apeks xl4 free flow

[kent onufreichuk]

hi. i have a couple apeks xl4 regs.
had a few cold water free flows. just wondering if anyone else has had any surprises
(i am a certified reg technician)
only had issues in cold water <4c.

 

[runsongas]

did you already follow all recommendations like detuning/lowering the IP/avoiding pre breathing?

if so, it might be time to think about a norsok rated reg like the mtx-rc or poseidon xstream

 

[kent onufreichuk]

yes. my thought is maybe that since we use them in the pool for training, i should shorten up the service interval. the two free flows were at 65-70 feet. i took them out of service as i haven't had a chance to get them on the bench. i'm also wondering if maybe a tiny bit of water may have entered them, after pool rinse?

thanks for your reply. excellent points to consider.

 

[kent onufreichuk]

did you already follow all recommendations like detuning/lowering the IP/avoiding pre breathing?

if so, it might be time to think about a norsok rated reg like the mtx-rc or poseidon xstream

and yes, definitely considering upgrade to higher end cold water regs, and keeping these as
my warmer water sets.

 

[John C. Ratliff]

yes. my thought is maybe that since we use them in the pool for training, i should shorten up the service interval. the two free flows were at 65-70 feet. i took them out of service as i haven't had a chance to get them on the bench. i'm also wondering if maybe a tiny bit of water may have entered them, after pool rinse?

thanks for your reply. excellent points to consider.

Well, I cannot say much about the Apex regulator, as I have not seen this one. But maybe knowing something about why free flows occur in single hose regulators will help. There is quite a pressure drop from the IP to ambient pressure, along with a lot of flow. Both contribute to temperature drops. If the ambient temperature of the water is near the freezing point, the drop in pressure/flow will cause the air to be below the freezing point as it exits the regulator’s nozzle into the regulator’s ambient pressure area to go into the diver’s mouth. If there is water in there, it will freeze and adhere to the lever system, causing the free flow. So the trick is to keep the second stage inside as dry as possible.

Sometimes the design of the second stage Venturi system actually contributes to the potential for free flow. The MR-12 II, for instance, with the tube outside the regulator and subject to the ambient pressure of the water, contributes to freeze up free flow in that regulator. Regulators with higher IP will also contribute to the potential for freeze up free flow, due to the physics of temperature drop in the air. Google the Ideal Gas Law to understand better the relationships between pressure and temperature (but realize that you need to use pressure and temperature in Pascals and degrees Kelvin).

SeaRat

 

[John C. Ratliff]

What I wrote above was specific to a second stage ice-up and free flow. I have a Sherwood Magnum Blizzard regulator from the later 1980s that has two copper vanes inside the mouthpiece which are screwed into the top of the second stage valve, which transfers the heat from the diver's breath to the mechanism, which significantly reduces the potential for second stage freeze up.

The Magnum Blizzard also has a unique first stage, which has a modification to the first stage which allows pressure to be transmitted to the piston, but excludes water. So water never gets into the first stage, thereby eliminating the possibility of water freezing inside the first stage.

Other regulators have displaced the water in the first stage near the piston by silicone grease. Care must be taken to ensure that the silicone stays on the outside, displacing water, and doesn't get inside to the mechanism, where it can be transmitted through the intermediate stage/hose system to the second stage, where the possibility of inhaling the silicone grease present themselves.

So we really have two separate situations that can cause a freeze up and subsequent free flow of air.

SeaRat