Fireworks Overpressure Test


A few weeks ago I wrote a post about some 3” display shells that where run through a CT scanner by the CPSCat their testing center in Rockville, MD. Todays article is an extension of that post featuring some awesome test videos and a very interesting report by the CPSC on “Fireworks Safety Standards Development”.

If you read my last post on this topic, you’re generally aware of the CPSC’s infamous “ear test” and the fact that they’ve been (thankfully) working on a more objective replacement to the “ear test”.

testchamberAs you’ll find in the report, the CPSC used the AFSL“ball test” as a starting point. They found that the ball test was good for measuring the explosive force produced by the burst charge of a shell, but didn’t take into account things like the construction quality and strength of the shells casing (because the shells had to be dissected to extract the burst charge for testing).

To solve this problem they began development of a new test that involves an aluminum and wire mesh chamber, laden with pressure transducers. The test procedure involves removing a shell’s lift powder, wiring the shell with an electric match and placing it into the chamber. The shell is then ignited and the overpressure is measured.

Below you’ll find three very cool videos of the test being performed. I didn’t get exact specifications on the shells tested, but I’ve estimated that the “small consumer fireworks shell” is a 1″ cake insert, the “medium consumer fireworks shell” is a 1.5″ reloadable shell and the third video is an actual 3″ display shell.





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