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AFT Blog

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Stephanie Villars

Raise the bar using Vacuum Breaker Valves

Vacuum breaker and air valves are useful tools in the industry for protecting pipelines against vacuum or near vacuum conditions. High points in the pipe can be susceptible to these low-pressure conditions during surge events, as pressure waves moving through the system cause a sudden pressure upsurge or downsurge. AFT Impulse can help engineers to...
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Trey Walters

When Pipe Stress Analysis Meets Waterhammer Hydraulics: New Waterhammer Guidelines for Engineers

I am sitting on an airplane at this moment somewhere over the Atlantic Ocean and I am excited. Something that has been in the works for 22 years will happen next Monday, July 16 in Prague, Czech Republic. That is where the ASME PVP 2018 Conference will happen and I get to make a presentation.

Last year I helped AECOM, an AFT customer and AFT Impulse user, develop a set of pragmatic internal design documents for their project on handling radioactive fluid transport. Two of these documents provided their engineers guidance on interpreting and applying transient cavitation predictions. 

We proposed these two documents to the ASME PVP Division and they liked them enough to allow us to publish two new papers at their conference. I will be presenting these papers on behalf of AECOM and AFT.

But why I am so excited about this?
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Trey Walters
Yes, the link in the blog now points to the full papers here: http://www.aft.com/learning-center/technical-papers... Read More
Tuesday, 24 July 2018 14:47
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Jake Miller

NPSH got you under pressure? This’ll get you pumped!

Cavitation is an important subject in piping systems. Quite often, cavitation is an operating condition that is to be avoided, such is the case with pumps. Not only can cavitation cause serious decreases in pump performance, but it is also a maintenance nightmare if left unaddressed. Such issues are costly and may lead a system to be deemed unsafe. As you are likely aware, cavitation exists when the local pressure falls below the vapor pressure of operating fluid. Overtime the pressure may increase again so that the cavity formed then collapses. When this collapse occurs on the vanes of a centrifugal...
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John Rockey

Benefits of the Discrete Gas Cavity Model

AFT Impulse 5 now includes a second cavitation model option: The Discrete Gas cavity Model (DGCM). So, what is it and how is it different from the existing cavitation model? This article will provide a very high level overview. The method of characteristics (the finite difference basis for 1D transient flow modeling) assumes a constant wave speed for each pipe, from time step to time step. There are, however, many things that would cause a change in wave speed; cavitation being one the most significant. A change in wave speed will have a dramatic effect on the pressure spike that occurs...
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John Rockey
Hi Aqeel, AFT Impulse allows vapor cavity sizes to grow and shrink as is dictated by the system hydraulics, meaning that there is ... Read More
Thursday, 17 August 2017 16:41
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