Building insulation materials jagged, shredded, or scuffed). When found in the home, asbestos often resembles grayish-white corrugated cardboard coated with cloth or canvas, usually held in place around pipes and ducts with metal straps. Things that typically might contain asbestos: All polyurethane foams are composed of petrochemicals. Foam insulation often uses hazardous chemicals with high human toxicity, such as isocyanates, benzene and toluene. The foaming agents no longer use ozone-depleting substances. Personal Protective Equipment is required for all people in the area being sprayed to eliminate exposure to isocyanates which constitute about 50% of the foam raw material. Fiberglass is the most common
Thermal insulation commonly used. For some materials, thermal conductivity may also depend upon the direction of heat transfer. The act of insulation is accomplished by encasing an object with material of low thermal conductivity in high thickness. Decreasing the exposed surface area could also lower heat transfer, but this quantity is usually fixed by the geometry of the object to be insulated. Multi-layer insulation is used where radiative loss dominates, or when the user is restricted in volume and weight of the insulation (e.g. Emergency Blanket, radiant barrier) For insulated cylinders, a "critical radius" must be reached. Before the critical radius is