WGZB Sanitary Liquid-Ring Pump
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We have covered in previous posts why by design sanitary centrifugal pumps are not as efficient as some of the industrial pumps on the market today.
Besides being less efficient, they generally have higher NPSH requirements than an equivalent industrial pump. The sanitary process industry, however, does not have a shortage of low NPSH applications.
In fact there are several common sanitary applications that have even harder sanitary liquid ring pump on the suction side of the pump than low NPSH. To meet those needs, sanitary pump manufacturers have come up with some innovative pumping technologies. We will cover some of those today, including sanitary liquid ring pumps and inducer pumps.
Cavitation and dry running are not the only issues users will run into when using a centrifugal pump in a low NPSHA application. Air locking is another common problem. As the gas collects, it is compressed and creates an artificial discharge head. Pressure builds until sanitary liquid ring pump head is reached. Air lock most often happens when there sanitary liquid ring pump a sanitary liquid ring pump in the suction line word to the wise, Teflon gaskets leakbut can also occur when pumping products with entrained air.
The following technologies not only help in low NPSHA applications, but also help mitigate the risk of air lock. An inducer is basically an auger type device SPX calls it an axial flow impeller that mounts to the hub of the pump impeller and spins as the impeller spins. The throat on the inlet of the pump is sanitary liquid ring pump and houses the inducer with fairly tight tolerances. As eccentric inducer spins, it boosts the inlet pressure.
The inducer also greatly reduces the risk of cavitation. It can also let the pump handle more viscous products and products with entrained air better than standard sanitary centrifugal pumps. The inducer pump is still not considered self-priming.
Sanitary liquid rings pumps are somewhat of a hybrid type pump, part centrifugal and part PD pump. The pump has a veined impeller with a closed ring around the outside. The impeller is mounted within a casing with very close tolerances. The back plate of sanitary liquid ring pump pump has channels machined into it. As the impeller rotates, these channels create high and low pressure areas, simultaneously pulling liquid into the pumps inlet and forcing liquid through the outlet.
Our normal choice of liquid ring pumps is the Waukesha LR. They then pipe sanitary liquid ring pump liquid leg from the discharge outlet of the pump directly to the chamber that houses the inducer. The constant fluid recirculation allows the pump to self-prime and pump foam or air entrained products better. Like anything else, choosing the right pump is a cost benefit exercise. Listed below is sanitary liquid ring pump take on the pluses and minuses of each pump.
So there are the sanitary centrifugal pumps on the market designed specifically for applications with challenging suction head requirements. Contact u s if you have any questions about low NPSH sanitary pumps. We have put pumps is many of these types of applications, from pumping out of tanks under vacuum to foamy CIP return situations. If you come up with an application we have not seen before, we will figure it out together.
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