Rebreather Maintenance

[Inspirationdiver]

It can be difficult to tell which o-ring is not sealing and causing you to fail the negative pressure check. Whenever I am having problems, I do the positive check and spray a mild dishsoap solution on all the fittings with a spray bottle. You can easily identify where any leaks are, just look for the formation of bubbles. It really depends on personal tolerance as to how long the negative check should hold. Both the positive and negative checks are important and should be performed before every dive to verify the integrity of the loop, but they are extremes. In the water the loop is at ambient pressure and is less likely to leak. Plus, in most cases a very small leak would allow air to leak out of the loop, not water in. Oh, and you're welcome for the fills. Have fun this weekend.