Interfacial Tension (IFT) :
The Interfacial Tension (IFT) is determined by means of Tensiometer, in which force necessary to detach a planar ring of platinum wire from the surface of the liquid of higher surface tension, i.e. upward from the water-oil interface is measured. The Interfacial Tension between oil and water provides a means of detecting soluble polar contaminants and products of deterioration in insulating oil. Interfacial Tension of insulating oil is expressed in mN/m.