Driver-Harris alloy wire

Citation

(1999), "Driver-Harris alloy wire", Aircraft Engineering and Aerospace Technology, Vol. 71 No. 5. https://doi.org/10.1108/aeat.1999.12771eab.046

Driver-Harris alloy wire

Driver-Harris alloy wire

Keywords: Kanthal, Alloys, Publication

Specialist resistance materials producer, Kanthal AB, has issued a 28-page technical brochure on its range of Driver-Harris alloy wire used for thermocouples, extension and compensating cables.

The range of Driver-Harris alloys was acquired by Sweden's Kanthal AB with its takeover of the products and production facilities of Harrison Alloys Inc. in February 1996.

The new brochure details the full range of Kanthal's Driver-Harris thermocouple alloys used in some of the most demanding applications from nuclear reactors and submarines to jet aero and industrial furnaces. The introductory pages show the main types of thermocouple wire produced, the working atmosphere and temperature recommended for each type and key criteria for the choice of a particular thermocouple alloy.

A table shows the maximum recommended temperatures for thermocouples used as bare and protected wires for different wire diameters (between 0.25mm and 3.26mm), working in air without cycling. The temperatures are given as a guide to obtaining a satisfactory life before burn out of the thermocouple occurs. A second table shows the grades, chemical composition and physical properties of Kanthal's thermocouple and compensating alloys.

There are detailed descriptions of each of the five most used Driver-Harris thermocouple alloy combinations, including EMF reference tables and technical discussion of the benefits, applications and, where appropriate, recommended restrictions on use.

Typical alloys featured are Type N - Nicrosil/Nisil thermocouple, a developed alloy which has improved oxidation resistance and therefore much longer life, and Type E which has the largest EMF output of any common thermocouple.

Unless otherwise specified, thermocouples, compensating and extension materials are supplied to standard EMF tolerances. Special tolerances are available on request. The brochure lists the standard and special tolerances by thermocouple type for a range of US, European and Japanese standards.

The brochure also contains thermocouple manufacturing information. There is, for example, a description of hot junction forming, necessary to ensure good electrical contact between thermocouple wires. Different welding methods are described. Information on connecting thermocouples to instruments is also given. It is essential that cables have the same EMF output as the thermocouple. Tables list, by thermocouple type, the appropriate compensating or extension cable, its chemical composition and temperature tolerances for a range of international specifications.

Also included are tables of gauge dimensions, length per kilogram and weight per metre for different wire types as well as wire manufacturing tolerances.

In the final section, Kanthal describes its capability in the manufacture of Protection Tubes.

Copies of the new brochure can be obtained from Kanthal Limited. Tel: +44 (0) 1782 224800; Fax: +44 (0) 1782 224820.