FIPROPLUS 704

It may be sufficient to measure the pH value which will be carried out with a special device or with an indicator paper; the values ​​to be maintained depend on the mode of work and must vary between 10.5 and 12. A more exact control of the bath can be done by chemical titration according to the following method:
using a calibrated pipette, exactly 10 ml of bath are taken, diluted with 20-30 ml of demineralized water and added to 4-5 drops of green indicator solution of bromcresol. The liquid, which will take on a blue color, will be titrated with a 0.1 N hydrochloric acid solution until it changes from blue to yellow.
The n ° of ml of Acid used for the color change will correspond to the score of the bath whose concentration can be traced by consulting the following:

CONCENTRATION [g/l]          POINT [ml hydrochloric acid 0.1 N]

              5                                                            2,40

             10                                                           4,80

             15                                                            7,20

            20                                                            9,60

            25                                                            12,0

            30                                                            14,4

To obtain the concentration of the passivating agent, the n ° of ml of acid must be multiplied by the factor "2.08".
For the reconcentration of the bath it is necessary to add about 2.08 gr / lt for each point found less than the preset value. The alkalinity values ​​can be varied by the salinity of the water.