Swivel adaptors with central screw - BAD IDEA

[viakovlev]

I have five of 360 degree swivels at the 2nd stage in my equipment. 2 proprietary Atomic and 3 generic with a central screw holding two parts together. The screw is in a position that has a turning force every time the swivel moves. The screws in 2 out of 3 got loose. First time on a regular dive at 15-20m. Just had bubbles coming out, not disastrous at that time. Second time I was in pool playing with sidemount configuration. Suddenly I was in a cloud of boiling bubbles. Shut down the valve (could not even see at first which side is busted). It was fun because I was in a pool with two tanks, but, what would you say if it was a single tank 40 min into a dive deeper that 20m (and a buddy against current and looking at you)?

Steer away from the swivels with central screw!!!! They will come apart eventually. Another lesson I learned, GET A REDUNDANT AIR SUPPLY! Anything can fail.

The atomic swivels have an actual ball coupling, which cannot come apart. Do not know if it can leak though, I had them just for 1 year.

 

[Peter_C]

This issue is well documented within the Scubaboard community. The screws back off. The funny thing is people still swear it won't happen to them, and that they "need" the swivel.

 

[viakovlev]

I am sure this stupidity in the design can or even have caused accidents. I learned another thing recently as well that yoke/clamp regs can move around the seat and apply a shear force on the o-ring. That is why O-ring gets busted on these so frequently. My busted again, in the pool, and again with doubles. The tank was off me and was adjusting the strap, then boooom a cloud of bubbles. It's amazing how much air escapes from a little nick on the O-ring. I am now converting all my regs into DIN.

 

[Colliam7]

I have five of 360 degree swivels at the 2nd stage in my equipment. 2 proprietary Atomic and 3 generic with a central screw holding two parts together. The screw is in a position that has a turning force every time the swivel moves. The screws in 2 out of 3 got loose. . . . Steer away from the swivels with central screw!!!! They will come apart eventually.

This issue is well documented within the Scubaboard community. The screws back off. The funny thing is people still swear it won't happen to them, and that they "need" the swivel.

While the issue has been extensively discussed, and is documented in the SB community, there is also an element of urban legend associated with what is the actual risk.

Yes, generic swivels using a central screw have been documented to fail. Why would anyone knowing the history of generic swivels trust a generic 360 degree swivel anyway?

Yes, a previous design of the Omni 360 swivel was associated with at least one report of failure associated with screw loss.

But, I am not aware of a single documented case of any re-engineered Omni brand, 360 degree swivel - produced in the past 4 years - failing because of the screw loosening and coming out. If there are any such cases, it would be good to post them. (When I see an instance of this issue being re-discovered I ask the same question. And, to date, nobody has responded with a documented case.)

A swivel is a matter of convenience, not need. I personally find them to be convenient for sidemount diving. But, I agree that anything can fail so I won't say a Omni swivel failure cannot happen to me. Instead, I will say that based on available data, the probability of an Omni 360 degree swivel failing because of the loss of the screw is substantially less likely than the failure of my inflation system, of my second stage regulator, or my first stage regulator.

Another lesson I learned, GET A REDUNDANT AIR SUPPLY! Anything can fail.

A very good lesson.

 

[Peter_C]

Why use an omni swivel, when there are captured swivels that don't have the screw?

 

[viakovlev]

I found swivels convenient, and the captured design, or a "ball" type are a much better design. Can probably leak, but I cannot imagine it can fall apart. My second stage actually fell on the bottom of the pool when Omni-swivel came apart (it was a tank, from which I was not breathing at the time). My adaptors were 1.5-2 years old, advertised as new model when I bought them. I do not think they had more than 60-70 dives. Two of three failed by now. The third will not be used. So, the stats for my adaptors are >/=66% fail rate.

 

[Colliam7]

I found swivels convenient, and the captured design, or a "ball" type are a much better design. Can probably leak, but I cannot imagine it can fall apart. My second stage actually fell on the bottom of the pool when Omni-swivel came apart (it was a tank, from which I was not breathing at the time). My adaptors were 1.5-2 years old, advertised as new model when I bought them. I do not think they had more than 60-70 dives. Two of three failed by now. The third will not be used. So, the stats for my adaptors are >/=66% fail rate.

Good information. But, I will ask a very simple question: Was it an OMNI brand swivel? I don't mean an 'omni-swivel' - e.g. a 360 degree swivel. Rather was it an Omni brand? If so, what was the serial number? The nice thing about Omni brand - they have a S/N. And, when was it produced? If you have the serial number, it is easy to determine the production date. If it doesn't have a serial number, it is NOT a current Omni brand swivel. Simple enough. So, what was it? Omni, or generic, as you previously asserted?

 

[viakovlev]

Good information. But, I will ask a very simple question: Was it an OMNI brand swivel? I don't mean an 'omni-swivel' - e.g. a 360 degree swivel. Rather was it an Omni brand? If so, what was the serial number? The nice thing about Omni brand - they have a S/N. And, when was it produced? If you have the serial number, it is easy to determine the production date. If it doesn't have a serial number, it is NOT a current Omni brand swivel. Simple enough. So, what was it? Omni, or generic, as you previously asserted?

They are generic, not Omni brand. There are no markings on them. Hi gloss chrome finish. I can think that there may be some design changes to eliminate the contact between the moving part and the screw (spacers?) but that can jam too theoretically. And then each movement counterclockwise is forcing the screw out.... Captured ball design is near inseparable. However, I am not sure if the ball cannot "fall in". In this case it will be pushed back by the pressure and stay in one piece, but likely leak. I will use 120 degree angles on my sidemount. It appears that swivels are more prone to failure, some more some less, but all are not as good as a fixed connection.

 

[axxel57]

I have been diving with a generic 360' swivel on my octopus for hundreds of dives, only once it started to produce some bubbles, I cleaned it and put new o-rings in and did not have any problems since.
According to the comments here it seems that the screw connection can cause problems, I read about it before, so I check it frequently.

I will check about the original 'Omni' swivel, haven't heard much bad things about them.

I have some fellow instructors here around, using the same swivel as I do, never heard about a problem, but I will notify them.

 

[The Chairman]

I use these for sidemounting: