Regulator Failed at depth
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clownfishsydney
Contributor
Well, about 30 years after my last reg failure, I had one last night. Doing a night shore dive and had just reached the bottom at 7 metres (at this spot) and gone about 40 metres (2.5 minutes) when there was a loud bang and a huge amount of water. Swam over to one of my buddies and took his octopus (Safe second) and signalled to him what happened. He had trouble seeing the bubbles due to the night dive and other divers' torches. We ascended and swam back on the surface to shore (a lot further than where we started from as you cannot get out there).
I suspected a first stage high pressure seat failure. Took it to my service technician, he confirmed this. Funny thing, I was going to put in for a service on Sunday afternoon!
I suspected a first stage high pressure seat failure. Took it to my service technician, he confirmed this. Funny thing, I was going to put in for a service on Sunday afternoon!
OP
scuba2you
Registered
Likewise, after I talked to the people at DAN during the processes of my troubleshooting, they lead me to a great article on just this subject. Following the instructions to pinch the braided hose between your fingers, as you look for changes in the hose wall flexibility.....Well, it didn't take long to easily feel a total collapse of the LP hose.
Now, every time I see a braided hose I just want to walk up and pinch it, must be the engineer in me. haha
Sorry for the dumb question but what is a 1st stage HP seat failure and what are some possible causes ?
Not a dumb question... questions are how we learn! I apologize if I cover some things you know already;
The first stage (connected to the tank) is a normally open valve that is closed by pressure in the low pressure manifold side (the LP ports feeding your second stages and inflator). Ordinarily (in most designs), this is accomplished with an orifice (small opening with a pointed edge) being covered (thereby closed) by a polymer "seat". The seat or orifice may be the moving part... but for this it doesn't matter. A seat can fail by being dislodged, or physically damaged. An example of damage failures is very old Conshelf/Royal Aqua-Master seats at one point used a polymer that tended to prematurely dis-bond from the metal seat carrier. When that happens, you could get a bang (seat material abruptly departing the carrier, but still contained in the reg body) accompanied by uncontrollable free flow of both second stages. You could also get seat material lodging in an air passage cutting off pressure. Thankfully, modern materials and design give us a ridiculously low failure rate, and most regs are designed to "Fail Safe," as in the vast majority of failure modes result in free flow (which can still be breathed off of to get you to the surface) rather than a failure to deliver air.
Respectfully,
James
Edit to add: the "HP Seat" is the seat in the 1st stage (stepping High Pressure, HP, to Intermediate Pressure, IP). As opposed to he LP/IP Seat in the second stage.
Rusty Shackleford
Contributor
clownfishsydney
Contributor
An Australian made regulator called Sea Hornet, have used various models for 32 years, very reliable (my previous failure was a Swedish Posideon). From memory, it is a piston type. Very popular in Australia in 1990s and early 2000s till the company that made them went broke after the GFC. The Royal Australian Navy used them exclusively.
I still can get service kits and a few years ago I purchased enough to last me for the rest of my diving years I reckon.
clownfishsydney
Contributor
And today I got my regulator back. The seat had totally collapsed. It appears that when the company that made the regulator collapsed, the former owner sourced new service kits to sell and the material the seat was made from was not as good as it should be. The service technician told me he has now seen three similar cases. Now have different material as seat.
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