Test arrangement was identical to the one described in the main body 
of the report except that a retaining ring was used to restrain the window 
in the flange (Figure 2) during the hydrostatic tests. The reasons for 
it were two-fold: (1) to determine whether the presence of the retaining 
ring has a significant effect on the pressure at which catastrophic 
failure occurs, and (2) the actual installation of windows in the EDU 
chamber does require retaining flanges. 
The testing of windows was performed at 650 psi/minute rate in 120°F 
ambient environment till catastrophic failure of the windows took place. 
Only the failure pressure was recorded for each test. 
FINDINGS 
All of the following findings apply directly only to EDU windows, 
although it can be postulated that they may apply also to windows with 
other t/D, and t/D, ratios. 
1. There appears to be no significant difference in failure pressure of 
windows tested with, or without, bearing gaskets on the window seat in the 
flange. 
2. There appears to be no significant difference in failure pressures of 
windows tested on thin or thick bearing gaskets. 
3. There appears to be no significant difference between failure pressures 
of windows tested on bearing gaskets fabricated from different materials. 
4, There appears to be no significant difference between failure pressures 
of windows fabricated from shrunk Plexiglas "G'', umshrunk Plexiglas "G", 
or Swedlow 350 plastic. 
5. There appears to be no significant difference between failure pressures 
of windows held in flanges with or without retaining rings. 
CONCLUS LON 
In the selection of bearing gaskets for flat disc acrylic windows, 
other criteria than failure pressure of the window should be used in the 
selection of gasket material and its thickness. 
RECOMMENDATIONS 
For future hyperbaric chamber window assembly designs it is recommended 
that the bearing gaskets on the high and low pressure faces of the window 
be made of 0.125 thick commercial cork material. The sealing of the window 
is to be accomplished by radially compressed o-ring contained in a groove 
around the circumference of the window. A properly bolted rataining ring 
is to constrain the window inside the flange cavity. A proposed window 
design for service at 1000-foot simulated depth utilizing the EDU window 
dimensions is shown in Figure B-3. 
Si 
