Snippets #1 – Regulator Checks

Fizzing 1st stages & leaky 2nd stages – we see them on dives up and down the UK with casual regularity. Normally pointed out by our buddy on the 6m safety stop or mentioned in the pub afterwards and generally discounted or dismissed by the average recreational club diver. So when should we start taking more interest in checking our regulators?

A lot of my dives are ‘average’ club dives and I have to admit to being a bit complacent in the past. If it’s a non-deco dive on my favourite twin 7’s then a quick buddy check before rolling off the boat has more than sufficed in the past. I have full redundancy and I’m pretty slick at swapping 2nd stages (the bit that goes in your mouth for my non-diving friends!) underwater.

Once I start thinking of deeper dives requiring decompression stops then things become a bit more focused. A fizzing 1st stage or a less than optimal 2nd stage at depth is far from ideal and is likely to cause problems the deeper you go.

Where I become even more meticulous is when decompression and/or bailout gasses are involved. The impact of losing a decompression gas, whilst managable through planning, is one that should be avoided at all costs. The loss of a shallow oxygen rich mix could easily turn a one hour dive in to a two hour nightmare. The loss of my deep bailout gas whilst diving my rebreather is equally as worrying.

So what checks/pointers can we follow to ensure regulators are working before we get in to trouble during a dive?

Most of us are familiar with the pre-dive checks as they’re instilled in us during our training, these include:

  • Ensuring regulators are serviced as per manufacturers recommmendations and are ‘in test’
  • Checking cylinder pressure & gas mixes prior to the dive
  • Breathing from the regulators before the dive to check they are functioning correctly

What I would also add in here is a ‘breath down’ test where the cylinder is opened to pressurise the regulator and then closed. I then breath down the regulator, watching the pressure drop as I do so, until there is no more gas left and the guage reads zero. At this point the regulator should seal and I shouldn’t be able to draw any gas through the 2nd stage in my mouth. If I can still draw air through there is a problem that requires investigation!

If all is well I’ll continue to get ready for the dive and perform a final buddy check before entering the water.

If the site allows I will also perform in-water checks including a bubble check to ensure no equipment is leaking before the descent. I might also check the breathing of deco/bailout gases whilst underwater too – though sea diving from a boat in low UK visibility with a strong current means that this is not always feasible.

But back to the breathe down test – what might this pick up? In short it’s likely to pick up assembly problems with the 2nd stage and any issues with the internal diaphragm. This happened to my buddy recently as we prepared for a 75m dive involving two seperate decompression gases.

I’d suggested my buddy breathe down his cylinders containing the decompression gases and he found he was able to breathe through the 2nd stage whilst the cylinder was turned off…


Breathe down test


Checking the 2nd stage


Diaphragm & retainer


Diaphragm looks ok?


But on closer inspection – torn diaphragm

So what may’ve have happened if we hadn’t have spotted this? Well, there’s always the chance that nothing would’ve happened and he could’ve remained oblivious to the problem. More likely he would’ve had what we call a ‘wet breathe’ as water leaked past the diaphragm underwater – he’d likely manage this underwater and investigate afterwards. Worst case the 2nd stage would’ve remained flooded and been unuseable during the dive, meaning a long decompression stop on the remaining deco gas. It could also have caused him to breathe in water leading to complications/panic during the dive.

The checks we carried out ensured we didn’t have to deal with any of these scenarios.


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