Don’t try this at home. I have experience in destructive testing and I have a safe location to perform these tests.
Don’t construe any results as approved methods for shrapnel mitigation.
Don’t construe any results as suggestions for any action.
Don’t construe any results as anything other than the results of an experiment.
Don’t try this at home.
No students were present during these tests. Experienced adults only.
We are experimentalists here on 95. Given the recent chatter on CD about failing plastic air tanks, and several proposed (or implemented) mitigation techniques, we decided to test some of these solutions. We have a video coming, but I thought I would share our preliminary results.
Most of this year’s discussion, and several proposed or implemented solutions, is in this thread: http://www.chiefdelphi.com/forums/showthread.php?t=127695
Some background information about using plastic to transport compressed gasses from The Plastic Pipe Institute: http://plasticpipe.org/pdf/recommendation-b_transport_compressed_gas.pdf
Safety during a destructive test is paramount, so we did a little research and found this paper detailing the radii for various threats at different amounts of stored energy. On Page 4.7 the thread radii are listed. We calculated that the energy stored in a single plastic storage tank at 120psi was around 370lbft of energy. To be safe we used the shrapnel radius for a 500lbft radius and gave ourselves a factor of safety of at least 10, and wore eye and hearing protection.
No mitigation - we found shrapnel of appreciable size up to 45ft away lots of small shrapnel pieces, and some larger ones
2-3 layers of Gorilla tape - as some hypothesized the ends of the tank shot out at high velocity, we found one in a snow bank about 25ft away. Virtually all of the small shrapnel was eliminated, but the tank broke into 4 large pieces. However, the larger pieces didn’t travel as far, 20-30ft or so.
Bumper fabric zip-tied around the tank - the zip-ties failed almost immediately and the fabric simply un-rolled from around the tank. Shrapnel was slightly mitigated, but large and small pieces were still found 20-30ft away.
Completely Assembled Bumper - we essentially replaced the pool noodles with an air tank. This actually contained virtually all of the shrapnel. It was a completely assembled bumper (3/4in plywood, screwed-in angle aluminum, stapled nylon fabric*). The angle aluminum ripped off of the plywood, and many of the staples failed, but it held together long enough to keep basically all of the shrapnel inside.
*This fabric is considerably stronger than your average bumper fabric. It is heavy-duty nylon, double rip-stop, and impossible to tear by hand along any direction.
Un-mitigated. Not bad for finding white plastic on a snow-covered driveway!
Buper fabric and zip-ties.