User avatar
tripplec
Master Diver
Posts: 371
Joined: Thu Mar 28, 2013 1:44 am
First Name: Chris
Location: Coos Bay Oregon
Contact: Website

No air emergency

Sun May 14, 2017 1:59 am

I've run through the search feature with several phrases and haven't seen any posts on this. Is there any reason a properly functioning reg (mainly 1st stage) would stick closed cutting off your air, what mechanically would cause it, and is there anything you could do besides going for your buddy or pony? Only reason I ask is I like to think about what if situations. We've all heard the story about the guy that overheard the guy that knows the guy that was diving with the guy that suddenly had his reg stick closed.

Sent from my SAMSUNG-SM-J320A using Tapatalk

User avatar
Herman
VDH Moderator
Posts: 1202
Joined: Thu Oct 25, 2007 1:45 pm
Location: Raleigh NC

Re: No air emergency

Sun May 14, 2017 6:51 am

In a first stage, the only thing I can think of is the main spring breaking and collapsing to the point it would not hold the HP seat open. I have never seen one break but it could happen.

Second stages have a few more failure modes, the lever breaking, a large hole/tear in the diaphragm, the exhaust valve coming out and the nut coming off the lever come to mind. But again, never heard of it actually happening and they would likely the cause of poor servicing, coming on slowly, getting worse and worse as the dive progressed.

Nothing you can do if any of those happens other than the diaphragm and exhaust valve failure, you could force a freeflow with the purge button and breath off of that while going up.
Herman

User avatar
Drado
Master Diver
Posts: 640
Joined: Mon Feb 07, 2011 6:11 am
First Name: Eduardo
Location: Manila, Philippines

Re: No air emergency

Sun May 14, 2017 6:56 am

Theoretically? In a diaphragm first stage, if the main spring were to break, or if the pin were to bend, then there wouldn't be any force to open the valve against the flow of gas.
_______________________________
Ed

User avatar
luis
VDH Moderator
Posts: 1583
Joined: Thu Jun 30, 2005 9:28 pm
First Name: Luis
Location: Maine

Re: No air emergency

Sun May 14, 2017 9:05 am

I have heard of one case were a Scubapro Mk-5 flow through piston shut off because the piston knife edge got embedded and jammed into the HP seat. Scubapro changed the type of seat and the seat material. There were probably several factors that caused the incident, but Scubapro still took action for it not to happen again.

With diaphragm regulators (and even piston first stages) I can come up with several failures that could in theory keep the seat from opening or not fully opening. In addition to what has already being mentioned, I think particles or debris jamming the seat closed.

The design of every regulators in production today (and most vintage regulators) would tend to fail by leaking or a free flow.

With a few exceptions, the probability of a failure, were the regulator shuts off the air, falls in the same category as being hit by a meteorite. Yes it definitely can happen, but you will not see me buying meteorite insurance any time soon.


Note: The exceptions would normally involve a bad design (only applies to some vintage regulators) or an incorrectly assembled regulator.


The more likely air shutoff situation is from debris in a tank clogging the valve or regulator filter, and I am afraid that has happened more than once. In this situation, you need a true alternate air source: a dive buddy, a pony bottle or alternate cylinder with regulator, or the surface. Unless you are on a overhead environment, the surface is always reliable, you should always know where it is and it never malfunctions or runs out of air…
Luis

Buceador con escafandra autónoma clásica.

User avatar
tripplec
Master Diver
Posts: 371
Joined: Thu Mar 28, 2013 1:44 am
First Name: Chris
Location: Coos Bay Oregon
Contact: Website

Re: No air emergency

Sun May 14, 2017 12:52 pm

Great answers. Good to know it's verry rare. Free flow has never worried me. I've practiced taking my take off so much under water (just for fun), I know if I'm to deep to make it up on whatever is left in the tank, I can always take my tank off and run the valve. Only free flow I ever had was on a cheep plastic second stage at 80 feet. I was running twin tanks not connected so I had my partner shut that one off.

Sent from my SAMSUNG-SM-J320A using Tapatalk

User avatar
couv
Master Diver
Posts: 327
Joined: Tue Jul 18, 2006 10:26 pm

Re: No air emergency

Sun May 14, 2017 2:41 pm

In addition to the items mentioned above, Oceanic had a bad batch of seats in their first stages a while back leading to a recall:
https://www.oceanicworldwide.com/us/new ... egulators/

The Mk 5 turret retainer has been known (rarely) to shear. This anomaly is/was caused by a combination of a soft material (chrome plated brass) being over-torqued by the person assembling the turret. While this failure is unlikely, careful inspection of the turret retainer is necessary and the correct torque being applied. Thankfully, Bryan has SS replacements available to make this complication less likely. One can imagine the consequences of the turret coming off. For the same reason, properly torquing said retainer is necessary to ensure it does not come loose.

What to do in case of a total loss of gas delivery? That should never be a life threatening event. If too deep for a swimming accent, good buddy contact skills or an independent source of air is necessary.......do as I say, not as I do.
A sincere THANK YOU to all at VDH who make this wonderful resource available and to all the thoughtful contributors.

User avatar
tripplec
Master Diver
Posts: 371
Joined: Thu Mar 28, 2013 1:44 am
First Name: Chris
Location: Coos Bay Oregon
Contact: Website

Re: No air emergency

Sun May 14, 2017 4:27 pm

My Oceanic sure seems to come up a lot in these forums. Fortunately between you guys, the download section, Regulator Savvy, and a stock pile of "old junk" regulators to play with, I'm getting quite the arsenal of rebuilt oldies but goodies for the day my cdx5 tries to kill me.

Sent from my SAMSUNG-SM-J320A using Tapatalk

User avatar
antique diver
Master Diver
Posts: 1843
Joined: Sun Dec 10, 2006 12:50 pm
First Name: Bill
Location: North-Central Texas

Re: No air emergency

Sun May 14, 2017 6:04 pm

tripplec wrote:I've run through the search feature with several phrases and haven't seen any posts on this. Is there any reason a properly functioning reg (mainly 1st stage) would stick closed cutting off your air....

Sent from my SAMSUNG-SM-J320A using Tapatalk
Here's one catastrophic first stage seat failure that occurred while diving with my RAM. When the new, old stock USD seat material extruded up into the orifice cone further than the throw of the activating pin and pad I was left with a total lockup of my first stage. No air. Not my favorite way to decide when to end a dive :shock:
1scary hp seat.JPG
I advise throwing out any seats made like this one, and going with later versions in which the sealing material is captured within the smaller boundary of a circular hole in the metal seat base. This seat was NOS, US Divers original equipment, that I had made about 4 dives with. Unknown date of manufacture, and questionable storage conditions before I acquired it along with about a dozen just like it. Maybe time and Texas heat had a serious effect on the molecular structure of the material. I wasn't sure how well it would actually hold up, but sort of "assumed" that a failure would just result in air leaking instead of ceasing! :?

Anyone know the time range that these particular seats were made?
You do not have the required permissions to view the files attached to this post.
The older I get the better I was.

User avatar
tripplec
Master Diver
Posts: 371
Joined: Thu Mar 28, 2013 1:44 am
First Name: Chris
Location: Coos Bay Oregon
Contact: Website

Re: No air emergency

Sun May 14, 2017 6:08 pm

Thats kind of a scary looking seat there. Almost looks like chunks of it were blown into the lp chamber.

Sent from my SAMSUNG-SM-J320A using Tapatalk

User avatar
Fibonacci
Vintage Diver
Posts: 98
Joined: Wed Oct 19, 2016 5:08 pm
First Name: Graeme
Location: Melbourne, Australia

Re: No air emergency

Sun May 14, 2017 8:30 pm

antique diver wrote:
I advise throwing out any seats made like this one, and going with later versions in which the sealing material is captured within the smaller boundary of a circular hole in the metal seat base. This seat was NOS, US Divers original equipment, that I had made about 4 dives with. Unknown date of manufacture, and questionable storage conditions before I acquired it along with about a dozen just like it. Maybe time and Texas heat had a serious effect on the molecular structure of the material. I wasn't sure how well it would actually hold up, but sort of "assumed" that a failure would just result in air leaking instead of ceasing! :?

Anyone know the time range that these particular seats were made?
Diving the President Coolidge in Vanuatu in 1985 a member of our group had a catastrophic first stage failure of his recently serviced USD SH regulator ... at 40m on a decompression dive. Cannot recall the model number but it was quite new and top of the range back then... perhaps a similar seat design?
The HP seat blew out and dumped the entire contents of his 88 cu ft tank in a few minutes :shock:
Luckily he was still on the outside of the wreck, kept a cool head and buddy breathed in a vortex of bubbles all the way up to the deco stop where a stage tank was hanging.
'A man can never have too much red wine, too many books or too much ammunition' Rudyard Kipling

User avatar
Bryan
Plank Owner
Posts: 5225
Joined: Fri Jun 24, 2005 11:40 am
First Name: Bryan
Location: Wesley Chapel Florida
Contact: Website

Re: No air emergency

Sun May 14, 2017 8:47 pm

There was a clear version of that seat as well

Sent from my SM-J700T using Tapatalk
Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB

User avatar
antique diver
Master Diver
Posts: 1843
Joined: Sun Dec 10, 2006 12:50 pm
First Name: Bill
Location: North-Central Texas

Re: No air emergency

Mon May 15, 2017 8:30 am

tripplec wrote:Thats kind of a scary looking seat there. Almost looks like chunks of it were blown into the lp chamber.

Sent from my SAMSUNG-SM-J320A using Tapatalk
I should have completely gone through the reg looking for little pieces, but being out of country and not having enough tools, I just popped in a spare seat (later version) and used it on shallow dives. Luckily I wasn't playing deep-diver when the first one failed and blocked air flow. I will go completely through the reg before taking it on another outing. Thanks for the reminder, Tripplec !
The older I get the better I was.

User avatar
antique diver
Master Diver
Posts: 1843
Joined: Sun Dec 10, 2006 12:50 pm
First Name: Bill
Location: North-Central Texas

Re: No air emergency

Mon May 15, 2017 8:34 am

Bryan wrote:There was a clear version of that seat as well

Sent from my SM-J700T using Tapatalk
How have the clear ones held up? I have a few of them that I have never tried. Mine have a little raised bump at the center, around the little pin hole. Is that the one you are referring to?
The older I get the better I was.

User avatar
Bryan
Plank Owner
Posts: 5225
Joined: Fri Jun 24, 2005 11:40 am
First Name: Bryan
Location: Wesley Chapel Florida
Contact: Website

Re: No air emergency

Mon May 15, 2017 9:13 am

Bill I'm not sure where that cache of old parts is offhand but I don't remember a bump on them? I'll look when I get the chance but for those rebuilding regulators please do not use early Conshelf seats just to be sure. Most likely the material has degraded to the point that it wouldn't seal anyhow but why take a chance.
Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB

User avatar
antique diver
Master Diver
Posts: 1843
Joined: Sun Dec 10, 2006 12:50 pm
First Name: Bill
Location: North-Central Texas

Re: No air emergency

Mon May 15, 2017 9:57 am

Bryan wrote:Bill I'm not sure where that cache of old parts is offhand but I don't remember a bump on them? I'll look when I get the chance but for those rebuilding regulators please do not use early Conshelf seats just to be sure. Most likely the material has degraded to the point that it wouldn't seal anyhow but why take a chance.

I agree. Go for the latest seats available!

I have experienced a variety of regulator malfunctions over the years, but that was the only time I have ever had a total shutdown of air. I am thankful that it didn't happen while I was playing around somewhere below the "recreational dive limit" with no redundant source of air. (If I was ever foolish enough to do such a thing!) :roll:
The older I get the better I was.

Return to “General Discussions”

Who is online

Users browsing this forum: No registered users and 3 guests