HAZARDOUS MATERIALS
CHEMICAL DATA NOTEBOOK SERIES #58: CALCIUM HYPOCHLORITE
Calcium hypochlorite is an oxidizing, reactive, corrosive, toxic, irritating, white, crystalline solid with an odor of chlorine. It is used as an algicide, bactericide, bleaching agent, deodorant, disinfectant, fungicide, oxidizing agent, and water purification agent. It is available in commercial grade (70 percent strength mixed with other calcium salts) or as essentially pure (99.2 percent) material. The properties that follow are given for the pure grade and are characteristic of the anhydrous form rather than the hydrated form.
PROPERTIES
Calcium hypochlorite will not burn, but it is a very dangerous fire hazard since it is such a powerful oxidizing agent. This means that it will support the combustion of anything that will burn. Its oxidizing power is determined principally by the purity of the product and the method in which it is used. It has a specific gravity of 2.35 for the anhydrous grade and a molecular weight of 143, and it decomposes at 212°F, possibly explosively. It is soluble in water in all proportions but may react in water if it is added to a small amount. The product’s molecular formula is Ca(CIO)2.
HAZARDS
The major hazard of calcium hypochlorite is its oxidizing power. The more concentrated the product (that is, the more calcium hypochlorite present in the mixture), the more powerful the oxidizing activity and therefore the more hazardous the situation becomes if the calcium hypochlorite is released and/or is allowed to contact a combustible material. The most dangerous, of course, would be the pure form of the product.
Oxidizers, or oxidizing agents, operate by supporting the combustion of materials. The decomposition of calcium hypochlorite liberates oxygen and chlorine, both very powerful oxidizing agents. The more intimate the mixture of the oxidizer and the fuel, the more easily the material will ignite and burn. If released calcium hypochlorite is allowed to mix with any organic material, a violent fire will occur with only a small input of energy. The presence of such a powerful oxidizer makes difficult-to-burn materials readily combustible and easy-to-burn substances explosive.
The first rule in handling and storing oxidizers is that they should never be allowed to come into contact with fuels. Fuels are defined as anything that will bum. Calcium hypochlorite, therefore, must never be stored near any organic material, since all organicmaterials burn, This should be picked up in preplanning inspections. iTiese inspections traditionally have been to inspect occupancies, particularly manufacturing operations, for fire hazards, and hazardous materials usually are overlooked. The hazardousmaterials incident can be preplanned just as a fire can, and it is easy to spot hazardous materials because of the required marking.
Bleaching is the same type of chemical reaction as combustion, since it is also an oxidation reaction. The presence of an organic material in a fabric usually lends color to the fabric; and indeed, organic pigments and dyes are the colorants used to impart color to clothing and other textiles. Calcium hypochlorite and other powerful oxidizers will “burn up” (oxidize) the organic matter present and leave the substance colorless (or white). All bleaches work in this manner, but they work only on organic materials since all organic materials will burn (are capable of being oxidized).
Disinfection is also an oxidation reaction, just like bleaching. All bacteria are made of organic matter, and contact of this organic matter with calcium hypochlorite will result in the oxidation (burning up) of the germs. Calcium hypochlorite is a very powerful disinfectant; commercial product derivatives are used to disinfect public water supplies and swimming pool water.
This last use can lead to unexpected fires, since homeowners who have swimming pools seldom understand hazardous materials and safe storage rules. Most homeowners do not realize they have hazardous materials in their possession, so they often keep products like those containing calcium hypochlorite stored with organic materials. The accidental spilling of calcium hypochlorite on a garage floor and mixing with certain other organic materials already there can in time cause a spontaneous ignition.
Calcium hypochlorite has a tendency to become unstable if heated. This instability, usually overlooked because of the greater hazard of its oxidizing power, is very dangerous since heat could cause the container to explode from the overpressurization of released gases. The heat causes oxygen and chlorine to be released from the solid material.
Although calcium hypochlorite is not classified as a water-reactive material because it dissolves readily in water with no apparent hazardous reaction, calcium hypochlorite placed in a very small amount of water could cause an adverse reaction. Rather than thinking of adding a large amount of calcium hypochlorite to a small amount of water, think of the converse: the addition of a small amount of water, such as rain or a splash of water, onto a pile of dry calcium hypochlorite. In this case, chlorine may be liberated. Chlorine (see Fire Engineering, July 1986) is an oxidizing, toxic, corrosive gas that is extremely hazardous itself. This makes it doubly important to protect inventories of calcium hypochlorite from water as well as prevent a spill of calcium hypochlorite from getting wet. In this case, a large amount of water will dissolve the product with no apparent danger, as long as the resulting solution is contained.
Calcium hypochlorite is reactive with all organic substances. On contact with amines, carbon tetrachloride, iron oxide, manganese oxide, wet sulfur, or urea, an explosion is possible. When in contact with acids or acid vapors, chlorine gas will be liberated. All compounds containing nitrogen are incompatible with calcium hypochlorite, and that includes, of course, all ammonia compounds.
Contact of calcium hypochlorite with most metals will corrode them, particularly if moisture is present. If the metal is in the form of powder or flakes, it is possible that the mixture will ignite violently or even detonate.
Calcium hypochlorite is considered moderately toxic. Its TLV/TWA (threshold-limit value/time-weighted average) is 1 ppm (parts per million in air), and its STEL (short-term exposure limit) is 3 ppm (as chlorine gas) for 15 minutes. Ingestion of the material will cause irritation and burns to the mouth, esophagus, and stomach. Ingestion of a sufficient quantity of calcium hypochlorite will cause nausea and severe pain and also may cause the victim to become comatose. If the ingested material perforates the esophagus and/or stomach and penetrates into vital areas, death could result.
Inhalation of the dust will cause damage to both the upper and lower respiratory systems, with possible delayed effects such as pulmonary edema and other symptoms that resemble a heart attack. Inhalation of a large quantity of calcium hypochlorite dust can be fatal.
Dust also will be hazardous to exposed eyes, causing soreness, irritation, and burns. If contact is minimized and the contaminant is washed away quickly, the damage may be reversible.
Contact of calcium hypochlorite with the skin will cause irritation, and prolonged contact will cause severe burns. Again, prompt removal of the product and avoidance of chronic contact will lessen the damage to the body.
NONFIRE RELEASE
As in the case of all releases of any hazarous material, notify the proper environmental authorities immediately. Your local emergency response plan, as dictated by Section 303 of SARA Title III and implemented by your local emergency planning committee, should outline the procedures to be used in the notification process. If the responsibility for such notification belongs to an agency other than the local fire department, the incident commander still must double-check to make sure notification has been carried out.
Concern for the environment comes second to life rescue activities. Once it is certain that all human life (including the emergency responders) is in no immediate danger, then environmental concerns can become a part of the mitigation techniques. The first action considered, however, may be evacuation of the immediate area of the spill, a radius of at least one-half mile (unless the spill is small), and some increased distance downwind.
The accidental release of calcium hypochlorite from its container always will be hazardous, with the danger increasing as the concentration of the oxidizer in the mixture increases. If the release of pure calcium hypochlorite allows it to come into contact with any organic matter, a rapidly developing fire is possible. Oxygen and chlorine will be released from all forms of calcium hypochlorite, and an intimate mixture of any fuel and any oxidizer will result. This represents two legs of the fire triangle, and all that is missing is a small amount of energy to cause a violent ignition and perhaps an explosion, depending on the kind of fuel with which the calcium hypochlorite has mixed.
If the spilled material can be covered by a sheet of compatible material, it should be done immediately. This will prevent calcium hypochlorite dust from being blown about and also will lessen the chance that the material will get wet if it rains. Small amounts of the spilled product simply may be shoveled into a secure container and covered tightly. Large amounts should be salvaged by a professional salvage company or by trained, qualified employees of the manufacturer, buyer, or shipper of the product.
The entry of calcium hypochlorite into the sewer system must be prevented. Sewers always contain organic matter, and the addition of a powerful oxidizer, especially in concentrated form, will always produce an explosively dangerous situation lacking only the ignition source to set it off. If any product does enter a sewer, notify any downstream sewage processing plant immediately.
In any spill of calcium hypochlorite or any other hazardous material, the manufacturer of the product, the buyer, and the shipper all should be notified at once. They usually will have expert advice on how to handle the release and may even have an emergency response team they can dispatch. The manufacturer also may have suggestions on neutralization or other special mitigation techniques.
If the calcium hypochlorite has been contained and no immediate threat exists to life, the environment, vital systems, or property, salvage of the product (if it can be done safely) may be called for, but this should be done by the manufacturer or shipper—not emergency personnel.
Entry of calcium hypochlorite into waterways also must be prevented because of the immediate hazard to waterfowl, fish, and other life in the immediate area of the entry. The calcium hypochlorite immediately will be diluted by the water as it enters and the dilution factor is dependent on whether the waterway is a pond or lake (with no moving water) or a stream or river (which may have large or small volumes of water moving slowly or rapidly). In any case, notify all downstream users of the water at once, since the intake of water contaminated with calcium hypochlorite can be corrosive to intake equipment at best and explosive at worst.
The environmental authorities will be invaluable in their monitoring of the water, and they will be able to declare when the w ater is safe. Since the calcium hypochlorite immediately will dissolve in any water it enters, removal techniques will be very difficult, again depending on the nature of the waterway it enters.
If by chance the product is already in a water solution, a release of the liquid will allow the calcium hypochlorite to seep into and contaminate any soil it contacts, thus spreading the contamination. After successful mitigation of the incident, the environmental experts must be relied on to determine the extent of the contamination and the method of cleanup. Emergency responders should never be involved in the salvage or cleanup of hazardous materials. Contractors specializing in these activities have employees who are properly educated, trained, and equipped to handle such duties.
IDENTIFICATION NUMBERS AND RATINGS
CAS
(Chemical Abstract Services)
7778-54-3
STCC
(Standard Transportation Commodity Code)
4918715, dry mixtures with more than 39% available chlorine 4918795, hydrated material with more than 39% available chlorine
4945307, powder or solution with 39% or less available chlorine
4945308, powder with 39% or less available chlorine 4932332, solution of chlorinated lime
RTECS
(Registry of Toxic Effects of Chemical Substances)
NH3485000
UN/NA
(United Nations/North America)
1748, dry material or mixtures with more than 39% available chlorine
2208, dry mixtures with 39% or less available chlorine 2880, hydrated or hydrated mixtures of calcium hypochlorite
CHRIS
(Chemical Hazard Response Information System)
CHY
NFPA 704 Rating
1-0-2-OXY
DOT
(U.S. Department of Transportation)
Oxidizer
IMO
(International Maritime Organization)
5.1, oxidizing substance
EPA
(U.S. Environmental Protection Agency)
10 pounds reportable quantity
If the calcium hypochlorite is in a water solution, the usual containment techniques for holding liquids, such as building a containment pond or digging a containment pit, will become necessary. As in the handling of any hazardous material, any equipment or tools used in the mitigation of the incident must be compatible with the product.
The addition of large amounts of water to a spill of calcium hypochlorite safely will dissolve the material with little or no release of chlorine into the atmosphere. If this technique of diluting the product by dissolving it in water or by adding water to a concentrated solution of calcium hypochlorite is used, it is imperative to contain the resulting solution. The volume of any containment pond or pit must be known before water is added.
FIRE SCENARIO
Any container of calcium hypochlorite exposed to fire poses a very serious problem. Heat from impinging flames or radiated from the fire will cause the calcium hypochlorite to become very unstable, and the generation of oxygen and chlorine will occur. If the container is sealed, the hazard is greater since there first will be a buildup of pressure inside the container as oxygen and chlorine are forced from the calcium hypochlorite molecules. If the container is a bag, it will heat up and begin burning rapidly as oxidizing gases are generated from within.
Cooling water applied to the containers will help reduce the threat of drum failure. If water is applied, especially to bags of the product involved in the fire, use caution with runoff water. In some cases, it will not be possible to extinguish the fire, since an intimate mixture of a fuel and an oxidizer will burn very hot and it cannot be “smothered” because it has its own independent source of oxidizer. In many situations involving oxidizing agents exposed to fires, the best option may be to evacuate and secure the area and protect exposures.
SYNONYMS
anhydrous calcium hypochlorite
B-K powder
bleaching powder
calcium chlorohydrochlorite
calcium hypochloride
calcium oxychloride
calcium salt
Caporit
CCH
chloride of lime
chlorinated lime
HTH
HTH dry chlorine
Hy-chlor
hypochlorous acid
lime chloride
Lo-bax
Losantin
Perchloron
Pittchlor
Pittcide
Pittclor
natural anhydrous calcium
hypochlorite
Sentry
Catastrophic failure of a container aside, any product leaking from the container in the vicinity of a fire immediately would increase the combustibility of any organic material nearby. If vented vapors entered the fire, the effect would be that of a blow torch, as oxygen and chlorine would enter the flames under pressure. Firefighters never must allow themselves to come between the fire and containers of calcium hypochlorite or any other hazardous material that suffers pressure rises when heated.
PROTECTIVE CLOTHING AND EQUIPMENT
Protective clothing and equipment should prevent contact of calcium hypochlorite with the skin or eyes. This includes any material impervious to calcium hypochlorite and its solutions. Neoprene, nitrile, or butyl rubber gloves and boots, chemical splashproof goggles, and face shields may suffice on very low concentrations, but fully encapsulating suits are recommended in all exposures. Compatible materials may include neoprene and polyvinyl chloride (PVC). Neoprene will offer protection against any chlorine released, but PVC may not. Consult manufacturers of calcium hypochlorite and protective clothing for further information such as the length of time protection will be maintained and whether the products protect against liberated hazardous gases or liquids. Respiratory protection in the form of positive-pressure, self-contained breathing apparatus is required.
FIRST AID
For inhalation, move the victim to fresh air and keep him/her calm and warm. If the victim’s breathing has stopped or has become labored, administer artificial respiration (be aware that such action might expose the first-aid giver to the material in the victim’s lungs and/or vomit). Seek immediate medical attention.
For eye contact, flush the eyes immediately for at least 15 minutes, occasionally lifting the eyelids. Immediate medical attention will be required.
For skin contact, wash the affected areas of the body with large amounts of soap and water. Irritation will continue after washing, so immediate medical attention will be required.
For ingestion, make a conscious victim drink large quantities of water immediately, and induce vomiting. Remember, never try to make an unconscious person drink anything or vomit. Seek immediate medical attention.
