ASTM B389-81(R2020) pdf free download

ASTM B389-81(R2020) pdf free download.Standard Test Method for Thermal Deflection Rate of Spiral and Helical Coils of Thermostat Metal
3. Terminology
3.1 thermostat metal, n—a composite material, usually in the form of sheet or strip, comprising two or more materials of any appropriate nature, metallic or otherwise, that, by virtue of differing expansivities of the components, tends to alter its curvature when its temperature is changed. 3.2 thermal deflection rate, n—the ratio of angular rotation to temperature change. It is a measure of the coil’s thermal activity. It may have the units of angular degrees per degree Fahrenheit, or Celsius, and is expressed by the equation D = (A 2 − A 1 )/(T 2 − T 1 ) where A 2 and A 1 are angular positions at temperature T 2 and T 1 respectively. 3.3 spiral coil, n—a part made by winding strip on itself. Fig. 1 and Fig. 2 show typical spiral coils, which can be wound with the low-expansive side inside or outside, mounted on the specimen holder. 3.4 helical coil, n—a part made by winding strip in a form wherein the plane of the width of the strip is parallel to the axial length. Fig. 3 shows a typical helical coil, which can be wound with the low-expansive side inside or outside, and right-hand or left-hand, mounted on the specimen holder.
6. Apparatus
6.1 Temperature Bath—A stirred liquid bath or uniformly heated enclosure in which the specimen and mounting fixture can be placed shall be used. An adjustable heating source is desirable for maintaining the specimen at the desired tempera- tures with a variation in temperature throughout the specimen not to exceed 0.5°F (0.3°C).6.2 Protractor—The angular position at each test tempera- ture shall be measured by a protractor with a minimum division of 0.5°. 6.3 Temperature-Measuring Apparatus—The apparatus for making temperature measurements shall be of such accuracy that the individual temperatures shall be known to be within 60.5°F (60.3°C). 6.4 Specimen Holder—The preferred methods of holding spiral and helical coils are as follows: 6.4.1 Spiral Coils—The specimen holder for spiral coils shall provide means for securely holding the coil. Although other means of support are possible, the holder or mounting arbor shall be preferably circular cross section whose diameter shall be as large as possible without touching the inner turn of the coil under any conditions of test temperatures. The arbor shall be slotted across its diameter and to a depth greater than the width of the specimen. The width of the slot shall be slightly narrower than the thickness ofthe specimen so that the inner tab will be a push or snug fit in the slot. The edges of the slot shall be sharp where it intersects the circumference of the arbor. The slot shall be so positioned in the arbor that the center of rotation of the coil and the center of the arbor coincide. 6.4.2 Helical Coils—The specimen holder for helical coils shall provide means for securely holding the coil. Although other means of support are possible, the coil shall be held with its axis in a vertical position, the bottom end ofthe coil secured and the top end allowed to rotate freely with a temperature change. Preferably the end of the coil with the center tab shall be considered the bottom and secured by clamping or press- fitting the tab into a slotted arbor similar to that described in 6.4.1 for spiral coils. The depth ofthe slot shall be such that the full height of the tab shall be held. If the coils do not have a center tab, the arbor shall contain provisions for attaching the coil with screws, rivets, or by welding. A transmission pointer can be affixed to the top end. The center line of the coil, the transmission pointer, and the protractor shall coincide. 6.4.3 Deviations from these procedures of holding may be necessary when simulating the mounting used in the device for which the coil was designed, or in cases where coils are press fitted on arbors. In these cases, the details of mounting should be mutually agreed upon between the manufacturer and the purchaser.