Shearwater transmitter failure

[Glenn Williams]

Call them what you will. Suunto calls them restrictors. What they do is eliminate the initial high pressure from entering the pod and damaging the internals, so back to my original question to all of you is would these be beneficial in the shearwater pods to keep the over pressure valve from blowing out?

Or am I barking up a wrong tree? I would imagine there are a ton of shearwater pods in use with no restrictors and they work just fine. Suunto’s original design did not have these restrictors installed but after a rash of failures this was their fix.

Just wondering if these would benefit the shearwater pods or no?

Glenn

 

[JackD342]

They're spools.

The Suunto flow restrictors were added during the recall from a year or two ago. There were two units that failed to contain the pressure when pressuring the 1st stage. (I did not hear of any injuries.)

The one that is used with the 1st stage is NOT a spool, but similar. The one that is used with a short hose looks like a spool, but I think the hole that passes air through is narrower than a typical spool.

I can't say if a Pelagic transmitter might or might not be subject to the same issues that the Suunto transmitters had, but I do suspect that the Pelagic item might have a sealed battery compartment that separates the battery area from the pressure sensor and the electronics, making it very unlikely for any water/corrosion in the pressurized section. The Suunto is just one compartment, and a shoddy battery change led to some corroded contacts that contributed to the recall event.

 

[Glenn Williams]

Ok thanks for the clarification. I was hoping that we were on to something to help out. Oh well.

Glenn

 

[JackD342]

Ok thanks for the clarification. I was hoping that we were on to something to help out. Oh well.

Glenn

By the way, that “rash of failures” was exactly two. I think same owner, also.
It was really more user error than anything else, but they acted with caution anyway.

 

[Glenn Williams]

I thought there were more cap blow outs than just 2. Anyway I wonder what caused the OP’s overpressure valve to blow out. I just bought a Perdix Ai and am getting the pod for Christmas. Trying to learn and hope the same doesn’t happen to mine.

Glenn

 

[Brian G]

In a wireless transmitter, the high pressure gas is measured by a pressure transducer that is sealed to the other end of the orifice. The rest of the compartment is at surface air pressure and is not designed to withstand the high pressure from a tank. If the seal between the pressure transducer and the high pressure orifice is somehow compromised, then high pressure can leak into the other parts of the transmitter. The over-pressure valve is there so that if that leak does occur, the pressure is released in a controlled direction (towards the first stage) instead of potentially at your head.

 

[scubadada]

I thought there were more cap blow outs than just 2. Anyway I wonder what caused the OP’s overpressure valve to blow out. I just bought a Perdix Ai and am getting the pod for Christmas. Trying to learn and hope the same doesn’t happen to mine.

Glenn

Hi @Glenn Williams

The Pelagic Pressure Systems MH8A transmitter has been around since 1996. It is sturdy and dependable, I would imagine why Shearwater chose it. It has been successfully used by many brands since its introduction. I would say that you have little to worry about.
List of Perdix AI compatible transmitters
Are Pressure Transmitters compatible across brands?

 

[CWK]

If the seal between the pressure transducer and the high pressure orifice is somehow compromised, then high pressure can leak into the other parts of the transmitter.

My thoughts:
- Water ingress from first stage. Unlikely that any water can progress that far up a system that is sealed at one end.
- Water ingress from OPV end. Possible if OPV is not securely seated?
- Bending/flexing of transmitter. Unlikely. I don't think the transmitter capsule has been subject to any bending/flexing over and above normal use.
- Temperature fluctuations causing repeated expansion and contraction. My regs go in airplane baggage holds on average about 4 times a month. But baggage holds are normally withing operating parameters of the transmitter.

Any thoughts on what could compromise the seal?

 

[lamby66]

On a possibly related note (at least related as my transmitter failed as well)
I have a transmitter I purchased with a perdix ai in November 2016 (about 3 years old) that failed without warning.

I will be going to cozumel in a couple weeks, and my last dive was about a year ago. I wanted to check and make sure all was good. I gassed up my regs and the transmitter was working fine and showed a good battery charge. The spg and the ai were within 50psi of each other. Life is good.

I packed up my gear for a pool refresher the next day...

I gassed up my rig and I heard what sounded like a 1st stage oring leak for a split second then stopped.

My transmitter never turned on. Replaced the battery.. Nothing. Removed and re gassed up the regs.. Nothing.

Not sure what happened, but this transmitter only has about 20-30 dives on it and when it failed, it was bone dry. The transmitter shows no signs of ever being flooded or damaged in any way.

The tank I was using had 2500psi in it at the time.

Here is a picture to show what mine looks like and what the OP is missing where the rust stain was.. A little red plug.

 

[Bigbella]

By the way, that “rash of failures” was exactly two. I think same owner, also.
It was really more user error than anything else, but they acted with caution anyway.

It had to be more than two. There were a small number of failures in California as well. I know personally, of, at least three, and was told of half dozen others . . .