ASTM B389-81 pdf free.Standard Test Method for Thermal Deflection Rate of Spiral and Helical Coils of Thermostat Metal.
The specimen holder for spiral coilsshall provide means for securely holding the coil. Althoughother means of support are possible, the holder or mountingarbor shall be preferably circular cross section whose diametershall be as large as possible without touching the inner turn ofthe coil under any conditions of test temperatures.The arborshall be slotted across its diameter and to a depth greater thanthe width of the specimen. The width of the slot shall beslightly narrower than the thickness of the specimen so that theinner tab will be a push or snug fit in the slot.The edges of theslot shall be sharp where it intersects the circumference of thearbor. The slot shall be so positioned in the arbor that the centerof rotation of the coil and the center of the arbor coincide.The specimen holder for helical coilsshall provide means for securely holding the coil. Althoughother means of support are possible, the coil shall be held withits axis in a vertical position, the bottom end of the coil securedand the top end allowed to rotate freely with a temperaturechange.Preferably the end of the coil with the center tab shallbe considered the bottom and secured by clamping or press-fitting the tab into a slotted arbor similar to that described in6.4.1 for spiral coils. The depth of the slot shall be such that thefull height of the tab shall be held. If the coils do not have acenter tab, the arbor shall contain provisions for attaching thecoil with screws, rivets, or by welding.A transmission pointercan be affixed to the top end. The center line of the coil, thetransmission pointer, and the protractor shall coincide.This test method simulates,to a practical degree, theoperation of the thermostat metal coil.
The thermal deflection properties of a coil may varyfrom lot-to-lot of thermostat metal material.This method isuseful for determining the optimum thickness and length of thematerial for a given deflection specification.This method is useful as a quality test to determineacceptance or rejection of a lot of thermostat metal coils.ASTM B389 pdf download.