[rEvo] Petrel 2 controller intermittently shows 0.0/low PPO2 for all sensors

[SavageSeaCow]

I agree with @stuartv - our sensors are pretty cheap and the overall fix cost, $100 in my case, was a rounding error compared to the total CCR costs.

Perhaps there is an intermediate solution. Molex connectors and wiring are quite cheap. So put a moisture resistant connector between a molex connector and the potted part of the piggy tail:

View attachment 816480

If moisture gets into the wire, it will travel up to the connector. Then replace the molex/connector part for less than 0.50 USD.

I was just going to suggest this! I think you can even purchase the molex pre-wired with tails that you could just insert into the water proof connector. The connectors I have been looking at look smallish but the wild card here is if there is enough space in the tray.

 

[mr_v]

Which connectors have you been looking at, @SavageSeaCow?

 

[stuartv]

Adding those connectors is adding another failure point. Another joint/connection that could affect reliability and stability of the pO2 reading.

That is a tradeoff versus replacing pins every so often and spending $100 for the cable every few years.

Also, I think @mr_v's experience with the cable he just replaced is not entirely representative. I think they normally last much longer than his did, so his particular data point should not necessarily be used to drive a change in protocol.

 

[mr_v]

Adding those connectors is adding another failure point. Another joint/connection that could affect reliability and stability of the pO2 reading.

That is a tradeoff versus replacing pins every so often and spending $100 for the cable every few years.

Also, I think @mr_v's experience with the cable he just replaced is not entirely representative. I think they normally last much longer than his did, so his particular data point should not necessarily be used to drive a change in protocol.

Stuart, I'll reply to you in private.

 

[Divermikey]

I store my Revo in the garage open with the cover off, the scrubber canisters in Tupperware tubs and the cell tray out of the unit so the cells and lungs can breathe and dry out.

Thought about using the Narked cell caps but would imagine that they would just keep any moisture in the cell connector area and not clear to evaporate.

Really like the idea of injecting some Tribolube into the molex connector. Fluids don’t compress.

I've been using tribolube on my revo molex cell connectors for at least 5 years with no issues.

 

[stuartv]

I asked Richard at Dive-tronix about using those caps from N@90 and filling the cavity with Tribolube. Here is his response:

This could be a bad idea. Just pack the Molex connectors full of Tribolube. These caps do help keep some of moisture off of the sensor, but this is electronics and they do need air to get them so they don't overheat or short out. Tribolube is conductive.

I think I'll stick to what I've been doing and has been working for me for at least (approximately) 4 years on my current rEvo. What Richard said. Just Tribolube in the Molex connectors and that's it.

 

[Divermikey]

I've been using tribolube on my revo molex cell connectors for at least 5 years with no issues. It just takes a little bit injected in the 2 molex connector openings that plug into the o2 sensor. probably less than 2 cents worth.

 

[LFMarm]

Great thread! I have just done continuity test on all cables and they seems to be good but I am now implementing the silicone + tribolube advice to keep them in good shape. Thanks everyone for sharing these learnings.

 

[stuartv]

Great thread! I have just done continuity test on all cables and they seems to be good but I am now implementing the silicone + tribolube advice to keep them in good shape. Thanks everyone for sharing these learnings.

I can't remember if this has already been stated, so just in case.

Tribolube is conductive. Use it - but don't put so much in there that it is coming out the back end and creating a short circuit between pins.

 

[justinthedeeps]

Re: the 'necessity' of oxygen-safe lubes and sealants in the head and low-pressure (≤10 bar) places

Aren't there already a bunch of other non-'oxygen safe' materials in the head/loop/canister/lungs of all rebreathers? Isn't the sensor body itself not 'oxygen safe' according to relevant definitions being used here?

I can report no issues using silicone lubes in a ~7.5 bar oxygen MAV, or on the scubber o-rings etc.
What is the proposed ignition source in a head at ≤1.6 atm ppO₂? Electronics? The voltages aren't high enough.

The cylinder/reg is at 20-200 atm, ignition risk there is rapid [micro]heating from sudden pressure change.

For me, the primary risk of using silicone lubes in the low pressure areas is cross-handling--lube up a large canister o-ring, then handle the high pressure DIN fitting without a thorough hand washing.

Is tribolube (PFAS / polyfluoroalkyl substances?) a forever chemical once in the lungs/body?