Base Metal Thermocouple Characteristics
Fiberglass insulated - Thermo-couples utilize a flexible thermo-couple wire of duplex construction. Each wire is insulated with a primary wrap of ANSI color-coded fiberglass. The wires are then laid side by side and a secondary wrap of fiberglass covers both conductors. The wire can be left plain or have another wrap of stainless steel braid wound over it for added protection against abrasion. The thermocouple wire is then placed inside of a metal sheath to offer rigidity for accurate placement and added protection to the junction. Temperature Limitations -Although the base metal thermo-couple wires by themselves are capable of operation at elevated temperatures, the temperature limitations are often directly related to the insulation or sheath material, or both.
Fiberglass-insulated thermo-couples are limited to 9000 F maximum continuous operation due to the characteristics of the fiberglass insulation. Thermocouple calibration can also be determined from the standard ANSI color coded primary insulation on the conductors of the flexible leads.
Code Positive Negative
K Chromel- Yellow Alumel-Red
T Copper-Blue Constantan-Red
E Chromel-Purple Constantan-Red
Standard Dimensional Tolerances
Sheath Diameters: All diameters ± .002"
Up to 3" ± 1/8"
3" to 48" ± 1/4"
48" to 96" ±1/2"
96" and over ± 1"
Minimum Bend - The minimum bend radius is equal to twice the cable diameter.
-Bend Radius: ± 1116"
-Bend Location: ± 1/8"
-Location of Sheath Mounted
Accessories, such as flanges
or bayonet fittings ± 1/16"
ANSI Calibration Tolerances - A complete choice of ANSI sensing ranges can be supplied depending on environment and read out equipment.
Premium grade thermo-couple wire is always used. Unless otherwise specified, thermocouples will be supplied with standard limits of error.
Stock fiberglass thermocouples are available in
J, K, and T calibrations. Mineral insu-lated thermocouples available in J and K only.