Blended transformer oil

Claim 1

AN IMPROVED TRANSFORMER OIL HAVING, WHEN TESTED IN THE ABSENCE OF INHIBITORS IN THE DOBLE OXIDATION TEST FOR ELECTRICAL INSULATING OILS, AN INTERFACIAL TENSION OF AT LEAST 15 DYNES PER CENTIMETER, A NEUTRALIZATION NUMBER LESS THAN 0.2, AND LESS THAN A TRACE OF SLUDGE AFTER 48 HOURS, CONSISTING ESSENTIALLY OF A BLEND OF 50-80 VOLUME PERCENT OF A HYDROFINED OIL BOILING IN THE RANGE OF 460* TO 775*F., HAVING AN API GRAVITY IN THE RANGE OF 27* TO 30*, A VISCOSITY AT 100*F. IN THE RANGE OF ABOUT 55 TO 60 SSU AND 50-20 VOLUME PERCENT OF AN ACID-TREATED OIL BOILING IN THE RANGE OF 460* TO 775*F. HAVING AN API GRAVITY IN THE RANGE OF 27* TO 30*, A VISCOSITY AT 100*F. IN THE RANGE OF 55 TO 60 SSU; SAID HYDROFINED OIL BEING PRODUCED BY CONTACTING A DISTILLATE BOILING IN THE RANGE OF 450* TO 900*F. FROM A NAPHTHENIC CRUDE WITH A HYDROFINING CATALYST AT A TEMPERATURE IN THE RANGE OF 550* TO 650*F. AND A FEED RATE IN THE RANGE OF 1 TO 3 V./V./HR. IN THE PRESENCE OF ABOUT 500 TO 900 S.C.F./BBL. OF FREE HYDROGEN FOLLOWED BY TREATING THE OIL SO HYDROFINED WITH IN THE RANGE OF 0.6 TO 1 LB./GAL. OF AN ABSORBENT CLAY AT A TEMPERATURE IN THE RANGE OF 250* TO 300*F., AND SAID ACID-TREATED OIL BEING PRODUCED BY TREATING AT A TEMPERATURE IN THE RANGE OF 85 TO 105*F. A DISTILLATE BOILING IN THE RANGE OF 450* TO 900*F. FROM A NAPHTHENIC CRUDE WITH 0.5 TO 1.0 LB./GAL. OF SULFURIC ACID HAVING A CONCENTRATION IN THE RANGE OF 96-105% AND RECOVERING THE ACID TREATED OIL IN YIELDS IN THE RANGE OF 97 TO 98 VOLUME PERCENT AND FURTHER TREATING IT BY NEUTRALIZATION, STEAMING AND CLAY PERCOLATION WITHIN THE RANGE OF 0.6 TO 1.0 LB./GAL. OF AN ABSORBENT CLAY AT A TEMPERATURE IN THE RANGE OF 80* TO 105*F.