2- Salt or surface purges
The former category are aimed at controlling the deposits of the heaviest dissolved substances which sink to the bottom, and the latter at avoiding an excessive concentration of salts in the water that has to travel around the circuit. Both types of purges are automatic, and those in the second category are usually continuous, or in other words, the amount of dissolved substances in the boiler water is controlled.
Dispersants to prevent build-ups of sludge or silt are available.
ATTSU manufactures and installs boilers equipped with both types of blowdown installations.