The Sigma 702ET Transformer Oil Analyzer is a standalone force tensiometer that provides accurate surface and interfacial tension measurements (Platinum Du Noüy ring, Platinum Wilhelmy Plate). It's easy to use and is up and running in minutes.

Features & Benefits

  • High precision microbalance and mechanics
  • Sigma 702ET is designed for oil-water interfacial tension measurements in accordance to the ASTM D971 and IEC standards. Its software is specifically designed to follow the measurement procedures defined in ASTM D971 for oil-water measurements.
  • Highly accurate motorized sample stages and an open design for convenient use
  • Stand-alone functionality without the need for an external computer


  • Quality control of transformer oil (ASTM D971)

Product details

The open design and convenient control keyboard operations makes the  Sigma 702ET extremely easy to use. Results are displayed on a large integrated digital screen. The instrument comes with data collection software and can be connected to an external computer for additional data storage and simple reporting.

Sigma 702ET is specifically designed for oil-water interfacial tension (IFT) measurements. The instrument is particularly suitable for IFT determinations of transformer oils and hydrocarbon fuels in accordance with ASTM D971 and IEC 60422 standards and comes with software designed for oil-water measurements. 

Sigma 702ET is typically used in the energy industry to check the interfacial tension between transformer oils and water.

Technical specifications

For a comparison chart, see:

Application examples

Application note ASTM D-971 Standard

ASTM D971 standard test method for interfacial tension of oil against water by the ring method

The ASTM D971 standard is used to determine the possible contaminants of hydrocarbon fluids. The purity of hydrocarbon fluids is important in many industrial areas, such as in aviation, diesel fuels and transformer oils.

It is well known that oil-water interfacial tension correlates with the purity and functionality of oils that are used in transformers for cooling, insulation and protection against arcing. Electrical stress and contamination may modify the oil performance. Sigma 702ET with a platinum Du Noüy ring can be used to control the oil quality according to ASTM D971-12 standard.