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Waterhammer News



Waterhammer Wednesday: Are your pumps a hidden danger to your system?  


Waterhammer: Not Just Valve Closures

Any rapid change to flow can trigger a surge event.

For example, as pumps start-up or trip, suddenly a system must react to ​​​​​rapid
changes in flow and pressure. If an engineer isn’t careful, these pump transients can:

- Exceed design pressures
- Slam check valves from reverse flow
- Pull a vacuum

Learn in this week’s newsletter about modeling pump transients
in AFT Impulse to anticipate and mitigate issues before they occur.


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How to Model Start-ups or Trips to Predict Responses to Pump Transients

Typically with pump start-ups, engineers want to look at peak pressure, system response, and pump suction cavitation. With pump trips, their focus will shift to reverse flow, check valve slam, and transient cavitation (liquid column separation). Yet, there is no way to understand all factors without modeling software. See how. 

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Wood PLC completed a surge analysis on a water injection system of an offshore platform to look at various cases including pump start-up, controlled pump shutdown, and emergency pump trips. 

It turned out the pump trip was too extreme for the system. See how they found that using a different check valve prevented reverse flow and check valve slam.

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No matter your user level with AFT software products, we have training and assistance available to help you continue your education, or tools to advance your knowledge to expert levels.
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Predicting Transient Pipe Forces
Caused by Water and Steam Hammer

September 21, 2022  |  10:00 AM (MDT)

Transient Pipe Forces can reach magnitudes upwards of 10,000 lbf (50 kN) during routine operations such as valve closures or pump trips. Prediction of transient forces from the results of simulations can be deceptively complicated. In essence, the calculation is simply an application of Newton’s Second Law, but the details of this application are full of potential pitfalls. Fortunately, AFT Impulse and AFT xStream can handle this complexity by delivering transient force results with very few simplifying assumptions from only simple inputs.

Close your valves the right
way with AFT Impulse

September 7 | 10 AM (MDT)

Valve closures are unavoidable, whether from emergency shutdowns, simple flow redirections, or anything in between. Figuring out the right way to close is nearly impossible without modeling software. There is no one-size-fits-all solution. The effective closure time is unique for every valve in every system - because it does not just depend on the valve and does not just depend on the system. It depends on the combination.

Waterhammer or Surge System Modeling Seminar:

AFT Impulse™
Location: Colorado Springs, CO, USA

October 5-7  |  3-Days  

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When there are so many demands for your attention in the office, it can be hard to focus on Zoom and Teams trainings. This is why AFT offers in-person training seminars. Whether you're new or experienced, you'll find AFT seminars a worthwhile investment of your time. 

  • Understand surge communication times
  • Modeling transient cavitation
  • Model pump transients, including​​​​​​inertial effects
  • Modeling time & event based transients
  • Model relief & vacuum breaker valves
  • Troubleshoot AFT Impulse models
  • Predict unbalanced pipe forces
  • Choosing the best trade-offs between model run times
  • Model pipe sectioning round off errors
  • Understand graph & animation features
  • Size & locate surge suppression equipment


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transients in piping systems caused
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