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61 JANUARY 2014 Terms Part 1 by Bill Corey Pentair Water Training Institute Terms: These are words or phras- es we use, but some of us aren’t really sure what they mean. So this month I think we’ll make sure everyone knows what these terms mean. Centrifugal Pump - This is a pump that uses centrifugal force to move water and create pressure. Centrifugal Force - This moves something from the inside to the out- side of a rotating object. I learned about this as a kid when we lived across the street from a playground. Some of us guys would get together, and one would get on the merry-go-round while the rest of us pushed as hard as we could. I found if you were in the middle you might get sick and vomit, but you would stay on the merry-go-round. However, if you tried to ride at the outside edge you would get tossed off in the dirt, but then that was the game. Of course this hap- pened because centrifugal force moves something from the inside to the outside of a rotating object. Head - In pump language, Head is the measurement of energy in a vertical column of water in feet; hence Feet of Head, but it can also be called Pressure Head meaning we now place a pressure gauge at the bottom of the column and weigh the water in pounds per square inch (psi). Shut-off Head - Since Head means energy, Shut-off Head means we turn the pump on, get the water flowing through it, and then shut the water off. On the discharge of the pump we have a pressure gauge and measure the total amount of pressure head coming out of the pump. We have to ask our- selves a question at this time which is: Is all this pressure coming from the pump, or is pressure being added to the suction side of the pump by a flood- ed suction? A combination gauge helps us to read the suction side of the pump. If it is reading pressure, then the read- ing we are getting on the discharge pres- sure gauge is not all from the pump and we must subtract the incoming pressure from the discharge pressure. Dead Head - Dead Head is the same as Shut-off Head except we are not there to turn the pump off or the water back on. So now the pump is turning the impeller, but the water has been stopped on the discharge side, a plug of some kind. Maybe there is a pressure switch and it is stuck in the on position so won’t turn off and just allows the pump to keep building pressure. Or maybe we have some kind of timer that says to turn the pump on, but then a solenoid valve refuses to open and the pump is turning the impeller but again no water moves. These are Dead Head applications. It means something is going to die; could be the pump, could be the system, could be both. At any rate, something bad is going to happen. We’ll have more terms next month. Bill Bill Corey may be contacted via e-mail at admin@ worldwidedrillingresource.com WorldWide Drilling Resource ®