Method of control
Restore the volume of the tank to its original level, if necessary, by adding water. Thoroughly mix and take a sample of 100-200ml. After allowing to cool to ambient, add active carbon, stir and allow to stand for 30 minutes. Filter solution through a Whatman No1 paper until about 100ml is obtained. Pipette 25ml into a 250ml volumetric flask. Make up to the mark with distilled water. Pipette 10ml of this solution into an Erlenmeyer flask and add 5-10 drops of Indicator No.13. Titrate against Testing solution No.9 until the blue colour is discharged leaving a pale yellow-green solution. Record the volume used as (V)ml.
The bath strength is calculated as follows:
Measured strength (%v/v RXSOL1854) = V x 1.18
Record this as (MS).
If the bath is below the required strength, add further RXSOL 1854 according to the following:
Volume RXSOL 1854 required = (CR – MS) ÷ (1 – (CR x 0.01)) x (TV ÷ 100)
Where CR = concentration required (%v/v).
TV = volume RXSOL 1854 solution in tank
MS = measured strength.
Effects on materials :
RXSOL 1854 is safe to use on all Ferrous Alloys but it will rapidly attack aluminium, zinc and tin. There is a negligible effect on magnesium, cadmium, nickel, cobalt, titanium and their alloys. Slight attack on copper may occur. Glass and ceramics will be etched by RXSOL 1854. Polythene, PVC and PTFE are substantially unaffected but degradation of some plastics and rubbers is possible.