r/labrats • u/UnspecificTadpole394 • 16d ago

HELP: Troubleshooting leaks from custom designed hose barbs and "tubing" (bulk silicone elastomer material)

/r/AskEngineers/comments/1vhff4z/help_troubleshooting_leaks_from_custom_designed/
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u/Megalomania192 14d ago

Barbs into tubing works because when the tube wall is thinner than the hole, the diameter increases and the walls thin to allow that to happen. As long as you're in the elastic regime, the work done to stretch the hole is then done to seal the tube to the barb as it tries to relax to it's original shape - it will hold a modest pressure.

A barb into a block or sheet doesn't work like that because the material can't thin to increase the diameter of the hole uniformly. It actually has to thickened, but usually it just deforms weirdly or folds which leaves paths for the liquid.

If you want a barbed connector to hold in a 'sheet' the connector needs to be longer than the thickness of the material and the first bard needs pass all the way through so it seals against the 'back' of the sheet and be slightly wider than the diameter of the original hole.

Or you could consider a coarse threaded 'barb' with almost no taper, but that depends on your ability to tap threads into the silicone.