SPG starts leaking on the surface

[raftingtigger]

You were the experienced diver, awesome! Any chance there was water ingress into the SPG?

Yes I was. IDK, possibly, but not likely the way he described it to me.

 

[Umuntu]

This might help put the problem into perspective and relates to @bamafan's post above:

View attachment 435721
(Reprinted by permission)
This table appeared in Life Ending Seconds, 3000 to Zero in 72 Seconds, Advanced Diver Magazine by Curt Bowen​

Interesting data !

For LP Hose failures and 2nd stage free-flows, a 1st stage regulator which has a high flow rate like flow through balanced pistons (eg SP MK25 - over 3000l/m) should empty twice as fast as the typical diaphragm regulator (less than 1500l/m). I consider the MK25's high static flow rate as a potential disadvantage, because this is the only circumstance where it makes a practical difference.

.

 

[Akimbo]

His leak was because the SPG unscrewed from the hose as he twisted the SPG to look at it. O-ring (spool) was fine. 2 wrenches and a firm, but not excessive tightening and then a check for leaks sufficed to fix his problem...

That shouldn't have any effect on the flow rate, even if the spool and gauge are completely removed. Take a close look at the HP port in any first stage made in the last 30 years and you will see that there is a tiny hole designed as a flow restrictor, typically in the 0.75-1mm (0.03-0.04") diameter range. You will often see a similar hole in the HP hose fitting at the first stage end.

 

[raftingtigger]

That shouldn't have any effect on the flow rate, even if the spool and gauge are completely removed. Take a close look at the HP port in any first stage made in the last 30 years and you will see that there is a tiny hole designed as a flow restrictor, typically in the 0.75-1mm (0.03-0.04") diameter range. You will often see a similar hole in the HP hose fitting at the first stage end.

It didn't affect the flow rate. Flow rate is limited at the 1st stage with the pinhole opening just as you know.

This problem was the SPG was installed with the connection just not quite firm enough, so that over several dives as the SPG in his console was checked (and twisted) it loosened the connection. Final straw was when he looked at the SPG before descent (I'm speculating here) it got just enough of a twist to break the seal and the leak started. By the time I saw it, the connection was quite loose and once out of the console the problem was obvious. He was lucky, the only extra high pressure hose with me that day was a 9" for SM , I'll have to correct that in my spares...

 

[Akimbo]

Just to complete the information loop, some readers may find parts of this thread useful: O-rings for Divers

 

[Chavodel8en]

Thanks again raftingtigger - i thought my dives were over and my gear kaput -- and, with your help, I was able to get my 2 dives.

I think that no water entered the SPG. I kept the SPG high & dry as I shut off my air and swam back. I'll keep an eye on it.

And I will likely ditch the big ol' rubber boot - or maybe trim it so the hose is visible. I want some protection for the SPG in case its dropped or bumped.

 

[raftingtigger]

Thanks again raftingtigger - i thought my dives were over and my gear kaput -- and, with your help, I was able to get my 2 dives.

My pleasure. With the spectacular conditions we had that weekend it would have been tragic to have to sit out the dives.

 

[undrwater]

And I will likely ditch the big ol' rubber boot - or maybe trim it so the hose is visible. I want some protection for the SPG in case its dropped or bumped.

I cut mine out of the boot completely. It's quite robust, and nothing is hiding potential corrosion or other issues.

 

[lermontov]

This might help put the problem into perspective and relates to @bamafan's post above:

View attachment 435721
(Reprinted by permission)
This table appeared in Life Ending Seconds, 3000 to Zero in 72 Seconds, Advanced Diver Magazine by Curt Bowen​

yes pretty sobering and bear in mind you might have a leak when your half way through the dive so less gas = less time

 

[scubadiver888]

My favourite video showing how slow it takes to drain a tank from a HP hose is this: