Nitto Kohki pumps and aerators provide efficient wastewater treatment and effective koi pond aeration


NITTO KOHKI pumps feature a unique, patent-awarded linear-motor-driven free piston system that is globally proven in the wastewater treatment and aquaculture industries. This unique design theory eliminates the wear components typically found in conventional air compressors and vacuum pumps, such as crank shafts, connecting rods and ball bearings. The only moving part is the piston! Also eliminated is the need for any lubrication. Fewer parts translate into fewer problems.

A silicone diode between the coils converts the alternating current sine wave into a half-rectified input. The result is a pulsating electro-magnetic field energizing the resonant spring-mass (piston). When the electro-magnet is energized, the intake stroke of the piston compresses the return spring and draws air into the cylinder through the inlet valve in the head of the piston. When the electro-magnet is de-energized, the spring releases and the compression stroke of the piston forces the compressed air out of the cylinder through the reed style outlet valve.



  • Low Noise Level
    The pumps operate at a very low noise level, about that of a light ballast, as there are no crankshafts, connecting rods or ball bearings to create additional noise.

  • Low power consumption
    With the piston as the only moving part, frictional losses are diminished which allows for lower starting and running current. Line current requirements are only 50-60% of that typically used by diaphragm pumps.

  • Automatic Pressure Adjustment
    Designed to self-adjust should the pressure exceed the rated value of the pump, the piston stroke will automatically shorten to reduce the strain on the pump. At the same time, power consumption of the pump will decrease to protect against possible increasing temperatures.

  • Self-cooling design
    Air drawn in through the intake valve over the coils reduces the temperature seen in the interior of the pump.

  • Easy Maintenance Providing maintenance on the pump is relatively easy with a completely oil-less design and no need for additional lubrication. Along with changing the filter as required, the only component to replace in the pump afte an extensive operating period is the piston.