[Q&A Question 274] 2017.10.02

I) Flash point: It refers to the lowest temperature, expressed in °C, at which, under specified heating conditions and with the flame passing over the mixture of vapors emitted by the oil and air at regular intervals, ignition of the oil surface occurs. The flash point of a fuel indicates its flammability, the content of volatile compounds, the degree of vaporization, and its safety level. The hazard classification of fuels is also determined based on their flash point. Oils with a flash point below 61°C are flammable, while those with a flash point above 61°C are combustible. It is prohibited to heat the oil to its flash point during storage, transportation, and use; the maximum heating temperature should generally be 20–30°C below the flash point. There are two methods for determining the flash point of oils: the closed-cup method and the open-cup method. The main difference between the two is that in a closed-cup flash point apparatus, the oil vapor is heated inside a sealed container, whereas in an open-cup flash point apparatus, the oil vapor can freely disperse into the surrounding air. As a result, the flash point values obtained using these two instruments for the same oil are different; the higher the flash point of the oil, the greater the difference between the two values. The closed-cup method is used to determine the flash point of fuels and light oils, while the open-cup method is used to determine the flash point of heavy oils. (II) Ignition point: Also known as the flash point, it refers to the lowest temperature at which, under specified heating conditions and when the oil is brought near a flame, it not only flashes but also continues to burn for more than 5 seconds. The ignition point is generally 0–20°C higher than the flash point. (III) Autoignition point: The lowest temperature at which, after heating the oil to a very high temperature and exposing it to air, the oil begins to burn spontaneously due to intense oxidation under certain ignition conditions is known as the autoignition point. The main difference between the autoignition point and the flash point and ignition point is that no ignition source is required for the former, whereas the latter requires an external fire source to be ignited. The auto-ignition temperature of all petroleum products is much higher than that at room temperature; however, when hot oil leaks from connections such as pipe fittings and flanges and comes into contact with air, it can often cause a fire on its own. Among various types of oils, the lighter the oil, the lower its flash point and ignition point, while its auto-ignition point is higher.

Flash point: It refers to the lowest temperature, expressed in °C, at which, under specified heating conditions and by passing a flame over the mixture of vapors emitted from the oil and air at regular intervals, ignition of the oil surface occurs. The flash point of a fuel indicates its flammability, the content of volatile compounds, the degree of vaporization, and its safety level. The hazard classification of fuels is also determined based on their flash point. Oils with a flash point below 61°C are flammable, while those with a flash point above 61°C are combustible. It is prohibited to heat the oil to its flash point during storage, transportation, and use; the maximum heating temperature should generally be 20–30°C below the flash point. Ignition point: Also known as the flash point, it refers to the lowest temperature at which, under specified heating conditions and when the oil is brought close to a flame, it not only flashes but also continues to burn for more than 5 seconds. The ignition point is generally 0–20°C higher than the flash point. Autoignition point: It is the lowest temperature at which, after heating a petroleum product to a very high temperature and exposing it to air, the product ignites on its own due to intense oxidation under various ignition conditions; this temperature is known as the autoignition point. The main difference between the autoignition point and the flash point and ignition point is that no ignition source is required for the former, whereas the latter requires an external fire source to be ignited. Flash point, ignition point, and autoignition point are safety indicators for oils.

Flash point: It refers to the lowest temperature, expressed in °C, at which, under specified heating conditions and by passing a flame over the mixture of vapors emitted from the oil and air at regular intervals, ignition of the oil surface occurs. The flash point of a fuel indicates its flammability, the content of volatile compounds, the degree of vaporization, and its safety level. The hazard classification of fuels is also determined based on their flash point. Ignition point: Also known as the flash point, it refers to the lowest temperature at which, under specified heating conditions and when the oil is brought close to a flame, it not only flashes but also continues to burn for more than 5 seconds. The ignition point is generally 0–20°C higher than the flash point. Ignition point: The lowest temperature at which, after heating a petroleum product to a very high temperature and exposing it to air, it begins to burn spontaneously due to intense oxidation under certain ignition conditions is known as the autoignition point. The main difference between the autoignition point and the flash point and ignition point is that no ignition source is required for the former, whereas the latter requires an external fire source to be ignited. The auto-ignition temperature of all petroleum products is much higher than that at room temperature; however, when hot oil leaks from connections such as pipe fittings and flanges and comes into contact with air, it can often cause a fire on its own. Among various types of oils, the lighter the oil, the lower its flash point and ignition point, while its auto-ignition point is higher.

1. Flash point: A flammable liquid can evaporate into vapor and enter the air. As the temperature rises, vaporization accelerates. When a mixture of volatile vapor and air comes into contact with a fire source and sparks are generated, this brief combustion process is called flash ignition, and the lowest temperature at which flash ignition occurs is known as the flash point. From a fire safety perspective, the flash point of a liquid is the lowest temperature at which it can cause a fire. The lower the flash point, the greater the risk of fire. 2. Ignition point: Whether in solid, liquid, or gas form, combustible substances will burn when in contact with an ignition source once a certain temperature is reached, even after the ignition source is removed. At this point, the lowest temperature at which a combustible substance can burn is called the ignition point, or burning point. Generally, the ignition point of liquids is higher than their flash point; for flammable liquids, the ignition point is 1–5°C higher than the flash point. 3. Spontaneous combustion: Under normal conditions, when common combustible materials come into contact with air, a slow oxidation process occurs; however, this process is very slow, and little heat is generated. Meanwhile, heat is continuously dissipated into the surrounding environment, so no light is produced as in the case of combustion. If the temperature rises or other conditions change, the oxidation process accelerates, generating more heat. If this heat cannot be dissipated entirely, it accumulates, causing the temperature to rise gradually. When it reaches the temperature at which this substance burns on its own, it will ignite spontaneously; this is known as spontaneous combustion. The lowest temperature at which a substance catches fire on its own when heated is known as its autoignition point, or autoignition temperature.

The flash point is the lowest temperature at which the vapor surrounding the fuel surface can be ignited; the ignition point is the lowest temperature at which a substance burns; and the auto-ignition point is the lowest temperature at which a substance burns on its own without being ignited.

Answer: The flash point is the temperature at which a fuel, when heated in a container of specified design, releases flammable gases that mix with the air near the liquid surface; when this mixture reaches a certain concentration, it can be ignited by a spark. The ignition point is the lowest temperature at which a substance begins to burn and continues to burn when heated in air. The minimum temperature at which a combustible material can catch fire spontaneously is known as the autoignition temperature. Put simply, the flash point is the lowest temperature at which vapor around the fuel surface can catch fire; the ignition point is the lowest temperature at which a substance burns; and the auto-ignition point is the lowest temperature at which a substance burns on its own without being ignited. Different oil types have different combustion parameters, and these parameters also change when the oils are mixed together.

Flash point: It refers to the lowest temperature, expressed in °C, at which, under specified heating conditions and by passing a flame over the mixture of vapors emitted from the oil and air at regular intervals, ignition of the oil surface occurs. Ignition point: Also known as the flash point, it refers to the lowest temperature at which, under specified heating conditions and when the oil is brought close to a flame, it not only flashes but also continues to burn for more than 5 seconds. Autoignition point: It is the lowest temperature at which, after heating a petroleum product to a very high temperature and exposing it to air, the product ignites on its own due to intense oxidation under various ignition conditions; this temperature is known as the autoignition point. The main difference between the autoignition point and the flash point and ignition point is that no ignition source is required for the former, whereas the latter requires an external fire source to be ignited. The auto-ignition temperature of all petroleum products is much higher than that at room temperature; however, when hot oil leaks from connections such as pipe fittings and flanges and comes into contact with air, it can often cause a fire on its own. Among various types of oils, the lighter the oil, the lower its flash point and ignition point, while its auto-ignition point is higher.

(1) Flash point: Refers to the lowest temperature, expressed in °C, at which, under specified heating conditions and by passing a flame over the mixture of vapors emitted from the oil and air at regular intervals, ignition of the oil surface occurs. (II) Ignition point: Also known as the flash point, it refers to the lowest temperature at which, under specified heating conditions and when the oil is brought near a flame, it not only flashes but also continues to burn for more than 5 seconds. (III) Autoignition point: The lowest temperature at which, after heating the oil to a very high temperature and exposing it to air, the oil begins to burn spontaneously due to intense oxidation under certain ignition conditions is known as the autoignition point. The ignition point is generally 0–20°C higher than the flash point. The main difference between the autoignition point and the flash point and ignition point is that no ignition source is required for the former, whereas the latter requires an external fire source to be ignited. The lighter the oil, the lower its flash point and ignition point, while its autoignition point is higher.

The flash point is the temperature at which a fuel, when heated in a container of specified design, releases flammable gases that mix with the air near the liquid surface; when this mixture reaches a certain concentration, it can be ignited by a spark. The ignition point is the lowest temperature at which a substance begins to burn and continues to burn when heated in air. The minimum temperature at which a combustible material can catch fire spontaneously is known as the autoignition temperature. Put simply, the flash point is the lowest temperature at which vapor around the fuel surface can catch fire; the ignition point is the lowest temperature at which a substance burns; and the auto-ignition point is the lowest temperature at which a substance burns on its own without being ignited. Different oil types have different combustion parameters, and these parameters also change when the oils are mixed together.

(1) Flash point: Refers to the lowest temperature, expressed in °C, at which, under specified heating conditions and by passing a flame over the mixture of vapors emitted from the oil and air at regular intervals, ignition of the oil surface occurs. The flash point of a fuel indicates its flammability, the content of volatile compounds, the degree of vaporization, and its safety level. The hazard classification of fuels is also determined based on their flash point. Oils with a flash point below 61°C are flammable, while those with a flash point above 61°C are combustible. It is prohibited to heat the oil to its flash point during storage, transportation, and use; the maximum heating temperature should generally be 20–30°C below the flash point. There are two methods for determining the flash point of oils: the closed-cup method and the open-cup method. The main difference between the two is that in a closed-cup flash point apparatus, the oil vapor is heated inside a sealed container, whereas in an open-cup flash point apparatus, the oil vapor can freely disperse into the surrounding air. As a result, the flash point values obtained using these two instruments for the same oil are different; the higher the flash point of the oil, the greater the difference between the two values. The closed-cup method is used to determine the flash point of fuels and light oils, while the open-cup method is used to determine the flash point of heavy oils. (II) Ignition point: Also known as the flash point, it refers to the lowest temperature at which, under specified heating conditions and when the oil is brought near a flame, it not only flashes but also continues to burn for more than 5 seconds. The ignition point is generally 0–20°C higher than the flash point. , }7 M4 A’ y& ?9 e9 h$ b2 N (III) Auto-ignition temperature: The lowest temperature at which, after heating the oil to a very high temperature and exposing it to air, the oil begins to burn spontaneously due to intense oxidation under certain ignition conditions is known as the auto-ignition temperature. The main difference between the autoignition point and the flash point and ignition point is that no ignition source is required for the former, whereas the latter requires an external fire source to be ignited. The auto-ignition temperature of all petroleum products is much higher than that at room temperature; however, when hot oil leaks from connections such as pipe fittings and flanges and comes into contact with air, it can often cause a fire on its own. Among various types of oils, the lighter the oil, the lower its flash point and ignition point, while its auto-ignition point is higher.