A few thoughts...
The inner o-ring on a DIN or yoke retainer can get pinched during assembly - but it feels distinctly different to the tech torquing it as the fitting tims up much slower and mushier - indicating the o-ring is probably pinched/improperly seated.
Failing that, a newly serviced reg should be wet checked, or at least tested to ensure it will hold pressure after the reg is pressurized and the valve is turned off. I that regard it is a failure on the part of the reg repair technician. One possible partial qualifier here is that in some regs, that particular o-ring is not an annual service repalcement part as it is a static o-ring, and the o-ring can get quite old and can pressure test well but fail shortly there after. The Scubapro Mk 5 is one of the more egregious offenders there and a prudent tech will replace all the non-annual service o-rings if he or she does not know the service history of the reg.
However, it's also important to realize that you can give your self more control over the process by performing the same check by connecting the reg to a tank, pressurizing it, breathing a couple breaths then shutting off the valve and observing the SPG for 3-5 minutes to ensure the needle is rock solid. That will identify leaks in the first or second stage, and it will let you confirm that the reg breathes the way you expect it to breathe. Good shops will have a tank by the counter for you to use and will encouirage you to use it. It would suggest a shop is a very poor choice as a place to spend your money if they object to you testing the reg or refuse to provide a tank to allow you to check it.
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When properly designed and assembled both DIN and yoke attachments create metal to metal contact all the way around an o-ring. However, there are a couple critical differences.
DIN o-rings, since they are located on the first stage inlet fitting, will generally be retained if the fitting comes loose. Consequently when that happens, you shut off the valve, re-tighten the DIN wheel and repressurize the reg and it is no big deal. Plus if the reg remains pressurized it is highly unlikely for the connection to loosen in the first place.
In contrast, a yoke o-ring is located in the valve and if the reg comes loose, the escaping gas usually extrudes the o-ring or blows it out completely, making it almost impossible to quickly re-seat or replace underwater.
A further difference is that a yoke can stretch under pressure, particularly lighter / thinner yokes when used on 3300-3442 psi tanks. More importantly if the outside air temp is cold, the yoke will contract, and then if you jump into warm water (something that is common in September and October) the yoke will expand slightly. In otherwords, the yoke can be tight when put on the vlave but the combination of expansion due to pressurization and heat can create just enough play to allow the o-ring to extrude.
Finally, the face of a yoke valve is a critical sealing surface, and nicks and dings in that surface can create the potential for o-ring extrusion.
Consequently, DIN valves are less problematic than yoke valves in terms of both the frequency and consequences of o-ring extrusion.
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If the valve to first stage o-ring extrudes, the gas loss will look and sound a lot more impressive than it really is. Unless you already have a very low tank pressure, you will still have more than enough time for an ascent from any recreational depth within the NDL's. So signal your buddy and give him the thumb - the reason why will be obvious - and ascend normally. Your buddy shouidl stick close and be ready to hand off gas, but the odds are you will not need it, unless perhpas it is at the safety stop. You can monitor the decline in pressure on your SPG and that will give you a good idea of how close to empty you are getting and how long it will take to lose all your gas. If you are watching the SPG at your safety stop, you'll know when it's time to do the final 10-15 ft ascent and or to switch to your buddy's octo.
If you are doing decompression, pentreation diving, or solo diving as a solo certified diver, then you will be trained and configured to deal with a failure or gas loss scenario.
The inner o-ring on a DIN or yoke retainer can get pinched during assembly - but it feels distinctly different to the tech torquing it as the fitting tims up much slower and mushier - indicating the o-ring is probably pinched/improperly seated.
Failing that, a newly serviced reg should be wet checked, or at least tested to ensure it will hold pressure after the reg is pressurized and the valve is turned off. I that regard it is a failure on the part of the reg repair technician. One possible partial qualifier here is that in some regs, that particular o-ring is not an annual service repalcement part as it is a static o-ring, and the o-ring can get quite old and can pressure test well but fail shortly there after. The Scubapro Mk 5 is one of the more egregious offenders there and a prudent tech will replace all the non-annual service o-rings if he or she does not know the service history of the reg.
However, it's also important to realize that you can give your self more control over the process by performing the same check by connecting the reg to a tank, pressurizing it, breathing a couple breaths then shutting off the valve and observing the SPG for 3-5 minutes to ensure the needle is rock solid. That will identify leaks in the first or second stage, and it will let you confirm that the reg breathes the way you expect it to breathe. Good shops will have a tank by the counter for you to use and will encouirage you to use it. It would suggest a shop is a very poor choice as a place to spend your money if they object to you testing the reg or refuse to provide a tank to allow you to check it.
-----
When properly designed and assembled both DIN and yoke attachments create metal to metal contact all the way around an o-ring. However, there are a couple critical differences.
DIN o-rings, since they are located on the first stage inlet fitting, will generally be retained if the fitting comes loose. Consequently when that happens, you shut off the valve, re-tighten the DIN wheel and repressurize the reg and it is no big deal. Plus if the reg remains pressurized it is highly unlikely for the connection to loosen in the first place.
In contrast, a yoke o-ring is located in the valve and if the reg comes loose, the escaping gas usually extrudes the o-ring or blows it out completely, making it almost impossible to quickly re-seat or replace underwater.
A further difference is that a yoke can stretch under pressure, particularly lighter / thinner yokes when used on 3300-3442 psi tanks. More importantly if the outside air temp is cold, the yoke will contract, and then if you jump into warm water (something that is common in September and October) the yoke will expand slightly. In otherwords, the yoke can be tight when put on the vlave but the combination of expansion due to pressurization and heat can create just enough play to allow the o-ring to extrude.
Finally, the face of a yoke valve is a critical sealing surface, and nicks and dings in that surface can create the potential for o-ring extrusion.
Consequently, DIN valves are less problematic than yoke valves in terms of both the frequency and consequences of o-ring extrusion.
----
If the valve to first stage o-ring extrudes, the gas loss will look and sound a lot more impressive than it really is. Unless you already have a very low tank pressure, you will still have more than enough time for an ascent from any recreational depth within the NDL's. So signal your buddy and give him the thumb - the reason why will be obvious - and ascend normally. Your buddy shouidl stick close and be ready to hand off gas, but the odds are you will not need it, unless perhpas it is at the safety stop. You can monitor the decline in pressure on your SPG and that will give you a good idea of how close to empty you are getting and how long it will take to lose all your gas. If you are watching the SPG at your safety stop, you'll know when it's time to do the final 10-15 ft ascent and or to switch to your buddy's octo.
If you are doing decompression, pentreation diving, or solo diving as a solo certified diver, then you will be trained and configured to deal with a failure or gas loss scenario.
Glad it didn't happen at depth though because the air came out so quickly. Went from 2000 psi to 1500psi in no time
