Trouble removing yoke after a dive.

[LeadTurn_SD]

Another thought, something that is an issue with one of my oldest Al 80 tanks: An o-ring issue on the tank valve / 1st stage yoke connection.

I have one old Al 80 tank, that after replacing an o-ring about a year ago, is now a bear to remove yoke first stages after a dive. What I think is happening is that with this very old tank valve (circa late '70's J-valve) is that the replacement o-ring is just slightly the wrong size (a hair too large), or maybe after years of use the groove the o-ring sits in is slightly deformed. Air gets trapped behind the o-ring, and even though the tank valve is off, the reg is depressurized and the purge button held down, you have to be quite strong to loosen the yoke, and there is a "pop" as a tiny bit of air is released from connection when it finally budges... and the o-ring often falls out!

The usual suspects may have a better explanation... but in my case I'm fairly sure it is not air being retained in the regulator, as this only happens with this one particular tank valve, and happens 100% of the time, and happens even if the purge is depressed on the 2nd stage.

Just something else for the OP to consider, if it is not a "sticky yoke thread" issue.

Best wishes.

 

[Luis H]

Another thought, something that is an issue with one of my oldest Al 80 tanks: An o-ring issue on the tank valve / 1st stage yoke connection.

I have one old Al 80 tank, that after replacing an o-ring about a year ago, is now a bear to remove yoke first stages after a dive. What I think is happening is that with this very old tank valve (circa late '70's J-valve) is that the replacement o-ring is just slightly the wrong size (a hair too large), or maybe after years of use the groove the o-ring sits in is slightly deformed. Air gets trapped behind the o-ring, and even though the tank valve is off, the reg is depressurized and the purge button held down, you have to be quite strong to loosen the yoke, and there is a "pop" as a tiny bit of air is released from connection when it finally budges... and the o-ring often falls out!

The usual suspects may have a better explanation... but in my case I'm fairly sure it is not air being retained in the regulator, as this only happens with this one particular tank valve, and happens 100% of the time, and happens even if the purge is depressed on the 2nd stage.

Just something else for the OP to consider, if it is not a "sticky yoke thread" issue.

Best wishes.

Yes, I have seen that happen a number of times with the older type of valves. They use the slightly fatter O-ring (the same one used on DIN valves, the -112). The regulator pressed on the O-ring surface and there was no outside ledge to create a metal to metal contact.

Sherwood changed to a new valve interface that uses the smaller O-ring (the -014) and added a small ledge on the outer perimeter for the regulator to seat on and to provide a metal to metal contact with zero gap (if properly seated).

With the older style valves, air would get behind the O-ring and get trapped in the corner behind the O-ring. The O-ring sealed on the bottom and one of the sides of the groove to form a pocket in the corner. I can't remember if we had a solution, but I think that tighten it a bit higher than it is normally recommended did solve it most of the time. I would also try a higher durometer O-ring.

Again, what I just wrote only applies to the old style of yoke valves that use the fatter O-ring.

 

[Couv]

Is this happening with a particular tank? If so, I'm pretty sure one of the previous dirty dozen posters have come up with the correct explanation. If not, then have a look at the yoke itself. Is it deformed due to being dropped? If it's ok have a look at the surface that mates with the tank. Could it be pitted or scratched and allow gas to be slowly be trapped?

 

[LeadTurn_SD]

Yes, I have seen that happen a number of times with the older type of valves. They use the slightly fatter O-ring (the same one used on DIN valves, the -112). The regulator pressed on the O-ring surface and there was no outside ledge to create a metal to metal contact.

Sherwood changed to a new valve interface that uses the smaller O-ring (the -014) and added a small ledge on the outer perimeter for the regulator to seat on and to provide a metal to metal contact with zero gap (if properly seated).

With the older style valves, air would get behind the O-ring and get trapped in the corner behind the O-ring. The O-ring sealed on the bottom and one of the sides of the groove to form a pocket in the corner. I can't remember if we had a solution, but I think that tighten it a bit higher than it is normally recommended did solve it most of the time. I would also try a higher durometer O-ring.

Again, what I just wrote only applies to the old style of yoke valves that use the fatter O-ring.

Thanks Luis!

I think that is exactly what is happening with my tank valve, I will try the higher durometer o-ring, sheesh I should have thought of that.

Based on what Luis explained, I would doubt my "theory" could apply to the OP. Sorry about that. I have never experienced it with "modern" tank valves, only my "golden oldies". So something else must be going on in his case.

Best wishes.

 

[Nemrod]

It is air being trapped behind the O-ring. I have that happen on a number of tanks, it can be a bear to remove the regulator. It has nothing to do with patina or threads or anything like that.

N

 

[Rudebob]

Thanks for all the responses. Lots of good theories. The problem is that is has happened on different tanks (mine and supplied tanks from boat dives). The yoke threads and screw look great with no evidence of corrosion. I am now wondering if it may be due to expansion and modest pressure buildup from heat after sitting for periods of time the sun. Thinking about it, this happened in Aruba and last week in Phoenix, AZ where both sites were very hot. I am going to replace the screw regardless, minimize the hand tightening pressure and we'll see how it goes from there.

 

[Hawkwood]

Rudebob,

After you have "tightened up" yoke screw and before you open the tank up to pressurize it, can you still wiggle the first stage from side to side?

Bill

 

[sunnyboy]

Has anyone encountered this? I use what I would consider normal hand pressure to tighten the yoke when putting on a fresh tank. However, at the end of the dive it takes all my strength and sometimes even tools to loosen the yoke. This just started happening over the last dozen or so dives. I have a couple hundred dives on this reg setup so it is not like I am unfamiliar with it. Yesterday the soft plastic knob finally stripped so I had to cut it off the threaded end allowing me to put a wrench on it to changes tanks. Does anyone know why this would be happening and how to avoid it? Also, can replacement knobs be found, a brief search did not reveal much out there.

Thanks, 'bob

Bob,

I have had the same problem with my apex reg, until I stopped tightening the knob so much.

Now I teach putting on the yoke with the "three finger rule". That is, grasp the knob with only three fingers (i.e. thumb, index and 2nd) and tighten.

The yoke screw does not need to be reefed really tight against the tank - just enough to seal the o-ring when pressurized.