Table 5. Catastrophic Failure of EDU Acrylic Plastic 
Windows Under Cyclic Pressure Loading 
Window Diameter Thickness Peak Pressure Number of Cycles 
inches (D,) inches (t) (psi) at Failure 
5500 
5000 
4500 
4000 
3500 
NOTE: 1. Duration of a typical pressure cycle was 24 hours. 
The window was alternately 7 hours under sustained 
hydrostatic loading and 17 hours under zero pressure. 
2. Ambient temperature for all tests was 120°F. 
3. 0.025-inch thick neoprene impregnated cloth was used 
as the bearing gasket on the flange seat under the 
window. 
4. No retaining ring was used to restrain the window in 
the flange. 
5. The opening in the flange @,) was 3.000 inches in 
diameter. 
6. The windows were fabricated from Swedlow 350 acrylic 
plastic. 
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