ASTM C1371-15
Standard Test Method for Determination of Emittance of Materials Near Room Temperature Using Portable Emissometers

Standard No.

ASTM C1371-15

Release Date

2015

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM C1371-15(2022)

Latest

ASTM C1371-15(2022)

Scope

5.1 Surface Emittance Testing: 

5.1.1 Heat transfer from a surface by radiation transfer is reduced if the surface of a material has a low emittance. Since the controlling factor in the use of insulation is sometimes condensation control or personnel protection, it is important to understand that a low emittance will change the surface temperature of a material. One possible criterion in the selection of these materials is the question of the effect of aging on the surface emittance. If the initial low surface emittance of a material is not maintained during service, then the long-term value of the material is diminished.

5.1.2 This test method provides a means for comparative periodic testing of low emittance surfaces in the field. In this way the effects of aging on the reflective properties can be monitored.

5.1.3 This test method determines the total hemispherical emittance with a precision of better than ±0.02 units.(1) The emittances of the calibration standards shall have been obtained from accurate independent measurements of total hemispherical emittance. This test method shall not be used for specimens that are highly anisotropic or transparent to infrared radiation. This test method also shall not be used for specimens with significant thermal resistance (see 7.3.4).

5.1.4 Once a reliable emittance measurement has been determined, the value is available to be used to calculate radiative heat flow from the subject surface. For example, if the temperature of the surface, T₁, and the temperature of the surroundings, T₂, are known, then the radiative heat flow, Q_rad, is given by:

where A is the area of the surface, and either A is assumed to be much smaller than the area of the surroundings or the emittance of the surroundings is assumed to be unity. This radiative heat flow when combined with convective and conductive heat flows provides the total heat flow from the surface (a method for calculating total heat flow is described in Practice C680).

1.1 This test method covers a technique for determination of the emittance of opaque and highly thermally conductive materials using a portable differential thermopile emissometer. The purpose of the test method is to provide a comparative means of quantifying the emittance of materials near room temperature.

1.2 This test method does not supplant Test Method C835, which is an absolute me......

ASTM C1371-15 Referenced Document

• ASTM C168 Standard Terminology Relating to Thermal Insulation
• ASTM C680 Standard Practice for Determination of Heat Gain or Loss and the Surface Temperatures of Insulated Pipe and Equipment Systems by the Use of a Computer Program
• ASTM C835 Standard Test Method for Total Hemispherical Emittance of Surfaces up to 1400°C
• ASTM E177 Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• ASTM E408 Standard Test Methods for Total Normal Emittance of Surfaces Using Inspection-Meter Techniques
• ASTM E691 Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

ASTM C1371-15 history

• 2022 ASTM C1371-15(2022) Standard Test Method for Determination of Emittance of Materials Near Room Temperature Using Portable Emissometers
• 2015 ASTM C1371-15 Standard Test Method for Determination of Emittance of Materials Near Room Temperature Using Portable Emissometers
• 2004 ASTM C1371-04a(2010)e1 Standard Test Method for Determination of Emittance of Materials Near Room Temperature Using Portable Emissometers
• 2004 ASTM C1371-04a Standard Test Method for Determination of Emittance of Materials Near Room Temperature Using Portable Emissometers
• 2004 ASTM C1371-04 Standard Test Method for Determination of Emittance of Materials Near Room Temperature Using Portable Emissometers
• 1998 ASTM C1371-98 Standard Test Method for Determination of Emittance of Materials Near Room Temperature Using Portable Emissometers