VR3 PPO2 in CCR mode

Juz · 30th June 2005, 18:49

Ok, so you have a VR3 set to CCR mode at 1.3PPO2.

You have a dil of 20/40

You dive to 70m.

In sim mode the VR3 seems to overide the 1.3 PPO2 to the 1.6PPO2 of the Dil. It does not seem to allow for the fact that you have breathed the loop down to 1.3PPO2.

Does this mean....

1. It's using 1.3 for Deco and 1.6 for CNS to be conservative

or

2. It's using 1.6 for BOTH Deco and CNS meaning that it would actually give you a lower Deco obligation than you should have

Juz

Andy Del · 30th June 2005, 19:15

I believe it is basing all of it's calulations on the PO2 displayed.

Ignoring your choice of diluent and the dive, my VR3 will change PO2 depending on depth.

For example, using dil of say, 30% O2, and leaving the VR3 at a lower setpoint (0.5) and diving to 20m, will see the VR3 assume your PO2 (you are diving a constant PO2 unit, right?) move from 0.5 on the surface, to 0.9 at depth. In much the same way, if you set your PO2 to be 1.6, the unit will reset the PO2 s you ascent past 6m. On my 3m stops (with a PO2 of 1.3 set) My VR3 will read a PO2 of about 1.25 (and it's not linked in) and gradually lower as I ascend to the surface...

Now, why would you use this diluent for this dive?

Juz · 30th June 2005, 19:22

Just being curious really, I was looking at bail out options yesterday and playing with the Sim mode on the VR3 and it led to this question.

Juz

Barrie Law · 1st July 2005, 15:48

Juz,
The Vr3 will run the PP02 at 1.6 for the dil gas in simulator mode even if your dils PP02 at target depth is higher than set-point.
Total Partial Pressure on a dive will be dictated by the PP02 in the dill because to breath it down you would need to replace the volume with dil or have less volume in the loop.
I think the simulator is a good way to see approximately what to expect on an actual dive but only that a 'simulation'.

Cheers

30th June 2005, 18:49	#1 (permalink)
Juz Team Kinky Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: London UK Posts: 147	VR3 PPO2 in CCR mode Ok, so you have a VR3 set to CCR mode at 1.3PPO2. You have a dil of 20/40 You dive to 70m. In sim mode the VR3 seems to overide the 1.3 PPO2 to the 1.6PPO2 of the Dil. It does not seem to allow for the fact that you have breathed the loop down to 1.3PPO2. Does this mean.... 1. It's using 1.3 for Deco and 1.6 for CNS to be conservative or 2. It's using 1.6 for BOTH Deco and CNS meaning that it would actually give you a lower Deco obligation than you should have Juz __________________ ~KINKY DIVERS~ Because going down is fun We are all prompted by the same motives, all deceived by the same fallacies, all animated by hope, obstructed by danger, entangled by desire and seduced by pleasure. Welcome to Kinky Divers!
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30th June 2005, 19:15	#2 (permalink)
Andy Del Classic KISSer Current Rebreather/s: Sport Kiss Classic Kiss Other Rebreather/s: Join Date: Feb 2005 Location: Australia, Sunny Sydney Posts: 421	I believe it is basing all of it's calulations on the PO2 displayed. Ignoring your choice of diluent and the dive, my VR3 will change PO2 depending on depth. For example, using dil of say, 30% O2, and leaving the VR3 at a lower setpoint (0.5) and diving to 20m, will see the VR3 assume your PO2 (you are diving a constant PO2 unit, right?) move from 0.5 on the surface, to 0.9 at depth. In much the same way, if you set your PO2 to be 1.6, the unit will reset the PO2 s you ascent past 6m. On my 3m stops (with a PO2 of 1.3 set) My VR3 will read a PO2 of about 1.25 (and it's not linked in) and gradually lower as I ascend to the surface... Now, why would you use this diluent for this dive? __________________ Yellow - the colour of greatness!
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30th June 2005, 19:22	#3 (permalink)
Juz Team Kinky Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: London UK Posts: 147	Just being curious really, I was looking at bail out options yesterday and playing with the Sim mode on the VR3 and it led to this question. Juz __________________ ~KINKY DIVERS~ Because going down is fun We are all prompted by the same motives, all deceived by the same fallacies, all animated by hope, obstructed by danger, entangled by desire and seduced by pleasure. Welcome to Kinky Divers!
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1st July 2005, 15:48	#4 (permalink)
Barrie Law RebreatherWorld Sponsor Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Jun 2005 Location: Ireland Posts: 726	VR3 PP02 in CCR mode Juz, The Vr3 will run the PP02 at 1.6 for the dil gas in simulator mode even if your dils PP02 at target depth is higher than set-point. Total Partial Pressure on a dive will be dictated by the PP02 in the dill because to breath it down you would need to replace the volume with dil or have less volume in the loop. I think the simulator is a good way to see approximately what to expect on an actual dive but only that a 'simulation'. Cheers __________________ Barrie Law Rebreather World Store Supplying the Rebreather World Tel:US +19548403892 Fax:US+19543333792 Tel:EU+442071930496 Fax:EU+442077606344 Mobile+353876880628 Skype:barrielaw Email: barrie@rebreatherworldstore.com
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