Until its collection (often every 2 or 3 days), milk is stored at the farm in cooling tanks. After the collection, the tanks must be thoroughly cleaned to avoid the development of bacteria.

Most tanks have an automatic cleansing system, using hot and cold water combined with a variety of cleansing agents in acidic and basic solutions.

A centrifugal pump expels the cleansing solution on the inner walls of the tank, and then the water based rinsing solution, through a sprinkling mechanism.
The pump body must withstand high and low pH and also resist abrasion from sandy water often used in farms.

The sprinkling mechanism can be made part of the stirring mechanism. The cleansing solution thus flows through the hollow shaft of the gear motor, then fitted with a watertight washing unit (picture).