Water Well Journal

May 2016

Water Well Journal

Issue link: http://read.dmtmag.com/i/668983

Contents of this Issue

Navigation

Page 50 of 77

Although electric motors are the most common method of driving a VTP, they are not necessarily the most effi- cient or desirable, even in regions with adequate power supplies. In these in- stances, this selection will usually be made based on available power sup- plies, including the related utility and electrician installation costs and power use costs vs. the cost of an engine/right- angle drive combination, maintenance, or local fuel costs. In some regions, even where ade- quate electricity may be available, the preferred choice is to use an engine drive pump. This is done through use of a right-angle drive gearhead. This is es- pecially true in many Midwest regions of the United States. In all cases, the driver must have a provision for adjusting the impellers at the top of the driver, have adequate bearings to handle all imposed vertical thrust loads, and be able to produce or transmit the needed total horsepower at the specified speed. The driver must also have a provision to prevent back- spin of the pump bowls during shut- down, which can lead to unscrewing of the pump shaft. Backspin is caused by draining of the pumped fluid back through the bowls following shutdown. This event can have a disastrous effect on the pump. A non-reverse ratchet, self-release coupling, or a foot valve are three de- vices used to prevent unscrewing of the pump shaft. Without these devices pro- visions must be made to prevent the operation of the driver in the opposite direction than planned, particularly with three-phase electric motors. This concludes the first part of this two-part series on selecting a vertical turbine pump for our hypothetical appli- cation. In the next installment, we will take the information in this column and apply it to several different manufactur- ers, consider and evaluate several differ- ent bowl and pump options, and finally select the single best overall selection for our example. Until then, keep them pumping! WWJ Figure 3. Typical nomenclature for vertical turbine pumps Ed Butts, PE, CPI, is the chief engineer at 4B Engineering & Consulting, Salem, Oregon. He has more than 35 years experience in the water well business, specializing in engineer- ing and business management. He can be reached at epbpe@juno.com. WWJ May 2016 47 Twitter @WaterWellJournl

Articles in this issue

Links on this page

Archives of this issue

view archives of Water Well Journal - May 2016