I have my first free flow, so what went wrong?

[Nick of Bristol]

Looking for feedback...........

We were in the NDC at Chepstow the other weekend and coming up from 57 metres (at the 40 metre point) I noticed a strange sensation / vibration. I checked the non-breathing 2nd stage, and that appeared normal. It felt like a moderate amount gas was escaping from somewhere, but I my breathing felt normal. Gas was certainly not being forced into my mouth.

I suspected that gas was escaping from the 1st stage. On signalling my buddy to do a second bubble check, he indicated that I should switch regs. I could then see that the breathing second stage was free flowing. Apparently, the gas may have been exiting from the front of the 1st stage. Hence the lack of a strong breathing sensation.

On reg switching my buddy turned off my first stage. The reg in question was and Scubapro Mk11 with S555 2nd stage. It was last serviced between 9-12 months ago. The other reg was a bullet-proof Apeks XTX200.

There was no panic as I had loads of gas and was diving independents. A minute later when I turned the first stage on again there was no problem.

In diver training I recall that a free flow was simulated by holding in the purge button and air was forced into ones mush giving one a very clear sensation of a free flow. In this instance there was no sensation (it was more of a vibration), there was less gas escaping. Hence my slow reaction / disbelief.

So what went wrong with my regulator ?

Would the problem be the 1st or 2nd stage ?

Are all free flows like this ?

Have I forgotten my training ?

Is a Mk11 not man enough at 7 degrees C and 5 bar ?

Many thanks in advance

Nick

[Ron Evans]

Looking for feedback...........

We were in the NDC at Chepstow the other weekend and coming up from 57 metres (at the 40 metre point) I noticed a strange sensation / vibration. I checked the non-breathing 2nd stage, and that appeared normal. It felt like a moderate amount gas was escaping from somewhere, but I my breathing felt normal. Gas was certainly not being forced into my mouth.

I suspected that gas was escaping from the 1st stage. On signalling my buddy to do a second bubble check, he indicated that I should switch regs. I could then see that the breathing second stage was free flowing. Apparently, the gas may have been exiting from the front of the 1st stage. Hence the lack of a strong breathing sensation.

On reg switching my buddy turned off my first stage. The reg in question was and Scubapro Mk11 with S555 2nd stage. It was last serviced between 9-12 months ago. The other reg was a bullet-proof Apeks XTX200.

There was no panic as I had loads of gas and was diving independents. A minute later when I turned the first stage on again there was no problem.

In diver training I recall that a free flow was simulated by holding in the purge button and air was forced into ones mush giving one a very clear sensation of a free flow. In this instance there was no sensation (it was more of a vibration), there was less gas escaping. Hence my slow reaction / disbelief.

So what went wrong with my regulator ?

Would the problem be the 1st or 2nd stage ?

Are all free flows like this ?

Have I forgotten my training ?

Is a Mk11 not man enough at 7 degrees C and 5 bar ?

Many thanks in advance

Nick

Were you on 'mix/??

[Richard Whitcombe]

Any reg can freeflow in cold water, even "cold water" regs. I had a first stage freeze up in NDAC a few years ago and that was a massive reg blown out of my mouth and started spinning with the air freeflow. Forget breathing from that, just shutdown!

Not really enough detail in the post to tell if its first stage freeze, ip creep or the second stage at fault really.

Would second the above, were you on air or trimix as that might effect the regs tendency to freeflow if cold.

I had a stage reg sort of act as you mentioned the other day - my 50% reg started flowing 3-4 seconds after inhale stopped so produced a constant but slow stream of air. That was first stage IP creep since replicated on land. My only other main freeflow was the one described above so in answer to your question - no. not all freeflows are like yours but some are!

[Nick of Bristol]

Yes I had a lean mix with 7% He.
(just using up the left-overs !)

[Hamish]

Hi Nick,

Like yourself, I experienced a trembling sensation when exhaling from my reg earlier this year(Scubapro MK20, R390 second stage). The water temp was around 7 deg and I was on air at 20 mtr. I took my reg in for servicing and was told it was likely the first stage intermediate pressure causing the problem (IP creep as Richard put it). This is caused when the valve is not seating correctly and allows air to pass through the first stage thereby opening the second stage during exhaling.

I am told this can also happen to recently serviced regs as well as those due servicing when the HP valve has not seated correctly.

regards

Hamish

[Tristan]

Sounds quite normal for Cold water diving to me. I had a regulator freeflow in Vobster Quarry and switching the air off/on fixed it. That was my main 2nd stage that was in my mouth at the time. I just switched to my alternate supply and my buddy isolated it and turned it back on for me.

[Richard Whitcombe]

I just switched to my alternate supply and my buddy isolated it and turned it back on for me.

Shouldn't you be able to isolate yourself?

(IP creep as Richard put it)

IP creep is fairly easy to diagnose, turn a tank on, nothing comes from the reg as normal, after a few seconds it starts to freeflow but slowly and stays like it. Breathe it from it and it stops flowing for a few seconds then starts again. Of course the extreme side of this is the IP builds up so quickly its constantly flowing.
If it is IP creep though it'll be possible to replicate on the surface not just underwater.

FWIW all 4 of my Apeks DST and DS4 first stages (interestingly, not my FSR which gets used a lot more) have had this issue in the last year or so and one of them is "fixed" and the problem comes back a few weeks later so i suspect the casing is scratched somehow.

[Woz]

Shouldn't you be able to isolate yourself?



IP creep is fairly easy to diagnose, turn a tank on, nothing comes from the reg as normal, after a few seconds it starts to freeflow but slowly and stays like it. Breathe it from it and it stops flowing for a few seconds then starts again. Of course the extreme side of this is the IP builds up so quickly its constantly flowing.
If it is IP creep though it'll be possible to replicate on the surface not just underwater.

FWIW all 4 of my Apeks DST and DS4 first stages (interestingly, not my FSR which gets used a lot more) have had this issue in the last year or so and one of them is "fixed" and the problem comes back a few weeks later so i suspect the casing is scratched somehow.The symptoms youe describe are rarely IP creep. That's the first thing people suspect but certainly for Apeks regs, it's more likely to be the 2nd stage seat bedding in which lifts the lever. Unscrew the hose, tweak the seat clockwise a teeny tiny bit then test again. This should be done with the cracking adjustment knob fully out then screwed in a turn. Opened all the way out you should get a teeny hiss which stops when you screw it in a turn.

New and freshly serviced regs suffer from this.

[Richard Whitcombe]

Nope - confirmed as IP creep (by way firstly of different second stages then by getting hold of an IP gauge). It creeps up to 20 bar.

[Tristan]

Shouldn't you be able to isolate yourself?

Of course but if your buddy is right on the case and closing the valve your not going to push them away and do it yourself when your losing Air rapidly.

[Woz]

Nope - confirmed as IP creep (by way firstly of different second stages then by getting hold of an IP gauge). It creeps up to 20 bar.In that case either the HP seat or the crown is buggered.

However everyone does tend to shout IP CREEP when it mostly isn't. But it is easy to check with an IP gauge which is why I have one in my boat toolkit along with a set of service kits.

People do get a little worried when you start stripping regs down though on a boat... :) but if you have a technical bent, there's nothing complicated about regs. In fact I would say a housbrick is more complicated than a S'pro mk2.