Last week we talked about the chemical flow and learned the purpose of the proportioning equipment is to compensate for external conditions to create good quality foam. This week we are going to dive into some general processing guidelines for open cell spray foam.
First things first, it is critical that we understand the appropriate equipment that is necessary to properly process and apply open cell foam. This includes a positive displacement proportioning pump, like the Graco Reactor 2 E-30 or the PMC PH-25, 200 to 300 foot of heated hose, a compatible spray gun, like the Graco Fusion AP Gun or the PMC AP-2 Spray Gun, and a drum mixer and circulation system for open cell foam. This equipment will be used to prepare, process and apply the raw materials, resulting in the on-site manufacture of your spray foam insulation product.
As we have discussed before, the application of these raw materials is temperature sensitive, therefore the storage temperature and starting temperature of the drum is critical to your process. If your SPF manufacturer’s recommended processing temperature is 135°F, the applied material is going to react significantly different if the drum temperature is 60°F vs. 90°F. Make sure to refer to your SPF manufacturer’s recommendations for ideal drum temperature, but remember, higher material temperatures lower viscosity, allow the material to flow more freely and improve the mixing process between the resin and the iso.
You can be proactive in managing the material temperature in the drum with two key steps: keep your open cell resin and iso drums in a warm, dry storage room and incorporate a circulation system into your preparation process with open cell foam. The circulation loop will allow you to heat the raw material by moving it through the proportioning unit, thereby increasing the material temperature in the drum. Of course, the time required to circulate and pre-heat a 60°F drum vs. a 75°F drum, to your manufacturer’s ideal drum temperature, could be saved by the choice to store your drums in a warmer location.
Additionally, many of the leading open cell manufacturers recommend stirring the open cell resin with a drum mixer, both before and during application. This continuous blending helps lower the viscosity of the material and keeps the drum temperature consistent.
When it comes time to process and apply the material, all of the commercially available products have a “window of application”, or an optimum temperature processing range that will produce good foam and minimize problems. The wider the window of application, the more forgiving the product and the easier it is to work with. When you operate above the upper limit of the range, you will generally have shrinkage, and below the lower limit you will have voids. In general, the closer you can operate to the higher end of the processing range, without problems, the higher your yield. When you encounter shrinkage or voids you can adjust your temperature settings, in small increments, to compensate for this effect.
Your job is to convert drums of material into sq. ft. of good quality, applied foam, therefore maximizing your yield and minimizing your waste is critical to your bottom line.
Stay tuned next week as we discuss processing closed cell SPF.
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