First stage issue
- Thread starter uncfnp
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
Not fully purged. Try breathing primary down hard. Trigger LPI. Breathe down octo hard. All three..
Got a mk-20 that does the same thing....
OP
uncfnp
Solo Diver
Tried it. Still pop. Then I placed a tissue over the yoke and confirmed air coming from the connection with valve. It is an insert so changed out both o-rings. Much less noticeable now but still there. Then tried another tank. Huge swish, blew my hair back! If I open the valve slowly, just the usual soft sound of engagement. If I open with my usual *enthusiasm* huge swish. I’ll change the o-rings on it too and see what happens. Then try the first tank again. These tanks have not been used with the inserts installed in several years.
ACD? This can happen with a failing o ring at the base of the yoke screw.
OP
uncfnp
Solo Diver
Nope. Thankfully it is pre ACD. But its 4 years since serviced. Was hoping to make it to 5. Guess I know how my afternoon will be spent.
Bob you said you had MK’s that did something similar. Both not this reg. At least not to this extent. Worried it might worsen my next trip. I always carry a back up but still would rather be proactive on the problem if there is one.
GJC
Contributor
Is the yoke retaining nut tight?
If it is, the o ring at the end of the retaining nut may need to be replaced.
If it is, the o ring at the end of the retaining nut may need to be replaced.
If you look carefully at the oring seat in the tank valve, you may see a little eccentric lip. This feature enables a little air to slip behind the oring to speed its seating against the land of the first stage.
A brief hiss/pop that you hear is the escape of a tiny amount of air before the oring seals. It is completely normal.
This feature is common to "thin o-ring" tank valves. The thicker o-ring versions don't always have this.
Having said all this, your sound on your second video is a bit more than I would expect. The first video sounds like the usual sealing pop. But I've had a couple tanks that always seemed problematic in sealing, and would hiss endlessly after a vigorous opening. I assumed it was my choice of o-ring as I substituted them over the years. If your yoke bolt is tight (no swivel possible when pressurized), and if you seal completely after the initial hiss, I wouldn't sweat it.
Why? Because if the yoke bolt is tight, you've eliminated the problems:
1) you localized it to the tank/1st interface.
2) you were able to obtain a sealed condition
3) your IP is stable, eliminating other possible causes
You can prove this to yourself by trying several tanks. Each one will be different, due to tiny differences in the seat design. And not all may seal. I've had two thin o-ring tanks over the years that I grew to really dislike for a very similar problem. I bought new valves for them for the next time I emptied them. $50. Problem solved. In your case, it may be even easier. If lubing the o-ring doesn't help (by making it easier for it to shift in its land), then just try a new DIN insert.
A brief hiss/pop that you hear is the escape of a tiny amount of air before the oring seals. It is completely normal.
This feature is common to "thin o-ring" tank valves. The thicker o-ring versions don't always have this.
Having said all this, your sound on your second video is a bit more than I would expect. The first video sounds like the usual sealing pop. But I've had a couple tanks that always seemed problematic in sealing, and would hiss endlessly after a vigorous opening. I assumed it was my choice of o-ring as I substituted them over the years. If your yoke bolt is tight (no swivel possible when pressurized), and if you seal completely after the initial hiss, I wouldn't sweat it.
Why? Because if the yoke bolt is tight, you've eliminated the problems:
1) you localized it to the tank/1st interface.
2) you were able to obtain a sealed condition
3) your IP is stable, eliminating other possible causes
You can prove this to yourself by trying several tanks. Each one will be different, due to tiny differences in the seat design. And not all may seal. I've had two thin o-ring tanks over the years that I grew to really dislike for a very similar problem. I bought new valves for them for the next time I emptied them. $50. Problem solved. In your case, it may be even easier. If lubing the o-ring doesn't help (by making it easier for it to shift in its land), then just try a new DIN insert.
Similar threads
