Science-based Steps Of The Cleaning Process This is part five in a series on the science-based steps of the cleaning process. Each step contains scientific concepts and principles explaining cleaningʼs effectiveness in putting unwanted matter in its proper place. Published with permission by the Cleaning Industry Research Institute © 2008 By: Michael Berry, Ph.D. Heat’s Role In Cleaning H Michael D. Berry, Ph.D., was chairman of the Science Advisory Council for the Cleaning Industry Research Institute (CIRI) in 2006. The information contained in this article was extracted from Dr. Berry’s papers and presen-tations at CIRI’s 2007 Cleaning Science Conference and Symposium. His entire paper and PowerPoint presentation, as well as those of other symposium presenters, are available at www.ciri-research.org. for more info Visit www.cmmonline.com and type in search keyword: CIRI . For more information on related products, visit www.cmmonline.com , select SUPPLIER SEARCH from the main navigation bar, and enter keyword: Consultant services . Heat — as measured by temperature — is an important element in cleaning, especially its affect on the solvents breaking down pollutants. Usually as temperatures increase most solid and liquid substances in a liquid solvent become more soluble. Heat always improves cleaningʼs effectiveness by increasing reaction rates and dissolving abili-ties caused by entropy. Even without soap, small amounts of grease will dissolve in water. The dissolved amount increases in hot water, sometimes ten-fold. Heat contributes to melting making it easier for soapy water to penetrate, detach and surround the unwanted matter. Temperature solubility varies among sub-stances. As the temperature of the solution in which a substance is being dissolved increases, however, the substance dissolves faster and more com-pletely. Without heat, solubility becomes more a state of equilibrium. The substance breaking down dissolves at the same rate it rejoins or crystallizes. When introduced into the cleaning solution heat sets matter in motion. This momentum keeps dissolved particles from sticking when they collide. Instead they bounce off each other or disperse in an expanding fluid. Elevated temperatures increase cleaningʼs effectiveness and require less solvent to dissolve a specific amount of substance. Increased temperature conditions a liquid sol-vent to dissolve elements quicker. Traditionally, moist and dry heats control dis-ease by killing or controlling harmful living organ-isms. Both have advantages and limitations. At ambient or normal pressure boiling water kills organisms, sanitizes and disinfects. Generally, however, this process is not used as a sterilizing agent because of its relatively low temperature. In contrast, steam is hotter under pressure, rel-atively inexpensive and rapidly sterilizes materials and exposed surfaces. Dry heat requires high temperatures for clean-ing which makes using it expensive. It will, however, penetrate oils and other water-resistant materials. Destroying living organisms with heat depends on: The organismʼs ability to resist heat What temperatures can be achieved How long the heat can be delivered to the organism. Some living organisms can survive in extremely high temperatures. For example, to destroy (deactivate) 100,000 bacterial spores of stearothermophilus they must be exposed to steam at 121 degrees Celsius for at least 12 minutes. Molecular motion and reactivity affect a whole range of cleaning related actions including solvency, detergency, thermodynamics and transport functions. 38 CM/Cleaning & Maintenance Management ® • June 2009
CMM – Archives Jun 2009: 38
