Do all rebreathers require a bailout bottle on board ?

[WOB0.01J]

Hello divers

Just a random thought that pop into my head. So why do you need a bailout bottle if you have a diluent bottle full of air? Why can't you just flip a switch on your mouthpiece and go to your diluent bottle and use that as an emergency gas to get you to the surface? The bottle line is if i am not diving too deep and have enough diluent gas on board. Maybe this is a dumb question but i can't seem to find an answer. P.S. i am not rebreather certified, but going to very soon.

 

[formernuke]

With my unit the diluent is only 23 cuft. That is going to go real quick on OC especially at any depth at all.

Some units you can do this with as you use bigger tanks with them.

 

[beldridg]

Most on-board CCR cylinders are 2L or 3L which might get you a few breaths at depth, but won't last very long using it as an open circuit bottle.



- brett

 

[jlcnuke]

Some rebreathers don't require that you use a separate diluent bottle. I dive the Chest mount O2ptima, which is typically setup with an onboard O2 bottle and you use your full sized bailout as the diluent source. You still have to ensure you have an adequate amount of bailout gas, after accounting for your planned diluent usage, with this type of setup however.

 

[Wibble]

On a "standard" backmounted rebreather, the diluent is a small 2 or 3 litre cylinder, insufficient for bailout from much deeper than a few metres/feet. It is good practice to have completely separate bailout, hence ali40, ali7 litre, ali80s are all used.

There are other rebreather configurations that have "large" shared bailout and diluent (sometimes called dilout), such as the gooist JJ, sidemount and chestmount rebreathers and the recreational semi-closed rebreathers

 

[Tracy]

Hello divers

Just a random thought that pop into my head. So why do you need a bailout bottle if you have a diluent bottle full of air? Why can't you just flip a switch on your mouthpiece and go to your diluent bottle and use that as an emergency gas to get you to the surface? The bottle line is if i am not diving too deep and have enough diluent gas on board. Maybe this is a dumb question but i can't seem to find an answer. P.S. i am not rebreather certified, but going to very soon.

As the others have said, it all comes down to volume. My unit has a 35cf diluent tank and a bailout valve. I don't have an issue using it in a pool without a bailout tank. I wouldn't use it for any depth.

 

[WOB0.01J]

Some rebreathers don't require that you use a separate diluent bottle. I dive the Chest mount O2ptima, which is typically setup with an onboard O2 bottle and you use your full sized bailout as the diluent source. You still have to ensure you have an adequate amount of bailout gas, after accounting for your planned diluent usage, with this type of setup however.

Do you prefer using sidemount setup or the backmount setup for the O2ptima?

 

[WOB0.01J]

On a "standard" backmounted rebreather, the diluent is a small 2 or 3 litre cylinder, insufficient for bailout from much deeper than a few metres/feet. It is good practice to have completely separate bailout, hence ali40, ali7 litre, ali80s are all used.

There are other rebreather configurations that have "large" shared bailout and diluent (sometimes called dilout), such as the gooist JJ, sidemount and chestmount rebreathers and the recreational semi-closed rebreathers

So does BOV connect to the loop for bailout, and BOV uses the dilt gas ?

 

[Wibble]

So does BOV connect to the loop for bailout, and BOV uses the dilt gas ?

If you have a BOV (bailout valve) mouthpiece, then this is plugged into your bailout cylinder. It can be connected to the small diluent cylinder but this is generally considered sub optimal or even bad practice.

The major benefit of a BOV is the speed and simplicity of switching to bailout, especially if you have a CO2 hit.

A drawback of a BOV is the shared mouthpiece. Therefore you must have a separate 2nd stage regulator and hose connected to the bailout cylinder. This is also your emergency regulator to donate to other divers.

 

[stretchthepenn]

Do you prefer using sidemount setup or the backmount setup for the O2ptima?

You didn't ask me, but I'mma jump in anyway 'cuz @jlcnuke and I dive the same unit in many of the same places.

I got trained on the Choptima in SM, but I've been using a BM setup (HP100 twinset, to be specific) for the past few months. The BM is convenient 'cuz it adds weight to counteract my drysuit's loft, and the setup is faster than SM. Plus, this winter saw low water levels at the quarry I usually dive, so gearing up with heavy steel SM tanks in shallow water was actively uncomfortable.

That being said, I adore SM and will probably use that configuration for diving the Choptima wet, especially with LP50 tanks.