AFT Blog

Welcome to the Applied Flow Technology Blog where you will find the latest news and training on how to use AFT Fathom, AFT Arrow, AFT Impulse, AFT xStream and other AFT software products.

Waterhammer Analysis: Reactionary or Preventative?

You may have heard, “there is never enough money to do it right the first time, but there’s always enough money to fix it after it’s broke." As engineers and project managers it is our responsibility to provide safe solutions to complex problems in an economy that typically gives jobs to the lowest bidder. Often these two ideas, safety and cost, seem to be at odds with each other. The more time put into insuring safety can rise costs to an unviable level and often times a “sweet spot” must be reached. One cost saving measure in piping design is to...

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That was EASY! Quickly Change Pipe and Junction Input Data into AFT models using Excel Change Data

Users and potential users of AFT software frequently ask how they can expedite the model input process so that they can get the results they need as rapidly as they need. I’m pleased to report that AFT software has an abundance of features that make the model input process tremendously efficient: global pipe and junction editing, copying input data from other pipes and junctions, and finally, importing data using the Excel Change Data parameters spreadsheet (which is what we are discussing in this blog). The Excel Change Data feature works by importing data from an Excel spreadsheet populated according to a...

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The World in Motion - Understanding Results Through Animated Graphs

Previously, we talked about the Graph Guide and how to create Stacked Graphs and Dual-Y graphs. With AFT Impulse and with AFT Fathom’s XTS module, a great way to see how parameters change over time is through animated graphs. For the purpose of continuity, I am going to again start with the AFT Impulse model, ‘Pump Startup With Event Transient.imp’, which is installed in the Examples folder, and use the ‘One Pump Start With One Running’ scenario. In the previous blogs, we used a Stacked Graph and a Dual-Y Axis Graph to examine the pressures and flows at two valves (J6...

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Getting your Pressures Right: How to Account for Changing Ambient Pressure with Elevation

Scuba divers and casual swimmers alike are all too familiar with the discomfort (and sometimes outright pain) experienced in their ears as they descend deeper into the water. This discomfort is experienced for good reason: for each 33 feet you descend into the water, you experience considerably more pressure (about 1 whole atmosphere) due to the hydrostatic pressure of the water. As the pressure of the surrounding water increases, the air trapped in the middle ear remains at atmospheric pressure, but the pressure in the outer ear is significantly higher, which puts significant force on the eardrum. Anyone who has ever...

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Putting Out Fires with AFT Fathom's NFPA Calcs & GSC

If you are performing a hydraulic analysis on your fire system, chances are high that you are working hard and maybe scratching your head in order to adhere to the NFPA codes.  The good news is that you can streamline the calculations outlined in the codes with AFT Fathom! NFPA 15 is the standard for fixed water spray systems that are used in fire protection.  AFT Fathom has been able to perform all the standard hydraulic calculations for a fire protection analysis for a long time, including the usage of Hazen-Williams factors.  But now with AFT Fathom 9, you can easily...

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A Clever Way to Mitigate Waterhammer During a Valve Closure

One of the most common causes of waterhammer in pipelines is a valve closure. As the valve closes, the flowing liquid is forced to stop, resulting in a transfer of kinetic energy to potential energy, which ultimately causes a pressure increase. If this increase in pressure is large enough, extremely severe damage can result in the pipeline. Engineers frequently mitigate this waterhammer by selecting a valve that closes slowly enough to prevent the pressures from getting too high. However, a valve that closes too slowly can cause problems elsewhere in the pipeline or result in other undesirable outcomes in the process....

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Using Equivalent Lengths in AFT Fathom

One of the new features in AFT Fathom 9 was the ability to model equivalent lengths instead of K factors for various types of fittings. Since AFT Fathom's existence, the standard K factor loss models have been used to quantify the pressure losses across a fitting such as an elbow, a valve, etc.  One of the reasons why the K factor method is very useful is because it is broad and applicable to a wide range of different fittings.  However, the equivalent length method is also a way that engineers will typically quantify the losses through their fittings and they will...

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