Type ONW or Type OFW?

Unifin's first introduction to transformer cooling problems was more than half a century ago. It began by supplying coiled tube assemblies which were placed inside transformer tanks. Unifin's initial expertise was the manufacture of "Integral Finned Tube" which when applied to tank coolers meant increased capacity over formerly plain tube coolers. A smaller cooler resulted and the transformer rating was often increased. The internal ONW was born and Unifin's developing leadership in transformer cooling was started.

Industry advances meant higher ratings. Tank coolers were too small so the demand for a larger capacity external water operated cooler with natural oil convention was created. Unifin designed and tested prototypes and developed ratings for a series of sizes designated "Type ONW". Industry requirements for maximum safety led to Unifin's development of the Double Concentric Tube which combined with Double Tubesheets yield what Unifin calls its "Leak Detector Design". The ONW's latest format continues in use today.

Unifin developed its "Type OFW" for larger transformers using forced oil flow and water cooling. Combined with its "Leak Detector Tube" the "OFW" continues to forge industry leadership in transformer cooling.

The table below will help you select which alternative you require.

*A.S.M.E. Code Construction Available