Selecting Insulation - Communication is Key
The owner, engineer, general contractor, insulation contractor and insulation and accessories manufacturers must communicate with each other from the very beginning of a project in order to minimize problems in the stages of design, specification preparation, construction, operations, and maintenance. Open and frank discussion between all parties is critical to helping the engineer establish the proper design criteria, define pipe and duct dimensions, select the insulation materials types and thicknesses, facings or jackets, and define the installation procedures to be followed. Ambiguities and omissions diminish when communications is encouraged. Such a discourse, along with knowledge of the most important insulation criteria as detailed below, will aid the engineer in calculating the thicknesses required for the intended service.
Characteristics of Insulation
Insulations have different properties and limitations depending upon the service, location, and required longevity of the application. These are taken into account by engineers when considering the insulation needs of an industrial or commercial application.
The quantity determined by the temperature difference, at steady state, between two defined surfaces of a material or construction that induces a unit heat flow rate through a unit area. A resistance associated with a material shall be specified as a material R. A resistance associated with a system or construction shall be specified as a system R.
Apparent Thermal Conductivity
A thermal conductivity assigned to a material that exhibits thermal transmission by several modes of heat transfer resulting in property variation with specimen thickness or surface emittance.
Thermal Conductivity (commonly referred to as 'k')
The time rate of steady state heat flow through a unit area of a homogenous material induced by a unit temperature gradient in a direction perpendicular to that unit area. Materials with lower k factors are better insulators.
This is the weight of a specific volume of material measured in pounds per cubic foot (kilograms per cubic meter).
Surface Burning Characteristics
These are comparative measurements of flame spread and smoke development with that of select red oak and inorganic cement board. Results of this test may be used as elements of a fire-risk assessment which takes into account all of the factors which are pertinent to an assessment of the fire hazard or fire risk of a particular end use.
This is a measure of the material to resist deformation (reduction in thickness) under a compressive load. It is important when external loads are applied to an insulation installation. Two examples are deforming the insulation on a pipe at a Clevis type hanger due to the combined weight of the pipe and its contents between the hangers and....Resistance of an insulation to compress on an outdoor rectangular duct due to heavy mechanical loads from external sources such as wind, snow, or occasional foot traffic.
Thermal Expansion/Contraction and Dimensional Stability
Insulation systems are installed under ambient conditions that may differ from service conditions. When the operating conditions are imposed, metal surfaces may expand or contract differently from the insulation and finish applied. This can create openings and parallel heat flow and moisture flow paths that can degrade system performance. Long term satisfactory service requires that the insulating materials, closure materials, facings, coating, and accessories withstand the rigors of temperature, vibration, abuse, and ambient conditions without adverse loss of dimensions.
Water Vapor Permeability
This is the time rate of water vapor transmission through unit area of flat material of unit thickness induced by unit vapor pressure difference between two specific surfaces, under specified temperature and humidity conditions. It is important when insulation systems will be operating with service temperatures below the ambient air. Materials and systems with low water vapor permeability are needed in this service.
Ability of a material to be washed or otherwise cleaned to maintain its appearance.
Ability of a material to perform its intended function after being subjected to high and low temperatures which the material might be expected to encounter during normal use.
Ability of a material to be exposed for prolonged periods of time to the outdoors without significant loss of mechanical properties.
Ability of a material to be exposed for prolonged periods of time to normal physical abuse without significant deformation or punctures.
The dry bulb temperature of surrounding air when shielded from any sources of incident radiation.
Ability of a material to be exposed for prolonged periods of time to a corrosive environment without significant onset of corrosion and the consequential loss of mechanical properties.
Capability of an insulation assembly exposed for a defined period of exposure to heat and flame (fire) with only a limited and measurable loss of mechanical properties. Fire endurance is not a comparative surface burning characteristic for insulation materials.
Fungal Growth Resistance
Ability of a material to be exposed continuously to damp conditions without the growth of mildew or mold.
Noise control barrier installed over
dual walled 26 inch duct.
Over 20,000 square feet of
noise control barrier materials
were installed on this project.