Does a purcell prusik shock absorb enough as a personal lanyard to prevent an ascender from desheathing a climbing rope if you were to take a short fall while passing an obstacle? "A little" is the answer but 1/2" ropes are so burly that they won't desheath even with a static sling in our tests but we only had about 150lbs falling in this test. However, your spine may not appreciate 5kN+ so just don't fall.
OUR RESULTS
1/2" rope with purcell - 4.10kN - Did NOT desheath - purcell slipped half way
1/2" rope with purcell - 5.18kN - Did NOT desheath - purcell slipped half way
8mm rope with purcell - 5.36kN - Did NOT desheath - purcell slipped a little
8mm rope with dyneema sling - 5.69kN - Rope Desheathed!
1/2" rope with dyneema sling - 5.8kN - Did NOT desheath
Our guest: Matt O’Donnell from Ebbetts Pass Fire District - modonnell@epfd.org Our drop tower has a https://www.perfectdescent.com/
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They sell Samson SK75 & Marlow SK78 & SK99 Dyneema
Behind the Scenes
It's great to get insight from people like Matt O'Donnell to see what the concerns are for other industries like fire fighting. It was tricky to figure out how to drop test Decker to simulate the fall, where to connect the snap shackle and how to hoist him. In an ideal world I would have an assortment of dummies weighing progressively more, but I'm not there yet. 150lbs is not ANSI standards, but rather 300lbs and according to a testing facility that throws tips my way, 300lbs can desheath a 1/2" rope if it falls on an ascender. It's nice to test lighter weight stuff too. This wasn't a comprehensive test but it surely isn't our last ascender drop test video.
Check out this battery powered ascender and see one of the only videos online showing you inside of it.
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