Roking reconstructed existing machine and implemented automation, control and supervisory system with remote access for chemical dosing system on Neutralization plant at HBIS Serbia.

Scope of Work

Roking provided detailed and as-built electrical design, assembly, delivery and installation of electrical cabinet integrating Haiwell PLC, HMI and Frequency Convertors. Roking developed PLC and HMI application software for Polymer preparation unit and dosage pump systems for Sodium-chloride, commissioning of the system and training of personnel.


  • Increased concentration control of  the Polymer solution
  • Savings of chemicals
  • The reconstruction and replacement of electrical equipment increases the level of reliability of the whole system, as well as availability and flexibility
  • Remote supervision and parameters adjustment

Technical Description

The chemical preparation room is divided into two separate systems, a Polymer solution preparation unit and Sodium-chloride dosage system.
Polymer machine consists of a tank in which the solution is made by mixing powder and water. Desired percentage of solution is achieved by a system that feeds the powder through volumetric screw, driven by frequency converter, based on measured flow of incoming water to the tank during the refill. Water refill is activated/deactivated by a solenoid valve based on measured water level in the tank. Dosage of prepared solution is done by two pumps that are controlled by variable frequency drives which get reference based on the two independent measurements of water flow.
Sodium-chloride dosage system consists of two dosage pumps that get a reference based on measurements of pH values that go into PID regulators, whose output signal is a pump set point.

Polymer preparation system
Automation control cabinet

Daljinski pristup HMI-u

Remote access via Cloud