A process for purifying a processing fluid comprising: introducing a feed stream comprising used processing fluid containing high vapour pressure components and low vapour pressure contaminants into a first separation zone, said first separation zone consisting of a vacuum flashing zone, wherein the temperature in said first separation zone is from about 121.11°C to 176.67°C (250°F to 350°F) and wherein the pressure in said first separation zone is from about 4.00 kPa to about 66.66 kPa (30 mm Hg to about 500 mm Hg); recovering a first stream comprising purified processing fluid and high vapour pressure components from said first separation zone, said first stream being drawn by a vacuum system through a condenser, wherein the first stream forms a liquid which accumulates in a receiving vessel; recovering a second stream comprising processing fluid and low vapour pressure contaminants from said first separation zone; combining a first portion of said second stream with the feed stream and passing the combined streams to the vacuum flashing zone via a steam heat exchanger operating at a temperature of about 121.11°C to 176.67°C (250°F to 350°F); subjecting a second portion of said second stream to a second separation zone, said second separation zone comprising an evaporator, wherein the temperature in said second separation zone is from about 148.89°C to about 204.44°C (300°F to about 400°F) and wherein the pressure in said second separation zone is less than about 3.33 kPa (25 mm Hg); recovering a third stream comprising purified processing fluid from said second separation zone and either discharging the third stream as a product stream or sending the third stream to the receiving vessel where it is mixed with the liquid formed from the first stream; recovering a fourth stream from said second separation zone, the fourth stream comprising low vapour pressure contaminants removed from the feed stream; wherein any low boiling, high vapour pressure components that are not condensed elsewhere in the process are drawn into the vacuum system, compressed in a compression station and introduced into a final product stream constituted by the purified processing fluid collected in the receiving vessel. introducing a feed stream comprising used processing fluid containing high vapour pressure components and low vapour pressure contaminants into a first separation zone, said first separation zone consisting of a vacuum flashing zone, wherein the temperature in said first separation zone is from about 121.11°C to 176.67°C (250°F to 350°F) and wherein the pressure in said first separation zone is from about 4.00 kPa to about 66.66 kPa (30 mm Hg to about 500 mm Hg); recovering a first stream comprising purified processing fluid and high vapour pressure components from said first separation zone, said first stream being drawn by a vacuum system through a condenser, wherein the first stream forms a liquid which accumulates in a receiving vessel; recovering a second stream comprising processing fluid and low vapour pressure contaminants from said first separation zone; combining a first portion of said second stream with the feed stream and passing the combined streams to the vacuum flashing zone via a steam heat exchanger operating at a temperature of about 121.11°C to 176.67°C (250°F to 350°F); subjecting a second portion of said second stream to a second separation zone, said second separation zone comprising an evaporator, wherein the temperature in said second separation zone is from about 148.89°C to about 204.44°C (300°F to about 400°F) and wherein the pressure in said second separation zone is less than about 3.33 kPa (25 mm Hg); recovering a third stream comprising purified processing fluid from said second separation zone and either discharging the third stream as a product stream or sending the third stream to the receiving vessel where it is mixed with the liquid formed from the first stream; recovering a fourth stream from said second separation zone, the fourth stream comprising low vapour pressure contaminants removed from the feed stream; wherein any low boiling, high vapour pressure components that are not condensed elsewhere in the process are drawn into the vacuum system, compressed in a compression station and introduced into a final product stream constituted by the purified processing fluid collected in the receiving vessel.