Dow Química has a chlor-alkali plant in Bahia, which uses brine as one of the raw materials for the process. To automate the brine pits, Dow looked for a solution that offered security in the event of system failure. The wells are scattered, with significant distances between them. In this case, pneumatic actuators, normally used in safe failure conditions, would represent an unfeasible alternative in terms of maintenance cost.
Each well uses three automated valves. The first injects water that dissolves the rock salt. The second injects the oil that keeps the well impermeable and prevents it from collapsing. The third valve controls the production of the well. In the event of an accident or power failure, all valves must be closed in order to isolate the well.
To perform the failsafe operation, Dow used 18 Skilmatic actuators models SI1 and SI2 from Rotork, which have an electro-hydraulic operating principle with spring return and guarantee safety for application in small valves. By keeping the hydraulic fluid in a closed circuit, Skilmatic prevents contamination of the solenoids and any possible jamming, making it a highly reliable solution. Its electronic command also allows the monitoring of valve availability through the "partial stroke".