Combustibility: A measure of the resistance of a material to flame or high heat source. (Laboratory testing methods for this property are not intended to reflect the hazards presented by rigid urethane foam or any other material under actual fire conditions.)
Compressive Strength: The maximum compressive stress which a material is capable of sustaining. It is calculated from the maximum load during a compression test and the original cross-sectional area of the specimen. It is expressed in psi.(ASTM D1621)
Cryogenic Pipe Support: (also known as cold shoe) A type of assembly used to give necessary support to a piping system while not dissipating cryogenic temperatures of the piping system at a certain point. (see catalog)
Dimensional Stability: Change in dimensions of a specimen on exposure to various environments is called Dimensional Stability. It can be expressed as a % volume change or a linear change in dimensions. (ASTM D2126)
Frothing Process: A method of pouring the liquid ingredients of urethane foam in which partial extrusion takes place before the polymerization reaction begins. In appearance, frothed foam is like shaving cream from an aerosol can.
Hanger: A type of pipe support consisting of a clamp in which the piping system is upheld from an upper portion rather than from the base. This type of pipe support is available with or without insulation.
Mean Specific Heat: It is the quantity of heat required to change the temperature of a unit mass of a substance one degree, measured as the average quantity over the temperature range specified (ASTM C351)
Mechanical Contractors: Mechanical contractors installs the plumbing, ventilation, air conditioning, heating, and refrigeration systems in buildings. They usually work under the General Contractor to take care of all the Mechanical systems of the project.
Modulus of Elasticity: It is the ratio of stress to corresponding strain below the proportional limit. Since rigid foams do not conform to Hooke’s Law throughout their elastic range, a “tangent modulus of elasticity” is used – the tangent having the slope of the greatest part of the curve that follows Hooke’s Law (expressed in psi).
Rigid Urethane Foams: These include a variety of foams having a wide range of properties. Densities range from 60 lb / ft to below 1 lb / ft and the properties change with densities. Rigid Urethane foams have, in general, low elongation (<10%), and a low elastic limit (<10%). They can be crushed and will not recover if compressed beyond their elastic limit.
Roller Base: A pipe support assembly utilized to allow axial movement of a piping system by using rollers instead of slide plates. Usually, these rollers are attached to the base of pipe supports to allow necessary movement as the piping system expands or contracts. (See PT&P standard drawing ICS-RB-100.)
Shear Strength: It is the maximum shear stress a material is capable of sustaining. It is calculated from the maximum load during a shear test and is based on the original dimensions of the cross-sections of the specimen. (ASTM C273)
Slide Plate: An assembly of two plates utilized to reduce the coefficient of friction between their contact surfaces. Usually, these plates are attached to the base or sides of pipe supports to allow necessary movement as the piping system expands or contracts.
Strain: It is a measure of the change, due to force, in the size or shape of a body compared to its original size or shape. Strain is a non dimensional quantity, but it is frequently expressed in inches per inch (meters per meters) (ASTM D790)
Stress: It is the intensity at a point in a body of the internal forces or components of force that act on a given plane through the point (expressed as psi). It is calculated on the original dimensions of the specimen before it is tested. (ASTM D790)
Tensile Strength: It is the maximum tensile stress which a material is capable of sustaining. Tensile Strength is calculated from the maximum load carried to rupture during a tension test and the original cross-sectional area of the specimen (ASTM D1623)
Thermal Conductivity: It is the rate of heat flow, under steady conditions, through unit area, per unit temperature gradient in the direction perpendicular to the area. Thermal Conductivity is usually expressed in English units as BTU’s per square foot per hour per degree Fahrenheit for a thickness of one inch. (ASTM C518)
Water Absorption: It is the amount of water a specimen picks up on total immersion in water over a specified time. Water absorption is usually expressed as lbs.-water / ft of foam or as percent of the total foam weight. (ASTM D2842)
Water Vapor Transmission: It is the rate at which moisture will pass through a homogeneous material. The rate may vary on exposure conditions. Water Vapor Transmission is usually expressed as “per-inches” which is the grains of water transmitted per square foot per hour per inch differential of mercury for a one inch specimen thickness. (ASTM C355)
Yield Strength: It is the stress at which a material exhibits a specified limiting deviation from the proportionality of stress to strain. The deviation is expressed in terms of strain. Since low density rigid urethane foam exhibits a definite yield point, the yield strength is the stress at this point. High density rigid urethane foams do not exhibit a yield point so the yield strength is the stress at which there is marked deviation from the proportionality of stress to strain. An offset method can also be used (usually at a strain of 0.2%)