Vacuum Leak Test Update

For those who might be interested, I found a slight problem with the vacuum system leak test on my (Hugyfot) housing.

I was in the Maldives (on a boat) and assembled my housing during one particularly hot and humid afternoon. Others experienced condensation on their compact camera housings when they got into the water but I was confident that I would have no problem after pumping out the housing and getting the green light.

During the dive, all hell broke loose with both red and green lights flashing and a siren sounding. The camera continued to work and I did an hour serenaded by the siren. Despite the green light confirming there was no leak, there was water in the housing when I opened it. Where had it come from?

It transpired that when I vacuumed out the housing the water in the air must have precipitated at the pressure drop to form a tiny droplet that made its way to the moisture sensor in the bottom of the housing electronics (that I didn't know I had)!

I solved the problem by inserting a tampon in next to the camera when I re-assembled it next. This took care of any further precipitation.

We simply cannot do without ladies!

I have been using tampons for years, so to speak. They work! I had a similar problem not to long ago with a warm, humid galley and cold water. Got bad condensation. Each time I changed batteries I'd have to use some canned air to squirt in dry air by lifting the housing back slightly and blowing for about 10 seconds. Didn't have any issues after that. The vacuum issue happened to me a lot on my Nikonos cameras. Pacific camera had a pre-dive vacuum system hut it ruined two cameras before I took them off. Don't ever put a vacuumed system in a rinse bucket with other cameras. You will be asking for trouble.

I always took the precaution of inserting a tampon in my pre-Hugyfot housings. As an aside, I was well impressed by the Hugyfot siren moisture alarm. When I took it back on board and opened the housing, it was loud enough to send crew members scurrying to the engine room to see what was making the alarm!

Yes, those Leak Detector are for sure loud enough on surface.

Well, atleast you can hear them UW then as well.

It is for sure a stressful moment when the Siren goes off...

/Erik

Don't ever put a vacuumed system in a rinse bucket with other cameras. You will be asking for trouble.

I don't leave my camera in a rinse bucket anyway, but curious about your comment. Why would leaving a vacuumed system in a rinse bucket with other cameras be asking for trouble that is different from non-vacuumed systems?

And my part of curiosity as well: are you guys saying that condensation is more likely to occur when ambiant pressure is lower?

I don't leave my camera in a rinse bucket anyway, but curious about your comment. Why would leaving a vacuumed system in a rinse bucket with other cameras be asking for trouble that is different from non-vacuumed systems?

Because in my case any knobs that get bumped by another camera can cause an o-ring to temporarily "unseat" and while under a vacuum, it sucks in water. I actually got to prove this (at least on an old Nikonos system) in a lab environment at Pacific Camera when I was helping John troubleshoot why cameras were wet inside but not flooded. Result was that a knob when "jarred" by another housing hitting it cause a temporary, instant leak path into the camera.

That's my experience, anyway.

Joe

And my part of curiosity as well: are you guys saying that condensation is more likely to occur when ambiant pressure is lower?

Condensation is a funny thing. Condensation basically forms rain under certain conditions, pressure being one of these factors. Atmospheric condensation typically happens when air expands and cools. If the air that expands is heated to a certain point, vapor forms because water molecules bind together. A key part of the ambient pressure variance is heat. Under the right conditions, heat that is removed from air during expansion and evaporation can form vapor. So think of the air in your housing as ambient pressure and temperature. Dipping your housing in cooler water is akin to warm, ambient air rising into the atmosphere (heat rises) and forming clouds. Dipping your housing in cooler water after assembling it in warmer, humid conditions somewhat replicates what happens when clouds are formed. Our goal, of course, is to not have clouds form inside of our housings

People who live in the UK are very familiar with low-pressure conditions and precipitation.

Well,

that is one reason to NOT open the housing on the boat.

Another reason is that the probability to make a error or oversee a hair, salt or sand grain is x times higher than in a hotel room.

I dive in very different ambients and i rarely have problems with condensation,
nor in Oman (surprisingly humid) and Costa Rica (very humid and surprisingly cold water)
and i never use desiccants.

Before i close the housing i "fill it" with either cold and dry air from a scuba tank or the A/C in the hotel room, wrap it in a big, thick towel

and place it in a hard sided cooler on a shady place when i am on the boat.

Rinse tanks are a deadly creation invented by the camera and housing industry to kill cameras and housing as the camera floats around and will

bang against other cameras or the walls of the tank leading to leak(s).

It is my believe that vacuumized housing resist more as the vacuum sucks the o-rings in place while the o-rings on not vacuumized housings can be moved / unseat,

but if something happen the will suck in water while on non vacuumized the water will leak in. On the end it is a disaster in any case!

Chris

Well,

that is one reason to NOT open the housing on the boat.

Chris

 

After a few days, my camera battery needs charging. It's a bit expensive to ask the captain to put into land to do that!

Well,

that is one reason to NOT open the housing on the boat.

Another reason is that the probability to make a error or oversee a hair, salt or sand grain is x times higher than in a hotel room.

I dive in very different ambients and i rarely have problems with condensation,

nor in Oman (surprisingly humid) and Costa Rica (very humid and surprisingly cold water)

and i never use desiccants.

Before i close the housing i "fill it" with either cold and dry air from a scuba tank or the A/C in the hotel room, wrap it in a big, thick towel

and place it in a hard sided cooler on a shady place when i am on the boat.

 

Rinse tanks are a deadly creation invented by the camera and housing industry to kill cameras and housing as the camera floats around and will

bang against other cameras or the walls of the tank leading to leak(s).

It is my believe that vacuumized housing resist more as the vacuum sucks the o-rings in place while the o-rings on not vacuumized housings can be moved / unseat,

but if something happen the will suck in water while on non vacuumized the water will leak in. On the end it is a disaster in any case!

 

Chris

You beat me to it, John.

Well, i know that there are "some" situations where we need to open it under non-perfect conditions, but usually it leads to problems after that.

Battery dead, lens cap on, buttons not working or bad aligned, zoom gear not working/not installed, wrong lens for the type of dive or critters,

the list of reasons to open it on the boat is long .....

Chris

P.S. Well i did not realized that you where on a liveaboard

 

Condensation is a funny thing. Condensation basically forms rain under certain conditions, pressure being one of these factors. Atmospheric condensation typically happens when air expands and cools. If the air that expands is heated to a certain point, vapor forms because water molecules bind together. A key part of the ambient pressure variance is heat. Under the right conditions, heat that is removed from air during expansion and evaporation can form vapor. So think of the air in your housing as ambient pressure and temperature. Dipping your housing in cooler water is akin to warm, ambient air rising into the atmosphere (heat rises) and forming clouds. Dipping your housing in cooler water after assembling it in warmer, humid conditions somewhat replicates what happens when clouds are formed. Our goal, of course, is to not have clouds form inside of our housings

Thanks for the analogy :-)

I thought I read somewhere else that one benefit of depressurizing your housing was lower chances of condensation (compared to the same housing staying at 1 bar), guess I was wrong.

Thanks for the analogy :-)

I thought I read somewhere else that one benefit of depressurizing your housing was lower chances of condensation (compared to the same housing staying at 1 bar), guess I was wrong.

Yea, that's why I said condensation is a funny thing. You are correct that by putting a vacuum in your housing you should greatly minimize condensation. That should work most of the time.

I'm curious as to why people wouldn't release the vacuum, after they've tested their housings for watertightness. You basically reducing the effective operating depth of your housing. Of course, having flooded two housings in the past 8 years (one a mfr's defect....thanks guys, but what about that 3k video camera?... the other a hair in a seal), I have set up a meticulous routine. Once I assemble the unit for the morning's dives, I don't open it. But I do remove all port o-rings, clean the seats, re-silicone everything. The last part comes when I take a maginfying glass and check the o-rings/seats before reassembly.

While I see the benefit of a pressure check on the surface, not sure of the benefit of moisture alarms at depth. You can't exactly surface quickly. I simply am very careful when I first splash, and never roll in with my camera (regardless of what the DM on the rib tried to get me to do). I would think if you've got a leak, it's going to manifest itself pretty quick with a bubble trail. As noted in some comments, I tend to see more issues with torqueing the ports (I am not a fan of communal camera "barrels"). As for the condensation, I always close up in A/C, as well as a silica gel pack in the housing. The air from a tank is good, too, in a pinch. Since I have followed the AC/dessicant routine, have had no fogging in some years (you learn to ingore the condensation on the outside of the housing when you first leave the AC).

So I guess my question is whether the expense of the vacuum system is a substitute for good housing "hygiene".

dpaustex, one reason to leave the system under vacuum is to lock everything in place while at the surface, helping to prevent unintentional dislodgement of ports. I could even undo the latches on my housing and it will stay together while under vacuum. Also, I always recheck that I still have vacuum present right before entering the water to assure that nothing has gone astray since setting up my camera. A vacuum system certainly does not replace good camera hygiene, but it is an additional tool to prevent floods by "checking your work" and preloading your o-rings. As to your question if a vacuum system is worth the price, the risk benefit ratio will be influenced by the value of your camera, amount of money invested in getting to a remote shooting opportunity, and how much you value the piece of mind that happy little green light affords you.

I leave my housing vacuum at 10 inches Hg below surface pressure, which is roughly equivalent to 10 fsw. Since my housing is operational to 425 fsw, the vacuum preload is insignificant with regard to the effective operating depth of my housing for the vast majority of my diving.

As to moisture detectors, I had a system saved by one years ago when I had a push button develop a small leak during a dive. All damage to the camera was avoided by turning the dome port down, and painfully watching water slowly accumulate in it as I was ascending. No "bubble trail" at any time.

Silica packs do NOT have the ability to absorb enough water to usually be worthwhile in U/W photography IMHO. The exception would be when having to operate in non-A/C environment, AND leaving housing closed overnight to decrease humidity level, otherwise the amount they adsorb (at such a slow rate) is very small.

I too try to minimize housing opening, judiciously use a magnifier (and head light), and try to only open my housing in the A/C when it is possible to do so. On some trips this is not possible though.

If the conditions are very humid and you think you might have condensation problems in your housing, all you have to do is "flush" out the housing with air from your scuba tank just before you close it. Hold the two housing halves almost together and then blow air into the housing with an air blower that attaches to you LP hose. Then close the housing quickly and use your vacuum device.

Fred