justinthedeeps
Contributor
Reading carefully it sounds like we should relish the moment our controller fails and we get to remember our training doing a HUD manual setpoint deco ascent, truly prepared divers will also remove the mask
Petrel 3 Failure
- Thread starter InWay2Deep
- Start date
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GF99/99
Contributor
Haha yup or until your @Shearwater HUD fails. I am on my 3rd HUD now
My dive buddy really impressed with his @Shearwater HUD as he watched it slowly fill with water on deco.
Are you snapping the hud into the holder on your JJ, or sliding it in?
justinthedeeps
Contributor
After 50-100 hours on the HUDs I've had, we basically just unplug them when not in use, as they love to turn themselves on randomly even after a thorough soak and drying.
The blinky pill is really just a gateway to the amazing NERD, although the NERD does not serve as a mini buddy light like the binky can.
I hope they do release the bone conduction mouthpiece model soon. Resistance is futile
The blinky pill is really just a gateway to the amazing NERD, although the NERD does not serve as a mini buddy light like the binky can.
I hope they do release the bone conduction mouthpiece model soon. Resistance is futile
I bought the Petrel 3 so I would not need a HUD. The vibration alerts for PO2, Stacktime, and NDL are very noticeable and do the job. I guess I need to fall back on my Petrel2 for a while and send in the Petrel3 for service.
justinthedeeps
Contributor
How does the vibration mechanism work? Does it give vibration alarms for low voltage? Can it charge up a capacitor or something, so that if it does die suddenly, it gives a final discharge of the vibration to alert the diver?
It seems like most mobile phones do a little final vibration upon shutdown? (but not always)
It seems like most mobile phones do a little final vibration upon shutdown? (but not always)
justinthedeeps
Contributor
So our controller died and we didn't notice, and perhaps for some reason we also haven't been using or watching a secondary ppO2 monitor. (It should never happen)
What happens next?
A JJ-CCR, and probably any other DiveCAN unit(?) is designed so that the onboard head is supposed to keep maintaining a low setpoint (e.g. 0.7) via direct internal control of the solenoid, even with a dead controller. Thus on ascent, it should automatically add increasing amounts of oxygen to keep you alive? (But verify this)
A constant mass flow orifice alone (mCCRs) will continue to leak oxygen into the loop, but only at a replacement rate equal to the amount of oxygen needed to survive while calm, --without ascending--. Ascent could still be fatal.
If no oxygen is being delivered to the loop, the only physical way to notice is gradually not being able to take a full breath, even though we haven't descended. Depending somewhat on diluent mix, letting the ADV make up the lost volume might be survivable for a short time, but becomes hypoxic. Ascent is fatal (?)
I think I remember someone saying one reason they liked to close/remove ADVs was so that they might more easily notice odd or unexplained loop volume changes, possibly indicative of an oxygen delivery issue. But perhaps not really enough reason to risk a breathless sinking episode while grasping around for a MAV or shutoff.
What happens next?
A JJ-CCR, and probably any other DiveCAN unit(?) is designed so that the onboard head is supposed to keep maintaining a low setpoint (e.g. 0.7) via direct internal control of the solenoid, even with a dead controller. Thus on ascent, it should automatically add increasing amounts of oxygen to keep you alive? (But verify this)
A constant mass flow orifice alone (mCCRs) will continue to leak oxygen into the loop, but only at a replacement rate equal to the amount of oxygen needed to survive while calm, --without ascending--. Ascent could still be fatal.
If no oxygen is being delivered to the loop, the only physical way to notice is gradually not being able to take a full breath, even though we haven't descended. Depending somewhat on diluent mix, letting the ADV make up the lost volume might be survivable for a short time, but becomes hypoxic. Ascent is fatal (?)
I think I remember someone saying one reason they liked to close/remove ADVs was so that they might more easily notice odd or unexplained loop volume changes, possibly indicative of an oxygen delivery issue. But perhaps not really enough reason to risk a breathless sinking episode while grasping around for a MAV or shutoff.
Any divecan units I have seen maintain the last setpoint when the controller fails or comes unplugged. They don't drop to low setpoint.
justinthedeeps
Contributor
I think I remember seeing a video and/or article somewhere where they tested this feature of the DiveCAN internal setpoint maintenance by removing the controller battery inside a recompression chamber. Can't find it though
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