Were you taught this math in your entry level CCR class?

[The Chairman]

I was taught this in my fourth CCR class (SF2). Kudos to @Capt Tom McCarthy for his thoroughness, even on a crossover. I think understanding linearity is great, but there's more than one way to skin this cat. On the surface I calibrate my cells at %100 and check that they all go down to %21 with a dill flush and the mV should be within specs. Obviously, if the cells weren't linear, then they would show a skewed value for air. Then, at 20 ft I do an O2 flush, raising my PPO2 to 1.6. and then a dil flush which takes it back to 0.3. Again, if the cells were not linear or even limited, I would be getting skewed values, right? If my PDC reads all PPO2s correctly, then why is it important to do the mV math? Moreover, checking that my cells are able to go over 1.3 (my setpoint) is pretty damn important. Without any mV math, I've checked cell linearity as well as if they are limited. Why over-complicate a pretty simple process? Flame suit on, so fire away!

 

[rddvet]

I was taught this in my fourth CCR class (SF2). Kudos to @Capt Tom McCarthy for his thoroughness, even on a crossover. I think understanding linearity is great, but there's more than one way to skin this cat. On the surface I calibrate my cells at %100 and check that they all go down to %21 with a dill flush and the mV should be within specs. Obviously, if the cells weren't linear, then they would show a skewed value for air. Then, at 20 ft I do an O2 flush, raising my PPO2 to 1.6. and then a dil flush which takes it back to 0.3. Again, if the cells were not linear or even limited, I would be getting skewed values, right? If my PDC reads all PPO2s correctly, then why is it important to do the mV math? Moreover, checking that my cells are able to go over 1.3 (my setpoint) is pretty damn important. Without any mV math, I've checked cell linearity as well as if they are limited. Why over-complicate a pretty simple process? Flame suit on, so fire away!

I don't see that as flameable. I think that's a good option for someone who consistently does the flushes every single dive. I think unfortunately alot of people become complacent and wouldn't do them long term. Then again would that same person do the math too?

 

[rddvet]

Slightly off topic, but how many people use a cell checker? I thought about getting the divesoft one, but really don't know that it's worth the cost?

 

[JohnnyC]

Slightly off topic, but how many people use a cell checker? I thought about getting the divesoft one, but really don't know that it's worth the cost?

I've got the narked mini. I use it and like it.

 

[The Chairman]

I think unfortunately alot of people become complacent and wouldn't do them long term.

Every dive. I actually start the dive with full O2 and my ADV turned off. It's easy to do an O2 flush on an SF2 and even easier to do a DIL flush: just turn on the ADV, raise your head 6 inches above your butt and smile. It really only takes a few seconds to accomplish the whole thing. The more complicated, harder and confusing you make the process, the less likely peeps are going to buy into it and keep doing it.

 

[tbone1004]

Slightly off topic, but how many people use a cell checker? I thought about getting the divesoft one, but really don't know that it's worth the cost?

do you have a liberty? If so I think it's worth the cost. I'm not sure if they have one for a non-liberty though. I have a standalone and I use it to check once before trips to make sure the cells are behaving. I have a De-Ox and really like it because I can use air and pressurize at high pressures. The cells seem to behave differently under high pressure in response time, so it's good to see how they behave under 8-10ata. Also don't have to worry about any issues with purging the system with O2.

I think the Liberty's is slick because it uses the internal pressure sensors and solenoids to run the calibration and linearity checks automatically. I think APD has the next best thing where you swap the DSV over for a pressurizing tool and you pressurize the whole loop. Do your positive pressure check while you check linearity of your cells. Not all CCR's can hold that high of a positive pressure though so the Liberty definitely has the best system.

 

[rddvet]

do you have a liberty? If so I think it's worth the cost. I'm not sure if they have one for a non-liberty though. I have a standalone and I use it to check once before trips to make sure the cells are behaving. I have a De-Ox and really like it because I can use air and pressurize at high pressures. The cells seem to behave differently under high pressure in response time, so it's good to see how they behave under 8-10ata. Also don't have to worry about any issues with purging the system with O2.

I think the Liberty's is slick because it uses the internal pressure sensors and solenoids to run the calibration and linearity checks automatically. I think APD has the next best thing where you swap the DSV over for a pressurizing tool and you pressurize the whole loop. Do your positive pressure check while you check linearity of your cells. Not all CCR's can hold that high of a positive pressure though so the Liberty definitely has the best system.

Fathom. I think that the divesoft one (at least the mini) will work with any units, but there's an attachment for the liberty, but I could be wrong. It would be nive to know for sure.

 

[rddvet]

PS, where can you get the De-ox one from in the US?

 

[tbone1004]

Fathom. I think that the divesoft one (at least the mini) will work with any units, but there's an attachment for the liberty, but I could be wrong. It would be nive to know for sure.

I don't think Divesoft makes one other than the caps for their head. Those literally clamp the head so you don't have to do anything with the cells which is ideal.
You may be thinking of the Narked at 90 one? That one is universal and has adapters for the different connectors on the cells. Deox is similar concept to that.
I bought mine used so no idea where to get it in the US sorry

 

[_Ralph]

Not in the "A + B = C therefore Z" way, but did touch on the subject of expected values at certain PPO2

I'm thinking of utilizing it more like Pete (Thanks @The Chairman for the idea) suggested, O2 flush and DIL flush during the bubble check at 20ft/6m

_R