Thermocouple measures continuously in flowing gaseous hydrogen at temperatures up to 4000 deg F, in environments made hazardous by radiation, and where rapid response and calibration reproducibility are critically important. Thermocouple wires extend continuously, without splice or foreign material, from cold junction to probe's tip

Gracey, C. M.

Hoff, R. G.

English

NASA Technical Reports Server

November 1970
	 Brief 70-10564 
CORRECTED COPY 
..
	
AEC-NASA TECH BRIEF 
-	 - -
	
-AEC-NASA Tech-Briefs announce new technology derived from the research and development program of the U.S. 
AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial application. -Tech Briefs are - -	 - - - 
available on a subscription basis from the National Technical Information Service, Springfield, Virginia 22151. Requests 
for individual copies or questions relating to the Tech Brief program may be directed to the Technology Utilization 
Office, NASA, Code KT, Washington, D.C. 20546. 
High-Temperature Rapid-Response Thermocouple for Reducing Atmospheres 
A new thermocouple has been developed that can 
measure continuously in flowing gaseous hydrogen 
at up to 4500°F, in environments made hazardous by 
radiation, where rapid response and calibration 
reproducibility are critically important. 
Housing
\\	 ,/ 
rThermocouple
uppo / 
e
Support Shield
Thermocouple	 Blackbody (Ref.) 
Wiresj 
Insulation
High-Temperature Thermocouple
housed in a right-angled support, made of type-347 
stainless steel, to prevent breakage of leads. 
Location of the two thermocouple lead wires on 
opposite sides of the plug, 180° apart, eliminates 
accidental shorts in the probe's stem, and effects a 
position of the sensory junction at the wall and plug 
that minimizes the distance of the heat's flow before it 
reaches the junction. As a result the design reaches 
63% of a step change in temperature within 0.25 sec; 
this rapidity is essential for dynamic stability in an 
automatic control loop system requiring 1-sec overall 
response. 
The thermocouple wires extend continuously, with-
out splice or foreign material, from the cold junction 
to the probe's tip so that errors from secondary effects 
are eliminated. An operational range of from 500° to 
4500°F has been achieved, with accuracy within 1% 
at the high end and less than 1% at the low end. 
The probe can measure high-temperature gases in 
nonoxidizing atmospheres; after some development 
it could be modified for use in oxidizing atmospheres. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
AEC-NASA Space Nuclear Propulsion Office 
U.S. Atomic Energy Commission 
Washington, D.C. 20545 
Reference: B70-10564 
Patent status: 
No patent action is contemplated by AEC or NASA. 
The probe, made of tungsten-5% rhenium and 
tungsten-26% rhenium wire, is insulated by beads of 
beryllium oxide inside a tungsten-26% rhenium tube. 
The sensor junction is formed near the probe's tip, 
diametrically opposed by a tungsten-26% rhenium 
plug that forces each wire against the side of the tube 
and shorts them electrically through the plug. 
	
The outer end of the plug is fused to form a gas- 	 Source: C. M.Gracey and R. G. Hoff of 
	
tight metallurgical seal as well as a mechanical force- 	 Aerojet-General Corp. 
	
fit of the junction. A small hole, drilled part way into 	 under contract to 
	
the plug, serves as a blackbody reference for furnace	 Space Nuclear Propulsion Office 
	
calibration with an optical pyrometer. The wires are	 (NUC-10530)
Category 03 
Allk
This document was prepared under the sponsorship of the Atomic 	 liability resulting from the use of the information contained in this 
Energy Commission and/or the National Aeronautics and Space document, or warrants that the use of any information, apparatus, 
Administration. Neither the United States Government nor any per- 	 method, or process disclosed in this document may not infringe pri-
son acting on behalf of the United States Government assumes any vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19700000546 2020-03-17T00:40:12+00:00Z


High-temperature rapid-response thermocouple for reducing atmospheres

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server