Safe Handling and Storage of Chlorine

Properties of chlorine are :

Greenish yellow gas, liquid or rhombic crystals, MP – 101 degree centigrade, BP- 345 degree centigrade, VP 4800 mm at 20 degree centigrade, TLV 1 ppm, STEL 3 ppm and TC10 (human) 15 ppm.

In addition to toxicity it poses fire hazard when react with turpentine, ether, ammonia gas, hydrogen, powdered metals, polypropylene, wax, rubber, acetaldehyde, acetylene, alcohol and many materials.

When heated, emits toxic fumes. When reacted with water or steam produces toxic and corrosive fumes of HCL.

Employee Selection and Training:

Persons affected with asthma, bronchitis chronic lung conditions, and irritations of the upper respiratory tract should not be employed where exposure to chlorine might occur.

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Training classes for both new and old employees should be conducted periodically to keep them conscious and informed of the hazards. They should be instructed and trained to adopt preventive measure in case of emergency and to use safety equipment.

Leakage tools:

• Do not use water directing on leak.
• Keep “emergency kits” handy and in proper working condition to control chlorine leakage and train workers in this use.
• Appropriate facility for chlorine absorption through caustic soda/lime/soda ash solutions should be established and maintained in the event of leakage. The containers should not be immersed in same absorption media.
• Ammonia water torches should be located at nearby places where chlorine containers are generally received, stored or used in process so as to facilitate easy detection of any leakage by white fumes.
• Self-breathing apparatus, gas mask and emergency kits should be located at strategic points under working condition and to be easily accessible in the event of emergency.

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Storage Area:

• Storage area should be cool, dry, well ventilated, clean and protected from external heat source.
• Ventilation must be sufficient to prevent accumulation of vapour pockets. All fan switches should be outside the storage.
• It should be remote from elevators, gangways or ventilating systems.
• As far as possible, the building for the storage of chlorine should be entirely of non-combustible construction and separate from other building. In case of storage is not in a different building it should be ground floor with at least two exists opening outside and separated from other parts of the building by fire resisting walls and floors.

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Cylinders – Toners/Containers:

• Store chlorine cylinder up-right and secure them so that they cannot fall.
• Ton containers should be stored on their sides on rails a few inches above the floor. They should not be stacked or racked more them one high.
• Keep enough space between containers so that all are accessible in case of emergency.
• Store the containers in a covered shed only. Keep them away from hot sun or any other source of heat.
• Do not store chlorine container with explosive, acids, turpentine, ether, anhydrous ammonia, finely divided metals or other flammable material.
• Cylinders should be stored on a cement floor sloping towards a pit capable of collecting all the liquid in the cylinders. Under no circumstances should water be allowed to run on to the chlorine in the pit.
• Do not store containers in wet and muddy areas.
• Use cylinders in order of their receipt.
• Filled and empty cylinders should be stored separately.
• Protective covers for valves should always be secured, even when the cylinders are empty.
• No oil or any lubricant should be used on any valves of the containers.
• The correct tool should be used for opening and closing valves, they should never be hammered.
• Cylinders should never be lifted by means of the metal cap, nor should rope sling, chains or magnetic device be used. The ton containers should be handled with a suitable cradle with chain sling combination with a hoist or crane having at least 2 metric tonnes capacity.
• Never tamper with any fusible plugs of tonners or apply heat to them.

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Bulk Storage:

• Being a compressed gas all installations and tank vehicles used for storage and transport of liquid and gaseous chlorine have to be approved and licensed under the Static and Mobile Pressure Vessels (unfired) Rules 1981.
• Appropriate minimum safety distances as stipulated in the above mentioned rules have to be maintained from building or group of building or adjacent property.
• The tank has to be installed entirely above ground.
• The bulk storage tanks for chlorine should be installed near waste-air system.
• At least two safety valves should be connected to the waste-air system.
• Pressure indicator with alarm should be available in the control room.
• As an emergency measure, a perforated pipe, connected to the blower suction, around the leaked chlorine will get sucked through this pipe which leads to waste-air system where it can be neutralised.
• Safe bulk storage of chlorine call systematic inspection and maintenance.

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Handling Through Pipelines:

• For piping dry chlorine, the material of construction generally used is carbon steel. Piping arrangements should as simple as possible.
• The number of screws or flange joints should be kept to minimum.
• Piping system should be well supported and adequately sloped to allow drainage and low spot should be avoided.
• Suitable allowance should be provided for pipe expansion due to changes in temperature.
• Cleaning may be accomplished by pulling through each length of pipe a cloth saturated with trichloroethylene or other suitable chlorinated solvents.

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Emergency Measures:

• In case of leakage or spillage, any person tackling of chlorine should be equipped with emergency kits, self breathing apparatus or masks and other appropriate items of personal protection.
• In case of major leakage, all persons including neighbour (depending upon the situation) should be warned. Take the leaking cylinder to an isolated open place and roll it in such position so that the leaking point is on the top. In such case only gas and not liquid will escape.
• Approach from the windward side so that the escaping gas can be carried downwind to a lower level. In no circumstances should water or other liquid be directed towards leaking containers, so as to disperse the gas. Also the water solubility of chlorine is more at low temperatures; it will dissolved readily in the chilled water.
• In case of large leaks, try to stop the flow of liquid by closing the valves.
• After containing the liquids, one can use fluroprotein foam to prevent evaporation of the liquid.
• In case of large leakage, the alternate solution is to absorb the chlorine in an alkaline medium such as caustic soda, soda or lime slurry.