3. Test Results

3.1 Phase I

The phase I test results from the cylinders over-wrapped with all carbon and all Zylon, and tests 1-11 are as follows.

Phase I Test Result Table

Historically, a means of comparing pressure vessel performance is by PV/W, where P=Pressure, V=Volume, and W=Weight. In this first phase of testing all of the cylinders had the same volume and as such, V has been taken out of the equation. The following graph shows the performance of the Zylon, carbon, and hybrid tests as measured by P/W.

Test Matrix Phase I P/W Performance Graph

It is interesting to note that none of the tests had a higher P/W than the T-1000 virgin burst test, but the T-1000 also had the largest drop off with impact testing. The Zylon had the lowest P/W but saw very little degradation after impact. The optimized cylinders (Tests 9, 10, and 11) performed very well after impact testing, seeing little or no degradation upon impact testing.

It is also useful to compare how each test did as compared with the virgin burst from the same group. The impacted bursts from each set have been compared with the virgin bursts as a percentage drop-off from virgin burst. The following chart shows the percentage degradation of impacted cylinders.

Test Matrix Phase I Percentage Drop-Off

The cylinder filament wound with all T-1000 saw the largest percentage drop off. The cylinder wound with all Zylon saw only a small percentage drop off with impact testing. Once again, the optimized cylinders showed the best P/W performance with little or no degradation.

3.2 Phase II

The following chart shows the results of the Phase II testing.

Summary of Phase II Test Results

A graph showing the percentage degradation in performance as a percentage of virgin burst P/W follows.

Test Matrix Phase II Percentage Drop-Off

3.3 Phase III

The SCBA cylinders tested in Phase III demonstrated incredible resilience to high velocity impact. Both cylinders that were gunfire tested passed. The cylinder with an E-Glass over-wrap had a bullet exit hole about twice the size of other typical SCBA cylinders gunfire tested, as observed by HEI. The cylinder with no E-Glass had a bullet exit hole about four times the size of typical gunfire tested SCBA cylinders. Despite the larger exit holes, both cylinders still held together. A photo showing three tested cylinders follows.

Test Matrix Phase III Gunfire Tested Cylinders

The cylinder furthest to the left is a typical SCBA gunfire tested cylinder. The cylinder in the middle is the hybridized cylinder with the E-Glass over-wrap and the cylinder on the right is the hybridized cylinder with no over-wrap.

A comparison is also made in the following photo.

Test Matrix Phase III Pass and No Pass Cylinders

The cylinder on top is a typical SCBA development cylinder that failed the gunfire test. The cylinder on the bottom represents the significance of the new hybridization technology. Despite the fact that the hybrid cylinder was significantly lighter (in excess of 20% lighter), it still passed.

Copyright 2004 by HyPerComp Engineering, Inc. Published by Society for the Advancement of Material and Process Engineering with permission.

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