KBB - August 2009 - (Page 45)

Education Flushed Out Understand the science of toilets Developing a stylish, durable, reliable toilet requires a system involving multiple disciplines of math and science. Physics governs water distribution to ensure effective cleaning of the bowl and to prevent clogging. Mechanical and materials engineering governs valve operation and reliability, and chemistry is needed to understand the properties of clay, glazes, plastics and, increasingly, antimicrobials. Biology is critical to the understanding and controlling of sanitary properties and bacterial growth, and geometry is used to guide aesthetic innovations. Finally, statistical analysis of every element of the toilet design ensures reliable function. If this all sounds like the syllabus from hell, take heart. The science is all behind the scenes, designed with one main objective: better performing, stylish toilets that delight and please your customers. In North America, the washdown method is most commonly used on dual-flush toilets. However, a new generation of dual-flush, high-efficiency toilets just now arriving on the market have been reengineered to use siphonic action, increasing the appeal of these water-savers with a larger water spot and less splashing. • Pioneering a New Flush. Engineering a completely new flushing system can take as long as 18 months to develop. As with kitchen and bathroom design, computers now do much of what used to be done by hand. Starting with the aesthetics and performance attributes in highest demand by consumers, a computer-aided design (CAD) model is generated that has the entire geometry of the toilet in a virtual 3D format. The model then undergoes flush simulations using computerized fluid dynamics (CFD), which examines the physics of how the water flows through the Developing a stylish, durable, reliable toilet requires a system involving multiple disciplines of math and science. A FULL CURRICULUM • Flushing Physics. The physics of flushing starts when the toilet is flushed. The tank releases water into the bowl through the flush valve, the opening between the tank and the bowl. In today’s high-performance toilets, some water flows straight into the bowl through a “jet channel,” and some is diverted into the rim of the bowl, where it’s released through small holes to clean the sides of the bowl. As the water level rises in the bowl, it also rises in the up-leg of the inverted U-shaped trapway. When the water reaches the top of the trapway— called the “weir”—gravity pulls it into the downward leg of the inverted U. When the water fills the entire up-leg and down-leg, gravity pulls additional water over the weir using the cohesive forces in the water itself. Hence the term, “gravity fed.” The rush of water running downhill pulls the waste and water out of the bowl. The stronger the push of the water, the stronger the pull-action created. This pull action is called a siphon. Gravity-fed siphonic toilets are the most common toilets in the Americas. A variation on gravity-fed toilets is a washdown flush. Commonly used in Europe, washdown toilets rely on all “push” and no “pull.” When the toilet is flushed, water floods into a bowl that is noticeably more sharply sloped. This adds more force to the push action, which is ideal for preventing clogs, but can increase splashing. Washdown toilets also typically have a smaller water surface area in the bowl. system under the force of gravity and how it interacts with the surfaces. After the optimum design is determined, it is verified through a prototype made of advanced polymers. Individual components are bolted together to create a bowl and trapway, and can be easily replaced without having to redo the entire prototype. Although quite Frankenstein-ish in appearance, the prototype can actually be flushed to see if it performs in real life as it did on the computer screen. • Materials Science. Most people know that toilets are made of vitreous china, but not everyone understands why. Vitreous china is an exceptionally strong material. A floor-mounted vitreous china toilet can literally hold thousands of pounds. It is also essentially as nonporous as a glass vessel and does not absorb water, thus impeding bacterial growth, which requires water. In addition, proprietary glazes give bacteria a one-two punch: antimicrobial elements that inhibit growth and super-smooth surfaces that impede sticking. • Valve Mechanics. Toilet mechanical systems can mean the difference between a satisfied customer and repeated callbacks. The best valves and trim available are of impact-resistant, chemically resistant plastics and silicones, the same materials that might be used for protective headgear, aerospace applications and even children’s toys. The quality of materials applied accounts for the new longer warranties now available on toilets, particularly those that also cover the trim. Continued on page 46 www.kbbonline.com / August 2009 July 2004 + K BB 45 http://www.kbbonline.com

Table of Contents for the Digital Edition of KBB - August 2009

KBB - August 2009
Contents
Online Contents
Online News
Editorial
Focus
Trends
Products
Profile
Design
External Analysis
Southern Comfort
Tech
Additions
Education
Editorial Index
Ad Index
Favorites

KBB - August 2009

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