In Japan, the Hazardous Materials Handler’s certification exam tests candidates on the common properties of hazardous materials classified into different categories. This knowledge is essential not only for passing the exam but also for implementing proper safety measures in the workplace. This article provides a detailed explanation of the chemical and physical properties common to the six categories of hazardous materials. By understanding this information, you can prepare for the exam and further develop your expertise as a Hazardous Materials Handler. Let’s take a closer look at the characteristics shared by hazardous materials in each category.
Properties of Hazardous Materials
The properties of hazardous materials can be organized into several categories as follows:
| Category | Property | State | Combustibility | Characteristics |
|---|---|---|---|---|
| Category 1 | Oxidizing solids | Solid | Non-combustible | Does not burn itself but burns violently when mixed with combustibles |
| Category 2 | Combustible solids | Solid | Combustible | Ignites at relatively low temperatures; may emit toxic gases |
| Category 3 | Spontaneously combustible substances Water-reactive substances | Solid Liquid | Combustible Partially non-combustible | Ignites spontaneously on contact with air Ignites or emits flammable gas upon contact with water |
| Category 4 | Flammable liquids | Liquid | Combustible | Ignores or explodes when mixed with air vapors |
| Category 5 | Self-reactive substances | Solid Liquid | Combustible | Reacts violently or emits heat when heated or shocked |
| Category 6 | Oxidizing liquids | Liquid | Non-combustible | Does not burn itself but enhances the combustion of other materials |
Each category of hazardous materials includes solids in categories 1 and 2, liquids in categories 4 and 6, and both forms in categories 3 and 5. Understanding this table should sufficiently equip you to tackle related questions.
Sample Exam Questions
Let’s look at some sample questions. Be aware that slight variations may occur, so practice by solving multiple questions to get accustomed to the format.
危険物の類ごとの性質として、次のうち正しいものはどれか。
(1) 第２類の危険物は、すべて引火性固体である。
(2) 第３類の危険物は、すべて自然発火性物質である。
(3) 第４類の危険物は、すべて引火性液体である。
(4) 第５類の危険物は、すべて酸化性液体である。
(5) 第６類の危険物は、すべて自己反応性物質である。
Which of the following statements about the properties of hazardous materials is correct?
(1) All Category 2 hazardous materials are flammable solids.
(2) All Category 3 hazardous materials are spontaneously combustible.
(3) All Category 4 hazardous materials are flammable liquids.
(4) All Category 5 hazardous materials are oxidizing liquids.
(5) All Category 6 hazardous materials are self-reactive substances.
危険物の類ごとに共通する一般的な性状について、次の うち妥当でないものはどれか。
(1) 第１類の危険物の多くは、無色または白色の酸化性固体である。
(2) 第２類の危険物は、燃焼により有毒ガスを発生するものがあり、金属粉は、水または酸の接触により発熱・発火のおそれがある。
(3) 第３類の危険物は、自然発火性と禁水性の両方の危険性を有している物質である。
(4) 第５類の危険物は、燃焼速度が極めて大きく、加熱、衝撃、摩擦 などにより発火・爆発のおそれがある。
(5) 第６類の危険物は、不燃性であるが酸化力が強く、多くは腐食性 があり、蒸気は有毒である。
Concerning the general properties shared by hazardous materials, which of the following statements is invalid?
(1) Many Category 1 hazardous materials are colorless or white oxidizing solids.
(2) Category 2 hazardous materials can emit toxic gases when burned, and metal powders may ignite or heat upon contact with water or acids.
(3) Category 3 hazardous materials have both spontaneously combustible and water-reactive dangers.
(4) Category 5 hazardous materials can ignite or explode from high combustion rates when heated, shocked, or subjected to friction.
(5) Category 6 hazardous materials are non-combustible but have strong oxidizing powers, many are corrosive, and their vapors are toxic.
危険物の類ごとに共通する性状にとして、次のうち誤っているものはどれか。
(1) 第１類の危険物は、加熱、衝撃、摩擦などにより分解し、容易に酸素を放出して可燃物の燃焼を助けるものが多い。
(2) 第２類の危険物は、微粉状にすると空気中で粉じん爆発を起こすものが多い。
(3) 第３類の危険物は、空気または水と接触することにより発熱し、可燃性ガスを発生して発火するものが多い。
(4) 第５類の危険物は、自ら酸素を含む自己燃焼性のものが多い。
(5) 第６類の危険物は、加熱、衝撃、摩擦などにより発火・爆発するものが多い。
Regarding the properties shared by hazardous materials, which of the following statements is incorrect?
(1) Many Category 1 hazardous materials decompose upon heating, shock, or friction, easily releasing oxygen to aid the combustion of combustibles.
(2) Finely powdered Category 2 hazardous materials can cause dust explosions in the air in the presence of an ignition source.
(3) Category 3 hazardous materials that are either spontaneously combustible or water-reactive generate heat or flammable gases upon contact with air or water.
(4) Many Category 5 hazardous materials contain oxygen and are self-combustible.
(5) Category 6 hazardous materials often ignite or explode upon heating, shock, or friction.
Conclusion
To pass the Japanese Hazardous Materials Handler’s certification exam, it is crucial to understand the unique properties of hazardous materials categorized by their types. This article has thoroughly explained the basic properties of hazardous materials classified in each category, illustrating how these properties directly relate to safety measures and accident prevention.
We hope that all candidates will use this information to successfully pass the certification exam and contribute to safer workplaces in Japan and beyond.
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