Avoiding cold water Free Flow - best practices

[Landlocked123]

Would like to get insights from experienced cold water divers (32-45 degree water) on best practices we as divers can follow to diminish the probability of a free flow when diving cold water. The assumption of this question is we are diving with cold water rated regs that are properly serviced. Does lowering IP pressure at lower end of scales help? avoiding excess work at depth to ensure slow breathing..etc etc. What factors do we have control of as divers?

 

[grf88]

I reduce the IP on my Apeks regs down to about 125 psi. Avoid using you primary buoyancy inflator while inhaling or preferably run it off a second first stage on doubles or an H-valve.

 

[rhwestfall]

Free-Flow - service
Freeze-Flow - environmentally sealed and diaphragms. IP lowered. When on doubles: my primary regulator and my primary buoyancy are on different posts. I can monitor use easily, avoiding breathing and inflation simultaneously, and, in the event of having to donate, I am in control of the stress on the first stage sending me air for breathing and buoyancy while the recipient doesn't have to have his breathing timed with my needs..... When on singles, very close attention to not do things like trigger LPI and breathe simultaneously, not intentionally purge a reg (like to fill a bag - use exhalations), don't do long bursts of air (DS inflation or air bladder)

GO EASY, DON'T OVERWORK!

 

[Landlocked123]

This is very insightful. I dont dive doubles now. So not sure how to route BCD inflator to a different first stage as my other first stage is already utilized by pony bottle.

 

[Gareth J]

See below from one of my posts in a previous thread ---

I am sure there are a few here (from Scandinavia) who can give better advice but as a first shot.
[1]
If you are using your equipment in cold water.

1. Don't leave the regulators in the car overnight. Ideally, don't leave cylinders in the cold overnight either..
2. Keep the regulators dry prior to use. (Use good air - dry).
3. When testing kit before entering the water, don't exhale through the regulator. (The condensation freezes).
4. Once you start breathing from a regulator, don't remove it from your mouth. (see condensation freezing).
5. Breath normally and steadily when in the water.
6. Add gas for buoyancy control in small amounts.
7. Don't use a second stage for DSMB inflation - if you do short burst of the purge valve, (not long bursts).
8. Makes sure your regulators are in good operational condition. Properly serviced, no leaks, or slow dribbling of gas from the second stages.

Most regulators will cope with cold water (a proper cold water regulator is better, with an environmental kit)[1]. Travel regulators are often not designed for water below 5C.
It is the drop in gas pressure that causes the icing. High volume's of gas passing through the first stage increase icing risks. So heavy purging of a regulator is a bad idea (DSMB), holding the inflate button down, high breathing rate. Two people breathing off the same first stage is bad news, especially in high stress periods such as a rescue when breathing rates are increased.
The big issue is first stage failure. If the second stage fails, the increased gas flow normally results in quick icing of the first stage and failure of the first stage. Fitting a shut off device would allow you to stop a second stage failure. If done quick enough it would stop the first stage failing. However. if the first stage fails, the second stage acts as the emergency pressure relieve.


Gareth

[1] - I still use Poseidon Cyclon's on my bailout cylinders. They are not environmentally sealed and are more than happy in very cold water.

 

[grf88]

See below from one of my posts in a previous thread ---

I am sure there are a few here (from Scandinavia) who can give better advice but as a first shot.
[1]
If you are using your equipment in cold water.

1. Don't leave the regulators in the car overnight. Ideally, don't leave cylinders in the cold overnight either..
2. Keep the regulators dry prior to use. (Use good air - dry).
3. When testing kit before entering the water, don't exhale through the regulator. (The condensation freezes).
4. Once you start breathing from a regulator, don't remove it from your mouth. (see condensation freezing).
5. Breath normally and steadily when in the water.
6. Add gas for buoyancy control in small amounts.
7. Don't use a second stage for DSMB inflation - if you do short burst of the purge valve, (not long bursts).
8. Makes sure your regulators are in good operational condition. Properly serviced, no leaks, or slow dribbling of gas from the second stages.

Most regulators will cope with cold water (a proper cold water regulator is better, with an environmental kit)[1]. Travel regulators are often not designed for water below 5C.
It is the drop in gas pressure that causes the icing. High volume's of gas passing through the first stage increase icing risks. So heavy purging of a regulator is a bad idea (DSMB), holding the inflate button down, high breathing rate. Two people breathing off the same first stage is bad news, especially in high stress periods such as a rescue when breathing rates are increased.
The big issue is first stage failure. If the second stage fails, the increased gas flow normally results in quick icing of the first stage and failure of the first stage. Fitting a shut off device would allow you to stop a second stage failure. If done quick enough it would stop the first stage failing. However. if the first stage fails, the second stage acts as the emergency pressure relieve.


Gareth

[1] - I still use Poseidon Cyclon's on my bailout cylinders. They are not environmentally sealed and are more than happy in very cold water.

Items 1-4 are more for cold air temperatures so not as important when the air temperature is 85 and the water at depth is 32.

 

[Landlocked123]

I dive sherwood blizzards and have had them down to 40-42 degree water with no issues but going to extend this year's season well into Dec so this is great insight thanks for sharing

 

[EireDiver606]

Taking care of your equipment is what I’ve heard from dive shops to be the easiest way to prevent free flows. If it’s cold water, it could be the reg. Or if you’re breathing regs at very cold surface, the water vapor freezes when brought into the water.

Don’t have any personal experience though.

 

[Roger Hobden]

Has there been any attempts to create minitiature heaters to prevent freeze flow ?

The basic know-how to create such technology probably exists.

Would it be affordable is another question.

 

[EireDiver606]

Has there been any attempts to create minitiature heaters to prevent freeze flow ?

The basic know-how to create such technology probably exists.

Would it be affordable is another question.

I think the Apeks first stages have something similar. I thought I remembered reading something about a heat trap or something before I bought my singles set.