kevlar49
Materials
- Jun 1, 2006
- 287
I am trying to develop a test method for an alkaline cleaning detergent. The cleaner is in a heated spray booth and is used to clean oily metal parts for heat treating. The test method I am trying to employ involves titrating a with dilute phosphoric acid. I am trying to control when I replace or refresh the solution by using the ratio of free alkalinity to total alkalinity. I determine the free alkalinity by titrating to about 8.7 or the change from pink to clear with a phenolphthalein (p end point) and the total alkalinity by tirtating to about 3.9 or the color change of yellow to orange with methyl orange (m end point). The ratio is calculated by dividing the difference between the starting and the p end point by the difference between the starting and the m end point. The problem I am having with this cleaner, EC81, is that I will take some of the solution from the bath and add detergent, heat it up but get a lower ratio than what I started with. Wouldn't you expect the free alkalinity to rise instead of fall? Can someone explain what I am doing wrong?
