# G — Thermocouple type letter to alloy pair, ANSI/IEC color code and tolerance class

For G, usable temperature range is 0 to 2320°C; source document is ANSI and IEC Color Codes, verified against its source on 2026-08-19.

- **Type letter:** G _(verified: appears in the quote below)_
- **Usable temperature range:** 0 to 2320°C _(verified: appears in the quote below)_
- **Source document:** ANSI and IEC Color Codes _(verified: appears in the quote below)_

## What the source says

> G* Vacuum, Inert, Hydrogen. NONE ESTABLISHED + – TUNGSTEN W TUNGSTEN- 26% RHENIUM Beware of Embrittlement. Not Practical Below 399°C (750°F). 0 to 2320°C 0 to 38.564 NO STANDARD USE ANSI COLOR CODE G (W) W-26% Re Not for Oxidizing Atmosphere 32 to 4208°F (W)

## Source

- https://assets.omega.com/pdf/test-and-measurement-equipment/temperature/sensors/thermocouple-probes/tc_colorcodes.pdf

Last verified: 2026-08-19. Review by: 2028-08-18.
Part of [Thermocouple type letter to alloy pair, ANSI/IEC color code and tolerance class](https://referencesource.org/thermocouple-type-color-code-crosswalk/).