With an expanded knowledge base and tools like Impulse 9, AFT hopes pipe systems can avoid potentially catastrophic effects of water hammer.

By Reinaldo Pinto, Applied Flow Technology

One of the toughest aspects of hydraulic system design is accepting that a system cannot always operate at steady state. Whether system transients are intentional or unintentional, routine or emergency, understanding a transient’s impact on a system is critical to ensuring safe, continuous operation.

Applied Flow Technology has released AFT Impulse™ 9 for engineering teams to better understand their systems during deviations from steady state. 


Water hammer and surge analysis performed in AFT Impulse helps engineers around the world mitigate failures and avoid downtime by providing the reliable information necessary to prevent incidents before they happen. While new features and capabilities strengthen this analysis software with each new version, AFT Impulse has been a premier and reliable transient analysis tool since its release in 1997. 

New features in AFT Impulse 9 include the following: 

  • A redesigned gas accumulator window to improve usability and add new features such as calculating liquid height.
  • Improved multi-scenario graphing to compare and animate design alternatives with different time steps.
  • Options to convert shear rheometer data for power law and Bingham plastic viscosity models. 
  • The Herschel-Bulkley viscosity model for shear thinning or thickening fluids with a yield stress.
  • A streamlined setup from the new Analysis Setup menu, a user-friendly workflow condensing several model-wide specification windows into one.
  • An overhauled Library Manager (previously the Database Manager) offering a consolidated way to access and customize libraries of fluids, pipe materials, components, and more.
  • Color-coded, organized, and prioritized list for warnings, errors, and design alerts shown in the output for quick review.

Often water hammer issues are addressed only by specialist consulting companies due to water hammer’s esoteric nature, but AFT Impulse continues to be developed with the everyday engineer in mind. Not only will an engineer understand the cause of a problem with AFT’s visualization tools, but they can also design, test, and implement their solution.

AFT Impulse is a powerful dynamic simulation and analysis software used to calculate pressure surge transients in liquid piping systems caused by water hammer, easily modeling a wide range of system components and surge devices. Key to the system’s efficacy is its ability to understand the transient response of your system, knowing how valves, pumps, and other components will dynamically interact with each other. This allows technicians to evaluate the effect of pressure surges due to vapor cavity collapse by modeling vapor cavitation and liquid column separation, validating the design of safety features to produce safer, more economical pipe systems.

AFT Impulse 9 model featuring the multi-comparison graphing feature.


Engineers accumulate a lot of knowledge over their career about how to solve very particular problems. Often a concern with water hammer and surge analysis is where to start, especially since rapid transient events are not covered in a typical undergraduate (or even graduate) fluids course. In the past few years, AFT has noticed greater interest in water hammer from engineers hoping to understand this complex phenomenon. AFT has developed materials to meet this interest, not only for advanced topics like identifying and mitigating water hammer by modeling in software, but also introductory fundamentals and theory to help engineers understand the what and why of water hammer analysis. 


Engineers of all experience levels looking to expand their water hammer knowledge are welcome to join AFT in several ways:

  • View free educational webinars or watch recorded webinars available on the AFT website.
  • Subscribe to Water Hammer Wednesdays, a monthly email dedicated to delivering basic water hammer knowledge and upcoming events. 
  • Visit www.waterhammer.com for educational articles, videos, and resources. This site has something for all experience levels, from physics foundations to mitigation options and everything in between. Contact AFT if you would like to help provide content and resources. 
  • Join AFT as a member of the Hydraulic Institute’s Water Hammer Committee, focused on water hammer awareness and its impact on pumps and piping systems. Visit www.pumps.org for more information. 

With an expanded knowledge base and tools like Impulse 9, AFT hopes pump users can avoid potentially catastrophic effects of water hammer and other undesirable system transients, prevent transient pressure issues by properly sizing and locating surge equipment—such as surge tanks, gas accumulators, and relief valves—and initiate transients based on time or events in the system. 


Founded in 1993, Applied Flow Technology is a leader in the pipe flow modeling software market. With a primary focus on developing high-quality fluid flow analysis software, AFT’s comprehensive line of products for the analysis and design of piping and ducting systems is used in more than eighty countries to engineer safer, more efficient systems and solve operational problems.Learn more at www.aft.com.

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