100% Free flow at 135Ft and 41F water

[Web Monkey]

I guess I'm just confounded by two separate posts here recently. One where someone did a CESA because the zip-tie on his mouthpiece broke and it came off. Now this one with a freeflowing 2nd. It sure seems to me like "grab your octo" should be the very first thing you do in either case.

It wouldn't hurt, but unfortunately, given the conditions in OP's post, recreational equipment and procedures become much less of a "sure thing".

Breathing a freeflow is possible and not difficult and switching to the octo is possible, however neither actually fixes anything. No matter what a single tank diver does with his own equipment, there will soon be no air.

The only effective choices for a single tank diver are to head for the surface (and hope to not run out of air or die), or share air with a buddy, head for the surface and hope that the extra load doesn't provoke a freeflow on the buddy's equipment.

Once "blow and go" or sharing air are no longer reasonable options, diving safely requires more/better equipment, planning and training.

Terry

 

[MasterGoa]

In retrospect, I did not want to use the octo cause I got scared by the impressive
rate at which my air pressure was falling at depth. I did not remember to pinch
my main hose at that time.

Again, ascent was going fine untill I saw the air pressure and breath in water
during the gasping reaction to the dropping PSI needle...

MG

 

[chevy]

Thanks for posting and sharing the whole expirence. I too have learned from this..... once again thank you.

 

[Ayisha]

...It is consequently hard to say that Tusa regs do not make good cold water regs.

In ice dives or extremely cold dives around here in Ontario, the Scubapro MK's are NOTORIOUS for freeflowing - and that is with the environmental kit.

I agree that TUSA's and Scubapro's are really not your best choice for diving in frigid Tobermory, Ontario - especially for the Forrest City, where this event took place or the Arabia or any extremely cold deep dive.

I use the Sherwood Blizzard, which is an extremely coldwater reg, down to 38F often and it has never freeflowed yet. I have only ever heard of 1 Blizzard freeflowing. Some people swear by Apeks, but I have heard of them freeflowing on ice or very cold dives. How they are adjusted is of course very important.

 

[MasterGoa]

I dove the San Jancinto for 47minutes without a hint of a problem.
My profile shows 117 ft at 42F. This is the only time my reg had not
performed perfectly. Hinting on the desing change from the rebuild,
I trust Tusa made their homework. Maybe I got a kit that had been on
the shelf for 2 years as well, no one knows.

I did make a few mistakes going down which did not help.

Here is what I learned from my experience:

Going down to the Wreck:

Do not inflate BC in large burst and do NOT inflate while inhaling.

When inflating, preflate so as to inflate at higher depts as airfow
is multiplied by depth, and accordingly, heatloss in the air expansion process.

At the wreck:

Do not lose eye contact with buddy-buddies. 3 way buddy system
is not soo good cause the two buddies will have a comfort level together
and may not pay a lot of attention to you.

If a freeflow occurs, manually undo your cummerbun and raise
the tank to reach the valve. Reduce the valve without shutting it off.

Do not inhale in a freeflow at depth cause 4-6 times more air is getting
out of the reg and it is like sticking your face out of a car going 90 miles an hour.

Use buddy reg from your kit. If your actual buddy is close, use his buddy reg
and close your tank valve to try and stop freeflow.

Going back up:

If freeflow cannot be stopped, use pony bottle. If all OK, ascend on Pony.
If not ascend with buddy.

Keep one hand on deflater at all times. Air expands exponentially and that
vest will pull you up like a winch.

Observe recommended decompression stages.

Out of the water:

Have someone observe your eyes for blood spots.


Now some people say go to pony immediately, but I disagree
as the pony is the insurance and I would like to avoid a crash
before I call the insurance, I also have a buddy or two to think of.

MG

 

[DA Aquamaster]

For a freeze flow, if you can reach the valve and have a pony, just shut the primary tank off and switch to the pony for a couple minutes. The primary will thaw and you can return to it and proceed accordingly.

For example of the freeze flow was the result of operator error such as a long blast on the dry suit inflator followinga descent, and not much air was lot in the freeze flow, you could consider sontinuing the dive once you thaw out the primary. Similarly, if you ascended above a thermocline, and have adequate gas, continuing the dive may be an option.

On the other hand if you lost a lot of gas from the primary and/or lack enough gas in the pony to perform this particular evolution a second time and still ascend on the pony if the primary re-freezes, then ending then dive is prudent.

In either case, shutting the primary off and switching to the pony conserves as much total gas as possible and that makes more sense than just reducing the freeflow of the primary and leaving the pony untouched.

 

[MasterGoa]

You raise good points, my point was to reduce primary to a normal breathing
rate. I guess this would prevent the frozen reg from thawing.

Is there a risk of water entering the air circuit of the primary is shut off
during a freeze flow?

 

[CDNScubaMoose]

I agree with Ayisha ... the Forest City is extremely cold and last September I had a temperature of 39 degrees at depth, so a TUSA that is certified to 38 degrees is just a bit too close for me. I do dive a Scubapro MK25/650 and have experienced some issues with 2nd stage freeflows but thus far nothing on the first stage ... although I am thinking of making a switch to MK17/G250V for the colder/deeper stuff.

One thing on the temperature of the profile ... I'm assuming you got that from your computer? It is possible that you computer didn't adjust completely to the colder temperature before your freeflow occured so although it read 42 you may have been colder. I have seen this happen with my own computer continue to drop for up to 10 mins after I pass through a thermocline.

I have also had a student diving a TUSA reg (sorry - not sure which ones) have a 1st stage freeflow after he went through a thermocline (took about 30 secs after the thermocline before the freeflow happened).

 

[Ayisha]

Do not inflate BC in large burst and do NOT inflate while inhaling.

Both of these points are very important for extremely cold water diving.
It is very demanding on a reg at those near freezing temps to provide gas to the second stage and the BC at the same time, especially if you hold the inflator button down, which you shouldn't do anyway. This has been known to cause freeflows in very cold water. During training here in Ontario, we were told the above, and also to avoid using the air horn while inflating and inhaling - same idea. And yes, having 2 people breathe from the same first stage puts that one working reg at higher risk of a freeflow at those temps for the same reason - too high demand for the temp and depth for that reg.

Use one, maybe two tiny short bursts of air into your BC. Then WAIT for the effect. It may take a few seconds. Use your lungs to control your buoyancy as much as possible rather than the BC.

Avoid inhaling while inflating the BC or using air horn

Control your buoyancy all the way down rather than frantically inflating toward the bottom. If holding a mooring line, go down without the line if there isn't too much current or periodically let go briefly to see if you're neutral and adjust as necessary all the way down. If your descent is controlled and neutral, you will not need to madly inflate near the freezing bottom. Tobermory has 2 or 3 thermoclines at the deep wrecks, and you want that sorted out before you get deep and extremely cold to avoid a freeflow.

And yes, you and your buddy/buddies should always be aware of what each of you are doing and any issues you are having, and you should be close enough to help/be helped quickly.

If freeflow cannot be stopped, use pony bottle. If all OK, ascend on Pony.
If not ascend with buddy.

bold added

Whether you have a pony or not, you should be ascending with your buddy. The pony does not replace your buddy. Too many people have made it to the surface alone and remain/get in trouble at the surface, even if everything seems to look ok during the ascent.

 

[MasterGoa]

Thank you for the insight Ayisha.

The point of ascending with the Pony was in reference
to the strain of two people on the same system.

I did not mean going back up alone, I still can be a buddy
to my buddy. At the limit, I would remove the stages and
breath from the bottle...

Regards.

MG