Solids Handling Non Clog Pumps vs. Vortex Pumps
Non Clog Pumps:
The discussion of solids handling when comparing Non Clog and Vortex pumps has raged for years. The name Non Clog is a misnomer. Non Clog pumps do clog and have a limited solids handling capability. Today, because of operational costs, Non Clog pumps are being selected for applications which are less than ideal. Many Non Clog pumps are misapplied, high maintenance and pump failure often result. When the end user/ operator realizes there is a problem, it is often either too late to do anything about it or the cost of rectifying the situation is too expensive. The customer is "stuck" with something that is a constant problem and drains maintenance budgets. The most common items that are often overlooked when applying a Non Clog pump are rags in the pumpage, grit and sand in the pumpage, long stringy material, rocks and nuts and bolts. These are very common in applications where a solids handling pump is required. The majority of these types of problems occur in 4", 6" and 8" pumps. Pumps with suction and discharge sizes 10" and larger are less susceptible to plugging than the smaller units.
100% Recessed Impeller Vortex Pumps :
In the practical sense, 100% recessed impeller vortex pumps are superior to Non Clog pumps for handling liquids containing debris. In many applications, liquids are used to transport debris and materials such as sand, gravel, hair (in leather tanneries), coal slurry, sewage, and rag laden liquids are just a few. Many engineers and end users recognize the value of a pump which is not easily plugged.
Often times pump manufactures try and pass off a “semi-recessed” impeller pump as being equal to a 100% recessed impeller pump. However, problems arise when a pipe sized solid or a large rag is introduced into the pump media. A 100% recessed impeller pump will pass a solid equal to its discharge size where a semi-recessed impeller pump generally will pass a solid 1" less than the discharge size. That is particularly problematical when pumping slurries. Often in applications like coal slurry transport the coal chunks will be equal to the discharge pipe size. Even applications which are considered “easy”, such as a sewage lift station, are better installations when 100% recessed impeller vortex pumps are installed rather than when Non Clog pumps are installed. Resort and beach installations have severe ragging problems. When underwear, tee shirts and other large solids are introduced into the pump station, a plugged pump can occur. A semi-recessed impeller will grab the large rag and it will wrap around and behind the impeller thus causing a clogged pump.
A large municipality in the Southern California has done comparison study and installed a 100% recessed impeller vortex pump next to a Non Clog pump of similar size. The results were the vortex pump required less maintenance (basically none over a 1 year period) while the Non Clog pump did have plugging and wear issues. When the power consumption was reviewed for each pump it was found that the over all cost of power between them was negligible. The result after testing several installations was that 100% recessed impeller vortex pumps became the standard and Non Clog pumps were not allowed.
Conclusion:
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 any other impeller 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!
