[National Qualifications You Can Aim For Even in Your 70s (8)] Let's Learn Representative Examples of Class 4 Hazardous Materials
So far, we have learned about the mechanisms of combustion, flash points, and ignition points.
Starting from this session, we will look at representative substances of "Class 4 Hazardous Materials," which are central to the Otsu-4 exam.
Class 4 hazardous materials cover flammable liquids among those defined by the Fire Service Act. Because they are common in our daily lives, this knowledge is important not only for the exam but also for practical work.
In this session, we will explain gasoline, kerosene, diesel oil, and alcohols, which appear on the exam with particularly high frequency.
Gasoline
Gasoline is classified as a Class 1 petroleum (water-insoluble).
Its most significant characteristic is its extremely low flash point of -40°C or below.
Therefore, it generates a large amount of flammable vapor even at room temperature, posing a risk of ignition from even minor ignition sources like sparks or static electricity.
Also, because gasoline vapor is heavier than air, it has a tendency to accumulate in low-lying areas such as floors or depressions.
Since vapor can flow far from the source of the fire and cause the flames to spread, extreme caution is required when handling it.
The reason you are instructed to touch a static electricity removal sheet at gas stations is to prevent this danger.
Kerosene
Kerosene is classified as a Class 2 petroleum (water-insoluble).
Its flash point is40°C or higher, making it less flammable than gasoline.
For this reason, it is widely used as fuel for household heaters and water heaters.
However, just because it is "harder to burn" does not mean it is "non-flammable."
There is a risk of ignition if it becomes hot or if a large amount is spilled, causing vapor to form.
For the exam, make sure to understand that while it is less dangerous than gasoline, it remains a hazardous material.
Diesel Oil
Diesel oil is also classified as a Class 2 petroleum (water-insoluble).
The flash point is 45°C or higher, and like kerosene, it has the property of being difficult to ignite at room temperature.
It is mainly used as fuel for diesel engines and is widely utilized in trucks, buses, and construction machinery.
Rather than memorizing the differences from kerosene in detail, it is easier to remember if you organize it as 'both are Class 2 petroleum products and are less flammable than gasoline'.
Alcohols
Alcohols are classified into an independent category called Alcohols among Class 4 hazardous materials.
Representative examples are ethanol and methanol.
The flash point of ethanol is approximately 13°C, and there is a risk of it igniting even at room temperature.
Furthermore, methanol is not only flammable but also highly toxic, and there is a risk of blindness or death if ingested.
In the Otsu-4 exam, you may be asked about the toxicity of methanol, so be sure to remember that as well.
Key points to remember for the exam
In this field, organizing the following content will lead to scoring points.
Gasoline is a Class 1 petroleum product (water-insoluble)
Kerosene and diesel fuel are Class 2 petroleum products (water-insoluble)
Alcohols are an independent category
Gasoline has an extremely low flash point and is the most dangerous
Gasoline vapor is heavier than air
Methanol is toxic
It is important to memorize the classification and characteristics as a set.
Conclusion
Class 4 hazardous materials is the field with the most questions in the Otsu-4 exam.
At first, it may feel like there is a lot to memorize, but it becomes easier to understand if you organize the information while comparing the characteristics of each substance.
First, make sure to firmly memorize these three points: "Gasoline is a Class 1 petroleum with a very low flash point," "Kerosene and diesel oil are Class 2 petroleums," and "Methanol is toxic."
Next time, I will explain the "designated quantities of hazardous materials." I will explain the concept of designated quantities and multiples stipulated by the Fire Service Act in an easy-to-understand manner, incorporating concrete examples.