NPSHr is a property of the pump and is a function of the flow. This value is determined by testing done by the manufacturer and is usually presented as one of the pump characteristic curves. You want to ensure that the available NPSH (NPSHa) is greater than the required NPSH (NPSHr), or the water will vaporize in the pump and damage the pump.
Picking the right number of pumps and which ones to run at any time without wasting energy is tricky. The problem gets especially tricky when you have the potential to mix constant and variable speed pumps, and there is no storage in the system, so you can’t simply run pumps efficiently and turn them off when a tank is full.
Pumping energy is usually one of the largest components of operating costs for most water systems. And it’s not a trivial cost for wastewater utilities either.
Water and wastewater do a very good job preparing for what I’ll call “routine emergencies”—pipe breaks, short-term power outages, sewer blockages, pump mechanical failures, etc. There are standard operating procedures and frequent drills in well-run operations to make sure we can deal with such conditions. But what about the big emergencies? The ones that never happen until they do. We’ve had a taste of this with Covid, and the folks in Texas received an even stronger dose during last winter’s big freeze.
Beyond these advantages of the software, OpenFlows SewerGEMS also integrates seamlessly with the most popular CAD and GIS platforms (MicroStation, ArcGIS Pro, ArcMap, and AutoCAD). You choose whether you want to run OpenFlows SewerGEMS as a standalone platform or run it within the other platforms.
This robust solution provides engineers and sanitary network designers to reduce time and error in their projects. OpenFlows SewerGEMS combines constraint-based design routines, advanced scenario management with an easy-to-use user graphic interface, as well as easy-to-build and easy-to-maintain tools. It allows you to keep your hydraulic model accurate and up to date, saving time and effort in your critical decision-making processes.
An OpenFlows HAMMER model can help identify where and how the pressure drops can occur and help design the needed control measures. Centrifugal pumps are great at pushing water through a pipe. They aren’t as proficient at sucking water through a pipe. As a pump pulls water into its impeller, it lowers the pressure.
There is no shortage of conferences serving the water industry. Each of them contributes something to our profession, and attending is usually worthwhile, if not life-changing. But which ones should you attend? You can’t attend all of them, or you wouldn’t get any work done. I’ll run through a few of the conferences I’ve attended, and I’ll give you my thoughts below.
Writers working with large numbers often feel compelled to display digits beyond a reasonable level. For example, they may want to report a pressure as 27,871 psf, when only the first two digits are meaningful. Two solutions to this are to use a more reasonable unit such as converting that value to 190 psi. The other option is to scientific notation and report 28 x 103 psf.