ASTM D7984-21 PDF

Full title and description

Standard Test Method for Measurement of Thermal Effusivity of Fabrics Using a Modified Transient Plane Source (MTPS) Instrument — a concise ASTM test method that defines how to measure fabric thermal effusivity (the initial warm/cool feel) using a guarded modified transient plane source sensor and associated apparatus.

Abstract

This standard specifies a comparative, instrumented procedure for quantifying the thermal effusivity of woven, knitted, and nonwoven fabrics in the dry state at ambient conditions. It describes required instrument configuration (guarded MTPS), specimen preparation, calibration against reference specimens, limits of applicability and reporting in SI units. The measurement supports fabric selection and comfort evaluation by providing a repeatable metric of initial thermal sensation.

General information

• Status: Active standard (current edition D7984-21).
• Publication date: 1 July 2021 (designation D7984-21).
• Publisher: ASTM International (ASTM).
• ICS / categories: 59.080.30 (Textile fabrics).
• Edition / version: D7984-21 (revises D7984-16).
• Number of pages: 5 pages.

Scope

This test method covers the quantitative measurement of thermal effusivity of woven, knitted, or non‑woven fabrics using a guarded modified transient plane source (MTPS) instrument. It is comparative (factory-calibrated reference specimens are used), intended for dry specimens at ambient conditions, and specifies that specimen thickness must exceed the heat‑penetration depth for the sampling time. The method applies to thermal effusivity values approximately in the range 35 to 1700 Ws1/2/m2·K. Values and reporting are given in SI units only.

Key topics and requirements

• Measurement principle: guarded Modified Transient Plane Source (MTPS) sensor that measures transient heat flux between a heated element and the fabric surface.
• Specimen requirements: fabric specimens must cover the sensor area and be thicker than the test penetration depth; multiple specimens (typically a minimum set) are measured and averaged.
• Calibration: apparatus is factory-calibrated using specimens of known thermal effusivity; calibration values are traceable to calculated properties (k, ρ, cp) for calibration materials.
• Environmental and test conditions: measure at the same temperature for sensor and specimen; keep air flow to a minimum; test in the dry state at ambient conditions.
• Measurement range and units: suitable for a wide effusivity range (≈35–1700 Ws1/2/m2·K) and reported in SI units only.
• Contact / compression: the method requires intimate contact between sensor and specimen; the standard specifies application of a controlled load (commonly referenced in practice as in the 10–50 kPa range) to ensure contact — practitioners should consult the standard text and instrument guidance for the exact load/fixture details and for materials that may change behavior when compressed.
• Reporting: report average values (from replicate specimens/tests), test conditions, instrument model/version, calibration information and any compression/fixture details affecting fabric structure.

Typical use and users

Used by textile and apparel labs, material scientists, fabric manufacturers, R&D teams and comfort/ergonomics groups to quantify the warm/cool touch of fabrics, compare materials, validate suppliers, and support product design decisions. Contract testing labs and instrument manufacturers offering MTPS testing also rely on this standard.

Related standards

Revises: ASTM D7984-16. Associated research reports and interlaboratory studies (RR:D13-1142, RR:D13-2000) provide precision/validation data for D7984. Related ASTM textile standards for conditioning and thermal/moisture measurement (for example D1776 practice for conditioning and other thermal test methods) are commonly used alongside this method.

Keywords

Thermal effusivity, MTPS, modified transient plane source, fabrics, textiles, thermal comfort, fabric testing, guarded sensor, ASTM D7984-21.

FAQ

Q: What is this standard?

A: ASTM D7984-21 is a Standard Test Method for Measurement of Thermal Effusivity of Fabrics Using a Modified Transient Plane Source (MTPS) Instrument; it gives a repeatable procedure to measure the fabric property commonly associated with warm/cool initial touch.

Q: What does it cover?

A: It covers specimen prep, instrument configuration (guarded MTPS), calibration with known specimens, limits of applicability (thickness and effusivity range), environmental/test conditions (dry, ambient) and reporting requirements.

Q: Who typically uses it?

A: Textile R&D, apparel and fabric manufacturers, independent test laboratories, instrument vendors and researchers studying fabric comfort and thermal properties.

Q: Is it current or superseded?

A: The D7984-21 edition (designation D7984-21) is the active edition published 1 July 2021. ASTM has an identified work item to revise D7984 (WK93640) initiated on 28 January 2025, so users should confirm whether a revised edition has been approved if they need the absolute latest status after that date.

Q: Is it part of a series?

A: It is part of the ASTM D13 committee textile testing suite (subcommittee D13.51) and replaces the prior D7984-16 edition; it is typically used alongside other textile conditioning and thermal test standards.

Q: What are the key keywords?

A: Thermal effusivity, MTPS, modified transient plane source, fabric comfort, guarded sensor, textile testing, D7984-21.