1st stage keeps getting stuck on my tank!

[phlegm]

This has happened a couple of times now. I have Seac Synchro regs, yoke fitting. I'll screw them in, go for a dive, then when it comes to unscrewing them I have to summon the strength of Odin to get them off. First time it happened they were sick for four days before I got it.

Second time I tried screwing them in very loosely, thinking I must have done them up too tight last time, but of anything this was worse. As I turned the pressure on I heard a pop sound, and they were immediately stuck on. Took the mother of all wrenches to get it unscrewed this time round.

Any ideas?

 

[Redshift]

You are purging the system before trying to take the reg off, right?

 

[boulderjohn]

Many people will think they have purged the system before undoing their regs but fail to get that last bit out. It does not take much pressure to make it too difficult to turn.

 

[Redshift]

Often it's because they don't do it for long enough. The HP hose has a very small orifice and air takes time to flow from the pressure gauge. After the initial stronger flow, it's noticeable that there is some air still coming out for a while longer.
This is particularly evident in twinsets, when comparing the purging of the two regs, the one where the pressure gauge is and the other.

 

[g1138]

If you're sure that:
- You're screwing finger tight; that is using the tips of your thumb, and 2 fingers only to screw your reg on.
- You're fully depressurized to 0psi and it's holding on 0.

Then the only other option is to make sure you offset your yoke when you install the reg.
And don't turn the reg and orientate hoses after you've screwed the reg on. Do that before you screw the yoke down.

I keep my thumb on the yoke while screwing down, so it is angled all the way off the tank knob.
If you don't do this, you can create a vise situation where if you twist the yoke&reg towards the tank knob, the yoke braces on the tank valve and tightens the yoke screw more into the reg while your brass is cold (ie contracted) under water. When it heats up (ie. your air in the tank expands on ascent, warm surface air makes the metal expand, sun rays make it expand etc etc), the metal expands and forms a very very tight fit.

Offsetting your yoke also avoids shredding some long style tank knobs (like those pure rubber ones), and helps to keep your hoses in the same orientation.

 

[tbone1004]

next time you go to remove it, put the primary in your mouth and inhale to fully purge the system, many/most first stages can't fully purge the system, they'll get most of it and the gauge may read 0 psi, but they're usually still some left in there.

 

[Wookie]

Aside from what all of the others said, which is your most likely cause, take the yoke screw out and put a dab of silicon on the yoke threads. This can be a double edged sword, it may make it easy to overtighten the yoke. But, the threads of the yoke screw and the yoke may be chattering and causing little tiny burrs in either the threads of the yoke or the screw to bind up just a little.

 

[halocline]

Sounds like you might be trapping a little air behind the tank valve o-ring. When that happens it keeps pressing on regulator even when the pressure is released. Try making sure your reg is pressed firmly against that o-ring when you put it on, and carefully screw it snugly in place. That might help.

 

[SouthSideScubaSteve]

As others have indicated, it amazing how a seemingly small amount of air in the lines can make it near impossible to remove a first-stage from a tank. I've found that purging BOTH my primary & secondary's at the same time is the surest way to make removing the yoke from the tank effortless ...

 

[Bob DBF]

I just keep the purge down to bleed down the air I can hear, and while unscrewing the yoke.



Bob