When you need to bring liquid up from a deep hole, such as pulling water from an aquifer, and you don’t have a lot of space – you need a centrifugal vertical turbine pump. These tall pumps are specifically designed to draw water straight up, which is quite the feat.
However, there is one key element that must be considered when implementing a vertical turbine pump: the minimum submergence. If this isn’t properly calculated and adhered to, the pump might only pull air.
What Is Minimum Submergence?
Minimum submergence describes how much water must be above the pump’s suction bell for it to be able to successfully draw in water continuously.
This is an issue because, if the pump is not inserted deep enough into the water, the suction it produces may create vortices instead. This vortex can draw down air from above the surface, pulling it straight into the pump. This, in turn, creates cavitation which can easily damage the internals of the pump, or at least reduce its operational efficiency.
The deeper the pump is, the less chance there is of vortices forming. Eventually, at a certain depth, that chance is effectively negated. This depth is minimum submergence.
How To Know The Minimum Submergence Of A Turbine Pump
The minimum submergence of a pump will vary from model to model, based on a wide variety of factors, including the intake size and pipe size, as well as the power of the turbines within. In most cases, the pump’s manufacturer will include its minimum submergence as part of its documentation, presented as part of its performance curve.
It’s also important that the submergence not be too deep. Having too much water above the pump will put additional pressure onto the mechanisms, effectively pushing water upwards into the pump. This might seem beneficial, but it actually reduces the net positive suction head – which is necessary to maintain steady pumping.
In addition, one other factor may affect the minimum submergence. If your pump relies on the water being pumped for cooling, there may be other pumping and suction requirements needed to maintain that effect.
Either way, always refer to your documentation before setting up a centrifugal vertical turbine pump, and ensure its submergence meets the minimum requirements.
FloRight Pump & Controls
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