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HOW VALVE CLOSURES AFFECT SURGE

How valves close matters, especially during an emergency.
Engineers often think slow valve closures are adequate, however, in most cases this strategy will not successfully mitigate waterhammer.

Have a better shutdown plan. Understand waterhammer and how to model valve closures. Dylan Witte, of the Purple Mountain Technology Group, lead a webinar explaining the uniqueness of valves & how their closure affects surge.
Purple Mountain Webinar


 

EXAMPLE: MODELING AN EMERGENCY VALVE

Knowing how to calculate the ideal time frame for
closure is nearly impossible without modeling


It's common for systems to have an emergency shutdown valve with a large flow coefficient to ensure negligible loss during normal operation. The valve likely won't restrict flow (with significant pressure drop) until it's mostly closed. Therefore, closing either slowly or quickly at the beginning has no effect on the system or surge. It is the last bit of closure that matters.

An engineer could use AFT Impulse to easily test and find the best closure rate. In our example closing the valve fast at the beginning and slowly at the end will result in a fast and effective valve closure.

This type of transient analysis by hand, while capturing the nuance of valve characteristics, is too much to ask. 

 

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EFFECTIVE CLOSURE TIMES

Learn about valve "effective closure time",
which is the time from when the valve actually controls flow until it is closed. It is typically
much less than the total closure time. The effective closure time is what engineers should be concerned about - not the total closure time. Grow your understanding of valve characteristics, so you know how to properly shutdown.


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UPCOMING TRAINING

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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JUNE TRAINING SEMINAR
Location: Colorado Springs, CO, USA
October 5-7  |  3-Days  |  $1,900


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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.

AFT Impulse™ Waterhammer or Surge
System Modeling Seminar: 

·     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

WEBINAR
Gas Accumulators in AFT Impulse 

Watch the Recording

Do you model or size gas accumulators?
You may have gotten a glimpse at these in a
previous AFT webinar. This webinar will dive
a bit deeper to explain uses of the updated Gas Accumulator junction in AFT Impulse.

 

We will also discuss the assumptions the
Gas Accumulator makes and how the
Gas Accumulator can be used to model
a closed tank.

 

 

 

 

 




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