Definition of wet flammable substances
Wet flammable substances are sometimes referred to as water-repellent substances.
Definition: Water, humid air, and hydrated substances can react violently, releasing flammable gases and a large amount of heat, causing combustion, explosion, or formation of explosive mixed gases, resulting in dangerous substances.
What are the wet flammable substances? How to classify?
Including: Na, K, CaC2 (calcium carbide), Ca3P2 (calcium phosphide), CaO (lime), NaNH2 (sodium amide), LiAlH4 (lithium aluminum hydride), HCl3Si (trichlorosilane), NaBH4 (sodium borohydride) Wait.
1, the first level of water flammables
The reaction with water is fierce and it is easy to cause spontaneous combustion or explosion, which is very dangerous.
2, the second level of water-burning substances
When it is in contact with water or acid, the reaction speed is relatively flat and can cause burning or explosion, but it does not often cause spontaneous combustion or spontaneous explosion.
3. Other water inflammables
Sodium peroxide, potassium peroxide, sodium hydroxide, potassium hydroxide, fuming sulfuric acid, chlorosulfonic acid, phosphorus trichloride, titanium tetrachloride, tin tetrachloride, anhydrous aluminum trichloride, quicklime, etc. When reacted with water, a large amount of heat is released, causing nearby organic matter and combustibles to burn and ignite.
Note: Not limited to the above examples!
Liquid sodium accident in Japan's nuclear power plant
Monjyu is Japan's first proliferating nuclear reactor, using a full-scale high-speed proliferation test furnace. In 1995, a major accident of liquid sodium leakage fire occurred.
Note: High-speed proliferation furnaces use helium as a nuclear fuel. Radon is a radioactive substance that does not exist in nature and is toxic and carcinogenic. It can generate huge energy when it splits, so it is suitable for making nuclear bombs.
Ordinary nuclear power plants have pure water as the coolant, but the high-speed proliferation furnace must use the highly dangerous liquid sodium to achieve the cooling effect. Wenshu furnace stopped for about 15 years after the accident.
Precautions for storage of wet flammable substances
1 sodium potassium should be placed in liquid paraffin or kerosene to seal and preserve
A substance such as sodium or potassium metal reacts with water, which releases hydrogen gas and causes combustion or explosion. Therefore, the sodium and potassium of the metal should be cut into small pieces and placed in liquid paraffin or kerosene to be sealed and stored.
When dissolving sodium metal, it can be put into ethanol to react, but care should be taken to prevent the generated hydrogen from catching fire.
When the metal potassium is decomposed, the same operation is carried out under the protection of nitrogen.
Of particular note is that its debris is also stored in liquid paraffin or kerosene.
For example, the scrap of metal sodium and potassium is not recycled in time due to the operator's inattention, and reacts with water or moisture to cause combustion.
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2 Pay attention to the danger of calcium carbide reacting with water
Calcium carbide reacts with water to produce acetylene, which can cause fire and explosion.
For example, when acetylene gas is produced in the laboratory, the acetylene gas collected in the collection bottle is impure and often explodes.
3 pay attention to the danger of sodium potassium and halide reaction
Metals such as sodium or potassium react with halides and can explode.
4 Note the danger of calcium phosphide reacting with water
Calcium phosphide reacts with water to release phosphine (PH3 is a highly toxic gas), which is accompanied by the release of pyrophoric P2H4, which causes combustion or explosion.
5 pay attention to the correct disposal of metal hydride
The action of the metal hydride with water (or water vapor) also burns. If it is discarded, it can be injected into ethyl acetate in small portions (the opposite operation is not possible).
6 Pay attention to the danger of exothermic reaction between quicklime and water
Quicklime (calcium oxide) acts with 1/3 of the weight of water, although it can not catch fire, but generates a lot of heat to raise the temperature to 150-300 ° C or higher, enough to cause the wooden barrel or covered tarpaulin to catch fire, or Other flammable substances around the fire.
7 Wear gloves and tweezers during operation
When using water-like flammable substances, wear protective gloves or use tweezers. It is not advisable to take them directly by hand, especially wet hands.
Potassium is very corrosive to the skin.
8 What should I do if the flammable substance in the water catches fire?
When fire is caused by water flammable substances, it can be saved with soda powder, dry sand, dry powder of sodium carbonate, dry powder of calcium carbonate, graphite powder, vermiculite powder, dry soil, salt or soda ash.
Avoid using water, moist things, foam, carbon dioxide fire extinguishers or halogenated hydrocarbon fire extinguishers.
9 What should you pay attention to when storing flammable substances in water?
1 Store in a dry place, pay attention to waterproof and moisture proof;
It is strictly forbidden to set up water source in 2 rooms;
3 with acid, oxidant, halogen, etc. to be divided into storage and transportation;
4 Do not store with flammable materials;
5 to prevent impact, vibration, friction;
6 Smoking is strictly prohibited, and heat sources and fire sources are strictly prohibited;
7 For flammable solids, special attention should be paid to dust explosion.
The most common preservation of metallic sodium
It is often immersed in liquid paraffin, mineral oil and benzene to be stored in a sealed form.
Metallic sodium with high purity requirements cannot be stored in kerosene because sodium reacts with organic acids such as kerosene to form a substance such as sodium silicate (yellow) attached to the surface of sodium.
Metallic sodium with high purity requirements cannot be stored in paraffin oil because oxygen in the air enters paraffin oil, causing the surface of metallic sodium to become gray and form an oxide film.
It can be stored in a small amount of sodium with low purity requirements, soaked in kerosene or stored in liquid paraffin. Under normal circumstances, the preservation of sodium in laboratory preservation, the purity is not high.
A large amount is usually stored in an iron drum and sealed with argon gas.
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10 water flammable substances encounter acid or oxidant, the risk is greater
In addition to the reaction of water, wet flammable substances can react with acid or oxidant, and react more strongly than water, and the danger is greater.
Therefore, storage, transportation and use should not be combined with acids, oxidants, chlorine, oxygen, nitrous oxide, bromine, iodine, sulfur, phosphorus, water-containing materials, heavy metal salts, other dangerous goods, and fire-fighting methods. Storage.