Standard Exposed Junction Thermocouple for Controlled Conduction Errors in Measurement of Air or Exhaust Gas Temperature
ARP690
The thermocouple design recommended herein is presented as one for which the correction to the observed emf, because of thermal conduction along the stem and wires, is within the limits presented in the accompanying figure. On referring to the figure, it is seen that no restriction is placed upon the diameter of the thermocouple or stem, and the longitudinal dimensions are expressed in terms of wire and stem diameters. The type of stem, such as packed ceramic stick, refractory insulating tubing, etc., also is left open to choice. Thus the sizes of wires and supporting stems may be varied over wide ranges to match particular requirements where conduction errors are to be limited or controlled.
Rationale: AIR690 has been superseded by the document AIR46, “The Preparation and Use of Thermocouples for Aircraft Gas Turbine engines”. AIR46 consolidates the contents of this document (AIR690 “Standard Exposed Junction Thermocouple for Controlled Conduction Errors in Measurement of Air of Exhaust Gast Temperature”) plus AIR65 “Thermoelectric Circuits and the Performance of Several Aircraft” and AIR691 “Recommended Ice Bath for Reference Junctions”. As such, AIR46 provides a comprehensive document for testing and calibrating thermocouple components for use in gas turbine engines making the contents of AIR65, AIR690, and AIR691 redundant and unnecessary. This document consolidation strategy was agreed to by the SAE E-32 Aerospace Propulsion Systems Health Management Committee as part of the Committee’s Master Plan.
CANCELLATION NOTICE
This Technical Report has been declared “CANCELLED” as of (MONTH YEAR WHEN PUBLISHED) and has been superseded by AIR46. By this action, this document will remain listed in the respective index, if applicable. Cancelled Technical Reports are available from SAE.
