The intake chamber is often referred to as a pump sump. It is a collecting chamber situated directly upstream of a centrifugal pump, through which the fluid handled, usually water, flows towards the pump. This ensures that the approach flow towards the centrifugal pump is evenly balanced on all sides and free of turbulence (see Inlet conditions). Such a smooth, disturbance-free approach flow is indispensable for high specific speed tubular casing pumps with propellers or mixed flow impellers because these pumps respond immediately to irregularities and disturbances in the approach flow. A simple intake chamber design is all that is required to avoid damage from cavitation and vibrations, and a possible drop in pump power output or pump efficiency caused by irregular approach flows. The risk of air-entraining vortices being sucked in from the water surface is avoided by ensuring that water levels in the intake chamber are sufficient.
The required excavation depth depends on the intake chamber's design and shape. See Fig. 1 Intake chamber
Intake chambers have a simple structural shape with a rectangular floor plan. A comparison of the four different intake chamber designs reveals that, given an identical flow rate, design variant I requires the highest minimum water level, variant IV the lowest. The designs I, II and III are open intake chambers suitable for axially parallel approach flow. Design variant IV with a splitter is also suitable for perpendicular approach flow. In the case of complex inlet conditions, model tests are advisable.
A disturbance-free approach flow can also be achieved using intake elbows. Economic efficiency should be calculated when deciding whether an intake chamber should be provided. They are often built for vertical cooling water pumps.
In power stations, operational reliability is of crucial importance for pump availability. The intake chamber therefore represents a structural unit which must be designed and built with great care.
Intake chambers are also employed in irrigation and drainage stations where simple designs can significantly reduce construction costs