Combustion is an exothermic process that takes place under conditions of progressive self-acceleration. Combustion can be caused by a chemical reaction of the compound, the decomposition of substances, and this is not only in contact with oxygen directly, but also with other products containing it. For example, lime. Combustion is divided into several types: flash, fire, ignition, spontaneous combustion.
What about flash point?
This is the smallest indicator at which, under certain conditions, an outburst of vapor forms above the surface when a flame is formed that forms above the surface of a substance, while stable combustion is not formed. The flash point is approximately equal to the lower temperature limit of ignition. But what is it?
Ignition is the rapid burning of a product, not accompanied by the formation of a compressed type of gas.
If the temperature indicators of the substance are lower than the ignition temperature, then it does not pose a fire hazard even with a brief exposure to a flame, spark or even an incandescent product. Is the substance heated to a flash point and even higher? Then a brief exposure to spark, fire, will lead to ignition, and under certain conditions of the fire can not be avoided.
Therefore, the flash point is a measure in the classification of substances according to the degree of fire safety. It is different for all substances.
Famous Examples
Flammable substances are often found in aviation, so their flash points are known to many.
- Acetone will flare up at +20 ° C.
- Gasoline flares up at + 14 ... +20 ° C.
- Benzene will flare up at +14 ° C.
- Diesel fuel at + 35 ... +90 ° C.
- Aviation fuel at + 25 ... +50 ° C.
- Fluids for hydraulic systems need + 93 ... +138 ° C.
Why do I need to know the flash temperature?
This value allows you to define safe methods for transporting, storing and using fluid for a variety of purposes. It should be remembered that at flash point there is no persistent combustion, and only the mixture of vapors with air formed above the substance burns. If the temperature of the substance does not exceed the set value, then the evaporation rate of the substance from the open surface will increase, and at the time of ignition the product will be able to emit vapors constantly in sufficient volume for stable combustion. This temperature is called the ignition temperature.
What is the flash point?
This is the smallest indicator of a substance at which, under certain conditions, a substance releases vapor and gases at a tremendous speed, and when an energy carrier acts on them, ignition is performed.
What is a flammable liquid?
Not many people know about liquids that are flammable, but it's a pity that this is extremely useful information. Even at your place there may be a household product that should be stored correctly, otherwise troubles cannot be avoided. So what are flammable liquids? These are pure mixtures or solutions containing solid inclusions in a solution, flammable vapors with a closed flash point of 61 ° C.
Flammable substances in liquid form also include products that:
- They differ in vapor pressure of 300 kPa and a temperature of 50 ° C and are not fully gaseous even at 20 ° C and a pressure of 101.3 kPa.
- They have a flash point of not more than 61 ° C.
What are the requirements for the transportation of such funds?
Flammable substances in liquid form include: gas oil, diesel fuel and light heating oil, whose flash point is more than 61 degrees Celsius, but below 100. All products in liquid form should be divided into packing groups, depending on the degree of danger that represent these mixtures during transportation:
- Group one. These are substances with a high degree of danger. This category includes flammable liquids with a boiling point of not more than 35 ° C, as well as mixtures with a flash point below 23 degrees Celsius, which are highly corrosive or extremely toxic.
- Group two. Substances with a moderate degree of danger are included here. They have a flashpoint not lower than 23 ° C, but these substances are not assigned to the first group.
- Group three. These are low hazard substances with a flash point of 23 to 61 ° C.
What are flammable solid products?
This group includes:
- Aluminum. It is a light, strong metal, characterized by its durability, ductility and resistance to corrosion. This material, especially in the form of alloys with other metals, is widely used in everyday life. It is involved in virtually all areas of activity: electrical engineering, food industry, metallurgy, chemical industry, mechanical engineering and so on. And at the same time, it is also a flammable substance.
- Sulfur. It is a solid crystalline product. It is used for the production of sulfuric acid, in paper mills, in agricultural, in the rubber industry, in the chemical industry, and so on. Fine sulfur is prone to spontaneous combustion if the product is in a humid environment, in contact with various oxidizing agents, coal, oils, fats. Together with nitrates, perchlorates and chlorates, sulfur forms explosive mixtures!
- Potassium. This substance is a silver shade, characterized by its fusibility. The product is actively used in agricultural, in the design of electroplating, in coolants and even in the medical industry. If potassium is combined with water, an explosion will occur.
- Sodium. This is a soft, ductile metal of a silver-white hue. It is used as a reducing agent in metallurgy, in the production of batteries, for creating a heat sink, in trucks and even in gas discharge lamps. If sodium comes into contact with water, it instantly ignites and even an explosion can occur.
- Coal. This is a flammable solid, black in color. It is used as fuel, in the form of a raw material base for the chemical and metallurgical industries, in the creation of graphite, and so on. Activated carbon is also created from the product, which is used in pharmacology for cleaning liquids, gas separation, etc.
- Paper with oils.
Can spontaneous combustion of products occur?
Yes, so you should be extremely careful with such products. These include:
- Pyrophoric substances. These are mixtures and products that even in the smallest quantities begin to ignite on contact with air for five minutes. These substances are subject to spontaneous combustion.
- Self-heating products, substances. These are products that, in contact with air and without having even energy from the outside, can undergo spontaneous combustion. Substances can also ignite, but only in large volumes and over extended periods of time. The reason for spontaneous combustion is simple - there is contact with oxygen, in which the heat that is released is not removed sufficiently outside.
How to store hazardous materials in large quantities?
The storage of flammable substances is not an easy task, therefore, adhering to fire safety is the best that can be done in order to eliminate unpleasant consequences. All products in solid form are stored in stacks and on racks.Combustible substances are stored in specially designated buildings, premises, objects, which are called storage facilities. Food is also allowed to be stored under awnings and in open areas. If you do not adhere to general standards, then combustible substances can cause a fire, therefore, to avoid such unpleasant incidents, it is necessary to take into account the compatibility of the substances and have suitable extinguishing agents at hand. Product storage compatibility is determined by the properties of the materials themselves: they can be compatible or not. Incompatible products are materials that, when interacting with each other, form a dangerous substance. If you stock up with a suitable extinguishing agent, which completely eliminates the interaction of materials, then a fire can be avoided.
How to exclude the possibility of fire?
To prevent tragedy, all products during storage are divided into the following categories:
- Safe. These are non-combustible substances and are contained in non-combustible packaging. In addition, in case of fire, such products do not emit toxic components.
- Low hazard. These are flammable and slow-burning components that are not safe.
- Dangerous. These substances, by their properties, can lead to an explosion and fire.
- Especially dangerous. These are products that are completely incompatible with materials of the same category.
What can be said about the fire safety of the storage of flammable liquids?
All flammable substances and materials in liquid form are usually stored in metal, synthetic or reinforced concrete tanks. This stationary vessel is intended just for saving liquid, gaseous substances. The most common are steel tanks. The following steel vessels are used in practice:
- Vertical cylindrical with a stationary cover.
- Horizontal
- Vertical cylindrical shape with floating cap.
- Vertical cylindrical with a pontoon.
These vessels are mounted underground or ground. Underground tanks are called that are buried in the soil or sprinkled with soil, while the maximum liquid level is lower, not less than 0.2 meters of the lowest planning mark. Ground tanks do not satisfy the above conditions. The most common are vertical, cylindrical, steel tanks, which have spherical, conical caps and a flat bottom.
How is the fire hazard of the containers themselves determined? This is established due to the fire hazard properties of flammable liquids that require storage, their volumes, the ability to form a vapor-gas cloud during large and small “breathing”.
When storing flammable liquids, ignition sources can be sparks due to discharges of static or atmospheric electricity, due to the use of a spark-forming object, faulty electrical equipment, open flames and the presence of pyrophoric components.
Basic requirements for fire safety during storage of combustible mixtures in tanks:
- It is required to install on all tanks: breathing valves, fire protection, reflective discs, control and signaling devices, clappers, foam generators, ventilation pipes, light and metering hatches, siphon drain valve, receiving and distributing pipes.
- All breathing valves must be adjusted to the design pressure, the correctness of its operation also needs to be checked so that everything complies with the instructions.
- Routine inspections of valves and all equipment are mandatory and must always be carried out on time!
- The tank must be filled strictly up to the valve capacity.
- Product level should be monitored by alarms.
- The slope must be non-combustible, the lid must be closed tightly.
- All tanks should be cleaned as scheduled.
- Is the container unusable? He needs a replacement!
Fire safety is the most important thing that you should strictly adhere to when working with flammable substances.