Finding Leak

I recently got a new Ikelite housing for my mirrorless camera.  I installed the vacuum pump port and did a test and noticed a tiny leak (visible only after a full day of sitting), but this was expected since I hadn't cleaned or lubricated any o-rings yet.  So I just went through and removed lint and such and added silicone to the main o-ring on the back of the housing, the one for the port, and the one for the port extension.  It looks like it is still leaking.  I also should note that I had installed both the vacuum pump port and the port for the strobe cable, so that gives me 5 possible leak sources of my own doing.  I trust the other buttons and such done by the company itself.

So my question is, is there an easy way to identify which o-ring is the cause of the leak?  Or do I just have to keep trying each one individually until I register no leak?

Thank you!

When you say you noticed a tiny leak, was this with a gauge?  Is it possible the temperature changed.  If it is colder the pressure inside will fall, if it is hotter it will rise.  It has to change a reasonable amount to detect.  A change 20 to 25°C would result in a pressure change of +0.02 bar or plus 0.3 psi

On the o-rings if they seal initially, then lubricating should not make any difference.  The lube does not provide the seal it just allows the o-ring to move in the seal channel so it can press against the surface in response to external pressure. 

The rear o-ring on ikelite housings does not need lubricant as it just presses against the back door, it does not need to move -there is no sliding between the o-ring and the part when you install it - unlike the port o-ring which needs lube.

If you installed the ports initially without lube you may have twisted or damaged your o-ring there when pushing on the port. Inspect your o-rings for twists or nicks and be sure they they sit properly in their groove.   Use magnification and good lighting to closely check the o-ring condition.

Also when you installed the vacuum port and bulkhead did you check the seats and o-rings were clean and did you lightly lubricate the o-rings on each of those ports?

Pack the inside with clean paper and submerse for a time.

Open case and look for wet spot location.

Hey guys.  I'm only just getting the time to circle back to this.  It currently is losing vacuum at around 0.25-0.5 inches of mercury in around 12-15 hours.  After a few days it gets around 1 inch or mercury lower than its starting point of 10.  I am leaving the pump connected the whole time since that has the gauge on it.  I don't know if there is a chance of the leak there or where the tubing connects to the plugs.  I doubt this is temperature related since it is just sitting on a table in my temperature controlled living room not near a window.  I've never used a vacuum pump before, but I would assume it should be perfectly stable no matter how long, right?

I have time today to do more thorough checks.  I have the paper towels in it now but haven't submerged it yet.  That is the plan later today.

That you both!

14 minutes ago, peterclark said:

Hey guys.  I'm only just getting the time to circle back to this.  It currently is losing vacuum at around 0.25-0.5 inches of mercury in around 12-15 hours.  After a few days it gets around 1 inch or mercury lower than its starting point of 10.  I am leaving the pump connected the whole time since that has the gauge on it.  I don't know if there is a chance of the leak there or where the tubing connects to the plugs.  I doubt this is temperature related since it is just sitting on a table in my temperature controlled living room not near a window.  I've never used a vacuum pump before, but I would assume it should be perfectly stable no matter how long, right?

I have time today to do more thorough checks.  I have the paper towels in it now but haven't submerged it yet.  That is the plan later today.

That you both!

There might very well be a leak in your evacuation device. It probably has a check valve to keep the atmosphere from leaking in that leaks just a bit. I would disconnect it and close up the evac. port on the housing like you would for diving and remeasure after a day and see if the pressure goes up as you have noted.

It is going up and not down. The 10 on the gauge in inches is actually -10 or about 1/3 of an atmosphere down from starting pressure. So what is left in the housing is about 2/3 of an atmosphere absolute.

If it also leaks with the evac device disconnected then it will be time to consider were the leak might be in the housing starting with the main o-ring and the port o-ring -- one at a time using a process of elimination.

Excellent thank you.  I've disconnected it now and will check again tomorrow.

Good luck!!

Your last reply, Peter Clark, six days ago was: "I've disconnected it now and will check again tomorrow."

So what happened?  Please tell us what you have done and found.

Sorry.  I've been rather distracted recently (and still working, just from home).  That and since my trip was canceled the rush was gone.

Anyway, after disconnecting it and leaving it a day, when I reconnected I saw the drop had still happened, so not in the pump/gauge.  When I did the water soak, I didn't leave it submerged long enough (maybe 15 minutes) so no water visible, so I'll need to try again for maybe a couple of hours.  I took off and cleaned the port and main o rings, but no luck.  I'll probably end up removing the connector for the strobe sync cable and replace with the plug that came with the housing since I installed that and it has an o ring (no lube on that one per the instructions).  I'm betting it is either from that connector or the vacuum valve o ring itself.

Also it should be noted that my house has 2 golden retrievers, so hair is EVERYWHERE!  Every time I check an o ring, have to be careful not to get new hair on them.

It might be more revealing if the housing is left in the water for several hours, or even overnight, seeing as this is low pressure, not depth, immersion.  Happy water dowsing!

On 3/21/2020 at 3:19 PM, peterclark said:

Also it should be noted that my house has 2 golden retrievers, so hair is EVERYWHERE!  Every time I check an o ring, have to be careful not to get new hair on them.

Lol, I can certainly understand that part.  Whenever I clean up the dog hairs from my single Golden, it looks like I should be able knit a sweater from all the hair.