This section provides guidance on selection of mechanical insulation materials, based on factors including temperature ranges, material characteristics, and system type.
1. Insulation Selection
In addition to thermal performance, other considerations are important in selection of insulation material. The following table discusses these considerations for each operating temperature range.
Table 2.3.1
Condensation control on ducts, chillers, roof drains and cold piping is a basic function of insulation in commercial buildings. Design objectives here are to choose materials and application methods that will achieve the best vapour retarder seal possible, and to calculate the thickness of insulation necessary to prevent condensation.
Insulation chosen for personnel protection and/or fire protection must be able to withstand high temperatures without contributing to a possible fire hazard. Engine exhausts which can reach temperatures of 455°C to 675°C should be insulated sufficiently to reduce surface temperatures exposed to personnel or flammable materials to under 60°C. Kitchen exhaust ducts which are subjected to flammable grease accumulation fall within the same design criteria.
A variety of weather and vapour retarder jackets and mastics is available to aid insulation materials in meeting and designing objectives such as fire safety, appearance and system abuse protection.
All insulation, jacket, adhesives, mastics, sealers, etc., utilized in the fabrication of these systems shall meet NFPA for fire resistant ratings (maximum of 25 flame spread and 50 smoke developed ratings) and shall be approved by the insulation manufacturer for guaranteed performances when incorporated into their insulation system, unless a specific product is specified for a specific application and is stated as an exception to this requirement.
Care should be taken in designing insulation systems to specify the thickness, material and finish. All materials, thicknesses, finishes, securements and design objectives should be carefully communicated to the insulation contractor.
2. General Materials Selection Tables
The following two tables provide general guidance on appropriate materials choices based on system temperature and system type respectively. Note that in some cases there may be exceptions to the temperature ranges shown; consult manufacturer’s product specifications.
For more detailed information on insulation materials descriptions, characteristics and physical properties, refer to Appendix B, Materials Reference Tables.
Table 2.3.2
* Indicates temperature range exceeds rating for insulation; in this case the material would be suitable only at the lower end of the temperature range.
†There are some fibre glass products available that can service the lower end of this range.
Table 2.3.3
3. Protective Covering Selection
The efficiency and service of insulation is directly dependent upon its protection from moisture entry and mechanical and chemical damage. Choices of jacketing and finish materials are based upon the mechanical, chemical, thermal and moisture conditions of the installation, as well as cost and appearance requirements.
Protective coverings are divided into six functional types.
Table 2.3.4
Specific materials have not been recommended for protective covering; commonly, the insulation and jacket must work together as a system to achieve the design goals. Manufacturers of these systems are best qualified to make recommendations, in consideration of the conditions.