4) Enter or change the Height (above some known reference point). The best values to use are the elevation levels from the piping isometrics. 5) Click OK. Entering data for an individual internal node To enter or change node data: 1) Double-click the internal node shape in the diagram. The Edit Node dialog opens. 2) Enter or change the Height (above some known reference point). The best values to use are the elevation levels from the piping isometrics. 3) Click OK. 25

30 VisualFlonet User Guide Entering data for pipes Once you have entered the node conditions you have to enter the physical data for each pipe. Like the node data you can enter the data with a single dialog, or doubleclick each pipe to define in turn. Entering data for all the pipes in the system The Edit Pipes dialog lets you enter physical data for all the pipes in the system. The parameters include pipe length, inner diameter, roughness and fittings loss coefficient. Use the standard piping calculators to enter many of these values. Note This dialog is the same for flow and pressure calculations. To enter pipe data: 1) Do one of: In the VisualFlonet menu, click Edit Pipes. On the VisualFlonet toolbar click the Edit Pipes button. The Edit Pipes dialog opens. 2) Enter the Length of each pipe. 3) To specify the Inner Diameter, right-click the field and click Pipe Inner Diameter Calculator to open the calculator. See Pipe inner diameter calculator on page 37. 4) To specify the Roughness, right-click the field and click Roughness Calculator to open the calculator. See Pipe roughness calculator on page 38. 5) To specify a Friction Loss Coefficient (K value), right-click the field and click KValue Calculator to open the calculator. See K-value calculator on page 39. 6) Enter the Temperature. 7) Click OK. 26

31 Chapter 5 Running a calculation Entering data for an individual pipe The Edit Pipe dialog lets you enter or change values for an individual pipe. Note This dialog is the same for flow and pressure calculations. To enter or change pipe data: 1) Do one of: Double-click the connecting line in the diagram. Right-click the connecting line in the diagram and click Edit. The Edit Pipe dialog dialog opens. 2) Enter or change the length of the pipe, if required. 3) To specify the pipe inner diameter, click the button on the right to open the calculator. See Pipe inner diameter calculator on page 37. 4) To specify the pipe roughness, click the button on the right to open the calculator. See Pipe roughness calculator on page 38. 5) To specify a friction loss coefficient, click the button on the right to open the calculator. See K-value calculator on page 39. 6) Enter or change the temperature, if required. 7) Click OK. 27

32 VisualFlonet User Guide Entering data for pumps Once you have entered the pipe data you have to enter the data for each pump. Like the node and pipe data you can enter the data with a single dialog, or double-click each pump to define in turn. Entering data for all pumps in the system The Edit Pumps dialog lets you define all the pumps in the system. For each pump, you enter the number of points on the manufacturer s pump curve and specify the head and flow rate for each point. Note This dialog is the same for flow and pressure calculations. To edit pump data: 1) Do one of: In the VisualFlonet menu, click Edit Pumps. On the VisualFlonet toolbar click the Edit Pumps button. The Edit Pumps dialog opens. 2) In CPC Points, select the number of points on the manufacturer s pump curve. 3) For each point, enter the head and the flow rate. 4) Repeat for each pump. 5) Click OK. 28

33 Chapter 5 Running a calculation Entering data for an individual pump The Edit Pump dialog lets you enter or change values for an individual pump. Note This dialog is the same for flow and pressure calculations. To enter or change pump data: 1) Do one of: Double-click the pump shape in the diagram. Right-click the pump shape in the diagram and click Edit. The Edit Pump dialog dialog opens. 2) Click the Characteristic Pump Curve tab. 3) For Number of Points, select the number of points on the manufacturer s pump curve. 4) For each point, enter the head and the flow rate. 5) Click OK. Entering physical properties data The Physical Properties dialog lets you enter three separate temperature/pressure points to span the operating range of the pipe network. You use the PPDS calculator tool to compute the density and viscosity of the fluid in the network for each of these points. Note This dialog is the same for flow and pressure calculations. 29

34 VisualFlonet User Guide To enter physical properties data: 1) Do one of: In the VisualFlonet menu, click Physical Properties. On the VisualFlonet toolbar click the Physical Properties button. The Physical Properties dialog opens. 2) Enter three different temperatures and three different pressures that span the operating range of the pipe network. 3) Click Calculate to run the PPDS Calculator. The density and viscosity for each pressure/temperature pair are added to the table. 4) Click OK. Running the calculation and viewing the results When you have entered all the data for your calculation you are ready to run the calculation and view your results. To run the calculation: Do one of: On the VisualFlonet toolbar, click the Calculate button. On the VisualFlonet menu, click Calculate. When the calculations are complete, the results appear in the Results dialog. The dialog shows the computed inlet and outlet pressures and flow rates for each pipe and each pump in the network. The Results tab let you see values for pipes, such as inlet and outlet pressure, flowrate and mean velocity of the flow. The Pumps tab shows values for pumps, such as mass / volumetric flowrates and differential head/pressure. Note This dialog is the same for flow and pressure calculations. The toolbar at the top provides options for saving and printing the results and for viewing graphs of the static pressure and mass quality changes along the pipe. 30

35 Chapter 5 Running a calculation Viewing pump results The Pump Details tab shows calculated values (such as mass and volumetric flowrates, density, and differential head/pressure) for all pumps in the network. Viewing the results manually You can also open the results dialog without running the calculation. This opens the Results dialog, showing the last set of calculated results. To view results (without running the calculation): Do one of: On the VisualFlonet toolbar, click the Results button. On the VisualFlonet menu, click Results. The Results dialog opens showing the last run results. Saving and printing your results The Results dialog contains command options to let you print the results or export the results data to a tab delimited text file that can be imported into an Excel spreadsheet. Printing results You can print the results of your calculation on the Results dialog. The full results are sent to the printer, that is the summary information, the conditions for each pipe section and the detailed physical properties of each pipe section. To print the results: 1) On the Results dialog, click the Print button. 2) Choose you printer and click OK. The results are sent to the printer. Saving results You can save the results of your calculation on the Results dialog. The full results are saved, that is the summary information, the conditions for each pipe section and the detailed physical properties of each pipe section. By default, you save the results as a tab delimited file. You can also save the results as an Excel spreadsheet or as an XML or HTML file. 31

36 VisualFlonet User Guide To save the results: 1) On the Results dialog, click the Save button. 2) Enter a name for the file, browse to where you want to save the file and click Save. A message tells you the file has been sucessfully saved. 3) Click OK. Viewing results data on your network diagram Once you have run either a flow or a pressure calculation on your network, you may want to see the pressure and flow data in one or more specific pipes. You can do this graphically on the Visio diagram by opening the Shape Data window. To open the shape data window: 1) In Visio 2007 or earlier, on the View menu click Shape Data Window. In Visio 2010, open the View ribbon and in the Show section click Task Panes and then Shape Data. The Shape Data window opens floating on top of your diagram. 2) Right-click the window and click Dock Window. You can also drag the window to the shape window to dock The window is docked to the Shapes Window above the VisualFlonet stencil. You may want to move the mouse pointer over the edge and drag to adjust the size. 3) Click any pipe or pump in your diagram to see the results data. 32

37 Chapter 5 Running a calculation Finding items on a large network diagram If you are trying to locate a particular node or pipe, for example, on a typically large network diagram you can use the standard Visio Find command. To find an item on a large diagram: 1) In Visio 2007 or earlier, on the Edit menu click Find (or press Ctrl+F). In Visio 2010, in the Edit section of the Home ribbon click Find (or press Ctrl+F). 2) Enter the identifier of the item in the Find what box, for example P102. 3) Select the Shape Name check box and clear Shape Text. This lets you find the shape and not the label. 4) Click Find Next. The identified item is selected in the diagram. 33

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39 Chapter 6 Standard calculators PPDS calculator VisualFlonet contains a number of calculators that are used to complete various process values for you. The PPDS calculator provides extensive physical properties data for fluids, performing process calculations involving this data. The standard piping calculators provide physical data and calculations for standard pipes and fittings. This chapter shows you how to use these calculators. They are common to all of the PEL applications. The PPDS calculator helps you complete physical characteristics (namely the density and viscosity) of the fluid (liquid or gas) in your network. The upper part of the dialog contains a stream composition worksheet, which lets you define the constituent parts of the process stream. Whenever you open the calculator the table always contains the last values used. This lets you run multiple calculations on the same fluid without having to specify or load the stream each time. You can add components to the stream and then specify the molar and/or mass quantities in the stream. To calculate physical characteristics fields: 1) On the Physical Properties dialog, click Calculate. 2) Add the various components, as described in Adding Components on page 36. The molecular weight of each component and the average molecular weight for the stream appear in the Mol Wt column on the worksheet. 35

40 VisualFlonet User Guide If you want to remove a component from the worksheet, click the component name to select the whole row, right-click the row and click Remove Selected Components. 3) Specify the quantities or realtive amounts of each component in one of the other four columns: Molar the molar quantity of each component. Mol Fraction the mole fraction of each component. Mass the mass of each component Mass Fraction the mass fraction of each component The worksheet calculates the values in the other three columns and the totals. If you enter fraction values, you must ensure that they total to 1. If you need to restart the calculation, right-click the worksheet and click Zero All Cells. 4) Click Calculate. The density and viscosity values for each pressure/temperature pair are completed. You can click on any calculated value to see its accuracy. 5) Click OK to return the values to the Physical Properties dialog. To clear all components: Click Clear Worksheet. All of the components are removed from the table. Adding Components To add a component: 1) Click Add Component. The Select Components dialog opens. 2) Click the Databank in the list and start typing a search string. Matching entries appear in the Search Results pane as you type. 3) Select the component you want and click Add to Stream. 36

41 Chapter 6 Standard calculators 4) Add all the components you want and then click Close. Saving the current stream The Files tab lets you save the current stream on the Feeds tab as a file or recall a previously saved stream file. The saved file (.psm) contains the components and the calculated molar/mass quantities, fractions and totals. To save the current stream: 1) Do one of: On the File menu, click Save Stream File. Right click the worksheet and click Save current Feed. 2) Change the file name and location, if required, and click Save. To open a saved stream: 1) On the File menu, click Click Open Stream File. 2) Browse to select the stream file and click Open. The recalled stream now appears on the Feeds tab. Pipe inner diameter calculator This calculator returns a pipe s inner diameter (in mm) based on the standard pipe size and the available pipe schedules for that pipe size. The calculator supports both the American (ANSI/ASME/API) pipe sizes standard, which is in imperial units, and the European (DIN) system which uses metric units. The calculator also derives the external diameter and the wall thickness. The American standard pipe sizes range from 1/8 inch up to 36 inch. The schedules, which give the pipe thickness, range from 5S up to XXS (Double Extra Strong). To calculate a pipe internal diameter: 1) Do one of: 37

42 VisualFlonet User Guide On the Edit Pipes dialog, click the field that is to contain the pipe inner diameter. Right-click the field and click Pipe Inner Diameter. On a component editor dialog, click the button next to the field. 2) Click the required standard in the drop-down list, select the required pipe size in the left pane and then select the schedule in the right pane. The calculated values appear in the three boxes at the bottom of the dialog, with the inner diameter selected for return. 3) Click OK. The inner diameter value is returned to the datasheet field. Pipe roughness calculator This calculator is used to return an absolute roughness value for a pipe s internal surface. A smooth surface such as glass or plastic has a low roughness value, while badly corroded metal or brick has a high roughness. The values are in millimeters. To calculate a pipe roughness: 1) Do one of: On the Edit Pipes dialog, click the field that is to contain the absolute roughness. Right-click the field and click Pipe Roughness. On a component editor dialog, click the button next to the field. 2) Select the required Surface Type in the list and click OK. The absolute roughness value is returned to the datasheet field. 38

43 K-value calculator Chapter 6 Standard calculators The Fittings Loss (K-value) calculator is a multi-stage tool that enables a process engineer to enter details of all the various fittings, such as bends, valves and t- junctions, that contribute to pressure drop in a piping system. The total loss calculation appears on the Summary tab, which is the default view when you call the calculator. To calculate the fittings loss (K-value): 1) Do one of: On the Edit Pipes dialog, click the field that is to contain the fittings loss. Right-click the field and click K Value Calculator. On a component editor dialog, click the button next to the field. 2) Add the various fittings on the other tabs as defined in the following sections. As you add details on a tab, the total loss for that tab appears on the summary tab. 3) If you need to enter any Manual Adjustment, enter the value and add a reason for the adjustment (optional). The manual adjustment field is for entering miscellaneous fittings not covered on the other tabs. You can also use it to manually adjust the model in the validation stage or for studying the effect of changes, such as a control valve position. 4) When you have completed the calculation click OK. The total loss value is returned to the datasheet field. Note As the calculator retains the values last used, you can click OK to save the calculation at any stage and then restart the calculator to continue. 39

44 VisualFlonet User Guide Adding tee junctions The Tee Junctions calculation takes into account any blanked off junctions. This can also be a line where the dead leg is isolated at a valve further downstream. To add tee junctions: 1) On the Fittings Loss Calculator dialog, click the Tee Junctions tab. 2) Click the Tee Junction Type in the list, enter the Quantity and click Add. The items are added to the table at the bottom of the tab, with the loss shown for each addition. The total for all junctions appears on the Summary tab. To delete tee junctions: Select the entry in the table and click Delete. The entry is removed from the calculation. Adding bends Bends are added in a similar way to tee-junctions. To add bends: 1) On the Fittings Loss Calculator dialog, click the Bends tab. 2) Click the Bend Type in the list, enter the Radius (of the bend) and the Diameter (of the pipe), enter the Quantity and click Add. 40

45 Chapter 6 Standard calculators Note You can enter any two of the radius, the diameter and the ratio of the two. If you enter the radius and the diameter, the ratio is calculated. If you enter the ratio and one other parameter, the omitted parameter appears as unspecified. The items are added to the table at the bottom of the tab, with the loss shown for each addition. The total for all bends appears on the Summary tab. To delete bends: Select the entry in the table and click Delete. The entry is removed from the calculation. Adding valves Valves are defined by type and by one or more categories within the type. For example, the Globe Valve type has two categories cast valves and forged valves. To add valves: 1) On the Fittings Loss Calculator dialog, click the Valves tab. 2) Double-click the Valve Type in the list and select the category you want. 3) Click the Pipe Size in the list, enter the Quantity and click Add. The items are added to the table at the bottom of the tab, with the loss shown for each addition. The total for all valves appears on the Summary tab. To delete valves: Select the entry in the table and click Delete. The entry is removed from the calculation. 41

46 VisualFlonet User Guide Adding expansions/contractions This tab is for adding expansion and contraction joints to the calculation. For exit losses: Select an expansion with a small/large area ratio of zero. For entry losses: Select a contraction with a small/large area ratio of zero. To add expansions or contractions: 1) On the Fittings Loss Calculator dialog, click the Expansions/contractions tab. 2) Click Contraction or Expansion, as appropriate, enter the Large Area, the Small Area, enter the Quantity and click Add. Note You can enter any two of the large area, the small area and the ratio of the two. If you enter the two areas, the ratio is calculated. If you enter the ratio and one other parameter, the omitted parameter appears as unspecified. You can also edit the calculated ratio for entry and exit losses. The items are added to the table at the bottom of the tab, with the loss shown for each addition. The total for all expansions appears on the Summary tab. To delete expansions or contractions: Select the entry in the table and click Delete. The entry is removed from the calculation. Adding User Defined (Process Equipment) items The easiest way to model process equipment (for example, heat exchangers and filters) is as a section of pipe with a fitting loss coefficient. The pipe length needs to be short so that the pressure drop is solely due to the fittings 1m is generally used. 42

47 Chapter 6 Standard calculators The values for mass flow, pressure drop etc. can be obtained from the process data sheet. Static head changes between inlet and outlet should not be taken into account as the node information deals with this. To add process equipment: 1) On the Fittings Loss Calculator dialog, click the User Defined tab. 2) Enter a name for the item and specify the following items: Pipe Inner Diameter Flow Rate Density Pressure drop 3) Enter the Quantity and click Add. The items are added to the table at the bottom of the tab, with the loss shown for each addition. The total for all process equipment appears on the Summary tab. To delete a process equipment item: Select the entry in the table and click Delete. The entry is removed from the calculation. 43

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49 Chapter 7 VisualFlonet options This chapter describes how you can change the various options settings that determine how VisualFlonet works. Naming the calculation The first field on the Project tab on the VisualFlonet Options dialog lets you enter a title for the VisualFlonet calculation. This can be up to 50 characters. To name the calculation: 1) Do one of: Changing units On the VisualFlonet toolbar click the Options button. In the VisualFlonet menu, click Options. The VisualFlonet Options dialog opens. 2) Enter a title for the calculation. 3) Click OK to save the changes. The Units of Measure tab on the VisualFlonet Options dialog lets you select the units for process values to appear in all the editor and results dialogs. Three predefined set of units are provided: Practical SI units also called engineering units, the units most commonly used in the chemical process industries. They are SI units, with a few variants, such as Parameter SI unit Engineering unit Temperature K (Kelvin) C (Celcius) Pressure N/m2 bar Dynamic viscosity N.s/m2 cp (centipoise) Other units differ just by degree, such as mm for pipe bore (instead of m). Basic SI units the international system of units, the standard metric system British units standard UK (Imperial) or US units 45

50 VisualFlonet User Guide Practical SI units are the default set when you install VisualFlonet.You can set one of the other predefined sets as the default or compile your own set. To change the units to a predefined set: 1) Do one of: On the VisualFlonet toolbar click the Options button. In the VisualFlonet menu, click Options. The VisualFlonet Options dialog opens. 2) Click the Units of Measure tab. 3) Click the option for the set you want to use, such as British. 4) Click OK to save the changes. Creating your own set of units The Units tab on the VisualFlonet Options dialog lets you set up your own set of units. These are then saved by the application and reloaded when you restart. To create a new set of units: 1) On the Units tab on the VisualFlonet Options dialog, click User defined. The table of units becomes available, showing the current default units. 46

51 Chapter 7 VisualFlonet options 2) If you want to use one of the predefined sets as a basis for your set click the appropriate Reset button. 3) Double-click the unit you want to change. Type the new unit and then click on another cell. An alert appears if VisualFlonet cannot convert from the existing unit to the unit entered. Click OK and correct the unit. 4) Repeat for other units as required to complete your set. 5) Click OK to save the changes. Changing decimal places The Application tab on the VisualFlonet Options dialog contains a section that lets you select the number of decimal places to be shown for various process values on all the editor and results dialogs. To change the settings: 1) Do one of: On the VisualFlonet toolbar click the Options button. In the VisualFlonet menu, click Options. The VisualFlonet Options dialog opens. 2) Click the Application tab. 3) Change the number of decimal places for a particular parameter as required. 4) Click OK to save the changes. Changing calculation options The central part of the Project tab on the VisualFlonet Options dialog lets you set various control parameters that determine how the calculations are run. Note It is recommended that these setting are only changed by advanced users, or if directed by PEL Support Services. The calculation time can be increased significantly if you make a mistake. 47

52 VisualFlonet User Guide To change the settings: 1) Do one of: In the VisualFlonet menu, click Options. On the VisualFlonet toolbar click the Options button. The VisualFlonet Options dialog opens. 2) Change the values, as required: Monitoring Level. Determines the level of monitoring information included in the results. You should only change this if directed by by PEL software support personnel. Calculation Accuracy. Defines the accuracy to which final results are to be calculated as a percentage. Identical results for 0.05% and 0.01% indicate adequate convergence. T Junctions. Calculates any T Junction losses (if present in the network). If the check box is cleared, VisualFlonet assumes that there is no pressure drop across branching modes within the network. If the check box is selected, VisualFlonet makes assumptions about the configuration of the T junction at that node based on pipe diameters and flow directions and will calculate the pressure drop/recovery accordingly. Calculating T junction losses in cases where the flow direction may reverse can cause problems. Damping Factor. The Damping Factor applied to the recalculation of pipe resistance at each step. This parameter can be changed if a calculation is proving difficult to converge. It is useful when losses are very significant as small changes in flow can produce disproportionate changes in the pressure profile. The damping factor reduces the change the solving algorithm would otherwise attempt to apply. Zero (no damping) is usually suitable as a default. A value between 20% to 50% should be sufficient if damping is required. 3) Click OK to save the changes. Changing iteration limits The last field of the Project tab on the VisualFlonet Options dialog lets you set limits for the number of recalculations that can occur in a flow calculation. Note This is only relevant for flow calculations. The number of iterations determine the number of recalculations of the network. The number of iterations for one recalculation is approximately equal to the number of unknown external flows and pressures. Ten recalculations usually suffice, so it is recommended that the number of iterations is set to 10 x the number of unknown external flows and pressures but you can increase this for a model that is proving difficult to converge. 48

53 Chapter 7 VisualFlonet options To change the iteration limits: 1) Do one of: On the VisualFlonet toolbar click the Options button. In the VisualFlonet menu, click Options. The VisualFlonet Options dialog opens. 2) Change the number of Maximum Iterations. 3) Click OK to save the changes. These settings affect the solvers that perform the calculations. Contact the PEL support desk on the Hotline telephone service if you want to make changes. Changing applications options The upper part of the Application tab on the VisualFlonet Options dialog lets you change various options that affect how the program works within Visio. To change the settings: 1) Do one of: In the VisualFlonet menu, click Options. On the VisualFlonet toolbar click the Options button. The VisualFlonet Options dialog opens. 2) Click the Application tab. 3) Change the values, as required: Prompt for object name on drop. If the check box is cleared (default), your nodes, pipes and pumps are automatically named as you add them. If the check box is selected, a dialog will prompt you to change this automatic name as you add each shape. Default object name base. Gives the naming convention of nodes, pipes and pumps as you add shapes to your diagram. Validate data before an editor is displayed. shape before opening the editor dialog. Runs a validation check on the Switch on auto-connect by default. If this check box is selected the Connector tool on the Visio standard toolbar is automatically selected when you start VisualFlonet so that shapes are connected automatically when you drag them onto the drawing area. 49