Use CasesStable operation during normal operation and countermeasures against unexpectedly strong rain

Liquid Type
Process Type


Local government (sewage treatment plant)

Customer's Needs and Problems

After precipitation and filtration, the water flows in a waterway. The flow rate of this waterway is measured, and the required amount of sodium hypochlorite is injected.
A diaphragm pump is used and dual control—stroke length control and control of the number of rotations—is performed, which posed the following problem.

  • If operation is performed with a reduced stroke length when the treated volume is small, injection defects occur due to gas lock (biting air).

TACMINA's Solutions

The pump was replaced with a Smoothflow Pump.

  • A wide range at up to 1:200 is supported just by controlling the number of rotations, which makes it possible for a single pump to handle both normal operation and strong rain.
  • No stroke length control is performed, so gas lock no longer occurs even with a low flow rate.