In the final "Know Your Pump & System Curves" blog series, I am going to discuss the complexities behind pump vs. system curves for systems with pumps in series and parallel configurations. Multiple pumps in series configurations are relatively straight-forward and will be discussed briefly. Operating pumps in parallel configuration involve a f...

While thinking in terms of pressure is often intuitive for engineers, thinking in terms of head can be more challenging. You may be surprised by the number of cases and questions that come to the support team here at AFT about the basic definition of head, and how it relates to hydraulic modeling. Let's get back to the basics with how head is defin...

Any time a rapid transient occurs in a piping system, there is a chance for unexpected surge to impact the system. Though system shutdowns account for many surge events, pump startups can cause water hammer as well. For this blog I am going to cover the basics of setting up pump and valve transients for the startup case in AFT Impulse 7, as well as...

The pistons, or diaphragm of a reciprocating (positive displacement) pump causes a cyclical variation, typically in some sinusoidal form, of both flow in pressure in a piping system. The magnitude varies, depending on the type and design of the pump. What is acceleration head? Acceleration head is the energy required to change the velocity of the liquid in the system from an at rest, or zero condition, to some non-zero value. To help us understand acceleration head a little more clearly, you could compare it to a race car. In a drag race, the race car will accelerate to some maximum velocity,...

What comes to mind when you hear the expression “planning for failure”? For some, it carries the negative connotation that failure is the direct result of a design – intentionally or otherwise. Benjamin Franklin said; “If you fail to plan, you are planning to fail!” and I believe he would agree that any good plan addresses potential failures. In fact, not "planning for failure" as an element of a system is essentially failing to plan and therefore inviting unexpected and unmitigated failures. Life Cycle Cost One of the many reasons to avoid failure when possible is to reduce cost. When a...

This past week I and Jeff Olsen, AFT’s V.P. of Technology, attended the annual conference of the Hydraulic Institute. The Hydraulic Institute (HI) was founded in 1917 and is America’s premiere pump organization. At this year’s meeting HI held a centennial celebration.

AFT Fathom can easily generate a pump and system curve for your piping system.  Creating a pump and system curve for a simple system with a single flow path and no control features is an easy and typically well-understood process.  However, as piping systems are quite complicated with lots of branch points, control features, and dynamic interactions, creating a useful system curve can quickly become a common source of confusion.  This three-part blog series is going to help clarify concepts regarding pump and system curves to better understand them.   This Part 1 blog will discuss the basics of what pump...