talk to me about O-rings and yoke DIN adapters

[3D diver]

Got tired of trying to find the "best" deal and bought a pair of Blue Steel 117's (3442lbs nominal pressure) with DIN valves and yoke adapters.

I'm loving the extra air, still fine tuning my bouyancy, but wondering about the yoke adapters & O-rings.

Here's what's happening:

When I mount my regulator on the tank & open the valve a bit of air is lost til the O-ring seats.

When disconnecting the regulator, if there's any 1st stage pressure the O-ring flys away.

After rinsing my gear yesterday I left my tank---with the regulator mounted & valve open (oops)---standing to dry. Well, the boots are none too wide and after about 20 minutes the tank falls over (duh, should have left it laying down). The jar pinches the O-ring, the O-ring splits, and about 1500lbs of air are gone before I can get to the tank and shut the valve.

So...I'm wondering:

Am I using the wrong sized O-rings? The ones that came with the tank, and the ones I've been replacing them with are pretty loose in the slot.

Am I at the hairy edge of reasonable pressure for a yoke, and need to start shopping for a DIN regulator?

 

[idive2]

There are a couple o-rings that are very close that are used with these inserts. Most are of one size but I have heard
of different manufacturers of these inserts that may take the other less common size.

I was surprised at how long it takes to completely purge all pressure from the hose after the valve is off. Most is
out with the first push of purge button but if you listen carefully at the regulator you will find it takes much longer than
you would think to purge all air from the hose. Many times I have seen first stages that people were struggling with removing
when it was nothing more than a few psi still left in the line. To much pressure in the hose when removing the first stage
will also cause a properly fitting o-ring to blow out when removing first stage. Assure you have the correct o-ring then confirm
how long it really takes to completely purge your hoses.

 

[Superlyte27]

If the o-ring is moving around where it's seated (when it's seated) then it is the wrong size o-ring. The o-ring should be barely too big enough to fit in the hole causing a tight fit. If it's loose in there, get a different o-ring.

 

[cbrich]

Go by a place that sells o-rings, and gaskets, and buy some Viton o-rings.

DIN: 112
Yoke: 014

These are standard o-rings, the DIN o-ring could be a different size, but the majority use the 112.

Most of the yoke o-rings I use, are typically tight, I have to use a regulator to seat them in.

 

[spectrum]

The reason for the slow full pruge is the HP side. Your SPG is fed via a very small orifice and acts as a reservoir. You can purge a second stage dry and still have air in the HP line. After a moment it bleeds back and you have a little air on the LP side again. This can repeat for several diminishing cycles. The pressure build-up can be enough to load up on the yoke screw.

A reliable yoke connection at 3442 should not be a problem.

Some of those inserts can be odd in how they accept a ring. Make sure the insert is clean, no silicone residue. Run it into the valve just enough to seat it. If you crank it you will cock it in the threads and sealing will be unpredicatable.

I have had times when it takes presurization to seat it correctly, almost like a tire bead poping into place.

Pete

 

[redacted]

The fat ones are mostly -112s but you will also find some that are -111s.

 

[The Chairman]

I use 111s and make sure that they are facing INWARD. Also, after you purge your valve, take a quick suck on the second stage to get ALL of the air out. I have seen some purge valves leave a 50 or more psi in the tank.

 

[Superlyte27]

Holy Crap, look at how many pete's are in this thread.

 

[halocline]

When disconnecting the regulator, if there's any 1st stage pressure the O-ring flys away.

After rinsing my gear yesterday I left my tank---with the regulator mounted & valve open (oops)---standing to dry. Well, the boots are none too wide and after about 20 minutes the tank falls over (duh, should have left it laying down). The jar pinches the O-ring, the O-ring splits, and about 1500lbs of air are gone before I can get to the tank and shut the valve.

The first part of your quote is sort of an unintended variation on a trick to remove a leaky yoke valve o-ring in a hurry (like on a dive boat). You basically try to push the o-ring off the tank valve with pressurized air by knocking the reg loose while there's still some air pressure. In your case, with the other things you're talking about, the o-ring is probably a bit too loose.

The second part is a little more concerning; if I understand it right, your tank fell over and knocked the regulator loose. That's a great way to distort the yoke or otherwise damage the 1st stage. It's somewhat doubtful that just the o-ring was damaged; there's metal to metal contact between the regulator and tank valve, and if the o-ring was destroyed, it's likely that one of the metal surfaces was dinged or bent. Have you since checked to make sure the reg seals well against the valve? If you're lucky, maybe only the yoke insert was dinged and you can just get a new one, or you might have dodged a bullet.

 

[3D diver]

The first part of your quote is sort of an unintended variation on a trick to remove a leaky yoke valve o-ring in a hurry (like on a dive boat). You basically try to push the o-ring off the tank valve with pressurized air by knocking the reg loose while there's still some air pressure. In your case, with the other things you're talking about, the o-ring is probably a bit too loose.

The second part is a little more concerning; if I understand it right, your tank fell over and knocked the regulator loose. That's a great way to distort the yoke or otherwise damage the 1st stage. It's somewhat doubtful that just the o-ring was damaged; there's metal to metal contact between the regulator and tank valve, and if the o-ring was destroyed, it's likely that one of the metal surfaces was dinged or bent. Have you since checked to make sure the reg seals well against the valve? If you're lucky, maybe only the yoke insert was dinged and you can just get a new one, or you might have dodged a bullet.

O-ring flying away due to residual pressure is nothing new, I've had it happen with other tanks over the years, just worse 'cause of the loose fit of the O-rings in the yoke adapter.

The tank falling over just jarred/shook the regulator from the shock of hitting the ground---the regulator didn't impact anything or come loose. I believe the shock pinched the O-ring causing it to split. I put another O-ring in and re-pressurised the system to check how much air was lost and didn't have any new issues. So if there was a bullet I guess I dodged it. My main concern regarding this incedent is whether such a thing could happen if I bang my first stage into a rock or other obstruction during a dive.

I want to thank everyone for their responses. It sounds like I need to look for a better fitting O-ring & see if that helps. I have a small assortment in my save-a-dive kit & will tinker with them this weekend.