Perdix AI - Different PPO2 for different gases

[CWK]

Hi,

Quick question.

I'm reading up for my SSI XR Nitrox course next week. Manual says PPO2 of 1.4 for bottom gas and PPO2 of 1.6 for deco gas.

I have only used Perdix in OC Rec mode and it seems to me that only one PPO2 can be set for all gases carried. Can Perdix AI be set to different PPO2 for different gases?

Thanks

 

[runsongas]

why would you need more than one pp02 alarm setting? at the extended range level, you should be aware of your maximum operating depth and plan accordingly such that you won't need a pp02 alarm on your computer

 

[NAM001]

CWK

look at this way. you set you computer for 1.4 that will alarm you if you exceed it. it is still ok to go to 1.6 if needed (not normal mod but extenuating circumstance mod)
as the deco goes the rule is 1.6 mod, cause you are motionless while you deco. That is how you use O2 at 20' and 50% at 70 '. mark your deco tanks with depths ie 70 ft is 50% etc. many have the tank marked OXYGEN followed by a depth number. ie OXYGEN 70 is a tank of 50% 70 is the MOD. That marking system restricts what you will ever put in the tank. You will NEVER NEVER put 100% O2 in a tank marked OXYGEN 70. Nothing but 100% will go in a tank marked OXYGEN 20. The word OXYGEN is a keyword to denote deco tanks and not nitrox tanks you would do the normal dive time on.

Look at it as the deco is seperate of the dive. Because it entails full concentration on your depth control and time at depth that the rest of the non deco time requires.

Below is a tank of 100% O2 it has a mod of 20'

 

[CWK]

@runsongas,
Looking to be able to set PPO2 of 1.6 on deco gas so that Perdix will flag the switch to the deco gas based on the MOD dictated by PPO2 of 1.6. Not thinking of this as an alarm.

@KWS,
Thanks for your insights.

I suppose I could set PPO2 of 1.6 on Perdix to generate the MOD for the deco gas switching, but observe the MOD for the bottom gas based on PPO2 of 1.4.

 

[RainPilot]

Agree with KWS but “OXYGEN “ is only ever written on a 100% tank. Everything else is depths.

 

[runsongas]

whether you set the pp02 to 1.4 or 1.6 in OC mode doesn't do anything other than determine whether you start seeing a warning above 1.4 or 1.6

it isn't like CCR where the deco calculation will change based on setpoint

 

[MargaritaMike]

Regardless of what you write on a tank, your PPO2 level is what your PPO2 level is. 1.1, 1.4, 1.6, 2.9. Set it where you want to be warned that your Oxygen partial pressure is at a certain point regardless of what tank you are currently sucking gas from.

Cheers - M²

 

[JohnnyC]

First, take it out of rec mode. You're going to want the additional information. The Perdix should have Max PO2 and Deco PO2 options in the advanced menu settings. At least my Predator does.....

Second, your PO2 is going to be whatever it is based on your depth. The "alarm" is just changing the gas PO2 to red on the screen if you exceed the limit.

I disagree with KWS as per tank markings. If it has oxygen written on it, it ONLY gets 100% O2 and the MOD is 6m/20ft. Any other gas is MOD only (eg: 21 or 70 for 50% in meters or feet). Sticker on the top inside, and the bottom outside. Top is for you, bottom is for buddy confirmation during a gas switch.

 

[CWK]

@JohnnyC,
Many thanks. I've found the Max PO2 and Deco PO2 settings under OC Tec.

 

[rongoodman]

I've never heard of an OXYGEN label on any tank other than one containing 100% O2, which of course has an MOD of 20'. Which agency teaches this practice?