AFT Blog

To model a valve opening transient from the closed position, apply the Special Condition / Closed on the specifications window Optional tab. Transient Data then starts with Cv = 0, increasing to the full open Cv value, or, if modeling the valve loss as a K value, transient data starts with K = -1 (K = infinity), decreasing to a K value for the open position (all K values other than the full closed K value are positive).

You can see output in the Workspace window by pressing the CTL key while right-clicking a pipe or junction (left-clicking for a left handed mouse). Output displayed is that currently selected within Output Control so, if you don’t see the information you’re looking for, simply open Output Control from the Analysis menu and add the desired parameter to the ‘Show Output’ list.

Design Alerts provide easy identification of output parameters that exceed specified limits and are available in all AFT pipe flow modeling software. Found on the Design Alerts tab of the Pipe Specifications window, an alert is defined by; Selecting the parameter upon which the alert is based from the available list (pressure, flow, velocity, etc.), Checking ‘Minimum’ or ‘Maximum’ (i.e. alert if the parameter value falls below the specified minimum of above the specified maximum), Specifying the value and units and, Clicking the ‘Add’ button to add it to the alert list. Any number of alerts may be defined for a...

A variety of resistance modeling methods are available within AFT software, including constant or variable K values for a wide variety of components, K or Cv for valves. Also, for most components, you may directly model a resistance curve. This is especially handy when you pressure drop (or head loss) vs. flow data from the component manufacturer or test data. Whether you're modeling a valve, spray discharge, orifice or general component junction, you'll find this option on the Loss Model tab of the junction specification window listed as "Resistance Curve". Clicking the button will highlight an 'Enter Curve Data' button, which...

Every once in a while users will ask 'what are those .001 files created in my model folders?'. Answer - These are backup files of your model. When the model is saved the previous version is saved with the same name and the extension .001. This file can be opened or renamed if desired. By default one level of backup file is created and saved, but you can specify up to 10 levels of backup files in Options / General Preferences / User Environment tab. While there, you'll also see the option to have backups created automatically on a time frequency...

Another common example would be large diameter fabricated steel pipe made from rolled plate.Nominal sizes, diameters and wall thicknesses are custom, but the thermophysical properties (density, thermal conductivity) can still use the built-in values for steel, so that you want to add these sizes and wall thicknesses to the Steel category of material. Simply select Steel then click on the New Size button. The window that appears will let you specify a nominal size, diameters and wall thickness. If you wanted to create various wall thicknesses for this custom size pipe, you would select the Size then click the New Type...

AFT software has a variety of features for editing and navigating around models. One of these is the ability to define and then easily jump to bookmarks. So, what are bookmarks? A bookmark is an identified location, a junction or pipe, within a model. To create a bookmark, select a junction or pipe by clicking it once. On the View menu, select Bookmarks\Set Bookmark. To jump to the bookmark, simply press F9 and the Workspace will pan to bring the junction or pipe into view and select it. Any number of bookmarks may be defined. When multiple bookmarks are set, pressing...