My Own Out of GAS Experience

So the other week I experienced my first very own out of gas situation and learnt something new. Downstream valves can fail shut!!! I was always told and understood they could only ever fail open creating a free flow.

This is going to be a little bit of a long post explaining what happened, so apologises, as I wanted to cover off what I hope will be the most common questions and comments others are going to make.

A group of us went to a local shore dive (max 9m, avg about 6m). I was in a group of 3 and were working on a specific task, to lay a line and measure the distance and baring’s between some small reefs. The reefs are a 100m ish apart and viz was about 5 to 6m. Due to the dive and the 3 of us being close together we were all on single 12’s.

The vast majority of my dives in double digits are on side mount for redundancy. For this dive we were happy that our redundancy was each other and as we regularly dived together and due to the depth the very very small risk was manageable instead of hiking redundancy equipment up and down the beach.

So I started with about 180 bar in a 12l and planned to come out with about 50bar being about an 80min ish dive. That 50 bar would still lasted be another 40-45mins at a push. Worse case was a bit of a surface swim back rather than surfacing a few meters off the beach if anything drastic went wrong.

I knew how much gas I started with as I used a handheld gauge at home when I was selecting a tank to take, and this was then confirmed in my pre dive check (https://grahamsavill.wordpress.com/2017/07/15/regulator-pre-dive-checks/). The checks showed no issues and off we went. A nice uneventful dive until the way in.

After about 45min dive on the way in, when reeling in the line my reg (XTX200 with FSR 1st, Serviced in Feb this year and the regs themselves are a good 8 years old with no previous issues and regularly serviced) started to breath funny as if I was running out of air. SPG showed about 100 bar, the pressure I was expecting.

I turned to buddy and signalled something was wrong. My first thought was my valve was not fully open, so I checked, fully open. As I was doing this breathing became more difficult, so again I signalled my buddy some serious wrong, stay really close. I switched to my backup reg, same issue.

My next thought was do I have a leak and stuck SPG or something else wrong, so I used the mirror I have on the back of my hand, and everything looked fine. I do check periodically during the dive anyway but it had been probably 20mins since I last had a look.

Then it happened, no air, SPG still showing about 100 bar. So I signalled to my buddy and took his spare octo. We then continued to head into the beach following the bottom and getting some practice in sharing air and switching between buddies and some other friends we came across on the way in. Was also a bit of laugh and fun, plus saved the surface swim.

During our return, I was sure the gauge was not stuck, yet I knew the reg should fail open. So I shut down my cylinder a couple of times and re-opened it, but the SPG did not move. We were in about 17c water so no chance of frozen or ice.

When we got out, I tried removing the stage from the cylinder but couldn’t due to pressure so ended up loosening the HP hose to de pressurise the HP chamber of the first stage as I did this the SPG needle went down. I then connected another set of regs and my SPG and gas was correct. When I did this, I first tried releasing the pressure via a MP hose, in case one of the hoses was blocked. I have mainly rubber hoses (expect pressure and a short 2nd reg hose which are miflex). When I did this no air came out. So this meant air was not moving from the HP to MP chamber of the first stage.

The 1st stage was stripped down expecting to see a stuck seat, or other issue, but nothing looked wrong. All looked clean and tidy. The reg was then cleaned and serviced. Will be getting in touch with Apeks to see what could have been the cause, I suspect it was IP pressure, but that was correct as I regularly test it every month or so and the IP adjustment screw was in the same place before and after the service (Anyone have an ideas on any technical issues it could be, please let me know. All springs looked and felt fine and even compared them to others).

I have a few take aways from this event, most I know already, but certainly reiterated them for me.

1) My choice of redundancy for deeper dives

2) Good Buddy diving and communication (especially on a single)

3) Doesn’t matter what checks are done shore side, they do not guarantee a failure free dive

4) Out of Gas does not always mean completely out. I still had 100 bar just couldn’t use it

5) Gas management – knowing your SAC rates

6) Know your problem solving drills and practice them (don’t assume you found the correct answer)

7) Long hose donate, or octo off the left side (when switching between buddies, the right side was a complete pain in the a..)

8) NEW ONE – downstream valves CAN fail shut!!!!

Happy Safe Diving

G-SAV