First stage failure, anyone ever saw?

[h90]

Did anyone ever saw a failure of the first stage in which it did not free flow, but instead it blocked the air total.
In my opinion it should be almost impossible. The only thing I can think of is water or dirt in the tank blocking it.

Anyone ever had a first stage from which you could not get air?

 

[pjones]

As you mentioned, I have only heard of debris blocking the first stage from inside the tank. The person went up side down and the debris fell to the spout. Having a dip tube installed can reduce the chance of this from happening apparently but I don't think this is too common of a problem. I haven't been around for too long though so my stories are limited.

 

[cloudflint]

The only time ive heard of a first stage jamming up is when a little bit of plastic broke off the inside of my friends tank valve and made its way into the first stage jamming it up. On another occasion moisture built up in his tank resulting in his 1st stage being blocked up with water when he went head down.

Also if you have upstream demand valves then if the 1st stage free flows the DV will lock up resulting in you not being able to breathe from them.

 

[h90]

The only time ive heard of a first stage jamming up is when a little bit of plastic broke off the inside of my friends tank valve and made its way into the first stage jamming it up. On another occasion moisture built up in his tank resulting in his 1st stage being blocked up with water when he went head down.

Also if you have upstream demand valves then if the 1st stage free flows the DV will lock up resulting in you not being able to breathe from them.

with the water: doesn't the pressure blows the water thru the first stage?
I have a downstream demand valve. I think upstream don't exist or are extreme rare.
A free flow first stage would cause one of the low hoses explode if the demand valves are upstream. Not a good idea....

 

[cloudflint]

with the water: doesn't the pressure blows the water thru the first stage?
I have a downstream demand valve. I think upstream don't exist or are extreme rare.
A free flow first stage would cause one of the low hoses explode if the demand valves are upstream. Not a good idea....

Im not sure about the water in the tank, it was a story that was told to me by one of my diving friends so i don't have any first hand experience of it happening. I cant really think how the 1st stage filling with water while under pressure would behave. The only upstream regulator i can think of that is still in production is the posiden x-stream which has overpressure valves built into the hoses in case it free-flows.

 

[jtivat]

I had a first stage freeze up and not deliver any gas. It was a deco reg, we will pressurize the reg then turn it off so we do not loose gas. This is what I think happened but am not sure. Before getting in the water the valve was turned on then off, on the way down it was somehow purged and water enter the first stage. My tanks where laid on the wreck, upon returning I turned all the valves on and off just to make sure (this is where I messed up I should have checked the SPG's). When I got to my first stop I deployed the reg checked the SPG and all looked fine. I took a breath and got some gas but it then free flowed a little. I turned the valve off and on tried again and got nothing. Checked SPG again all looked good so I tried the purge and just got a few bubbles. I then beat on the first and second stage a few times then tried the purge again and got a little more gas. After doing this a few times the reg started to free flow and I was able to complete my deco feathering the valve. Also keep in mind the water temp was 39F from top to bottom.

 

[redacted]

If you look at the mechanics of how a 1st stage works, you can probably come up with failure modes that deliver no air. For example, with a piston 1st, the spring must push the piston away from the seat for gas to flow. If the spring breaks, the reg may lock up closed.

 

[rjack321]

I have seen a diaphram rip/burst when the valve was turned on. This was before the dive but the reg definately didn't deliver any gas as it was all leaking past the diaphram and the IP was essentially zero.

 

[bleeb]

I vaguely seem to remember at least a couple of manufacturers' recalls over the last decade or so where certain manufacturing defects or maintenance errors had the potential to cause a complete blockage, although the recalls in question probably specified that they hadn't actually seen any serious accidents result from this. Some of these might be recent enough to be found in the Manufacturers' Recalls forum. (Of course, for recreational diving, one can argue that an unexpected OOA should be a serious situation but not a serious accident, in a competent diver, so serious accidents should have been unusual even with such a failure.)

 

[captain]

Not impossible, nothing is, but extremely unlikely for a properly maintained regulator. Cold water freeze up is not a regulator malfunction, it using a regulator in conditions it is not designed or equipped for.