Hope I am writing in the right section. I am making the vaccum test for the first time. And in 15 minutes I loose around 7inHg. Will it leak when submerged or am I still safe? How could I understand where are the leaks?
Unless the leak is in your vacuum pump, water will leak into your enclosure when it’s submerged.
You could spray a mixture of detergent and water around the penetrators, then put a positive pressure through the vent. Bubbles will form around the source of the leak.
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@MarcoMotaSubmarine I’m not very experienced myself, but I would say to definitely not dive it when it’s losing that much vacuum. Mine went from 10 inHg to 6-7 in 10 minutes when i built it, and I had to abort my first 30 foot dive after a few minutes because a leak was detected.
Finding the leak can be very hard and there are a few ways. The previous poster described the easiest one. An alternative method is to positively pressurize it a little and hold it underwater to look for bubbles. I have also read about people having success with a ultrasonic leak detector, but I don’t have any experience with those.
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Hi Marco,
I have had some experience with similar type of connectors ( the white ones) and i believe you are getting the leak on the connector pins not the penetrators. This type of connectors are not built for underwater use and will leak through the cable itself following the copper. Just my two cents.
Joe
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It leaks through the copper you say? 
I thought this connectors where a cheap good idea. What a waste of time…
Thankyou! will try it out
The leak isn’t in the vaccum pump. tested it and it doesn’t loose pressure in time if I use a plug
Just made the soap test. The only bubbles I saw where coming from the connector of the vaccum.
Maybe BlueRobotics should make it a bit more tight fit.
Maybe the O-Rings on the plug are missing. I’d be really surprised if the vent plug was leaking.
I’m also concerned with the cables that you’ve potted to the penetrators - are they water-blocked connectors made for use underwater? If not, water/air can wick through the connector and wire into the enclosure.
What potting compound did you use?