By Gary Wright
Summary: With many technologies available to the water treatment professional, gas chlorine is often overlooked. Some of this may be due to misinformation. This is often a result of gas chlorine being confused with two other chlorine types when accidents are reported.
If you’re like many water purification professionals, you probably think that gas chlorine isn’t a viable method for residential water treatment. You may also think there are just too many safety ramifications for gas chlorine to be taken seriously. Well, you may want to reconsider.
The fact is that there are numerous myths and misconceptions regarding gas chlorination. Of the three types of chlorine used in water treatment—gas chlorine, sodium hypochlorite (liquid) and calcium hypochlorite (solid)—the former may now be the safest, most efficient and cost effective form of chlorine available due to a new delivery system.
“In order for water disinfection decision-makers to make an informed determination about which form of chlorine to utilize in the treatment of municipal water, you must examine all the facts,” said Eric Howie, sales manager for Piedmont Chlorinator Sales. “Once that task is completed, there is no doubt that you will determine that gas chlorine is the only viable choice.”
Role of the media
The “scare” impact of media reports on accidents related to chlorine usage have confused some water disinfection professionals’ mindsets when it comes to gas chlorine. The fact is that many industries place their faith in gas chlorine for water disinfection and wastewater treatment.
The dairy industry relies upon gas chlorinated water for washing cows, as well as for animals’ drinking water. Poultry plants depend upon chlorine for both processing and chilling water, using it to spray the chickens and equipment. Beverage bottling plants use gas chlorine to sanitize their facilities. Fruit and vegetable processing plants use it to wash down all produce. And canneries use gas chlorinated water to cool cans after cooking, as well as for facility maintenance. With such industries choosing gas chlorine over calcium or sodium hypochlorite, perhaps they’re on to something.
The safety issue
We’re all concerned about safety. And gas chlorine has taken a lot of hits in recent years regarding this issue. Therefore, you may be surprised to learn the findings of the 1998 National Poison Control Center (NPCC) Exposure Report, which analyzes chlorine exposures resulting in medical attention from 65 reporting stations across the United States. (Unreported household accidents aren’t included in the report.) The NPCC concluded that of the 69,804 chlorine exposures reported to poison control centers nationwide recently, gas chlorine accounted for only 9 percent of those exposures.
The other two forms of chlorine are responsible for the remaining cases reported. Calcium hypochlorite (CaCl2)—which comes in the form of granules or compressed tablets—accounts for 13 percent of the reported cases. The remaining 78 percent, or 54,685 of the cases, were related to sodium hypochlorite (NaCl), more commonly known as bleach.
Differences in chlorination
Although extremely dangerous, the use of sodium hypochlorite is, for the most part, unregulated. Sodium hypochlorite is highly sensitive to temperature changes and heat, making it a hazardous substance to keep and store. Rags and paper soaked in sodium hypochlorite run the risk of becoming combustible. When spilled, this form of chlorine can injure those who touch or ingest it and gas vapors can cause chemical pneumonia, an inflammation of the lungs that causes fever, cough, shortness of breath, chills and, in extreme situations, death. It’s also explosive, extremely flammable and can cause severe skin burns and dangerous eye irritation. Gas chlorine, on the other hand, isn’t flammable nor is it an explosive.
The handling of calcium hypochlorite and sodium hypochlorite isn’t regulated due to industry misinformation and lack of education. These results are reflected in the disproportionately high number of accidents that occur with the use of sodium hypochlorite and calcium hypochlorite compared to those incidents involving gas chlorine.
Extensive training on the safe transfer and use of gas is a top priority of gas chlorine manufacturers. During the past 50 years, an overwhelming majority of recorded incidents and accidents associated with gas chlorine occurred when sodium and calcium hypochlorites were mishandled and contaminated, causing a spontaneous chemical reaction that resulted in an uncontrolled chlorine gas release. This results in negative reporting via the media, which taints gas chlorine’s reputation.
The vacuum system
Fires due to spontaneous combustion or outmoded “pressure” systems also have played significant roles in the accidental release of gas. Government safety regulations are strictly enforced to ensure that comprehensive training processes are followed when handling gas chlorine. Regulations and government intervention have also led to introduction of an all-vacuum system that virtually eliminates gas chlorine leakage by preventing the chlorine from being placed under any pressure.
The vacuum draws the gas from the cylinder through the chlorinator and high strength vacuum tubing into the ejector. Once in the ejector, it’s mixed with water and carried to the diffuser, which passes it into the water that’s being treated. Additional safeguards in this system also prevent gas leaks by automatically shutting down the gas supply, if and when the integrity of any part of the system fails. These all-vacuum type delivery systems help make gas chlorine a safe method of disinfection. The use of this all-vacuum system also creates an effectiveness that’s not found in the other two forms of chlorine.
The strength comparison
Chlorine is made from common salt (NaCl). Chlorine is a gas that’s created without use of additional by-products, or 100 percent elemental chlorine. Gas chlorine’s natural properties and methods of administration make it, pound for pound, the most effective and efficient chlorine product. No matter how long gas chlorine remains in storage, it will always remain at full strength. Calcium hypochlorite, in comparison, loses its strength once the container has been opened. It takes 1.5 pounds of calcium hypochlorite to equal 1 pound of gas chlorine. Only 65 percent of chlorine is available per pound.
It takes 1.2 gallons of sodium hypochlorite to equal 1 pound of gas chlorine. Sodium hypochlorite is almost 13 percent aqueous. Once opened, because of its form and other factors such as storage, NaCl can lose up to 50 percent of its potency in the first 90 days. Plus, it will continue to degrade over time, even in its original unopened container.
Cost effectiveness is another factor that plays a major role in the choice of chlorine. If it costs $12,000 for a year’s supply of gas chlorine, sodium hypochlorite would cost about $34,000 per year and calcium hypochlorite would cost $54,000 per year. Gas chlorine would save you $22,560 over calcium hypochlorite and $42,000 over calcium hypochlorite.
Added Mr. Howie, “The question that remains is, why would you want to pay more for something that is clearly not as effective, is not forced to comply with strict government regulations and has serious safety ramifications? Gas chlorine is a safe, reliable choice for the disinfection of residential and commercial water systems”. The facts are clear. The choice is up to you.
About the author
Gary Wright is president of Wright Building Company, of Stuart, Fla., and a member of the Gas Chlorine Education Committee (GCEC). The GCEC is a consortium of industry professionals dedicated to educating users of chlorinated water—including dairy farmers, poultry plants, beverage bottling plants, fruit and vegetable growers and canneries—about the benefits of gas chlorination. Wright may be contacted at (888) 280-0047.