questions about VPS-100 pump for 6xxxx salted line

[mi000ke]

I have been using an old Canon s110 point & shoot and a Canon housing just to get used to underwater photography. That housing is a simple set-up with a fixed port and one primary 0-ring around the housing enclosure that I cleaned and greased before every dive, as it took only about 5 minutes. I recently upgraded to a Sony A6400 and a Seafrogs/Meikon underwater housing with a VPS-100 vacuum pump leak detection system. The Seafrogs housing has a removable port and pump vent, so a few more 0-rings and seals to deal with.

The Seafrogs housing has a vent into which the pump valve is screwed. When the valve is not in use the vent is closed with a screw-in plug (o-rings sit around the vent and the plug). I’ve tested (on land) the pump with and without camera and had no problem getting an air-tight seal (valve light goes from red to green when adequate pressure is reached). However, this is the first housing I have owned with the pump system, and I will be using it for the first time in a couple of weeks (and plan to dive with it empty the first time just to make sure it’s working properly), and have couple of questions:

If the valve indicates an air tight seal, can I be confident that either there is no debris (hair, sand, etc.) on the o-rings, or if there is, it is not affecting the ability to get a water-tight seal? In other words, if I get an air-tight seal, can I assume I do not need to clean the o-rings? (I’m trying to avoid having to clean the port o-ring every dive, as the port is a real PITA to install – hard to align the threads and requires a lot of force to get it to seat properly to be able to screw it on.)

Seafrogs recommends not diving with the valve installed, so the housing needs to be depressurized, (using the valve – the housing remains sealed), the valve removed, and the vent plug reinstalled. Does pressurizing create a tight seal that might be lost once the housing is depressurized, or can I be confident that the seal will hold even once the housing is depressurized?

 

[Barmaglot]

There is absolutely no need to clean the port o-ring after every dive, though it is a good idea to at least wipe it down with a lint-free cloth when you change ports.
The main o-ring can pick up dirt when you open the housing - I was diving in Anilao earlier this week, and I've had fine sand enter the gap between front and back parts of the housing, then get on the main o-ring when I opened it to swap batteries. On one occasion, I wasn't sufficiently thorough about cleaning it, and when I pumped the air out of the housing, the VPS-100 indicator went from green back to red within less than a minute, so I opened the housing again, removed the main o-ring, washed then dried and re-greased it, cleaned the o-ring channel in the front housing half as well as the sealing face in the back half, put it back together and the seals held.
I haven't experienced this kind of sand intrusion anywhere else, but I have had a tiny white cat hair get on the main o-ring when I was staying in a house full of cats, and the VPS-100 caught that, although it took well over an hour for it to go from green to red.
I dive with the VPS-100 mounted on the camera and active; haven't had any issues, although one thing that should be noted is that it needs some margin to work with - I'm guessing that the water pressure squeezes the front and back halves together, compressing the main o-ring and minutely reducing the internal volume, causing a corresponding rise in internal pressure. If I pump the housing just to the edge where the VPS-100 turns green, then it will usually start flashing red at depth, and go back to green as I get closer to the surface. This is a bit disconcerting, so I make sure to give it a dozen extra pumps when I seal the housing. I also try to prepare it in the evening and leave the VPS-100 active and flashing green overnight, so that even a very small leak can be discovered before the morning dive.
I've exchanged messages with SeaFrogs support and their rationale for removing the vacuum valve prior to diving is that the increased pressure gradient reduces the operating depth of the housing. Considering that I never come close to the 60m/40m rated limits, this is irrelevant for me. The valve survives seawater immersion just fine - I just checked my logs, and it's been in the water some 80 times since I got it a year ago, with one battery swap.

 

[mi000ke]

Thanks for the great info.

I dive with the VPS-100 mounted on the camera and active;

So do I understand correctly that you dive with the housing under pressure?

 

[Barmaglot]

Correct.

 

[Vojtěch Mlčoch]

There is absolutely no need to clean the port o-ring after every dive, though it is a good idea to at least wipe it down with a lint-free cloth when you change ports.
The main o-ring can pick up dirt when you open the housing - I was diving in Anilao earlier this week, and I've had fine sand enter the gap between front and back parts of the housing, then get on the main o-ring when I opened it to swap batteries. On one occasion, I wasn't sufficiently thorough about cleaning it, and when I pumped the air out of the housing, the VPS-100 indicator went from green back to red within less than a minute, so I opened the housing again, removed the main o-ring, washed then dried and re-greased it, cleaned the o-ring channel in the front housing half as well as the sealing face in the back half, put it back together and the seals held.
I haven't experienced this kind of sand intrusion anywhere else, but I have had a tiny white cat hair get on the main o-ring when I was staying in a house full of cats, and the VPS-100 caught that, although it took well over an hour for it to go from green to red.
I dive with the VPS-100 mounted on the camera and active; haven't had any issues, although one thing that should be noted is that it needs some margin to work with - I'm guessing that the water pressure squeezes the front and back halves together, compressing the main o-ring and minutely reducing the internal volume, causing a corresponding rise in internal pressure. If I pump the housing just to the edge where the VPS-100 turns green, then it will usually start flashing red at depth, and go back to green as I get closer to the surface. This is a bit disconcerting, so I make sure to give it a dozen extra pumps when I seal the housing. I also try to prepare it in the evening and leave the VPS-100 active and flashing green overnight, so that even a very small leak can be discovered before the morning dive.
I've exchanged messages with SeaFrogs support and their rationale for removing the vacuum valve prior to diving is that the increased pressure gradient reduces the operating depth of the housing. Considering that I never come close to the 60m/40m rated limits, this is irrelevant for me. The valve survives seawater immersion just fine - I just checked my logs, and it's been in the water some 80 times since I got it a year ago, with one battery swap.

Hi Barmaglot,

How significantly reduces the operating depth when is installed VPS during dive?

 

[Barmaglot]

How significantly reduces the operating depth when is installed VPS during dive?

I have no hard data, but I haven't had any trouble at 30-32m.

 

[saxman242]

Just as a datapoint, I apparently managed to flood my vps-100 while snorkeling with it attached to the housing. I went to change the battery, and the inside was all corroded with definite salt water intrusion.

 

[mi000ke]

Just as a datapoint, I apparently managed to flood my vps-100 while snorkeling with it attached to the housing. I went to change the battery, and the inside was all corroded with definite salt water intrusion.

While the vps was attached, did you get any indication (red light or leak detector light) that you were getting any water intrusion? Did you always get a green light indicating a good seal before entering the water?

 

[saxman242]

While the vps was attached, did you get any indication (red light or leak detector light) that you were getting any water intrusion? Did you always get a green light indicating a good seal before entering the water?

I had a green seal before entering the water (and for several hours ahead of time). If memory serves, the vps started flashing red/green combos as I was getting out of the water. I did notice a drop or two of water in the area of the vps where one turns it on/off, but nothing in the camera housing.

I am going to try to clean the board of any contamination/bake it out and replace all the o-rings in the vps and give it a go. If that works, I'll do some tests and see if I trust it or not. It's entirely possible that I fouled the o-ring putting the cap back on or something.

If no luck there, I'll just replace it with a leak sentinel assuming I can get an adapter (or make one).

 

[saxman242]

I am going to try to clean the board of any contamination/bake it out and replace all the o-rings in the vps and give it a go. If that works, I'll do some tests and see if I trust it or not. It's entirely possible that I fouled the o-ring putting the cap back on or something.

As an update, I completely disassembled the vps today. Removed and replaced all the o-rings, cleaned everything with isopropanol, etc. Took the board out, caked on some baking soda and water until it dried and removed all the corrosion, then cleaned the board in isopropanol. Put a fresh battery in and everything appears to be working as intended now. I've got the housing sitting under vacuum to see that the vps does what it is supposed to. If it continues to work, I'll submerge it in the pool for a while to verify no intrusion, etc.