Enclosure leak spotting

There is nothing more frustrating than failing a pre-flight vacuum test the day before an important dive.  We suggest the following steps to help find that persistent leak:

  • Mix a liquid soap solution in water (more soap than water) and fill into a small spray bottle (at least 1/3 full).  Dishwashing liquid will do but avoid anti-bacterials
  • Place a towel under the ROV and close all enclosure vents except the leaking enclosure.  Make sure to protect the topside FathomX card from spray
  • Using the brass fitting and tubing from the vacuum tester, connect the leaking enclosure’s vent to a bicycle hand pump (NOT electric)
  • Carefully spray the leaking enclosure with the soap solution.  We suggest starting with the rear end-cap and penetrators.  If you aren’t able to find the leak there, repeat with the front end cap and flange edges.
  • Gently pump air into the enclosure and look for bubbles.  One or two pumps should be sufficient – too much pressure will cause the end caps to pop off.  The bubbles will narrow down the location of the enclosure leak(s).

Possible causes could be a loose penetrator, a cut or broken o-ring, dirt or hair on the o-ring, not enough silicone, etc.

Happy hunting!