ASTM B389-81 (2020) PDF

Full title and description

Designation: ASTM B389 − 81 (Reapproved 2020). Full title: "Standard Test Method for Thermal Deflection Rate of Spiral and Helical Coils of Thermostat Metal" — a standardized laboratory procedure for measuring the angular deflection of spiral and helical thermostat-metal coils in response to temperature change.

Abstract

This test method defines the procedure to determine the thermal deflection rate (the angular rotation per unit temperature change) of spiral and helical coils made from thermostat metal. The method describes required apparatus (temperature bath, protractor, specimen holder, pointer), specimen mounting, measurement steps and the calculation used to report deflection rate; it is intended for use as a quality/acceptance test and for design optimization of thermostat coils.

General information

• Status: Published / Active (reapproved edition).
• Publication date: Current edition approved October 1, 2020; published October 2020 (designation shows original year 1981 with reapproval in 2020).
• Publisher: ASTM International (ASTM Committee B02 — Nonferrous Metals and Alloys, Subcommittee B02.10 Thermostat Metals).
• ICS / categories: Historically associated with ICS 21.160 (Springs) and mechanical testing categories (relevant mechanical-testing ICS entries for thermostat metals).
• Edition / version: Designation B389 − 81 (Reapproved 2020); current edition approved Oct 1, 2020.
• Number of pages: Short test method — historically published as a brief procedure (about 4 pages in earlier document listings; final page count may vary by distributor/format).

Scope

This standard covers determination of the thermal deflection rate of spiral and helical coils of thermostat metal. It specifies units (inch‑pound standard; SI conversions informational), apparatus and mounting methods, measurement of angular position at two temperatures, and the formula used to calculate deflection rate (angular degrees per degree temperature change). The procedure is intended for quality control, acceptance testing, and material/design evaluation of thermostat coils.

Key topics and requirements

• Definition of thermal deflection rate (n or D) and the calculation D = (A2 − A1) / (T2 − T1), where A = angular position and T = temperature.
• Required apparatus: stirred temperature bath or uniformly heated enclosure, protractor for angular measurement, specimen holder/arbor, lightweight transmission pointer.
• Specimen types: spiral and helical thermostat-metal coils — guidance for mounting (center tab, press fit, or fastened) and orientation.
• Test procedure: equilibrate coil at baseline temperature, record angular position, change to second temperature, record angular position, calculate deflection rate; recommendations for repeatability and mounting to simulate service conditions.
• Significance and use: useful for lot acceptance/rejection, design optimization (thickness/length selection), and comparing material lots.
• Jurisdiction: under ASTM Committee B02 on Nonferrous Metals and Alloys, Subcommittee B02.10 (Thermostat Metals and Electrical Resistance Heating Materials).

Typical use and users

Used by materials and quality engineers, metallurgists, test laboratories, thermostat and temperature‑control device manufacturers, and suppliers of thermostat metal sheet/strip. Typical applications include incoming inspection, lot acceptance testing, product development (optimizing coil geometry), and R&D where consistent thermal actuation behavior is required.

Related standards

Standards commonly referenced alongside or related to B389 include: ASTM B388 (specifications for thermostat metal sheet and strip), ASTM B106 (test methods for flexivity of thermostat metals), and other ASTM test methods and specifications cited within B389 (for example thermometry/temperature-measurement standards used in the procedure).

Keywords

Thermal deflection rate; thermostat metal; spiral coil; helical coil; coil deflection; angular deflection; thermostat coil testing; ASTM B389; B389-81; reapproved 2020.

FAQ

Q: What is this standard?

A: ASTM B389 − 81 (Reapproved 2020) is a test method that defines how to measure the thermal deflection rate (angular rotation per temperature change) of spiral and helical thermostat‑metal coils.

Q: What does it cover?

A: It covers apparatus, specimen mounting, measurement technique, units, calculation of deflection rate, and guidance on significance/use for quality and design of thermostat coils.

Q: Who typically uses it?

A: Materials and quality-control laboratories, thermostat and thermal‑actuator manufacturers, suppliers of thermostat metal, and design/R&D engineers working on temperature‑responsive devices.

Q: Is it current or superseded?

A: The designation indicates original adoption in 1981 with reapproval in 2020 (current edition approved Oct 1, 2020). Users should confirm with ASTM for any later revisions or withdrawals.

Q: Is it part of a series?

A: It sits within ASTM Committee B02 work on thermostat metals and is related to other ASTM thermostat-metal specifications and test methods (for example B388 and B106); it is often used together with those documents for complete specification and testing programs.

Q: What are the key keywords?

A: Thermal deflection rate, thermostat metal, spiral coil, helical coil, coil testing, angular deflection, ASTM B389.