2nd stage free flow control device

[muddiver]

thanks for the imput, my reg is setup for cold water it has the eviro kit on the first stage , i was just looking through a website and came across this product and wanted opinions, thanks muddiver your setup was gunna be another option for me, but when you took the plug out in an emergency would it not free flow then??

If it is, as JeffG stated, 99.9% of regulator issues are due to not having the regulator serviced and tuned correctely. A second regulator that is not intended to be used during a normal dive should have it's cracking pressure raised so it will not free flow easily just because it is submerged.

 

[FIXXERVI6]

I have had my regs free-flow. In open water and ice diving it isn't much of an issue:

• You can try to solve it underwater by turning off your tank, breathing off your buddy's octo, and swishing the first stage around in the water - in a few tens of seconds the water should melt the ice which is causing the flow in the second stage;
• In ice diving the hole is rarely more than 100 feet away horizontally - abandon your dive and swim back to the hole while breathing off the flowing reg;
• Open water diving, call the dive and surface normally while breathing off the flowing reg

Cave divers may use such isolators because often they can't simply surface.

What I have found helps to prevent free-flowing is to not breathe from the regs while above the water in sub-zero air. Also, if you can adjust the breaking pressure on your second stage, tune it down to increase breathing resistance.

Planning to dive Minnewanka?

In back mounted doubles you shut down the post for a free flow, you don't isolate.

In side mount you simply feather the valve and continue to breath without the massive waste of gas, same as a deco free flowing reg.

If you have an adjustbile second stage you can do that to assist with free flow while scootering etc. The only time I've ever had free flow "issues" was pulling into devils ear when the flow was rippin, the flow was purging my regulator.

 

[Garrobo]

Do your diving in Florida and your problem is solved.

 

[Web Monkey]

I have had my regs free-flow. In open water and ice diving it isn't much of an issue:

• You can try to solve it underwater by turning off your tank, breathing off your buddy's octo, and swishing the first stage around in the water - in a few tens of seconds the water should melt the ice which is causing the flow in the second stage;

Sharing air is generally a bad solution for a recreational diver with a cold-water freeflow, since it stands a really good chance of freeflowing the donor's reg as well, meaning that now there are two divers with freeflows.

In any case, the first stage is what usually causes a cold water freeflow, so swishing the second stage won't do anything except keep you busy for a little while.

On a recreational dive, the safest solution is to take your buddy, safely ascend and end the dive.

Terry

 

[Crush]

In any case, the first stage is what usually causes a cold water freeflow, so switching the second stage won't do anything except keep you busy for a little while.

Terry

You have clearly been on more dives than me, but are you sure that the 1st stage is more likely to free-flow? I have looked at the physics and doubt that this is the case.

 

[Crush]

In back mounted doubles you shut down the post for a free flow, you don't isolate.

You tech divers have so much gear I don't know how much of it is real and how much of it is made up. I am aware of your isolation manifolds (which are very cool, by the way), but based upon earlier posts I had assumed that you also used the nifty little flow shut-offs that were mentioned in the OP.

It seems that I stand corrected with respect to diving doubles in caves. However, the essence of my post (this widget is unnecessary) is unchanged.

Cheers

 

[Crush]

In side mount you simply feather the valve and continue to breath without the massive waste of gas, same as a deco free flowing reg.

I hadn't thought of that... Like the idea.

 

[Web Monkey]

You have clearly been on more dives than me, but are you sure that the 1st stage is more likely to free-flow? I have looked at the physics and doubt that this is the case.

Cold water freeflows are usually caused by ice forming inside the first stage due to adiabadic cooling. This holds the first stage open, which increases the intermediate pressure beyond what the second stage is able to hold back, causing the second stage to freeflow.

Turning off the tank allows the first stage to thaw, however as I mentioned, unless the donor has a first stage rated for very cold water, the likely outcome is a freeflow (on the donor's reg).

Using the valve you posted will simply cause your backup second stage to freeflow. If you block that, something else will let loose (possibly your BC inflator), or eventually a LP hose.

Terry

 

[fppf]

I must disagree here. Unless your not using an Environmentally sealed 1st or your getting crappy fills 1st stage free flows are extremely rare. In order to freeze up and free flow you need ice, to get ice you need water. If water can't enter the sensing element of the 1st stage it can't freeze. That is why they are now sealing most regs. Piston 1st stages are a little more prone to freezing then diaphragms if there not seal because the ice can form in the clearance gap between the body and the piston. Diaphragms just need to flex a little and the ice tends not to bother them. But again, if there sealed, no water means no ice.
Having a 1st stage free flow from the inside of the reg would mean you have a lot of moisture in your breathing gas. Most dive shops in the north pay close attention to there filter systems to keep dew points low for this exact reason. The seat stresses on the first stage are also much higher which makes them less effected by a little ice on the seats. In addition most first stage seat designs are upstream, they use pressure to close.

The far vast majority of free flows are from the second stage, and the stage that is being used. For starters you have water, lots of water that will get on the seats. Every time you exhale you put warm moist air into the regulator body. Some passes near the seats in the reg and can condense on them. This is without even putting the reg in water, there is water in it. So its impossible to keep all the water out of a 2nd stage. Then most second stages are down stream designs, they use spring pressure to keep them closed. The seat stresses are lower and can't handle ice crystals as much.

For the OP
There are a few people I have seen use the isolator valve on there primary regulator when diving singles. When diving doubles like one poster said, they just shut off that reg and breath on the other side. When using that isolator only use it on the primary second stage. That is the one that will free flow 99% of the time. Regulators not being used typically don't just start free flowing for some reason. Also if someone comes up to you OOA you don't want to need to open the valve. 2nd stages also act as pressure relief valves for a failing 1st stage. Having an isolator on both 2nd stages and having them off would be really bad if the first stage had some IP creep to it.

Lastly, you can't use that isolator on an ocenaic EOS or the orignal Delta 4 with the swivel hoses. Oceanic uses a non standard thread on those regulators to acommadate the swivel. There are ways to deal with free flows, and unless your doing some more exteme dives they are normally not that big of issue. If you are doing more extreme dives your most likely in doubles and then its really not an issue.

I get the joy of diving in 40 degree water year round, I have seen a fair share of free flows. Never had one yet personally, knock on wood.

 

[elan]

If the first stage starts flowing this device is useless as it was already mentioned. If the second stag starts flowing it would most likely mean that the stage is either not appropriate for the cold water or mis configured so it's time to end the dive. If the reg is appropriate for the cold water simple flows like hitting the diaphragm accidentally or having it mouthpiece up are easily fixed with simple closing the mouthpiece with the finger even in cold water.