Field Applied Spray Polyurethane Foam in Building Envelopes: Performance Evaluation of System Components

Abstract

SPF as a category comprises either closed-cell or open-cell structures with densities ranging from 8 to 65 kg/m3 (0.5 to 4 lb/ft3). While the foam density cannot be used as the criterion of foam performance, the core density is extensively used in quality assurance programs. In a typical two-component foam fabrication, two transfer pumps deliver components A and B to the proportioning unit. Then, a heated dual-hose carries each ofthe components to the mixing gun. As a rule,A and B components are delivered to the spray gun in a one-to-one ratio. Compressed air is also delivered to the mixing chamber, though via a separate, unheated hose. Air is used to increase the mixing turbulence in the gun, assist in expulsion from the gun and direct the polymeric mixture to the substrate. Depending on the reactivity of the polymeric mixture and the delivery mechanism, SPF may be recognized as: