Chlorine Cylinder

Chlorine is a yellowish-green gas, heavier than air, with a pungent odor and a sweet, "metallic" taste, whose molecule consists of two chlorine atoms (chemical formula is Cl2). Chlorine is extremely active and directly combines with almost all the elements of the periodic system. In nature, it can only be found in the form of compounds in various minerals. The largest reserves of chlorine are found in the salts in the waters of the seas and oceans. Chlorine is present in human and animal bodies, mainly in intercellular fluids. Chlorine is liquefied at room temperature when the pressure rises above 0.8 MPa and at normal atmospheric pressure when the temperature drops below -34 °C. When liquefied, chlorine takes the form of a yellow-green liquid with a very high corrosive effect, and freezes at a temperature of -101 °C. Chlorine is produced on an industrial scale by the electrolysis of table salt solution, releasing sodium hydroxide and hydrogen together with chlorine. Three variants of the electrochemical method of chlorine production are used. Two of those are solid cathode electrolysis: diaphragm and membrane methods, and the third one is liquid mercury cathode electrolysis (mercury production method). Small quantities of chlorine are obtained by laboratory methods by the interaction of acid and sodium hypochlorite, by oxidation of hydrogen chloride with strong oxidizing agents.

APPLICATION:

Cylinders are not hazardous cargo until they are taken into use, but in any case they should be transported in conditions that exclude mechanical damage. Cylinders with liquid chlorine shall be transported by rail, water and road (in exceptional cases, by air) in accordance with the cargo carriage regulations applicable to the given mode of transport. Cylinders with liquid chlorine should be transported in an upright position in special crates. Cylinders may be transported in a horizontal position with a stack height of not more than half the height of the wagon wall or side wall of the car body. All cylinders must be stacked with their caps (valves) facing the same direction and have gaskets between the cylinders. Cylinders may be transported in railroad cars without crates in an upright position if they are equipped with safety rings and if the railroad cars are loaded tightly so that they cannot move (fall). When transporting cylinders with liquid chlorine by road, the speed of the vehicle is set in accordance with the prescribing traffic signs and specific road conditions, but not more than 60 km/h. When transporting small-volume cylinders with chlorine, they must be packed in wooden crates, the weight of the cargo in each crate must not exceed 65 kg. Crates of two or more cargo places are transported by rail in unit-load devices on pallets. By river transport cylinders with liquid chlorine are transported with the accompanying cargo owner. Cylinders must be transported with plugs on the fittings and caps screwed on.

Cylinders designed for storage and transportation of liquid chlorine must not be used for storage and transportation of other gases, and it is prohibited to perform any operations that may contaminate their internal surface and degrade the physical and chemical properties of the gas. It is forbidden to make any modifications to the cylinder bodies using welding or mechanical tools, which can lead to damage to the integrity or appearance of defects that degrade the technical characteristics of the cylinders. When using cylinders for liquid chlorine it is not allowed to install them in the places of people passage, movement of goods and passage of vehicles. Cylinders designed for storage and transportation of liquid chlorine are filled at the rate of 1.25 kg of gas per 1 dm3 of the cylinder capacity. The maximum permissible concentration of chlorine in the air of the working area of production facilities is 1 mg/m3. Work with chlorine must be carried out with the use of personal protective equipment against chemical factors of the skin, eyes and respiratory organs. It is not allowed to work with chlorine without personal protective equipment. For respiratory protection against chlorine gas vapour, industrial filter masks the B or BKF brand are used if the volume fraction of chlorine in the air does not exceed 0.5 % and the volume fraction of oxygen is at least 18 %. Oxygen breathing apparatuses such as KIP-8, RVL-1, IP-4 or ADI-GS, ASV-2 must be used for concentrations higher than those specified. Chlorine gas withdrawal from the cylinder (without a siphon) should be carried out with a vertical or inclined position of the cylinder, in which case the valve is in the upper position (the angle of inclination not more than 15°). Chlorine withdrawal is carried out at an inclined position of the cylinder - valve downwards. The withdrawal of liquid chlorine from cylinders should be carried out by the cylinder's own chlorine pressure. When filling cylinders with chlorine, the mass of gas in the filled cylinder should not exceed 1,250 kg per 1 dm3 of the cylinder capacity. The residual pressure in the emptied cylinder must be at least 0.05 MPa (0.5 kgf/cm2). Also, when using, it is always necessary to remember that the pressure of saturated chlorine vapors over the liquid in a closed cylinder changes with temperature. For example, at a temperature of -70°C there will be no pressure in a cylinder filled with liquid chlorine, at a temperature of 0°C the pressure will be 0.4 Mpa, and at a temperature of +70° the pressure will rise to 2.3 MPa.

Cylinders filled with liquid chlorine are stored in special warehouses in freestanding aboveground or semi-underground buildings. Liquid chlorine warehouses must be located in lower locations in relation to other nearby buildings and structures and predominantly from the leeward side of the prevailing wind directions relative to the location of the nearest settlements. There should be a solid blank fence with a height of at least 2 m around the liquid chlorine warehouse, with a blank, tightly closing gates, or other solutions should be provided to limit the spread of the gas wave in the initial period of the emergency situation and exclude access by unauthorized persons to the territory of the warehouse. Fire-fighting and gas rescue service vehicles must be accessible to the liquid chlorine warehouse. Buildings for liquid chlorine warehouses must be made of fire-resistant and low-thermal conductive materials with protection against the chemical effects of chlorine, and be equipped with two exits from opposite sides of the building or premises. The placement of cylinders with liquid chlorine in the warehouse must exclude the possibility of their falling or moving and provide free access to the shut-off valves (valves in horizontal storage should be located in the direction of the passageway). When stacked horizontally, chlorine cylinders are placed in one row near the walls and in two rows in the passageways. The height of the stack should not exceed five tiers. Cylinders may be stored on racks, but the top row of cylinders should not be higher than 1.5 m from floor level. When laying vertically, no more than two rows of cylinders should be placed at the walls; there should be four in the passageways. It is allowed to store cylinders filled with liquid chlorine outside special warehouses, under a shelter that protects the cylinders from precipitation and direct sunlight, but the time of stay under the shelter of filled cylinders should not exceed five days, unless otherwise justified by the project. Open areas must be convenient for access and loading operations and equipped with a system for detection and containment of possible leakage of chlorine from emergency cylinders. Cylinders with liquid chlorine and organic substances, metal powders, combustible liquids and gases must not be stored together. Cylinders should be stored with plugs on the fittings and caps screwed on.