Professional Engineeing Publication

Handling chlorine need not be a serious hazard if the personnel working with it are properly educated and trained in its handling. The following are some guidelines for assuring the safe handling of chlorine.

• Install leak detector sensors at appropriate locations.
• Provide proper instruction and supervision to workers charged with responsibility of chlorination equipment.
• Provide proper and approved self-contained breathing apparatus for persons working where there is a possibility of exposure to chlorine gas fumes. Locate the breathing apparatus close to the potential leak area but far enough away so that they are accessible in case of a major leak.
• Survey the areas of most likely chlorine emissions with an attempt to predict the downwind travel in case of accidental release. Use a wind sock to determine air movement so as to establish upwind areas.
  
  A convenient aid in formulating this prediction is the use of "Downwind Vapor Hazard Nomographs. "These are based on equations developed by Suction of the United Kingdom and modified by Calder and Milly of the U.S. Army Chemical Corps. Additional information on these nomographs may be obtained from the office of the Chief Chemical Officer, Department of the Army, Washington, DC.
  
  Another paper of more recent vintage often used by engineers to predict the spread of toxic fumes is the one published by the Chlorine Institute titled "Estimating Area Affected by a Chlorine Release" by A. E. Howerton March 1969. This publication contains other pertinent references.
• Never store combustible or inflammable materials in or near chlorine containers.
• Never apply direct heat to a chlorine container. Never attempt any welding operation on an empty chlorine gas line without having purged it with air.
• Always keep available close to the chlorine containers a water supply which can be used to keep containers cool in case of fire or by personnel if they accidentally come into bodily contact with chlorine gas or liquid.
• In case of a leak, determine if the rupture is in a faulty container or in the control apparatus or connecting pipe.
• If the leak is in a container, an appropriate emergency kit should be brought into action.
• If the leak is in the control of apparatus or connecting pipe, at least two persons should do breathing apparatus, find the leak by means of ammonia fumes, and secure the valves at the containers. The operation of the control equipment will drain the system of chlorine pressure. When the system is down to atmosphere pressure (zero gage), steps can be made to make the necessary repairs.
• After a worker has been exposed to a chlorine leak of sufficient magnitude while working with self-contained breathing apparatus, his clothes should be removed and his body showered. The clothes should be aired adequately. The danger here is that the normal perspiration absorbed by clothing retains a tremendous amount of chlorine gas, which will be released continuously after the exposure. When the worker has left the leak area, he may think he is still being exposed to a leak because of the chlorine given off by his clothing. Therefore, always remove breathing apparatus in an open area-never in a room or confined location.
• Spraying water on leaking containers may make the leak worse as a result of corrosion. Water in sufficient quantity and velocity can be used to confine or limit the spreading of moderate leaks.
• Never try to disperse chlorine gas directly from a container to an open body of water. Chlorine gas is only very slightly soluble in water at atmospheric pressure. It is often far more beneficial to attempt the dispersal of liquid chlorine in a body of water if the conditions are favorable. Liquid chlorine goes into solution much more rapidly than gaseous chlorine does at atmospheric pressure.
• Chlorine leaks must be given prompt attention.
• When entering a chlorine equipment area, always be on the alert. Take shallow breaths when entering and until it is ascertained that no leaks are in progress.
• Keep upwind of chlorine leaks. Although chlorine gas is two and a half times as heavy as air, it will always follow air currents, as it has an affinity for moisture in the air. It is therefore a fallacy that chlorine always settle to the ground or to the floor.
• Be aware of proper first aid procedure. Never give anything by month to an unconscious person.
• If a container develops a leak in transit, keep the vehicle moving. Conversely, if a stationary container develops a leak, try to transport it quickly to a predetermined disposal site until the emergency response team arrives.
• It is advisable to rely upon chlorine control and metering equipment for direct disposal into a natural stream or treatment plant facilities.
• Do not attempt to rely upon direct disposal methods of the contents of chlorine containers, evaporators, or liquid chlorine piping unless these systems are connected to a pre designed chlorine absorption tank.