Interesting AquaMaster modification

[Scuba Lawyer]

Saw this on an Ebay listing.
Never seen this modification before.
A new way to add a BC inflator perhaps?
Another method of attaching a hookah line?
Feed from a bail-out bottle?
Air-line to pressurize a camera housing?
Inquiring minds like mine want to know.

M

 

[Fibonacci]

Interesting!
Looking at the single retention flange on the spigot, and flat knurling to suit hand tightening I'd say a low volume bleed off to a camera housing?

 

[Compressor]

Wow. Not sure.

 

[GJC]

Wow, that's really interesting.

What's inside? Does it just go inside to the interior of the can, or did they tap into the IP or HP?

If it just goes to the inside of the can, it won't supply any air without a negative cracking pressure to open the second stage valve.

If it was for a second stage or BC inflator, it needs to tap into IP somehow so why not just use the hookah port?

My best guess is that they tapped into HP somehow inside the can so the quick connect can attach to a pressure gauge hose.

I think you need to buy it just to open it and see what it looks like inside!

 

[Luis H]

It is intended to equalize a camera housing.

It was not really a very good idea, because O-ring actually seal better when there is some pressure differential. But structurally the housing doesn't have to handle the pressure differential.


Added:

A lot of high end camera housing actually use a vacuum pump and a sensor that verifies that the vacuum is not compromised. The pressure differential is small, but it is enough to set the O-ring in the right direction and the sensor is supposed to give the user an advance warning of a leak.

It is very interesting (and not very intuitive) that an O-ring can create an air-tight seal, but water can leak due to the surface tension of water. To have a water tight joint you often need a bit more O-ring compression. Having some pressure differential across the O-ring help set the O-ring and increases the O-ring compression.

It is very common for camera housings to leak in the soaking tank aboard a dive boat or even back on a dive resort. Again, this is not intuitive, that the camera housing did OK during the dive, but it leaks in a soaking bucket where the pressure differential is minimal.