Sniffer type portable monitor detects hydrogen in air, oxygen, nitrogen, or helium. It indicates the presence of hydrogen in contact with activated palladium black by a change in color of a thermochromic paint, and indicates the quantity of hydrogen by a sensor probe and continuous readout

Dayan, V. H.

Rommel, M. A.

English

NASA Technical Reports Server

ing 
August 1966	 Brief 66-10356 
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. 
-	 ii: 
"Sniffer" Used as Portable Hydrogen Leak Detector 
Gas Inlet
The problem: 
To design a simple, rapid device, preferably port-
able, for the detection of hydrogen in air, oxygen, 
nitrogen, or helium. Many modern test facilities use 
large quantities of hydrogen and a safety hazard 
would exist if leaks of the highly flammable gas were 
not closely controlled.
The solution: 
A "sniffer" type portable monitor that indicates 
the presence of hydrogen in contact with activated 
palladium black by a change in the color of a thermo- 
chromic paint, and indicates the quantity of hydrogen 
present by means of a sensor probe and continuous
eadout r 
-	 - - -- - - - - -
	 (continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19660000355 2020-03-11T17:41:15+00:00Z
How it's done: 
The sniffer consists of a short, thin-walled glass or 
metal tube, packed with 0.5 g of powdered, activated 
palladium black held in place with compressed glass 
fibers. The outside of the tube adjacent the palladium 
black is coated with a thermochromic paint having 
two successive color change points, at 55° and 85°C. 
A temperature sensing probe is inserted and sealed 
into one end of the tube so that it penetrates the mass 
of the palladium black. The sensor is connected to 
appropriate instrumentation to give a continuous, 
direct indication of temperature changes. 
In operation, the ambient is drawn through the gas 
inlet so that it passes through the palladium black. 
As hydrogen contacts the palladium black, heat is re-
leased in direct proportion to the density of the hy-
drogen. As this temperature passes 55°C, the thermo-
chromic paint changes color to give a visual indication 
of the presence of hydrogen. Simultaneously, the tem-
perature sensing probe instrumentation registers the 
change, which, with instrument calibration, can give 
direct, quantitative data.
Notes: 
I. An alternate, more passive method uses a finely 
woven but porous glass fiber tape or pillow im-
pregnated with palladium black and coated with a 
pattern of thermochromic paint. Hydrogen enter-
ing the porous packet reacts with the palladium 
black to liberate heat and cause the thermochromic 
paint to change color. 
2. Inquiries concerning this invention may be di-
rected to:
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B66-10356 
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: Marjorie A. Rommel 
and Victor H. Dayan
of North American Aviation Inc.
under contract to

Marshall Space Flight Center 
(M-FS-846, 806) 
Brief 66-10356
	 Category 01


Sniffer used as portable hydrogen leak detector

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