Microminiature thermocouple makes precision gas sidewall temperature readings inside large thrust chambers. It is installed by a technique whereby the sensor monitors its own installation to insure against thermal damage to the thermocouple and ensure minimum disturbance to chamber surfaces

Garrett, A. J.

Sellers, J. P., Jr.

English

NASA Technical Reports Server

October 1966	 Brief 66-10463 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Microminiature Thermocouple Monitors Own Installation 
Quartz Lamp	 Heating Element 
240V	 I 
p	 Rheostat Console	 Nozzle Tube 
Thermocouple	 +	 Temperature 
Being Brazed	
-	 Indicator 
. The problem: 
To make precision gas sidewall temperature read-
ings inside large thrust chambers, it is essential that 
there be no disturbance to the thrust chamber tubes, 
thrust chamber coolant, or mainstream flow, and 
that there be no thermal shock damage to the sensor. 
The solution: 
A microminiature thermocouple that is installed 
by a technique whereby the sensor monitors its own 
installation to insure against thermal damage to the 
thermocouple and ensure minimum disturbance to 
chamber surfaces. 
How it's done: 
The thermocouple is brought to the gas side of the 
thrust chamber through small openings between the 
tubes. It is then bent to the tube contour and the 
tip (hot junction) is spot welded to the tube surface. 
A dam built of "stop-off" compound is built up 
around the thermocouple and a thin layer of powdered 
braze material is poured over the sensor. A quartz 
lamp, attached to a small rheostat console, melts the 
braze at a controlled rate that is dictated by the read-
ing on a potentiometer connected to the thermocouple 
output leads. In this way, the thermocouple may be 
said to be monitoring its own installation.
Notes: 
The braze must be selected on the basis of having 
a melting point in excess of maximum expected 
tube wall temperatures. 
2. A perfect installation results in a thermocouple 
so concealed with minimum braze that its pres-
ence cannot be detected without sectioning the 
tube. 
Inquiries concerning this invention may be di-
rected to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B66-10463 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546. 
Source: J. P. Sellers, Jr. and A. J. Garrett
of North American Aviation, Inc.,
under contract to
Marshall Space Flight Center
(M-FS-1 111) 
Category 05 
This document was prepared under the sponsorship of the National	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19660000462 2020-03-11T17:37:09+00:00Z


Microminiature thermocouple monitors own installation

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server