Out of air!

Out of air emergencies should not happen. Diving safely includes being sure that you have checked everything yourself, doing a buddy check and diving within your own personal limits. Always avoid making too many changes to your gear configuration and don’t test more than one new item at a time unless you are in shallow, confined water.

Most incidents are a culmination of several small mishaps and would most likely not have occurred had just one error being omitted. The other issue to be aware of is trusting your training and avoid thinking you know better. Here’s why…

I was diving in Mozambique, did a backward roll, and a negative entry (that’s when you don’t hang around on the surface with an inflated BCD, but start your descent immediately). Now, doing negative entries is not ideal, but the surface current was strong, we were diving a small reef and I wanted to get down quickly. So after the roll I finned down head first as fast as I could, without a buddy… Mistakes number one and two.

At 18 meters I found breathing to be difficult. Having just over-exerted myself I stopped to catch my breath but found as I reached the end of my breath my regulator stopped giving me air. Slow breaths were okay but it would not deliver what I needed. I instinctively looked at my pressure gauge, plenty of air in the cylinder but the needle dropped off as I took a deep breath.

“AHA my cylinder is not all the way open,” I thought so I reached up to try and check. It felt open, but convinced I was not doing it properly I took my kit off, held it in front of me and checked. The cylinder was all the way open, and now suddenly I was not getting air at all. I swam to the surface, slowing at about 8 metres to grab a few breaths from a buddy pair descending slowly.

On the surface I signaled the boat and whilst remaining in the water had the top man change my regulators – mistake number three. Straight back down to 18 metres I went, breathing normally and as soon as I turned face down to scan the sea for the group I ran out of air again. Back to the surface as fast as possible! A CESA from 18 metres is relatively difficult once you are stressed and short of breath from over exertion.

On the second descent logic was telling me the problem had to be my cylinder, but arguing with myself I dismissed this as I had serviced my cylinder less than three months prior to this and felt it could not possibly be at fault.

Back in camp I stripped my pillar valve and found it to be blocked with rust and sand. How could this be?

After investigating it turns out the cylinder was dropped from a vehicle a few weeks before this by the compressor operator. The pillar valve was damaged, so they drained it in a hurry, causing condensation, dropped it again in the sand, rinsed it with the water used for cooling cylinders whilst filling (salty water), emptied the water out, replaced the pillar valve with a used one, without a snorkel (a small pipe that runs from the bottom of the pillar valve into the cylinder). I got it back full of air unaware of the incident. The salty water inside rusted the cylinder, the absence of a snorkel meant that every time I was pointed head down the scales inside slowly drifted into the pillar valve until it was totally blocked.

It is not unusual for a little spot of rust to develop in a cylinder. It’s not ideal but it won’t kill you. However a snorkel ensures the pillar valve is supplied with clean air and the scales are kept out – in my situation in Mozambique, the scales would have settled around the top of the snorkel where it attaches to the pillar valve, instead of blocking the valve completely. The other end of the snorkel would have been a bit further into the cylinder, drawing clean air. When I took my cylinders to Orca Industries recently for their annual maintenance, I was very impressed that they insisted on checking each one for snorkels, and fitting them if they were absent.

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Tony

Scuba diver, teacher, gadget man, racing driver, boat skipper, photographer, and collector of stray animals

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