APPLICATIONS Heat Transfer Oils can be used in open installations where fuming of the oil could be a problem. Specific application ranges and advice are (temperature range for bulk fluids): -Closed systems: up to 300oC -Open systems: up to 160°C APPLICATION CONSIDERATIONS: Ideally Heat Transfer Oils should not be mixed with other oils since this may impair the excellent thermal and oxidation stability of the Heat Transfer Oils and may cause changes in other properties; thus complicating the interpretation of analyses made to determine the fluid’s useful life. If the fluid is used above the recommended maximum temperatures, vapor lock may result unless the system is designed to operate at the higher temperature by pressurizing with an inert gas such as nitrogen. However, at higher temperatures, fluid life will be shortened because the rate of thermal degradation increases markedly as temperatures rise above the recommended limit. In well-designed systems the temperature of the oil film surrounding the heating element should be about 15oC to 30oC above the bulk oil temperature. If higher than this, the service life of the fluid may be shortened and sludge and coke may be deposited, which would interfere with the heat transfer rates. As with other mineral oils, Heat Transfer Oils should be used only in systems with forced circulation. Systems that depend on convection for circulation of the heat transfer medium do not provide a rapid enough flow to prevent local overheating, resulting in a rapid deterioration of the fluid. Further, these fluids are not recommended for use in open systems where hot fluid is exposed directly to the air. If hot fluid sprays or escapes from leakage points, it may spontaneously ignite. Hi-Tec suggests that the equipment manufacturers’ recommendations for viscosity grade, performance requirements and general operating conditions should be checked prior to use.