Sensors: which gas shall I have in the loop when not in use?

[Agro]

Until now my 4 sensors did not last very long. Typically the last for 15 month but during this time at least one sensor died, I had to replace it after 1 month or after 10 month. So I ask mysel why.

As far as I understand a sensor is a battery, producing a voltage depending on pO2, so far so good. After diving my unit sometimes is stored for a few days as it is after diving, which means a breathable gas in there, usually pO2 0.8/0.9. Can this reduce sensor's life? High pO2->high voltage->high consumption on the cell?

One step further: does it make sense to store the sensors in argon or helim to reduce voltage and prolong sensor's life? In the Liberty head I could easily do so when unit is not in use.

 

[tbone1004]

storing them in high ppO2 will certainly reduce their life since the electrolyte is being consumed to produce voltage and at 0.8-0.9 it is being consumed at roughly 4x what it would be if stored in air. I wouldn't worry about purging with pure He or Ar, He especially since that's just a waste of money, but I would be more concerned with why you are leaving the loop closed for a few days. That is an extremely dangerous protocol since it allows nasties to start growing inside the system. You need to break it apart and let it dry out overnight and if you reassemble the next morning when everything is dry then your loop is full of air and is fine. That should have been covered during your class but leaving the loop fully assembled after a dive for several days is an extremely dangerous protocol and almost guarantees getting some sort of respiratory infection.

 

[Agro]

After those few days I break it apart and do my desinfection, no worry about infection.

Anyway I know that German military divers do desinfecton every 6 days only, IF (and that's very important) no one else had the mouthpiece in his mouth. One single breath form any other person ->desinfection.

 

[tbone1004]

After those few days I break it apart and do my desinfection, no worry about infection.

Anyway I know that German military divers do desinfecton every 6 days only, IF (and that's very important) no one else had the mouthpiece in his mouth. One single breath form any other person ->desinfection.

Disinfection isn't the problem, letting it dry is the problem. Why are you leaving it fully assembled for days? That is really bad for the unit, it's not designed to stay wet for a long time and the inside of that loop is at 100% relative humidity and as it cools off to room temperature a lot of that water starts condensing and that's just not good. I'm genuinely surprised your instructor didn't teach you how important it is to break the unit apart every night to let it dry out.

 

[Agro]

Why are you leaving it fully assembled for days?

After diving I have other things to do.

 

[Agro]

how important it is to break the unit apart every night to let it dry out.

Befor next dive a do disinfection and let it dry out.

 

[RedSix]

And now you know why your cells die so fast...
User error!
They are not made for humide gas.

 

[Agro]

I guess I will put some helium into the loop after every dive, that's an easy job. And when disassembled I will store the head with helim inside.

 

[Agro]

And now you know why your cells die so fast...
User error!
They are not made for humide gas.

Nonsense. The cells are exactly made for humide gas. What do they have during dive? Humide gas. Why do they have a membrane? For humide gas.

 

[RedSix]

Do you actually read the replies?
You just need to dry your loop, nothing else. Store the cells in air.