In-line 2nd stage valves

[Panama Jones]

Diving with groups in really cold water you realize that free flows are actually quite common. I was cruising an online dive store and came across in-line 2nd stage valves that you can slide to shut off low pressure airflow. Put just before 2nd stage or drysuit valve.
Has anyone see any value in these. Seems like it may be a good idea to save a tank of air and possible continue the dive after surfacing on octo and figuring out the free flow. Possibly another point of failure or error though?

 

[elan]

garbage just search through the board. it is discussed quite often

 

[Panama Jones]

Thanks I always search before posting but my keywords didn't return anything..then bang - I post and the suggested topics show up at the bottom.

Lots of good info on the other threads...let's kill this one

 

[Peter69_56]

Yes they are good, however if the free flow is due to primary regulator creep then with this valve closed it can blow the line. You can get a relief valve to prevent this.

I only use them on my sling tanks and only close them and then the tank valve if I have a free flowing reg (faulty). This way if the reg free flows its the only one that gets drowned as I close the shutoff valve. Prior to this I have had secondary and primary regulators get drowned due to secondary reg leaking down the line pressure. I habitually check sling tank pressures to ensure they don't leak down.

 

[swimmer_spe]

Diving with groups in really cold water you realize that free flows are actually quite common. I was cruising an online dive store and came across in-line 2nd stage valves that you can slide to shut off low pressure airflow. Put just before 2nd stage or drysuit valve.
Has anyone see any value in these. Seems like it may be a good idea to save a tank of air and possible continue the dive after surfacing on octo and figuring out the free flow. Possibly another point of failure or error though?

*facepalm*

Your reg is likely rated to 7C. Change your reg out, do regular maintenance and you should never have a problem.

Only had a free flow once, and it was because my reg was only rated to 7C.

I regularly dive in waters -1C to 10C

 

[beanojones]

Yes they are good, however if the free flow is due to primary regulator creep then with this valve closed it can blow the line. You can get a relief valve to prevent this.

I only use them on my sling tanks and only close them and then the tank valve if I have a free flowing reg (faulty). This way if the reg free flows its the only one that gets drowned as I close the shutoff valve. Prior to this I have had secondary and primary regulators get drowned due to secondary reg leaking down the line pressure. I habitually check sling tank pressures to ensure they don't leak down.

They would also be useful for drop tanks, because randomly flooding those regs is pretty common too, and because they are not on the diver to actually periodical recharge the lines.

When I have to leave tanks, I often have to do so on sandy bottom areas, and a good percentage of the time I come back to empty lines from sand wedging the purge button open.

 

[flots am]

Diving with groups in really cold water you realize that free flows are actually quite common. I was cruising an online dive store and came across in-line 2nd stage valves that you can slide to shut off low pressure airflow. Put just before 2nd stage or drysuit valve.
Has anyone see any value in these. Seems like it may be a good idea to save a tank of air and possible continue the dive after surfacing on octo and figuring out the free flow. Possibly another point of failure or error though?

If you have a freeflow caused by increased Intermediate Pressure from a malfunctioning first stage, such as icing in cold water, closing an inline second stage valve will stop the freeflow on your primary second stage regulator and start a new freeflow on your alternate second stage.

If you buy two of these devices and install them on both regs and turn them both off, in a few seconds, you'll have an exploding second stage hose and a lot of bubbles, soon to be followed by an empty tank.

They're just a bad idea.

Also, just to throw more poop on the heap, even if nothing is malfunctioning, if you do an air share with an out-of-air diver and forget about the valve, someone could easily die before you figure out what the problem is and fix it.

These valves are worse than the useless SCUBA trinkets because they actively make your dive less safe and fix nothing.

flots.

 

[Peter69_56]

I agree I would not put them on my bottom gas regs at all, only my sling cylinders for deco.

If your normal regs are so prone to free flowing all the time then I would replace them. Sling cylinder regs do get exposed to bumps etc and are not critical in the same way bottom gas/ normal regs are. Changing to deco gas is a planned thing and one prepares and takes time, not something rushed due to things like MOD etc.

If you are a recreational diver I would not recommend them for you as they are just a trap for inexperienced divers. Someone trying to grab your occy will panic if they try it and find no air. My opinion is they have their use but they are really specialty items not for normal consumption (which is what I should have said previously, forgetting I am talking to a broad diving spectrum, apologies).

 

[rick00001967]

They would also be useful for drop tanks, because randomly flooding those regs is pretty common too, and because they are not on the diver to actually periodical recharge the lines.

When I have to leave tanks, I often have to do so on sandy bottom areas, and a good percentage of the time I come back to empty lines from sand wedging the purge button open.

please forgive my ignorance as i really have no training in slinging deco bottles or leaving stage bottles etc. but i had always assumed that divers who either carry extra deco gas or divers who leave bottles at certain spots, would leave those bottles off at the tank valve. then open them when needed. is this not the case ??
sorry for being off topic here op.
i ask this because i am using a small pony (hangs in front of me) as a bailout bottle at times and when i do, i leave the tank valve off.

 

[beanojones]

please forgive my ignorance as i really have no training in slinging deco bottles or leaving stage bottles etc. but i had always assumed that divers who either carry extra deco gas or divers who leave bottles at certain spots, would leave those bottles off at the tank valve. then open them when needed. is this not the case ??
sorry for being off topic here op.
i ask this because i am using a small pony (hangs in front of me) as a bailout bottle at times and when i do, i leave the tank valve off.

(Neither of the following uses are particularly basic scuba uses, but)

Yeah, charge the lines and then shut the valve off, but if/when the purge on the second stage gets bumped, wedged with sand etc., which can happen on tank on one's body, or on a tank left behind, the line gets emptied and water can get in places. If a tank is on me, I can charge the lines repeatedly throughout the dive, if I wants to, but a tank left behind is unmanned. But when there a mess of tanks attached to one's body, having to repeatedly charge them is a pain, so an inline switch might be useful.

What inline switches are also useful for is to shut off access to gases that cannot be used except at certain depths, whether because hypoxic or hyperoxic. There are perhaps better ways to manage this when diving in teams, but in the water with 6 tanks and regs, gas switches have to be managed anyway, so having to remember to unlock a line is to use not really a big deal, especially when that gas can only be breathed at certain depths anyway.