The next day I needed to do some diving, both to test our kit, but also for me to just to get back into the “zen” that is cave diving. This shakedown left us with one broken fin strap and one dead primary light. Which is pretty much on par for the beginning of fieldwork. We brought the dead light in for repair at the Dreams Tulum Dive Shop, where the owner (who makes dive lights and turns professional housings on his lathe) kindly offered to test my humble DIY housings in a pressure chamber he had fashioned from a decapitated scuba tank. I was fairly confident about the o-ring design, but I still had lingering doubts about the one with the rubber end cap, so I jumped at the chance. While the unit was still dry, I stuffed it full of toilet paper to act as an indicator for any water that might leak in. Then I put in the calibration weight, and he lowered it into the chamber. He pressurized it to about 100 feet and there was an a loud “clunk” sound at the start of the procedure; I feared the worst.
For the next ten minutes I paced the floor like an expectant father, much to everyone’s amusement. Then we depressurized, I dried off the housing, carefully loosened the pipe clamps to remove the end cap, and . . .
Whoo Hoo! It survived with no leaks! Not bad for $10 worth of plumbing!
But still I wondered what that noise was…
Addendum: I did not find this out till after our trip was over, but the spec sheets list that caps maximum “working pressure” at a mere 4.3 psi. The pressure at 100 feet is almost 60 psi. OOOPS!