In an effort to curtail the use of HCFCs in polyurethane products, several manufacturers have developed insulations that use non-ozone-depleting hydrofluorocarbon (HFC). Foam-Tech, Inc., uses HFC-134a as the foaming agent in its SuperGreen polyurethane foam.
The hydrofluorocarbons (HFCs), compounds consisting of hydrogen, fluorine, and carbon, are a class of replacements for HCFCs. Because they do not contain chlorine or bromine, they do not deplete the ozone layer. All HFCs have an ozone-depletion potential of 0.4 The higher cost of this foaming agent results in an upcharge of about 10 percent over conventional polyurethane. Preferred Foam Products of North Branford, Connecticut, produces the HFC-based foam components for Foam-Tech, the sole customer. While HFCs are ozone-safe, they may still have significant greenhouse gas impact.11
Open-celled semirigid water-blown polyurethane does not contain any ozone-depleting chemicals, CFCs, HCFCs, fibers, formaldehyde, or asbestos. Open-cell SPF is applied with specialized equipment designed for the application of a two-component urethane system from the interior to open-wall cavities. (The foam expands up to 120 times its liquid volume within seconds and is applied by approved contractors with qualified installers.) The R – value is 3.81 per inch. Open-cell SPF, like all other SPF products, is used as an air barrier system that reportedly can withstand 160- mph wind gusts (Fig. 10.3).
Another manufacturer, Resin Technology Company, has developed a closed-cell water-blown polyurethane (RT-2050) with an installed density of about 2 lb/ft3 (32 kg/m3) and an open-cell water – blown polyurethane with an installed density of 0.5 to 0.8 lb/ft3 (8 to 12.8 kg/m3). The latter is described as a flexible open-cell polyurethane foam, similar to Icynene.6
Figure 10.3 Water-blown polyurethane. (Sealection 500)