pH is the degree of acidity and alkalinity of the aqueous solution. When pH 7.0 is neutral, it becomes acidic as it goes below it, and alkalinity increases as it goes above it. Most of the water-soluble oils are slightly alkaline, pH 8.5 to 9.0.
pH control with appropriate threshold is important The general environment in which water-soluble oils is used is in favorable conditions for microorganisms (bacteria, yeast, molds) to propagate. Proliferation of microorganisms decay oil and causes processing defects. In addition, processed parts and machine tools will rust due to deterioration of rust prevention. In addition, some microorganisms emit serious putrefaction odor, causing deterioration of work environment inside the factory. Proliferation of microorganisms is likely to occur in solutions that are weakly acidic to weakly alkaline, and as decay progresses, pH will decrease, which is an indicator of management. At the same time, high pH is not good either. The skin can be affected by alkaline state, oils with a high pH tend to cause dermatitis.
Managing pH in hydraulic fluid (water-glycol type). In the case of fresh oil, the pH is 10.0 and pH 9.0 to 11.0 is appropriate. When it falls below pH 9.0, deterioration starts. The lower the pH value is, the more degradation progresses.