ASTM E1225-25a PDF
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St ASTM E1225-25a
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Ст ASTM E1225-25a
Original standard ASTM E1225-25a in PDF full version. Additional info + preview on request
Full title and description
ASTM E1225-25a — Standard Test Method for Thermal Conductivity of Solids Using the Guarded‑Comparative‑Longitudinal Heat Flow Technique. This test method specifies a steady‑state, guarded‑comparative, longitudinal heat‑flow technique for determining the thermal conductivity (λ) of homogeneous, opaque solid materials and certain composite assemblies using a comparative guarded‑longitudinal apparatus.
Abstract
The standard defines the guarded‑comparative longitudinal heat flow technique used to measure steady‑state thermal conductivity of solids. Typical applicable conductivity range is approximately 0.2 to 200 W/(m·K) and the recommended temperature interval is roughly 90 K to 1300 K; SI units are required. The method includes requirements for specimen geometry and apparatus qualification and may also be used to evaluate contact thermal conductance/resistance.
General information
- Status: Active (designation E1225‑25A / E1225‑25a; current active edition/amendment).
- Publication date: 2025 (last updated / published in 2025; amendment edition “25a” implemented in that cycle).
- Publisher: ASTM International (Committee E37, Subcommittee E37.05).
- ICS / categories: 17.200.10 (Thermal insulation and thermal conductivity / related thermal properties).
- Edition / version: E1225‑25a (amendment to the E1225‑25 series; published as E1225‑25A on ASTM records).
- Number of pages: 10 pages (concise test method document).
Scope
This test method describes a steady‑state guarded‑comparative, longitudinal heat‑flow technique for measuring the thermal conductivity of homogeneous, opaque solids (and some composites when reported as apparent conductivity). It applies primarily to materials with effective thermal conductivities in the approximate range 0.2 to 200 W/(m·K) over a wide temperature range (about 90 K to 1300 K), with accuracy decreasing outside these limits. The standard requires use of SI units and provides notes on specimen homogeneity, infrared transparency issues, and apparatus qualification.
Key topics and requirements
- Guarded‑comparative longitudinal heat‑flow technique and steady‑state measurement principles.
- Applicable conductivity range: ~0.2 to 200 W/(m·K); recommended temperature range ≈ 90 K to 1300 K.
- Specimen requirements: homogeneity criteria, geometry and size guidance to limit apparent λ variation (notes on composite and layered specimens).
- Apparatus qualification and calibration procedures (requirements for qualifying a guarded‑longitudinal system are specified in the standard).
- Reporting of results in SI units and reporting of apparent conductivity when infrared transparency or heterogeneity affects measurements.
- Use of the method for evaluation of contact thermal conductance/resistance between materials where applicable.
Typical use and users
Common users include materials testing laboratories, research institutions, national metrology institutes, and industrial quality/control labs that measure thermal conductivity of ceramics, polymers, metals, graphites, refractories and composite solids. The method is used for characterization, product development, material selection and verification of thermal property data for engineering and scientific applications.
Related standards
Relevant complementary or alternative standards include ASTM E1461 (Laser Flash Method for thermal diffusivity, for high‑temperature diffusivity and when transient methods are preferred), ASTM C518 (Heat Flow Meter method for thermal conductivity of insulating materials), and international guarded‑plate standards such as ISO 8302 (guarded hot plate methods) for steady‑state thermal conductivity of insulating materials. These standards are commonly referenced when selecting the most appropriate measurement technique for a material, temperature range or sample geometry.
Keywords
thermal conductivity, guarded‑comparative, guarded‑longitudinal, steady‑state, solids, thermal conductance, thermal resistance, ASTM E1225, E1225‑25a, apparatus qualification, SI units
FAQ
Q: What is this standard?
A: ASTM E1225‑25a (also shown in ASTM records as E1225‑25A) is the ASTM Standard Test Method for Thermal Conductivity of Solids Using the Guarded‑Comparative‑Longitudinal Heat Flow Technique — a steady‑state comparative technique for measuring thermal conductivity of homogeneous, opaque solids.
Q: What does it cover?
A: It covers specimen preparation and geometric criteria, instrumentation and apparatus qualification, test procedures for establishing steady‑state longitudinal heat flow in a guarded system, ranges of applicability (approx. 0.2–200 W/(m·K) and ~90–1300 K), and reporting conventions (SI units, apparent conductivity when needed).
Q: Who typically uses it?
A: Materials test labs, research groups, industrial R&D and quality control labs, and metrology institutes use this method to determine thermal conductivity of engineering materials such as ceramics, polymers, metals, refractories, graphites and composites.
Q: Is it current or superseded?
A: The E1225‑25a amendment/edition is recorded as the active/latest amendment in the E1225 series (designated E1225‑25A in ASTM listings). Users should confirm the exact revision date and any subsequent amendments through ASTM records before citing or applying the procedure.
Q: Is it part of a series?
A: Yes. ASTM E1225 has earlier issued editions (for example E1225‑99, E1225‑09, E1225‑20 and the E1225‑25 series). The “25a” designation indicates an amendment or letter revision associated with the 2025 edition cycle. Check the ASTM document history for the exact relationships between editions and amendments.
Q: What are the key keywords?
A: Thermal conductivity, guarded‑comparative longitudinal, steady‑state, solids, specimen homogeneity, apparatus qualification, apparent thermal conductivity, ASTM E1225‑25a.