Efficiency- Hypothetical vs. Practical in solids handling centrifugal pumps
The discussion of pump efficiency in nonclog and vortex pumps has raged for years. The 'Hypothetical" or bowl efficiency is a measure of how well a pump liquid end handles a pumped media such as water with respect to consumed horsepower or BHP (Break Horsepower). This is an important factor for clean liquid handling pumps. Efficiency should become less important when solids are introduced into the liquid such as in a sewage lift station or other applications where large debris will be present in the pumped media. In applications where any kind of stringy material is likely to be present, efficiency should be a minimal consideration. Over the years as power costs have become increasingly more important, pump efficiency has also increased in importance. Maintenance records have shown that while 100% recessed impeller vortex pumps do not have as high of a bowl efficiency as a nonclog pump they provide superior performance to nonclog pump designs in all other aspects.
In the practical sense pump efficiency should be much less important when handling liquids containing solids. As debris is introduced in to the pumped media, the nonclog pump liquid end design begins to falter. Small debris such as sand is inconsequential in small amounts (less than 2%). As higher volumes of sand or other debris increases the nonclog liquid end is worn away at a high rate and the pump efficiency falls off rapidly. Even when hardened materials or rubber are used for wear rings, the close tolerances are still worn away, but at a slower rate. If stringy solids are in the pumped media, then the probability of plugging increases dramatically for nonclog pumps. Even though 100% recessed impeller vortex pumps do not exhibit as high a bowl efficiency as a nonclog unit they typically out perform and outlast nonclog pumps by a wide margin. When all cost aspects of owning and maintaining this type of equipment calculated the lower maintenance and dependability of a 100% recessed impeller vortex pump overshadows a nonclog pump.
In sewage lift stations, slurry applications, grit applications, sludge etc. 100% recessed vortex impeller pumps have been shown to be the best choice of pumps for the maximum life with the least required maintenance. When all factors are considered, total cost of ownership of a vortex pump is substantially less than that of a nonclog design. When a pump is not in service it doesn't matter how efficient the liquid end is supposed to be because when not operating the bowl efficiencies is zero!
When efficiency means the bottom line, demand ESSCO 100% recessed impeller vortex pumps for no downtime!