O-Ring Failure

[strongbow]

The old saying S... happens is alive and well and can occur at anytime and at anyplace. Well today was my turn in the barrell.It was my first dive of the day and my primary regulator hose o-ring failed. It was the o-ring on the reg. end of the hose.
I use Sherwoods Maximus Regulator and I really like this reg., until today it has not given me any grief, it's 3 years old. I keep all my gear well maintained and this reg. had it's annual service back in march of this year. My LDS is as good as they come, very professional,friendly;and knowledgable and have been established for a long time.I am not interested in placing any blame on anyone, this may not be their fault and I am not going there.
This was an ordinary recreational dive in a fresh water lake ( Jocassee ) a beautiful pristene mountain lake located in the up state area of S.C., ya'll should come and dive with us.The max. depth was 67 ffw.. After completing my safety stop at 15 ft. for 3 to 5 minutes I decided to burn a little more of the gas I had left. I was at about 20 feet looking at a large bass when suddenly it was bubble city. I first thought I had a free flow however the amout of air escaping was much larger than a free flow.
You know if you pay attention in class it may just save your life.I did not panic when this happened.I switched to my Oceanic safe second reg. and let the training kick in. I made a slow as ascent to the surface, inflated my bcd and gave the diver ok signal since the divers on the ramp saw me and probably thought is that a blue whale breaching over there.I got the air shut off and made my egress to the shore.
Upon closer examination I saw that it was indeed the o-ring that had blown.
I would appreciate any input regarding this incendent, if anyone has an experience similar let me know. Thanks and Dive Safe.:mil-pow-mia:

 

[Misplaced Priority]

Way to keep your head. Proper maintanence of equipment helps reduce the chance of failue but as you found out, if it is made by man, it can and will break at some point no matter how diligent you are. Just ask NASA about O ring failure. By the way, I would love to dive that lake. What is the water temp? Is a semi-dry required?

 

[strongbow]

Today It was 97 degrees ambient temp. with water temp. at 75 degrees. I dive Jocassee with a 3mil. in the summer, if going deep I use a 7 mil. with gloves and a hooded vest. You will see alot of divers using dry suits also. A semi-dry would also work well at Jocassee. Check it out on the web lots of info.to plan a trip.

 

[DA Aquamaster]

The o-ring in the second stage end of the LP hose is technically a dynamic o-ring as it is between the hose and inside of inlet fitting as the second stage swivels on the end of the hose. In my opinion, it should be replaced annually, but some techs view it differently as the occassional movement as the second stage swivels on the end of the LP hose is a lot less than, for example, the movement of a piston in the first stage with every inhalation cycle. The problem is that this particular juncture also tends to accumulate salt, silt, etc, and it's often neccesary to dip the LP hose fitting in an ultrasound bath to ensure it's clean. If not, any contaminants will wear away on the o-ring as the second stage swivels, severely shortening the life of the o-ring. There is not much movement as dynamic o-rings go, but there is less lubrication and more abrasion than other dynamic o-rings experience.

One other potential cause of that particular failure is the LP hose fitting not being tight and screwing itself off the second stage inlet fitting. Long before it reaches the end of the threads and comes totally loose from the hose, the o-ring in the hose passes the end of the sealing portion of the inlet fitting where it then usually blows out. It's not uncommon for 1/4 to 1/3 of the o-ring's diameter to be blown out causing a very large and attention getting leak.

 

[strongbow]

I think you nailed it sir, thank you for your insite.

 

[rainmaker]

Glad you are okay. Talk about "close to home"; I dive Jocassee almost every weekend (usually Sunday afternoons) from April - October.

Stop by and say hello if you get a chance, look for a blue/white folding lawn chair on the diver's ramp, all gear sitting on a camo tarp and "ScubaToys" duffle bag and reg bags.

 

[strongbow]

Thanks for the invite, maybe I'll see up at Jocassee sometime; dive safe.

 

[redacted]

I think you nailed it sir, thank you for your insite.

Nice job handling the incident.

Was that connection tight or loose when you checked it?

 

[Stormbringer]

I recently had a very similar experience at 25' with the HP hose connection to my SPG. I had just got my regs and gauges back from their annual service and was on my 2nd dive just after that annual. Everything was fine for 30 min into the dive till on the return to the dive platform at 25'. While there looking at the fish I signaled my dive buddy to take the lead and head on back to our entry point. He began to swim ahead of me and I reached down and looked at my SPG (in a standard rubber console with depth gauge) which read 1100 PSI. I released my console and proceeded to follow my dive buddy when all of a sudden I heard a loud "PSHSSST" sound and saw bubbles everywhere. I stopped and calmly assessed the situation...I tried to signal my dive buddy but he was already too far ahead of me to know what was happening. I still had a constant air supply in my 2nd stage so I knew I was ok on air at the moment but I knew I was venting alot of air and decided to make a direct and slow swiming ascent to the surface and swim back to shore. I'm sure I looked just like you on the surface with all the commotion caused by the air venting from my HP hose connection to the SPG. I signalled I was ok on the surface and just called out to the other divers on shore that I was ok...just having an o-ring failure. On shore I turned off the tank valve and found that the HP hose connection had come loose from the SPG itself...not completely off just loose enough to vent air.

Anyway, sounds like you did the right thing...calmly assess the situation and I am glad to hear all went well. Things happen...and every mechanical device can fail. Rely on your experience and training to handle these situations. To paraphrase: "that which doesn't kill us makes us better divers".

Jim

 

[redacted]

I recently had a very similar experience at 25' with the HP hose connection to my SPG. I had just got my regs and gauges back from their annual service and was on my 2nd dive just after that annual. Everything was fine for 30 min into the dive till on the return to the dive platform at 25'. While there looking at the fish I signaled my dive buddy to take the lead and head on back to our entry point. He began to swim ahead of me and I reached down and looked at my SPG (in a standard rubber console with depth gauge) which read 1100 PSI. I released my console and proceeded to follow my dive buddy when all of a sudden I heard a loud "PSHSSST" sound and saw bubbles everywhere. I stopped and calmly assessed the situation...I tried to signal my dive buddy but he was already too far ahead of me to know what was happening. I still had a constant air supply in my 2nd stage so I knew I was ok on air at the moment but I knew I was venting alot of air and decided to make a direct and slow swiming ascent to the surface and swim back to shore. I'm sure I looked just like you on the surface with all the commotion caused by the air venting from my HP hose connection to the SPG. I signalled I was ok on the surface and just called out to the other divers on shore that I was ok...just having an o-ring failure. On shore I turned off the tank valve and found that the HP hose connection had come loose from the SPG itself...not completely off just loose enough to vent air.

Anyway, sounds like you did the right thing...calmly assess the situation and I am glad to hear all went well. Things happen...and every mechanical device can fail. Rely on your experience and training to handle these situations. To paraphrase: "that which doesn't kill us makes us better divers".

Jim

Another good job.

The small orifices in that HP circuit tend to limit the volume of gas lost in that type situation. The LP circuits don't have such restrictors so gas lose can be much more rapid.

There is basically only one way that type failure occurs - the connection was not adequately tightened. It is not hard to make such an error when you finger tighten multiple connections and then come back and torque them. The right way to do it is finger tighten and torque each connection seperately.

As an end user, it would be a good practice to check each connection, by hand, as part of your reg prep. It does mean you would have to lose the boot for that SPG as well as some hose protectors. Probably a good thing in most cases.