Window gas monitor

A gas monitor for detecting the presence of absence of a noble gas in the space between two window glazing panels. The monitor is preferably non-reactive with the noble gas, but reactive in a visible way with ambient air. When the noble gas leaks out of the space between the glazing panels and ambient air infiltrates, the monitor provides a visual indicator of the occurrence.

SUMMARY OF THE INVENTION 
This invention relates to gas monitors, and will have special application 
to a gas monitor for sensing the presence of a noble gas between the panes 
of a multiple pane window. 
Double or triple paned windows have become extremely popular items for both 
residential homes and office buildings because of their excellent 
insulative properties. The space between the panes is referred to in the 
trade as "dead air" and is often filled with a noble gas such as argon or 
krypton. 
Problems arise when the seal about the window which traps the noble gas 
between the panes deteriorates or is defective. In such cases, the noble 
gas leaks out from between the panels which allows air transfer and 
resultant loss of insulative properties. Since noble gases are colorless, 
a slow leak in the window may go undetected for some time, and large 
amounts of energy wasted due to the ineffective insulation. 
This invention provides for a monitor to be placed in the space between the 
window panes. The monitor may take any one of several forms, such as a 
thin strip, a small bag of crystals, a liquid container, or any other 
acceptable form which is easily reviewed, but which does not detract from 
the aesthetic appearance of the window. The monitor is preferably formed 
from a material which exhibits two distinct chemical properties: it must 
be non-reactive with the noble gas contained in the space between the 
windows; and it must react with ambient air in such a way that the 
reaction is easily observed; i.e., a change in color, crystal structure, 
phase, etc., by the naked eye. 
Accordingly, it is an object of this invention to provide for a monitor 
which detects the presence of absence of a noble gas in a double or triple 
paned window. 
Another object is to provide for a window gas monitor which is easily read, 
but which does not detract from the aesthetic appearance of the window. 
Another object is to provide for a window gas monitor which is easily 
installed, is economical, and is highly efficient in detecting gas leaks.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The preferred embodiments herein disclosed are not intended to be 
exhuastive or to limit the invention to the precise forms disclosed. They 
are chosen and described to explain the principles of the invention and 
their application and practical use to enable others skilled in the art to 
utilize the inventive concept. 
Referring first to the drawings, reference numeral 10 generally indicates a 
window having dual spaced glazing panels 12, 14 fixed in a sash frame 16. 
It is understood that this invention is usable in any window arrangement 
which has two or more spaced glazing panels, regardless of the type of 
style of window. 
Normally, the space 18 defined between glazing panels 12, 14 is pressurized 
with a colorless inert gas such as argon or krypton. The space 18 with 
panels 12, 14 forms an insulative barrier which effectively seals the 
window 10 against air transfer and heat loss through the glazing panels. 
The insert gas is sealed within space 18 by conventional window sealants 
such as caulk or the like which serve to seal the glazing panels 12, 14 to 
sash frame 16. 
Monitor 20, shown in FIGS. 2-3 as strip of lithium metal, is placed between 
glazing panels 12, 14 and secured to either the sash frame interior 22 or 
to a glazing panel divider 24. Other examples of some possible compounds 
for use as a gas monitor are outlined in the examples below. It should be 
kept in mind that any substance which exhibits non-reactance with noble 
gases together with a reactance with oxygen, nitrogen, water vapor, or 
carbon dioxide which can be visually observed may be utilized as a gas 
monitor within the purview of the invention. The most efficient metals in 
this regard are the alkali metals and the alkaline earth metals. 
In operation, monitor 20 is positioned between panels 12, 14 after all 
ambient air has been evacuated from space 18. Space 18 is then filled with 
the preferred noble gas and sealed in a conventional manner. In the 
embodiment shown in the drawing, the lithium strip monitor 20 is initially 
very shiny on its surface as shown in FIG. 2. If the noble gas should leak 
out from space 18, ambient air will infiltrate the space, and lithium 
strip monitor 20 will rapidly oxidize to a dull black surface finish which 
is easily observed as shown in FIG. 3. 
The following examples of monitor 20 are also submitted for illustrative 
purposes, but are not intended to limit the invention to any particular 
monitor. 
EXAMPLES 1-5 
A hygroscopic compound was placed in a space between two sealed glazing 
panels and the results observed as a noble gas was first introduced into 
the space and then allowed to leak out and be replaced by ambient air 
which included water vapor. The following results were observed with (1) 
Silica gel - cobalt chloride crystals; (2) Calcium carbonate crystals; (3) 
Cobalt iodide crystals; and (4) Copper (II) chloride crystals as the 
monitor. 
1--Colorless Silica gel treated with cobalt chloride colorless crystals 
turned blue within seconds after noble gas evacuation. 
2--Colorless calcium carbonate crystals liquefied upon exposure to ambient 
air. 
3--Black cobalt iodide (CoI.sub.2) crystals turned green upon exposure to 
ambient air. 
4--CoI.sub.2 crystals became brownish-red after extended exposure to 
ambient air. 
5--Brownish-yellow CuC1.sub.2 crystals turned green upon exposure to 
ambient air. 
EXAMPLES 6-12 
A metal strip was placed in the space between the glazing panels as above 
described and the results observed when the noble gas was evacuated. The 
following results with metal strips were observed 
6-9--Silver, titanium and lithium changed from shiny to a dull black upon 
exposure to air. 
10--Copper changed from reddish brown to dark brownish black upon exposure 
to air. 
11--Calcium changed from silvery to white upon exposure to nitrogen in the 
air. 
12--Sodium changed from silvery to gray upon exposure to air. 
EXAMPLE 13 
Bromine liquid is enclosed in a capsule which deteriorates upon exposure to 
ambient air. After evacuation of the noble gas from between the glazing 
panels, the capsule deteriorated and reddish-brown bromine vapors escaped 
and were visible between the glazing panels. It is probable that this 
result could also be achieved with other volatile colored liquids or with 
volatile gases such as neon.