Appliance Design - March 2009 - (Page 38)

INSULATION While these agents have zero ozone-depletion potential, they have other disadvantages. The primary HFC expansion agents developed for rigid polyurethane foam are HFC-245fa and HFC-365mfc. Disadvantages of HFCs include their increased thermal conductivities compared to previous generation expansion agents and their high GWP values: HFC-245fa has a GWP of 1,020 and HFC-365mfc has a GWP of 782. In addition, HFC-245fa is characterized by a relatively low boiling point of 15 DegC, rendering the handling of HFC-245fa and the processing of its foams more troublesome compared to when the foam expansion agent is a liquid at room temperature. HFC-365mfc is a liquid at room temperature, but has the disadvantage of being a flammable compound. Hydrocarbon expansion agents such as pentane, isopentane, cyclopentane, and methyl formate all exhibit low GWP values (Pentane = 11 GWP), but exhibit flammability and thermal conductivities even greater than those of the HFCs. The ideal foam expansion agents should exhibit the following characteristics: 4Low vapor thermal conductivity. 4Nonflammable. 4Liquid at room temperature (Boiling point greater than 25 DegC). 4Low toxicity. 4Zero ODP. 4Low GWP. 4Chemically, thermally stable. 4Soluble in formulation. 4Low rate of diffusion. 4Economically feasible. DuPont Fluoroproducts has developed a novel FourthGeneration foam expansion agent for polyurethane foams that meets all of those requirements. FEA1100 is characterized by zero ozone depletion potential, very low acute toxicity, and has a low GWP value of 5. Because it is liquid at room temperature, the problems associated with the use of lower boiling agents such as HFC-245fa are eliminated. In addition, FEA-1100 has been shown to be non-flammable in standard ASTM tests. Polyurethane foams produced with FEA-1100 are characterized by low foam density, uniform cell size, and R values higher than HFC-245fa. (FEA-1100 R-value @ 75 DegC = 7.1 compared to HFC245fa R-value @75 DegC = 6.6.) Upon aging, the foams expanded with FEA-1100 retain R values higher than those expanded with HFC-245fa. Similarly, polyisocyanurate foams produced with FEA-1100 are characterized by low foam density, uniform cell size, and R values higher than foams blown with HFC-245fa. (FEA-1100 R-value = 7.7 compared to HFC-245fa R-value = 7.2.) Upon aging, the foams expanded with FEA-1100 retain R values higher than those expanded with HFC-245fa. While foam expansion agents can be used singly, mixtures of different physical foam expansion agents can be useful for optimizing foam performance and meeting customer demands, such as reduced expansion agent flammability, reduced vapor pressure, etc. Polyurethane foams produced with the azeotrope of FEA-1100 and cyclopentane as the foam expansion agent are characterized by low foam density, uniform cell size, and high R values. Initial R values for foams expanded with the FEA-1100/cyclopentane azeotrope are higher than those for foams expanded with cyclopentane alone or neat FEA-1100. Polyurethane foam employing an azeotrope-like mixture of FEA1100 and HFC-365mfc as the foam expansion agent are characterized by low foam density, uniform cell size, and high R values. Initial R values for foams expanded with FEA-1100 or the FEA-1100/HFC365mfc azeotrope-like mixture are higher than those for foams expanded with neat HFC-365mfc. FEA-1100 and mixtures of FEA1100 and HFC-365mfc also offer the advantage of reduced flammability compared to neat HFC365mfc. The conclusion drawn from tests of DuPont’s low-GWP FEA1100 foam expansion agent for polyurethane foams is that polyurethane and polyisocyanurate foams produced with this new agent are characterized by good dimensional stability and uniform cell size. In addition, R values for foams produced using this new foam expansion agent match or exceed those obtained with current generation blowing agents such as HFC-245fa. Foam Supplies A Comparison of the Physical Properties (and their causative factors) of Froth vs. Pour Foams, by John Murphy, Foam Supplies, Earth City, Mo. Since HCFC-22 has been phased out, many manufacturers of urethane insulation panels for the construction and commercial appliance industries are faced with the difficult decision of either staying with a froth type blowing agent such as HFC-134a, or transitioning to a liquid (or near liquid) alternative such as pentane, water, HFC-245fa, or ecomate, a patented methyl-formate use developed by Foam Supplies. The original appeal of froth formulations is their low boiling point that allows them to emerge from the foam unit with a shaving cream consistency. One of the major disadvantages is the requirement for pressurized foam dispensing equipment. Boiling point is one of three paramount factors in determining a good blowing www.applianceDESIGN.com Easy, when you use…Varglas Silicone Rubber Coated Fiberglass Sleeving. Varglas Silicone Rubber Sleeving is extremely flexible. Its dielectric strength (8,000 Volts for Grade A) is unaffected even when the sleeving is twisted or knotted. Varglas Silicone Rubber Sleeving is tough. It resists abrasion, deterioration and “cut-through” throughout a wide operatingtemperature range (-73ºC to 200ºC). It also resists acids, alkalies, jet fuel and water vapor and is impervious to sunlight and weather. And, it is flame retardant too! Available in a variety of colors and sizes in coils, cut lengths, or on spools. Send for a free sample kit. *Under UL’s Component Program, Grade A is recognized for 200°C, 600V, VW-1 service – File E63450.CSA File LR58486. Conforms to MIL-I-3190/6 and is listed on the Qualified Products List (QPL). Grades B thru C-3 comply with VW-1 under UL File E53690. Varflex Corporation 512 W. Court St., Rome, NY 13440 315-336-4400 • Fax 315-336-0005 1-800-648-4014 • www.varflex.com E-Mail: sales@varflex.com 38 applianceDESIGN March 2009 http://www.varflex.com http://www.varflex.com http://www.appliancedesign.com

Table of Contents Feed for the Digital Edition of Appliance Design - March 2009

Appliance Design - March 2009 Contents Editorial Shipments/Forecasts News Watch Transmitting Power Wirelessly Promises to Reduce the Ever-Growing Tangle of Cords and Cables Found in the Modern Home. There Are Different Technological Approaches for Achieving this Goal, and Some Are Already on the Market. Electrochemical Capacitors Can Provide an Extra Peak-Power Boost in Battery-Operated Appliances, Allowing Product Designs to Have Smaller Battery Packs. Metallic Foams Put the Properties of Metals into Lightweight Packages. Applications for this Emerging Technology Include Gas Burners, Heat Exchangers, and Electronics Housings. Hall-Effect Switches Are Compact and Provide a High Degree of Reliability and Durability as They Virtually Eliminate Mechanical Wear, Shock, and Contact Oxidation. Blowing Agents for Polyurethane Foam Insulation Face Increased Scrutiny Due to Global Warming Concerns, but Alternatives with Lower GWP Values May Provide Solutions to Meet These Challenges. Design Marts Association Report: AHAM Advertisers' Index

Appliance Design - March 2009

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.