The Importance of Monitoring Pump Inlets and Avoiding Vortex

June 28, 2017

In a pumping context, what is vortex? It's a pumping abnormality of some kind that much is certain. The term implies a flow irregularity, but what exactly is taking place in and around the impeller assembly? Well, pump suction and throughput physics is a complex topic, one governed by pressure variables and fluid dynamics. Let's just say that these vortices cause flow problems.

Identifying Flow Problems

Back at the pump inlet, that's where the whole cycle begins. If the inlet channel is optimally designed, then the liquid moves smoothly towards the pump inlet. The problems begin when the inlet architecture hampers that even current. A suction bell, a kind of fluted tube, acts as the fluid entry point. If there's an obstruction here or a submergence depth flaw in the design, perhaps due to a low water level, then a vortex may form. That vortex (vortices if there's more than one) will attenuate pump fluid conductance. Simply put, that conical spiraling action is formed by certain low-pressure changes, and those changes spell trouble for the inlet side of the pump.

Vortex Breaking Mechanics

Logically, then, as these vortices extend downward, through the water, air is carried into the pump volute, at which point the impeller experiences restrictive movement. After all, the pump in your pool or water feature isn't designed to convey air, so that unwelcome system additive is compressed. The resulting chugging and overworked vibrational noise issued by the water pump suggests this bubbling gas is unpalatable, like the gas a child belches after a heavy meal. But it's not like we can burp the system, is it? Trapped air can be removed, but a little bit of good housekeeping avoids that troubleshooting procedure so that no headaches are set off by these manifesting vortex spirals. First of all, set a minimum submergence depth for the inlet pipe. Monitor that depth and make sure the fluid level doesn't drop low. Certain weather conditions, perhaps a week of hot and dry weather, will soon drop the water, but the inlet monitoring routine keeps track of such conditions so that corrective action can be initiated before the vortex phenomena make an early appearance.

Fluid baffles and vortex breakers introduce a "breaking up" stage to the pumping equipment. In short, the architecture in and around the inlet suppresses vortex formation. Still, even with the engineering solutions soundly in place, an inlet monitoring strategy works well as an important safety net, one that serves as a pump performance attenuation avoidance tool.

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