Some unknown factor has increased the hardness of the water entering my laundry. How can we combat this change so we can produce high-quality linen without jeopardizing production efficiency? What options are available to me to address this hard-water problem?
CHEMICALS SUPPLY: Steven Tinker, the director of research and development for Gurtler Industries, South Holland, Ill., has more than 30 years of experience in laundry chemistry research, development and marketing. He’s secretary/treasurer of the Healthcare Laundry Accreditation Council (HLAC).
Water hardness is generally a combination of calcium and magnesium carbonates and similar salts that are only sparingly soluble in water. Water hardness is expressed in grains per gallon (gpg); one gpg equals 17.1 ppm (mg/l) of calcium carbonate (CaCO3). Usually when the hardness exceeds 4 gpg, laundries use a method of “softening” the water to remove the calcium and magnesium ions from the water.
The most common method is the use of an ion-exchange resin that exchanges sodium ions for the hardness ions. These softeners use sodium chloride (salt) as the source of sodium. Sodium salts of carbonates are completely soluble in water, and do not have the same problems as calcium salts.
Water hardness varies greatly across the country. For comparison purposes, typical water hardness in New York City is 0-2 gpg; Lake Michigan water in Chicago is 6-8 gpg; but well water in suburban Chicago can be as high as 30 gpg.
When hardness is present in your water, it can cause several problems in the laundry. First, when hard water is heated, the hardness becomes less soluble, and it will precipitate out of solution, usually forming a scale on the surfaces of the heating vessel.
If you experience hard-water problems for a long time, a hardness scale can develop in your boiler, decreasing the heat-transfer efficiency and potentially damaging the interior. You should contact your boiler chemical representative to make sure that they adjust the chemical dosage and maintenance of the boiler to minimize this effect.
Water hardness also becomes less soluble when exposed to alkaline pHs. Thus, in tunnel washers where the front modules are constantly exposed to an alkaline medium, a scale can form on the inside surfaces there. This can also cause inefficiencies in the process, and potentially harm the equipment internally.
The biggest impact of water hardness is its tendency to interfere with soil removal in laundering. Hardness can react with certain soils, such as natural fats, and with certain detergents. When hardness reacts with soils and detergents, it makes the soils more difficult to solubilize or emulsify, and can create issues with soil redeposition.
Your laundry chemical technical sales representative is the first contact you should make if you face a long-term increase in water hardness. They can quickly adjust your chemical dosages to make sure that you have adequate detergent to “overpower” the hardness, prevent soil redeposition and maintain soil removal quality. In addition, they most probably have a product designed to neutralize the effects of water hardness, usually classified as “water conditioners.”
A conditioner contains specific compounds such as organic polymers, phosphates or nonphosphate builders that sequester or chelate water hardness ions. Sequestration or chelation means to separate and isolate the water hardness ions, making them unavailable to react with soils and detergents.
Usually you’ll need to use about 1 ounce of a conditioner per 100 pounds of fabric for every 1 gpg of water hardness to effectively sequester the calcium and magnesium. These conditioners prevent scaling, and can even help dissolve scale if it’s already begun to develop. In addition, the polymers in these conditioners can help suspend soils and water hardness ions to keep them from redepositing on the fabric, which can cause long-term graying or yellowing.
One last note: If the water hardness has unexpectedly increased, there’s a high chance that other factors have increased, too, such as the inactive alkalinity and the iron content. The first thing your rep should do is run a complete water analysis, to make sure you know all the changes that may have occurred.
As a matter of standards for your facility, you should require periodic tests of your water quality so you can be alerted to drastic changes. Field tests can accurately measure water hardness, iron, inactive alkalinity and pH. Lab tests may be needed for more detail, so samples of both the cold- and hot-water sources can be sent in for analysis.
CONSULTING: Chip Malboeuf is vice president of operations for Turn-Key Industrial Engineering Services, Charlottesville, Va. It provides facility planning and process improvement services for companies in the laundry industry. His experience includes process engineering and plant design.
First, if this is a sudden change in the hardness level entering the facility, then the facility should contact the local water authority to inquire if the change in hardness is due to a change in the authority’s procedures. The laundry facility should also inquire if the change in hardness is something that is permanent or if the local water authority will have this situation rectified.
If the increase in hardness has been gradual, the laundry facility will notice this through the daily water testing that it performs. The facility has also probably noticed that the finished linen is not as bright as it has been in the past. This is caused by decreased effectiveness of the laundry chemistry.
Once the facility has identified the source for decreased linen quality, it must use continuous process-improvement techniques to rectify the problem. Using the standard Plan, Do, Check, Act (PDCA) cycle, the facility can address the situation.
[NP][/NP]The first step is for the laundry operator to contact their washroom chemical supplier. The supplier should be called in to analyze the incoming water quality along with the present washroom formulas. Some washroom chemical suppliers can make minor adjustments to the formulas so that the quality of the linen is not affected by the increased water hardness.
The washroom chemical supplier should provide the laundry operator with proposed formula changes along with an estimated cost per 100 pounds of linen processed. The revised cost should be compared to the existing cost.
The next step is to contact a company that provides water softeners. This equipment expert should also come into the facility to analyze the current situation (gallons per minute flow, water hardness, water delivery system, incoming water pressure, etc.) and then provide
a recommendation on a water softener (simplex versus duplex system, automatic regeneration versus manual regeneration, tank and flow sizing, etc.)
After receiving the recommendation from the water softener equipment supplier, the laundry operator should perform a financial analysis (return on investment, or ROI) that compares the higher recurring cost of washroom chemicals with the capital cost for the installation of a new water-softening system. In this analysis, the laundry operator should be sure to include the recurring costs that are associated with operating such a system.
If the ROI for a new water softener is acceptable to the laundry operator, then the operator should purchase and install it. If the new water softener’s ROI is not acceptable, then the operator should instruct the washroom chemical supplier to make the formula changes permanent, and the facility will continue to combat the increased hardness with modified washroom chemistry.
The laundry operator must continue to monitor the water hardness each day, the washroom chemical costs per 100 pounds processed and the quality of linen leaving the facility. If the washroom chemical costs are more than originally proposed by the chemical supplier or the quality of linens leaving the facility is not up to the facility’s standards, then the laundry operator must re-evaluate the need to install a water softener.