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This post was last edited by A Le on 2015-6-25 10:01. Basic parameters of heat transfer oil: 1. Density – The density ρ of heat transfer oil is 0.85 g/cm3; the total volume... Density is a physical and chemical parameter that reflects the composition of the product, and it has no relation to its heat transfer properties. 2. Viscosity and dynamic viscosity: Viscosity index of 120; viscosity variation not exceeding 15%; residue carbon not exceeding 1.5%; acid value not exceeding 0…. Dynamic viscosity: at 40°C. Viscosity is the most fundamental property of heat transfer oils, and it is generally expressed in terms of dynamic viscosity. The dynamic viscosity of heat transfer oil indicates the fluid’s resistance to motion, and it determines the fluidity and pumpability of the liquid at a given temperature. There is no strict limit on the kinematic viscosity required for heat transfer oils; different types and grades of heat transfer oils can have varying values. Viscosity varies depending on the oil’s boiling range and the degree of refinement. During use, changes in viscosity can be used to determine the degree of deterioration of the oil; a change of more than 20% indicates that the condition of the heat transfer oil warrants attention or that it should be discarded. 3. Freezing point: The freezing point refers to the highest temperature at which, under specified test conditions, the oil in the test tube is cooled and tilted at 45 degrees; after one minute, the oil surface no longer moves. The freezing point and low-temperature viscosity determine the low-temperature fluidity of heat transfer oil. The freezing point of low-viscosity base oils in our country is generally between -9 and -15°C, which is sufficient to meet the needs of areas south of the Yellow River; for frigid regions, heat transfer oils with a lower freezing point should be used. 4. Flash point: There are open and closed flash points. The flash point is a safety parameter for heat transfer oil, indicating the likelihood of the oil catching fire or exploding when exposed to an open flame or static electricity during operation. Generally, the flash point of heat transfer oils is above 180°C. Flash point and auto-ignition point: The flash point refers to the lowest temperature at which a mixture of oil vapor and air will continue to ignite when in contact with a flame. The flash point is determined by heating the oil under specified conditions; as the oil temperature rises, the concentration of oil vapor increases. The lowest temperature at which the oil vapor reaches a combustible concentration and ignition occurs when it comes into contact with a flame is known as the flash point of that oil. Flash points are divided into open and closed types. The flash point is a safety parameter for heat transfer oil, indicating the likelihood of the oil catching fire or exploding when exposed to an open flame or static electricity during operation. Generally, the flash point of heat transfer oils is above 180°C. 5. Ignition point and auto-ignition point: The ignition point of heat transfer oil is generally above 240 degrees, while its auto-ignition point is around 360 degrees. Although the flash point, ignition point, and auto-ignition point of heat transfer oil are relatively high, it still remains a flammable substance with strong permeability. Due to its high temperature and proximity to flames, when an adequate amount of oil vapor leaks or seeps out in the circulation system of the heat transfer oil furnace, it can catch fire or ignite spontaneously, leading to a fire.