NSA Series Aerators
Surface mechanical aerators fall into two categories: high-speed aerators and low-speed aerators.
• High-speed aerators use an electric motor to directly drive a pump impeller which pumps water up and sprays
it out horizontally. While this design is inexpensive, it has low oxygen transfer efficiency because the pump
impeller turns at higher-than-optimum aeration speed and wastes significant amounts of energy in moving
water faster than needed.
• Low-speed aerators are higher in efficiency than high-speed aerators because the aeration rotor operates near
the optimum aeration speed. However, low-speed aerators are more expensive because they must use a
gearbox to reduce motor speed to turn a large diameter aeration rotor. In addition, the gearbox is typically
mounted a few feet above the rotor and requires a long and large shaft with substantial supporting bearings.