Main indexes and meanings of heat transfer oil

Main indexes and meanings of heat transfer oil
1. Flash point
Flash point refers to heating oil products under specified conditions. With the increase of oil temperature, the concentration of oil vapor increases accordingly. When the content of oil vapor reaches the combustible concentration, the lowest temperature when the oil vapor moves into the flame to flash is called the flash point of oil products.
The flash point can be divided into open and closed.
2. Density
Density is a physical and chemical index reflecting product composition, independent of its heat transfer performance.
3. Freezing point
The freezing point refers to the highest temperature when the oil in the test tube is cooled and tilted 45 ° under specified test conditions, and the oil level cannot move after one minute. The freezing point and low-temperature viscosity determine the low-temperature fluidity of heat transfer oil. The freezing point index of low viscosity base oil in China is generally - 9 - 15 ℃, which can basically meet the needs of the areas south of the Yellow River. For high cold areas, heat transfer oil with lower freezing point should be selected.
4. Viscosity and kinematic viscosity
Viscosity is the most basic property of heat transfer oil, generally expressed as kinematic viscosity.
The kinematic viscosity of heat transfer oil indicates the kinematic resistance of the liquid, which determines the fluidity and pumpability of the liquid at a certain temperature. There is no strict limit for the kinematic viscosity of heat transfer oils. Heat transfer oils of different types and brands can be different.
The viscosity varies with the distillation range and refining depth of the oil. During use, the deterioration of the oil is judged by the viscosity change. If the viscosity exceeds 20%, the deterioration of the heat transfer oil should be paid attention to or scrapped.
5. Moisture
The fully processed heat transfer oil does not contain water. If it contains water, the oil will be turbid or emulsified. Generally, the water in the heat transfer oil is the trace.
Flash point is the safety performance index of heat transfer oil, indicating the possibility of combustion or flash explosion of heat transfer oil when encountering open fire or static electricity during operation. Generally, the flash point of heat transfer oil is above 180 ℃.
6. Ignition and autoignition points
The ignition point refers to the temperature point at which the mixed gas formed by oil vapor and air flashes continuously for more than 5 seconds when contacting with the flame. The self ignition point refers to the temperature point at which oil vapor can combust without contacting the flame. The ignition point of the oil is higher than the flash point and lower than the spontaneous ignition point. The ignition point and natural point are also safety indicators of oil products. The ignition point of heat transfer oil is generally above 240 degrees, and the natural point is above 360 degrees.
7. Copper corrosion
Corrosion is to guide the corrosion degree of the corrosive substances contained in the hot oil to the metal copper sheet caused by the oxides in the oil under the test conditions.
Copper strip corrosion of heat transfer oil refers to the copper strip corrosion grade 1 at 100 ℃ for 3h.
Copper corrosion of heat transfer oil also reflects the refining depth of base oil and the grade of oil products. Unqualified corrosion can basically indicate that the oil products are defective.
8. Sulfur content
The sulfur content is related to the refining depth of the product. If the sulfur content of heat transfer oil is high, the equipment may be corroded during use.
9. Neutralization value or acid value
The neutralization value or acid value of heat transfer oil refers to the milligrams of potassium hydroxide required to neutralize acidic substances in 1g oil. The acid value is the sum of organic acids and inorganic acids.
The acid content can be judged according to the neutralization value and acid value. The higher the value, the more acidic substances in the oil. It is also one of the main indicators for judging the oxidative deterioration of heat transfer oil.
10. Chlorine content
The chlorine content is related to the toxicity of the product. Chloride has a strong teratogenicity, and the index is not greater than 0.01%.
11. Carbon residue
Carbon residue refers to the black residue left after the heat transfer oil evaporates, decomposes and cokes when it is heated without air, and the burning gas is discharged, expressed in weight percent.
Carbon residue is an index reflecting the refining depth of base oil. Products with high carbon residue have high content of heavy components such as polycyclic aromatic hydrocarbons, dark color and poor thermal stability.
The carbon residue also reflects the degree of coking of the heat transfer oil under thermal oxidation conditions, and can also judge the deterioration of the heat transfer oil. If the carbon residue exceeds 1.5%, it indicates that the oil is scrapped.
12. Distillation range
Distillation range reflects the width of boiling range of heat transfer oil. The narrower the distillation cutting range is, the better the thermal stability is.