By Dave Meister, P.E.
Staged. High head. High flow. High efficiency. Solids handling. Non-clogging. What's the best way to begin the process of cutting through the maze of claims and the lists of pump characteristics when developing a new application or revamping an old one? The answer begins by looking at the past and getting a good feel for what has been successful for similar situations. The next step is collecting data on current conditions so that you can plan for the future.
Whether developing a completely new pumping system or updating an old one, reviewing the history of similar systems will go a long way in ensuring success when facing unknowns. In many cases, it's surprising to learn that what is expected from a system is not what actually happens. The pump must be able to function properly under the new requirements whether caused by the pipe friction coefficient affecting actual verses calculated head, the recovery head or lack of expected recovery head, or any other reasons. Obviously, the more experience you have at your fingertips to draw on, the fewer surprises you will encounter.
Garbage In, Garbage Out
A well-designed pump can have a life expectancy of 50 years or more. To take advantage of that feature, however, it is important to look as far into the future as possible. While initial installation is costly, prudent designers will think about the long-term future to come up with a pumping system that can easily be upgraded as demands grow, avoiding even costlier revamping. In fact, some progressive solutions have included the burying of a second parallel main that can be tied into an existing line when additional flow is needed. This preplanning effort will avoid the ongoing future costs of friction energy loss and the problem of too large of a pipe to keep solids in suspension.
But even the best laid plans can fail. That's why it is so important to work with a consultant, pump distributor, or company that can add to the experience circle. These partners can direct your team to the most flexible pump available to accommodate the range of conditions that the actual system might experience.
Power of Experience
To meet growing demands, a series of pumps were developed called the Ultra V. They can operate at higher speeds without the associated noise, maintaining many of the traditional features that users have come to expect from their high-performance pumps. At the same time, this new line of high-performance pumps have a broadened performance envelope, allowing for the surprises mentioned earlier in this article.
In conjunction with this new pump series, a more convenient method of staging two pumps was developed for applications that are beyond the capability of a single pump. Previously, conventional staging consisted of setting two pumps side by side and running plumbing from the discharge of the first stage into the suction of the second stage. While some friction loss does exist when pumping from stage one to stage two, the real problem revolves around the necessary floor space required, and the challenges involved in installing piping. To solve these problems, an innovative transition casting is now available that allows for a straight centrifugal pump (the UltraMate) to be mounted directly on top of the Ultra V's lower module self-priming pump discharge.
Regardless of the configuration or pump innovation being enlisted for any given challenge, it's important to stress the attention to detail that must be exercised in designing a total pump system. Keep in mind that friction is the most expensive element in a design. It not only requires larger motors and controls, but it also robs the user of electrical power each and every time it runs. When developing for the future, careful projections and planning will pay dividends in the end.
Dave Meister, P.E., is director of engineering at the Gorman-Rupp Co., a manufacturer of pumps and pumping systems for the municipal, water, wastewater, sewage, industrial, construction, petroleum, fire, and OEM markets. The company's pumps include self-priming centrifugal, centrifugal, submersible, priming assist, rotary gear, and air-driven diaphragm pumps. It also manufactures packaged lift stations and booster stations, which include pumps, motors, controls, piping, accessories, and enclosures. More information is available at www.grpumps.com.