According to BIPM First Edition, Technology for Approximating the ITS 90, many thermometers are formed by winding a fine platinum wire or coil on a glass support and embedding the winding in glass. This can introduce

strain into the wires at higher operational temperatures. Of the many techniques devised, the configuration that offers the best stability with the lowest hysteresis, is one in which a platinum coil is supported inside the capillaries of a two or four-bore, high-purity alumina insulator. Either the use of cement to clamp one side of the coil to the capillary wall, or, preferably, the insertion of soft alumina powder to prevent the platinum coil from vibrating freely helps achieve good reproducibility in industrial applications. Detectors supplied by SDI are of this wire-wound type, in which the platinum winding is partially or fully supported (application dependent) by a high temperature alumina powder inside a ceramic tube. This construction provides a detector in which stability, interchangeability, and accuracy are the highest available for industrial and scientific applications.

By concentrating on the manufacture of this type of detector, SDI is able to provide unparalleled service by offering the largest possible selection of sizes for various requirements.