Twin manifold plugs

[-JD-]

Good idea to secure it somehow. How does the DIN cap help with that?

ETA: Despite my comments in this thread - Retailers have specifically recommended that DIN sealing plugs should NOT be used on high F02 cylinders. See Twin manifold plugs

Deals with a valve roll-on, especially in the case of an accident where adding a stream of pure O2 to potentially loose hydrocarbons is probably not a good thing.
Even "secured", the cylinder may come loose. Other things may impact the cylinder valve handle, even in routine but uneventful transit.
If the valve isn't cracked open, plug removal shouldn't be an issue anyway.
In a fitted pelican case or the like it is probably not an issue, and if the valve is severely impact damaged, all bets are off even if plugged,

 

[Marie13]

Deals with a valve roll-on, especially in the case of an accident where adding a stream of pure O2 to potentially loose hydrocarbons is probably not a good thing.
Even "secured", the cylinder may come loose. Other things may impact the cylinder valve handle, even in routine but uneventful transit.
If the valve isn't cracked open, plug removal shouldn't be an issue anyway.
In a fitted pelican case or the like it is probably not an issue, and if the valve is severely impact damaged, all bets are off even if plugged,

What about keeping a reg on that tank instead of a plug?

 

[Lorenzoid]

I bought this setup from my local dive shop and it will be here in a week. I was wondering for people who have also bought this exact setup. Does it come with plugs for the valves so I can use them in a single tank setup? Or do I have to buy plugs separately. I want to get them on order now so I have them if I need to buy them. I looked everywhere and can’t find anything saying if this comes with them or not. If you look at just the manifold itself in the xs scuba catalog it shows them coming with plugs, but I can’t find anywhere saying this double setup comes with them.

HP Faber Hot Dip Galvanized Doubles Package

As others have said, ask your dive shop, because the dive shop will be assembling the setup using the manifold assembly--that is, two modular valves and an isolator valve--that you saw in the XS Scuba catalog. As the out-of-the-box modular valves will include those plugs, the dive shop will put them aside because they're not needed for a doubles setup. Whether the dive shop ultimately hands you the plugs at the time you pick up the assembled doubles setup is unknown, but I'm sure if you ask them, they will give you those plugs.

 

[doctormike]

Deals with a valve roll-on, especially in the case of an accident where adding a stream of pure O2 to potentially loose hydrocarbons is probably not a good thing.
Even "secured", the cylinder may come loose. Other things may impact the cylinder valve handle, even in routine but uneventful transit.
If the valve isn't cracked open, plug removal shouldn't be an issue anyway.
In a fitted pelican case or the like it is probably not an issue, and if the valve is severely impact damaged, all bets are off even if plugged,

Wait. So you recommend plugging your O2 bottle with a tight DIN plug that will prevent gas loss in case of accidental roll-on?

Yeah, I guess if you are in a fiery crash and also roll off your O2 that would add an O2 stream to the situation, but that's pretty much a multiple failure scenario.

On the other hand, if you do as you recommend, and get a roll-on, you now have pure O2 at tank pressure in a space which you now have to rapidly decompress with a big wrench, or which might spontaneously decompress (as mentioned upthread) if your plug is not steel. Sounds like a MUCH worse scenario.

As far as I can tell, the benefit of a non-occlusive DIN plug (e.g. Delrin with a vent hole) is to keep sand and dirt out of your DIN socket, and to maybe prevent deformation of the DIN socket if you drop the tank on the valve. The benefit of an occlusive (steel) DIN plug is to prevent loss of expensive trimix during transport. If that's what you are using it for, you might want to spring for the ones with the relief valve.

 

[-JD-]

What about keeping a reg on that tank instead of a plug?

ETA: Despite my comments in this thread - Retailers have specifically recommended that DIN sealing plugs should NOT be used on high F02 cylinders. See Twin manifold plugs

Better than open, but IMO, the reg is pretty vulnerable. Easy to shear off the first stage with an impact, rupture/shear a hose, crush a 2nd stage .... It also makes it more likely for the reg to get banged up in general transit.

I get it. I've hauled a pile of cans of gasoline in my vehicles through the years and that is almost certainly an order of magnitude riskier. (I generally haul them in a trailer now that I have one.)

I just think a metal DIN plug is probably a good (& cheap) idea for high FO2 cylinders and has little down side - worst case you need a wrench (or get a push-to-vent plug for a little more $) and that means that you have/had a leak.

 

[W W Meixner]

Be very careful using Din Plugs on valves and manifolds. It you have a valve accidentally bump open, the cap can explode sending plastic or delrin frags out to hurt you. I got really lucky way back in ‘91. I had a brand new set of double 95s laying out of the way inside my house. Obviously, my negligence precipitated my toddler son cracking open one of the valves. A plastic din cap exploded sending a large piece of plastic straight up and lodging into the ceiling drywall. Only dumb luck preventing an injury to my son.

just a couple years ago, a dive buddy of mine, was removing capped sidemount tanks from the back of his truck. Accidentally bumping a din valve open, his cap exploded severely injuring his hand.

I do still sometimes cap my din tank/valves when i think there is a good risk of dust, sand, or spiders. But I NEVER tighten them down, so if a valve cracks open, air can easily escape.

CE...

Off topic from the OP's modular valve plug question...but...

Delrin threaded DIN valve dust covers are drilled...not so much to provide mounting for the looped cord but to provide emergency gas exhaust if the valve should be accidentally opened...

Non drilled DIN dust plugs are dangerous and should be avoided...as they become pressurized if the valve is accidentally opened...

Metal DIN plugs should also be avoided as corrosion/seizing caused by dis-similar metal contact is common...

When purchasing DIN threaded dust caps...buying Delrin is preferable to buying plastic...plastic is brittle...cracking/breaking...where Delrin is very stable...far more durable...and because of the silicone content is self lubricating...twice as expensive as plastic...but we're only talking $4. as opposed to $2.

W.M...

 

[-JD-]

Wait. So you recommend plugging your O2 bottle with a tight DIN plug that will prevent gas loss in case of accidental roll-on?

Yeah, I guess if you are in a fiery crash and also roll off your O2 that would add an O2 stream to the situation, but that's pretty much a multiple failure scenario.

On the other hand, if you do as you recommend, and get a roll-on, you now have pure O2 at tank pressure in a space which you now have to rapidly decompress with a big wrench, or which might spontaneously decompress (as mentioned upthread) if your plug is not steel. Sounds like a MUCH worse scenario.

As far as I can tell, the benefit of a non-occlusive DIN plug (e.g. Delrin with a vent hole) is to keep sand and dirt out of your DIN socket, and to maybe prevent deformation of the DIN socket if you drop the tank on the valve. The benefit of an occlusive (steel) DIN plug is to prevent loss of expensive trimix during transport. If that's what you are using it for, you might want to spring for the ones with the relief valve.

ETA: Despite my comments in this thread - Retailers have specifically recommended that DIN sealing plugs should NOT be used on high F02 cylinders. See Twin manifold plugs

Yep, pressure-rated metal plug and it should be O2 clean/compatible like anything you would put in your DIN valve socket on a cylinder used for high FO2 (or PP blending), if for no other reason than not contaminating your DIN socket, and it has the benefit of reducing the potential for external contaminates getting in there.

You know as soon as you try to unscrew it if you have a significant leak(ed) situation and can crank down the valve and evaluate the situation before proceeding.
It should be a very small volume of O2 to decompress and really shouldn't be worse than a the case of a leaking o-ring or failure to fully tighten when a reg is installed, right?

Well, honestly it would suck arriving at the boat/dive site with significant loss of O2, also ...

 

[doctormike]

Yep, pressure-rated metal plug and it should be O2 clean/compatible like anything you would put in your DIN valve socket on a cylinder used for high FO2 (or PP blending), if for no other reason than not contaminating your DIN socket, and it has the benefit of reducing the potential for external contaminates getting in there.

You know as soon as you try to unscrew it if you have a significant leak(ed) situation and can crank down the valve and evaluate the situation before proceeding.
It should be a very small volume of O2 to decompress and really shouldn't be worse than a the case of a leaking o-ring or failure to fully tighten when a reg is installed, right?

Well, honestly it would suck arriving at the boat/dive site with significant loss of O2, also ...

Right, but if it leaked (roll-on), then that space is pressurized, and you need to open it with a wrench, even if you turn the valve back off. All I'm saying is that those occluding DIN plugs are meant to prevent gas loss of expensive gas, not to increase safety with rich mixes. If anything, it's a potential hazard:

"The typical use is to protect an expensive (or just plain important) gas fill from accidental loss while the cylinder is being handled or transported. .... If you discover you are unable to remove the plug by hand because it's being held in place by the pressure of the gas trying to escape, close the valve and break the seal by loosening the plug with a wrench.

We do NOT recommend the use of any type of Sealing DIN Valve Cover Plug with oxygen, as impact or the friction of loosening the plug against high pressure oxygen could cause ignition, fire, and explosion leading to injury or death."

 

[-JD-]

Right, but if it leaked (roll-on), then that space is pressurized, and you need to open it with a wrench, even if you turn the valve back off. All I'm saying is that those occluding DIN plugs are meant to prevent gas loss of expensive gas, not to increase safety with rich mixes. If anything, it's a potential hazard:

"The typical use is to protect an expensive (or just plain important) gas fill from accidental loss while the cylinder is being handled or transported. .... If you discover you are unable to remove the plug by hand because it's being held in place by the pressure of the gas trying to escape, close the valve and break the seal by loosening the plug with a wrench.

We do NOT recommend the use of any type of Sealing DIN Valve Cover Plug with oxygen, as impact or the friction of loosening the plug against high pressure oxygen could cause ignition, fire, and explosion leading to injury or death."

I guess for the record I should disclaim and state - Despite my comments in this thread - Retailers have specifically recommended that DIN sealing plugs should NOT be used on high F02 cylinders. See Twin manifold plugs

I got curious and looked around a bit ... DGX makes almost the exact same statement for their (equivalent? - same?) plug (DGX HP Sealing DIN Plug | Dive Gear Express®), but interestingly not on their push-button plug (DGX HP Sealing DIN Plug w/Pressure Release | Dive Gear Express®) - by intent or omission, I don't know, but the push button one is only listed as Nitrox ready.

- Of merit, DGX provides a much more thorough explanation of the issues of releasing pressure with a pressurized, plugged valve. Worth checking out. -

Serious question for others out there - Is this "standard" received wisdom, something from the manufacturer's lawyers as a CYA, or from the folks that deal with high FO2 as hands on experts.

I am dubious about the relative risk of the impact claim as both the burst plug and valve mechanism are also vulnerable to impacts and exposed to the gas at full pressure, all the time.
Obviously, it is much easier to keep the internals of the cylinder and valve clean, than the DIN socket and plug. So in that regard, yes, the risk is relatively higher, but also applies when a reg is on there and pressurized too.

As for the venting/friction the same sorts of mechanical processes are also present during cylinder filling with whipping/boosting and venting. Again, hopefully in a meticulously clean environment.

I think it really comes down the relative risk of being seriously O2 clean and plugged vs The risk O2 jetting out into a confined, potentially fuel rich environment.

Maybe I am very wrong in my thinking about the relative risks ...

 

[doctormike]

I guess for the record I should disclaim and state - Despite my comments in this thread - Retailers have specifically recommended that DIN sealing plugs should NOT be used on high F02 cylinders. See Twin manifold plugs

I got curious and looked around a bit ... DGX makes almost the exact same statement for their (equivalent? - same?) plug (DGX HP Sealing DIN Plug | Dive Gear Express®), but interestingly not on their push-button plug (DGX HP Sealing DIN Plug w/Pressure Release | Dive Gear Express®) - by intent or omission, I don't know, but the push button one is only listed as Nitrox ready.

- Of merit, DGX provides a much more thorough explanation of the issues of releasing pressure with a pressurized, plugged valve. Worth checking out. -

Serious question for others out there - Is this "standard" received wisdom, something from the manufacturer's lawyers as a CYA, or from the folks that deal with high FO2 as hands on experts.

I am dubious about the relative risk of the impact claim as both the burst plug and valve mechanism are also vulnerable to impacts and exposed to the gas at full pressure, all the time.
Obviously, it is much easier to keep the internals of the cylinder and valve clean, than the DIN socket and plug. So in that regard, yes, the risk is relatively higher, but also applies when a reg is on there and pressurized too.

As for the venting/friction the same sorts of mechanical processes are also present during cylinder filling with whipping/boosting and venting. Again, hopefully in a meticulously clean environment.

I think it really comes down the relative risk of being seriously O2 clean and plugged vs The risk O2 jetting out into a confined, potentially fuel rich environment.

Maybe I am very wrong in my thinking about the relative risks ...

Look, these are all cases of weighing relatively remote risks. It's hard to get real numbers.

But the reason why you aren't supposed to use a sealing plug with no pressure release mechanism with 100% O2 is that you might have to use brute force to rotate a tightly fitted screw thread in a 100% O2 environment at 3000 PSI. That doesn't happen with cylinder filling, whipping or boosting. Those DIN threads are screwed and unscrewed at ambient pressure.