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Glossary of Terms


Abatement: To reduce or make void any substance such as the removal of stairsnoise, asbestos or lead. See asbestos abatement definition as one form of removal.
Abrasion Resistance: The ability of a material to withstand abrasion without appreciative erosion.
Absolute Humidity: The ratio of the mass of water vapor to total volume of an air sample. The I-P units are pounds of: moisture per pound of cubic foot of air and the SI units are grams or kilograms of moisture per: cubic meter of air.
Absorptance: The ratio of the radiant flux absorbed by a body to that incident upon it.
Absorption: Transformation of radiant energy to a different form of energy by interaction with matter.
ABUSE COVERINGS AND FINISHES: Jackets or mastics used to protect insulation from mechanical and personnel abuse.
ACIDITY: The quality of a material to be acidic (pH under 7) when exposed to moisture or water producing a red/pink reaction to litmus paper. In the insulation industry, materials with pH between6 and 8 are generally considered non-acidic and non-alkaline.
Acoustical Treatment: Application of absorbing insulation for sound control.
ADDITIVE: Any substance that is added to a resin, usually in a relatively small percentage, to alter properties. Examples are slip additives, pigments, stabilizers and flame retardants.
Adhesive: A substance used to bond materials by surface attachment.
Aerogel: A homogeneous, low-density solid state material derived from a gel, in which the liquid: component of the gel has been replaced with a gas. The resulting material has a porous structure: with an average pore size below the mean free path of air molecules at standard atmospheric: pressure and temperature.
AIR CONDITIONED SPACE: Building area supplied with cooled conditioned air.
Air Conditioning: See conditioned air.
ALIPHATIC: An organic substance containing straight or branched chain arrangements of carbon atoms.
Alkalinity: The quality of a material to be basic or alkaline when exposed to moisture or water producing a: blue reaction to litmus paper. A pH measure greater than 7.0.
Ambient Temperature: The average temperature of the medium, usually air, surrounding the object under consideration.
Ambient: Surrounding-encompassing (Generally applied to temperature, humidity and atmospheric: conditions).
Annular Space (Annulus): The distance between a penetrating item and the surrounding opening.
Anti-Abrasive Coating: Cushioning material applied where insulation contacts the pipe, duct, vessel or adjacent: insulation to prevent eroding of either or both.
Anti-Sweat: Any application that prevents condensation.
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. (See conductivity, thermal).
Apparent Thermal Resistivity: A thermal resistivity assigned to a material that exhibits thermal transmission by several modes: of heat transfer resulting in property variation with specimen thickness, or surface emittance. (See resistivity, thermal, R-value).
Appearance Covering: Materials used to improve the aesthetics of the finished insulation.
APPEARANCE: Important in exposed areas and for coding purposes.
Application Temperature Limits: Minimum and maximum temperatures between which it is usually safe to service finishes,: adhesives and sealants without endangering the integrity of the material.
Area Weight: Weight per unit area for a specified sample, in units of lbs/ft² (kg/m²).
AROMATIC: A class of organic compounds containing a resonant, unsaturated ring of carbon atoms. Included are benzene, naphthalene, anthracene and their derivatives.
Asbestos Abatement: A procedure for the removal, enclosure or encapsulation of asbestos containing materials from: buildings or areas.
ASJ: All Service Jacket, otherwise described as a laminate facing or covering constructed with a white: kraft paper, fiber glass scrim and a thin aluminum foil.
Asphalt Cut-Back: Petroleum asphalt coating with mineral solvents. (This is a vapor-retarder mastic).
Asphalt Emulsion: A colloidal dispersion of petroleum asphalt coating with water. (This is a breather mastic).
ASTM International: ASTM International provides a global forum for the development and publication of: international voluntary consensus standards for materials, products, systems, and services.
ASTM: American Society for Testing and Materials. An independent association which has accepted responsibility for the development and administration of voluntary standards for the testing and evaluation of a wide range of products.
Attenuation: The limiting of sound propagation from one area to another.
Bands: Strapping used to fasten insulation and/or jacketing in place.
BASIC: See Alkalinity.
Batt: Blanket insulation manufactured to dimensions as required by a specific application.
Beading: Process of curling the edge of metal jacketing to accommodate sealing.
Bedding Compound: A plastic material (mastic) used to imbed insulation. Acts as a cushion, anti-abrasive and: adhesive.
Bends (Tube Turns): Pipe, factory or field formed, to pre-determined radii.
Binder: Substance contained in insulation material that stabilizes the fibers (sometimes called a thermal: setting resin).
Blackbody: The ideal, perfect emitter and absorber of thermal radiation. It emits radiant energy at each: wavelength at the maximum rate possible as a consequence of its temperature, and absorbs all: incident radiance.
Blanket Insulation, Metal Mesh: Blanket insulation covered by flexible metal-mesh facings attached on one or both sides.
Blanket Insulation: A relatively flat and flexible insulation in coherent sheet form furnished in units of substantial: area.
Bleeding: The diffusion of coloring through a coating from its base or substrate (such as bleeding of asphalt: mastic through a paint top coat).
Blister: Rounded elevation of the surface of a mastic resembling a blister on the human skin, usually the: entrapment of air or vapor.
Block Insulation: Rigid insulation preformed into rectangular units.
BLOWING AGENT: A substance incorporated in a mixture for the purpose of producing foam. For polyurethanes, this is usually either carbon dioxide generated from the diisocyanate/water reaction or introduced as liquid CO2 or a low boiling hydrocarbon liquid (such as pentane) volatilized by the heat of the polyurethane-forming reactions.
Board Insulation: Semi-rigid insulation preformed into rectangular units having a degree of suppleness, particularly: related to their geometrical dimensions.
BOCA: Building Officials and Code Administrators.
Body: The viscosity or consistency of a mastic or coating.
Bond Strength: The force in tension, compression, cleavage or shear required to break an adhesive assembly.
BONDING TIME: The time required for an adhesive to reach its optimum bonding strength.
Bonding Time: The time required for an adhesive to reach its optimum bonding strength.
BOX TRENCH: Built-up enclosure either in a shallow trench or buried underground.
Box Trench: Built-up enclosure either in a shallow trench or buried underground.
Branch: Distribution piping or ductwork, same as a main duct except, smaller and from or returning to the: main, serving two or more runouts.
BREAKING LOAD: In some installations the insulation material must "bridge" over a discontinuity in its support. The Breaking Load is the force necessary to create structural failure in a "bridging" condition. See Flexural Strength.
Breather Coating: A weather barrier coating designed to prevent water (rain, snow, sleet, spillage, wash water, etc.): from entering the insulation system, while still allowing the escape of small quantities of water: vapor resulting from heat applied to the moisture entrapped in the insulation.
British Thermal Unit (Btu): The amount of heat required to raise one pound of water one degree Fahrenheit at 59 F.,: specifically 778.26 ft. lbs.
Built-Up Roof: A composition roof composed of layers of roofing felt mopped with hot asphalt and usually: topped with gravel.
Butt Joints: The end joints of pipe insulation.
Butt Strip: Strips of similar jacket material applied around pipe insulation butt joints.
“C" VALUE (Thermal Conductance): A measure of the rate of heat flow for the actual thickness of a material. If the "K" of a material is known, the "C" can be determined by dividing the "K" by the thickness. The lower the "C", the higher the insulating value. CALCIUM SILICATE: A hard granular molded insulation manufactured from a hydraulic cured mixture of calcium, silicate, water and inorganic binders.
Calcium Silicate: Insulation composed principally of hydrous calcium silicate, and which usually contains: reinforcing fibers.
Canvas: A plain-weave cotton fabric used for jacketing or covering.
Capillarity: The ability of a cellular, fibrous or granular material to diffuse water into its structure.
CATALYST: A substance that causes or accelerates a chemical reaction when added to the reactants in a minor amount, and that is not consumed in the reaction.
Caulk: To seal and make water and/or airtight.
Cellular Elastomeric: Insulation composed principally of natural or synthetic elastomers, or both, processed to form a: flexible, semi-rigid or rigid foam that has a closed-cell structure.
Cellular Glass: Insulation composed of glass processed to form a rigid foam having a predominately closed-cell: structure.
Cellular Insulation: Insulation composed of small, individual cells separated from each other. The cellular material: may be glass or plastic such as polystyrene, polyurethane, polyisocyanurate or elastomeric.
Cellular Plastic Expanded: Beads of plastic expanded by chemical or thermal means and bonded together chemically or: thermally.
Cellular Plastic Extruded: Extruded plastic with cells formed by thermal or chemical means.
CELLULAR PLASTIC: Plastic expanded by thermal or chemical means, containing closed cells throughout.
Cellular Polyimide: Insulation composed of the reaction product in which the bonds formed between monomers: during polymerization are essentially imide units forming a cellular structure.
Cellular Polystyrene: Insulation composed principally of polymerized styrene resin processed to form a rigid foam: having a predominately closed-cell structure.
Cellular Polyurethane: Insulation composed principally of the catalyzed reaction product of polyisocyanate and polyol: compounds, processed usually with fluorocarbon or hydrocarbon gas to form a rigid foam having: a predominately closed-cell structure.
Cellulosic Fiber: Insulation composed principally of cellulose fibers usually derived from paper, paperboard stock: or wood, with or without binders.
Cement, Finishing: A mixture of dry fibrous or powdery materials, or both, that when mixed with water develops a: plastic consistency, and when dried in place forms a relatively hard, smooth protective surface.
Cement, Insulating: A mixture of dry granular, fibrous or powdery (or both) materials that when mixed with water: develops a plastic consistency, and when dried in place forms a coherent covering that affords: substantial resistance to heat transmission.
Ceramic Fibers: Pure silica heated and expanded to produce fibers from which high-temperature insulation can be: made. Sometimes called Refractory Ceramic Fibers.
Chalking: A soft white or gray appearance on the surface of a weathered finish.
Checking: Openings of a coated surface characterized by the appearance of fine cracks in all directions.
Chemical Resistance: Capability of a material to withstand exposure to acids, alkalis, salts and their solutions.
Chicken Wire: Hexagonal wire netting (poultry mesh) used as reinforcement or as a metal-mesh facing.
Cladding-Jacketing: Jacketing installed over insulation. Also, see “Jacketing.”
Clearance: Adequate space allowed for installation of insulation materials.
Closed Cell Foam: A material comprised predominantly of individual non-interconnecting cellular voids.
Coating: A liquid or semi-liquid that dries or cures to form a protective finish, suitable for application to: thermal insulation or other surfaces in a dry thickness of 30 mils or less per coat.
Code (Building): A set of construction and materials standards, usually statutory. Model building codes are: adopted by each municipality from the major code organizations. The major code authorities are: BOCA, (Building Officials and Code Administrators, primarily Midwest), ICBO (International: Council of Building Code Officials, West and Indiana) and SBCCI (Southern Building Code: Congress, International, South). The local municipality or state can choose which major building: code is adopted.
Coefficient of Expansion/Contraction: The change in a unit length of a material corresponding to a unit change in the temperature of the: material.
Combustible: Provides enough fuel to make insulation capable of burning.
Compaction Resistance: The property of a fibrous or loose-fill material that resists compaction under load or vibratory: conditions.
Compatible Materials: Two or more substances that can be mixed or used together without separating, reacting, or: adversely affecting the materials.
Compressive Strength: The property of an insulation material that resists any change in dimensions when acted upon by: a compaction force.
Concealed Spaces: Spaces not generally visible after the project is completed such as furred spaces, pipe spaces,: pipe and duct shafts, spaces above ceilings, unfinished spaces, crawl spaces, attics and tunnels.
Condensate Drain: Piping carrying condensed water from air conditioning or refrigeration drip pans to a point of: discharge.
Condensate Return: The liquid formed by condensation of vapor. In steam heating it is water condensed from steam.In air conditioning it is the water extracted from the air by cooling.
Condensation: The act of water vapor turning into liquid upon contact with a cold surface.
CONDITIONED AIR: Air treated to control simultaneously its temperature, humidity and cleanliness to meet the requirements of a conditioned space. (May be cool and/or heated and should be clearly defined.)
Conditioned Space: Building area supplied with conditioned air that is heated or cooled to a certain temperature and: may be mechanical controlled to provide a certain humidity level.
CONDUCTANCE (THERMAL) "C": The rate of heat flow for the actual thickness of a material.
Conductance, Air Film: The time rate of heat flow from a unit area of a surface to its surroundings, induced by a unit: temperature difference between the surface and the environment.
Conductance, Thermal, C-value: The time rate of steady state heat flow through a unit area of a material or construction induced: by a unit temperature difference between the body surfaces.
Conduction: The transfer of heat energy within a body or between two bodies in physical contact.
Conductivity, Thermal (k-value): The measure of heat that pass through a unit area of a homogeneous substance, through a unit: thickness, in a unit of time, for each unit temperature difference. The lower the k-value, the: higher the insulating value. Note: I-P units are Btu – in / hr – ft2 - °F and typical SI units are Watts / m - °C. Textbook definition: The time rate of steady heat flow through a unit area of a homogeneous: material induced by a unit temperature gradient in a direction perpendicular to that unit area.
Contact Adhesive: An adhesive that when tacky to the touch will adhere to itself instantaneously on contact.
CONTACT ADHESIVE: An adhesive which when dry to the touch will adhere to itself instantaneously on contact.
CONVECTION: The transfer of heat by movement of fluids.
Convection: The transfer of heat by movement of fluids.
Corrosion Retarder (as Related to Insulation Jacketing): See Moisture Barrier (as related to insulation jacketing): Couplings: Screwed, soldered, welded or mechanical/grooved connections between links of pipe.
Corrosion: Deterioration by chemical action such as rust on steel.
COUPLINGS: Screwed, soldered, welded or mechanical/grooved connections between links of pipe.
Cover: To place insulation and/or finish materials on, over or around a surface so as to insulate, protect: or seal.
Coverage: The area to be covered per unit volume of coating to obtain specified dry thickness and desired: performance.
Covering Capacity, Dry: The area covered to a dry thickness of 1 inch (25 mm) by 100 lb. (45.4 kg) of dry cement when: mixed with the recommended amount of water, molded and dried to constant weight.
Covering Capacity, Wet: The area covered to a wet thickness of 1 inch (25 mm) by 100 lb. (45.4 kg) of dry cement when: mixed with the recommended amount of water and molded.
Crimping: Corrugating of the metal edge to reduce diameter or facilitate bending. Used on fitting gores to: mate with beaded edge of adjacent segment or on end caps for tanks and vessels.
Cryogenic Insulation: Insulation for extremely low-temperature processes surfaces from –100 F to –459 F (absolute: zero).
Cupped Head Pin: Capacitor discharge welded insulation fastener pin with a fixed washer.
Cure: To change the properties of a plastic or resin by chemical reaction, usually accomplished by the: action of either heat or a catalyst.
C-Value (Thermal Conductance): See Conductance, thermal.
Damming: The use of a substance to support firestopping materials until cured.
Decibel (Db): A logarithmic measure of the ratio of like power quantities as used in describing levels of sound: pressure or sound power.
Decomposition: The separating or breaking down of a substance into its component compounds or basic: elements.
Delamination: The separation of the layers of material in a laminate.
Density, Apparent (of Applied Insulation): The mass per unit volume of in-place mass thermal insulation.
Dew Point: Saturation temperature where water vapor and liquid occur simultaneously.
Dewpoint Temperature: The temperature at which condensation of water vapor in a space begins for a given state of: humidity and pressure as the vapor temperature is reduced; the temperature corresponding to: saturation (100% relative humidity) for a given absolute humidity at constant pressure.
Diatomaceous Silica: Insulation composed principally of diatomaceous earth with or without binders, and which: usually contains reinforcing fibers.
Diffusivity, Thermal: The ratio of thermal conductivity of a substance to the product of its density and specific heat.
Dimensional Stability: That property of a material that enables it to maintain its original size, shape and dimensions.
Dry: To change the physical state of a substance by the loss of solvent constituents by evaporation, absorption, oxidation or a combination of these factors.
Dual Temperature: Systems of equipment that operate as cold condition and hot application.
Duct Flange (Stiffener): A structural or fabricated angle iron shape, attached to the exterior surfaces of a duct at specified: intervals for the purpose of reinforcing the metal and assembly of the ducts.
Duct: A passageway made of sheet metal or other suitable material used for conveying air or other gas.
Efflorescence: A white powdery substance occurring on the surface of coated insulation products caused by the: migration of soluble salts from the insulation, followed by precipitation and carbonation.
ELASTOMER: A material that at room temperature can be stretched repeatedly to at least twice its original length and, immediately upon release of the stress, return with force to its approximate original length. This definition is one criterion by which materials called plastics in commerce are distinguished from elastomers and rubbers.
Elastomeric: A closed-cell foam insulation containing elastomers that provide the property of high elasticity.
Emittance, Directional: The ratio of the radiance from a surface in a particular direction to the radiance from a blackbody: at the same temperature under the same conditions.
Emittance, Hemispherical: The average directional emittance over a hemispherical envelope covering a surface.
Emittance, Spectral: An emittance based on the radiant energy emitted per unit wavelength interval (monochromatic: radiant energy).
Emittance, Total: An emittance that is an integrated average over all wavelengths of radiant energy emitted.
Emittance: The ratio of the radiant flux emitted by a specimen to that emitted by a blackbody at the same: temperature and under the same conditions.
Emulsion: Insoluble fine solids or liquids dispersed in another liquid, usually water.
Epoxy Resins: A two-part compound of an epoxy and catalyst that cures at ambient temperatures to form: finishes which are highly resistant to solvents and chemicals. A high bond adhesive.
Exhaust Duct: A duct carrying air from a conditioned space to an outlet outside the building.
Expanded Metal Lath: See lath—expanded metal.
EXPANDED POLYSTYRENE (EPS): Expanded polystyrene, manufactured from styrene, is a closed-cell, thermoplastic material often molded into low-density foam articles, such as protective packaging, foam insulation and building and construction.
Exposed Spaces: Those spaces not referred to as concealed or as defined by the specifier.