Oil & Gas

Relative Solubility Number

What is Relative Solubility Number (RSN)?

The RSN of a demulsifier is a measure of its solubility properties. The RSN test method determines the hydrophile-lipophile balance of the demulsifier under test by means of a water titration. The RSN is the volume of water (in millilitres) necessary to produce a persistent turbidity in the given solvent system. We have developed a novel method for determining the RSN of a demulsifier. This method offers substantial reductions in the risks to health, safety and the environment that was inherent in historic tests.

Demulsifier Product Range

Test method for determining RSN

Historic tests typically involved hazardous solutions of benzene and 1,4-dioxane. Our novel method utilises a solution of dimethylisosorbide (75%), butyl diglycol (20%) and xylene (5%), a much safer and environmentally friendly test method with the results generated being directly comparable to those generated by the historical method.

Interpreting RSN values

All values quoted are determined with a solvent stripped demulsifier.

Products with an RSN < 13 are insoluble in water
Products with an RSN 13-17 are water dispersible
Products with an RSN > 17 are soluble in water

How does this help when formulating?

Final demulsifier formulations contain several demulsifier components and all of our demulsifiers are suitable to be blended. Often final demulsifier formulations have an RSN between 8 and 15 and the synergistic effects of blends between different Croda demulsifiers chemistries offer performance benefits to using single components.