Thanks for these videos. As a 24 year industrial instrument mechanic, I have seen an incredible increase in reliability of instrumentation, to the point where I do far less repairs and way too much PM's (preventative maintenance, or basically just check it out) and not much in the way of repairs. Solenoid valves when in a clean atmosphere with clean flow, they are exceptionally reliable, but gas sensors still drift over time and do require calibration and at some point, replacement. In our environment we mostly measure toxic gases, but we also measure O2, because even if there are no poisonous gases we still need the stuff. In my experience, I seldom have to replace the O2 sensors compared to an LEL or H2s sensor, but I do need to calibrate them more often. But I would still, without hesitation, trust my life to an assorted collection of instrumentation assembled by the lowest bidder, hired by a one of these companies to build a reliable rebreather unit. But that could be because, as I near retirement age, I would consider one incredible dive in an incredible place to be worth the price of ..........

Thank you so much for the information. I found you from watching Dive Talk and you guys at Blue World are Awesome!!

@BlueWorldplus

6 күн бұрын

Thanks!!

This has been a great series Johnathon!! Thank you!!

Thanks for the presentation (and great artwork). I'm probably never going to dive a rebreather but I'm an information junkie so there you go. Of all the folks posting scuba videos, I think yours are among the most engaging to watch.

Your series of videos "All about rebreathers" are absolutely perfect! I'm a technical diver starting to think about rebreathers and these videos was excellent as a first step to know an overview about it. Congratulations 👏🏻

I love this series on rebreathers! Super informative and well explained as always! Looking forward to the next episode to hear how the oxygen sensor works! 😉

@BlueWorldplus

10 ай бұрын

I'm a little behind schedule on that, but I'm going to get it finished.

@DKCGamerGirl

10 ай бұрын

@@BlueWorldplus That's alright, take your time! The education gained from any video you upload will be worth the wait! Got ahold of a few of your books and have been enjoying them in the meantime. Your photography in them is just beautiful!

Thank you for the breakdown! I’m looking in getting into CCR diving sometime within the next few years.

Great video and explanation. Cant wait for another tech video to come out!!

Great explanation. The only point I'd make about CCR's is in the beginning you're explaining it in FO2 terms rather than ppO2 terms. I understand that's probably due to the audience these video's are targeted at. For anyone making the switch or thinking of and reading this comment, when you're diving CCR you no longer think of the fraction (or percentage) of O2. Instead you're thinking of the partial pressure of O2. In OC scuba the fraction of O2 is constant which means the partial pressure of O2 changes with depth. With a CCR the partial pressure of O2 is held constant with the fractions (percentages) changing.

@BlueWorldplus

8 ай бұрын

We get into that later! Did a whole video on PPo2

I'm looking into ECCR becouse I live in Croatia and we have a lott of beautifull wrecks, but best wrecks are very deep, 60m - 120m. I asked my instructor why he chose ECCR and not MCCR he just said, "if something goes wrong with rebreather f*** it just close the loop and go on bailout", he has been diving 40+ years, still alive and diving never entered baro chamber, so his logic must work😂

@BlueWorldplus

9 ай бұрын

If you want to dive really deep, eCCRs have advantages.

Great video J!!! Bravoooo!!!!

Nice

I think this is called an "instant like situation" !

Is mCCR stands for mechanical rebreather or Manual rebreather? I thought it is mechanical rebreather

@Yggdrasil42

Жыл бұрын

Both. These days people commonly prefer "mechanical" over "manual" since manual implies you have to constantly operate the rebreather, which isn't true. With a properly tuned mCCR you need to manually add oxygen maybe every 15 minutes or less. Manual used to be the common name in the past.

@MaDeVa71

Жыл бұрын

I believe you are right, mCCR is mechanical CCR has it works through a mechanical valve (the orifice) instead of an electronic solenoid

@BlueWorldplus

Жыл бұрын

I think technically it's mechanical. I kind of use the terms interchangably.

Surely the "best" of both worlds is an eCCR with a constant flow valve as well? ie a backup to the electronic solenoid? Given the most likely failure by some margin is an oygen sensor failure, i suspect neither system is actually "more reliable", especially when human factors dominant CCR diving incidents?

@Yggdrasil42

Жыл бұрын

Adding more complexity doesn't necessarily make things safer. If things are working correctly you don't gain anything from having both systems. Adding a constant flow valve to an eCCR would only make sense if the "e" part isn't working correctly, at which point you don't want to continue the dive anyway. And vice versa. Troubleshooting a problem while both the solenoid and a constant flow valve are injecting O2 into the loop is much more complex than just one. I know people often buy an mCCR because they're simpler and are easier to understand if things go wrong. I'm not a rebreather diver yet so I may have things wrong.

@Gasnaald

Жыл бұрын

There are quite a lot of rebreathers who have exactly that. REVO rebreathers for example.

@BlueWorldplus

Жыл бұрын

True, and I know a few people who own REVOs and the first thing some of them did was remove the constant flow orifice. Everyone has a different opinion on the best way to rig and run these things.

@SeattleRingHunter

4 ай бұрын

Yes the O2 sensors are typically low hanging fruit along with solenoids when people start tossing out common components that will fail on a rebreather. However let us not he lazy minded as any diver open or close circuit can blow a common high pressure hose o-ring at any moment. Separate bail out cylinder with a 2nd stage necklace, inclining proper deco gas is a prudent mandatory part of proper gas planning practice not to be over looked. Cheers, #SeattleRingHunter

How does a dive computer sense PO2? You mentioned that the computer gives a measurement independent of the oxygen sensor in the loop. Or did I misunderstand?

@BlueWorldplus

4 ай бұрын

You should watch our video about oxygen sensors!

2nd question: with either system, significant changes in depth lead to changes in loop gas mass to hold the average loop volume constant. So climbing up over a reef by 20 feet is going to require you to vent system gas and dropping down the other side is going to trigger the value to add more diluent. In these circumstances neither the eCCR or the mCCR can hold a constant PPO2 can they?

@jordilopezmartin8851

Жыл бұрын

Yes, you're right. The counterlung volume will increase if you ascend, regardless is MCCR or ECCR, you have to vent. Descending you will trigger your ADV to add more volume into the counterlungs to compensate the pressure, in both MCCR or ECCR

@BlueWorldplus

Жыл бұрын

Well, you would only have to vent if the counterlung was very full, or the change in depth was enough to drastically affect your buoyancy. But yes generally, if you go up 20 feet like my example (rather than 5 feet for example) you would need to vent some volume.

@DontScareTheFish

8 ай бұрын

With a CCR you're always aiming for minimal loop volume so the popping over a reef example you've got a few options. If you're at a minimal loop at the bottom you might 'only' be a maximal loop volume at the top so choose not to vent. When you go back down you're then back at the same volume. That doesn't help your ppO2, With a mCCR the diver would need to add more O2 to maintain the setpoint at the desired level. With a eCCR if you know you're only popping over something you might switch from the high setpoint (1.2 or 1.3 bar ppO2) to the low setpoint (typically 0.7bar ppO2) go over the top, drop back down and switch back to the high setpoint. While you're doing that you're going to pay more attention to the ppO2 and either add a touch more O2, or take the extra deco. If it's more swimming along the top rather than a short up and down then you won't want to switch set points. In that case it will be go up, vent, go along and slowly go down. If you don't go down too fast you'll add Dil and metabolise the O2 at a rate that will maintain the ppO2 slightly above the trigger point for the eCCR. I haven't tried similar in a mCCR. In short there are options and it's like describing how someone stays balanced an on a bicycle to someone who's never ridden one, or all the things you're doing and managing while driving a car.

On mCCR, does the O₂ flowing into the system then become less and less as you go deeper, until nothing when you reach 300ft?

@Yggdrasil42

Жыл бұрын

No, the O2 inflow in the mCCR remains constant. It doesn't increase or decrease. The amount of O2 your body metabolises doesn't depend on depth either so that's perfect. However due to the way a constant flow valve works they don't function when very deep. For example the standard valve on a Sidewinder setup works to about 80m. You'd need to switch to a needle valve or another method for deeper dives.

@flinfaraday1821

Жыл бұрын

@@Yggdrasil42 I see, thanks.

Does that mean there is a max descent speed for rebreathers? If you descend fast, the o2 won't be removed quickly enough because only your breathing removes it.

@DavidMaruca_

Жыл бұрын

Remember, you also have access to your diluent! So this means that if you are decending quickly, you can flood the loop with more nitrogen (or helium), and the PO2 would lower to an acceptible level.

@DontScareTheFish

8 ай бұрын

For eCCR divers we don't tend to switch to the high setpoint (1.3bar for many) until we're most of the way down. In OC you'll flare out by adding gas to your BC. It's similar for CCR.

It's dynamic

@Yggdrasil42

Жыл бұрын

What is?

where's the 02 sensor video?

@BlueWorldplus

9 ай бұрын

I know I know!! I was traveling for a long time and we are doing some post production this week for clients....I will get to it soon!!

@steUK73

9 ай бұрын

Excuses excuses 😂

@BlueWorldplus

7 ай бұрын

It's up now!

let's be real for most people cost is always a huge part of the equation.

@BlueWorldplus

Ай бұрын

True

do i get a ping?

@walterunterwurzacher2854

Жыл бұрын

ping

@dreamz-plays

Жыл бұрын

@@walterunterwurzacher2854 thank you