Pony Bottle / Stage Bottle / Decompression Bottle. What's the difference?

[Boston Breakwater]

Hello. I was curious about these terms? Are they Generic? Recreational? Technical? Interchangeable?
I like many of you have heard these terms misused.(Which may cause confusion.) I was wondering what the meaning, and purpose of each term is, and is there a "Default size" for each bottle?
Cheers.

 

[PfcAJ]

The intended use.

A pony bottle is reserve gas, used on a recreational no-deco stop dive. It’s simply there for backup. 30-40cuft seems adequate. Opinions vary.

A deco bottle is for decompression. Often filled with a nitrox mix, up to and including 100% oxygen. This cannot be breathed during the bottom portion of the dive due to oxygen toxicity concerns. 40-80cuft depending on the needs of the dive. Technical.

A stage bottle is to be used on the bottom portion of the dive. Filled with bottom mix. When your main supply isn’t adequate for the planned dive, a stage bottle is breathed first. 80cuft. Technical, but most often specifically used in cave diving.

A safety bottle is extra reserve gas used in technical diving. Could be deco gas, could be bottom gas. Used on extended range cave dives and deco dives where the stops are very long. These are not planned to be used, and are only there in case of an emergency. Usually 80cuft, occasionally steels for oxygen due to their high capacity.

 

[Edward3c]

Hello. I was curious about these terms? Are they Generic? Recreational? Technical? Interchangeable?
I like many of you have heard these terms misused.(Which may cause confusion.)

It’s all just diving. The distinguishing terms are just marketing to increase the number of income streams.

When I learned to dive, 40+ years ago, twin sets where going out of fashion; and we were taught how to do dives with mandatory deco.

 

[Angelo Farina]

It’s all just diving. The distinguishing terms are just marketing to increase the number of income streams.

When I learned to dive, 40+ years ago, twin sets where going out of fashion; and we were taught how to do dives with mandatory deco.

We were also taught that a dive planned with slight deco (a few minutes at 3m) was safer than a dive planned to be without deco (there was no safety stop at the time),but on the edge of NDL.
I am still convinced that it is safer to dive being equipped and trained for a slight deco, even if, with modern computers, the real need of a deco is nowadays so rare...
Of course, being ready for a deco means to always have proper equipment redundancy. At the times, a twin set was the standard. Nowadays, renting a twin set is quite uncommon, so the modern solution is to carry a pony of reasonable size (depending on the depth). Call it as you like.
I always fill my one with air, I want to be able to breath from it at any depth...
It must be said that I last used my one perhaps 10 years ago. Nowadays I only make very shallow dives...

 

[Graeme Fraser]

Totally agree with the technical terminology confirmed by other posters.

Just to confuse things slightly, over here we tend to use the term 'stage' and 'deco' cylinder interchangeably. In other words, a UK diver will often use the term stage when referring to his / her deco cylinder.

Not saying it's right or wrong, it's just to save any misunderstanding when reading posts from over 'ere.

 

[Divin'Papaw]

The difference is one of function as @PfcAJ has covered. He pretty much nailed how I’ve also learned to use these terms.

Pony - used in rec no-stop diving as an emergency redundant air source. Gas not included in the plan for the dive.

Deco - used in tec decompression diving. A diver will carry at least one and often times multiple bottles of different mixes to accelerate decompression. Used on ascent. Factored into gas plan for the dive.

Stage - additional gas used during descent and/or the bottom part of the dive. Factored into gas plan for the dive. Often used in cave diving or deep open circuit trimix diving.

 

[tbone1004]

The intended use.

A pony bottle is reserve gas, used on a recreational no-deco stop dive. It’s simply there for backup. 30-40cuft seems adequate. Opinions vary.

A deco bottle is for decompression. Often filled with a nitrox mix, up to and including 100% oxygen. This cannot be breathed during the bottom portion of the dive due to oxygen toxicity concerns. 40-80cuft depending on the needs of the dive. Technical.

A stage bottle is to be used on the bottom portion of the dive. Filled with bottom mix. When your main supply isn’t adequate for the planned dive, a stage bottle is breathed first. 80cuft. Technical, but most often specifically used in cave diving.

A safety bottle is extra reserve gas used in technical diving. Could be deco gas, could be bottom gas. Used on extended range cave dives and deco dives where the stops are very long. These are not planned to be used, and are only there in case of an emergency. Usually 80cuft, occasionally steels for oxygen due to their high capacity.

@Boston Breakwater there are also bailout bottles used in rebreathers that are a weird combo of deco/stage/safety bottles. Basically it's all of the gas you'd need to get back to the surface on open circuit.

Use case is where they get their names though. Once you get to technical level diving, pretty much everything is an AL80 with an odd AL40 thrown into the mix on occasion.

You may look above and ask why the technical community accepts the use of safety bottles, but not pony bottles. My answer to that is pony bottles are often used as an equipment solution to a skills problem- " I don't trust my buddy", or used when someone really should be using a properly redundant configuration but chooses not to. When safety bottles come into play, they're usually on gargantuan sized exploration level cave dives and they are strategically staged in the cave as an extra buffer in case something crazy happened, i.e. siltouts at a restriction kind of thing. The divers all have enough gas to get home, but the dive plans or specific location may have meant that the normal reserves carried had to be cut a bit thin or too close for comfort. Different than the use of a pony bottle where for most all of those dives you could make a CESA if something really went sideways.

 

[tursiops]

It’s all just diving. The distinguishing terms are just marketing to increase the number of income streams.

Nah. Rather, it is to prevent confusion and improve communication. It is kind of like "food" versus "meat" and "potatoes." Having more specificity allows better communication. Does having the more specific terms cause people to buy more meat or potatoes?

 

[RyanT]

Just to confuse things slightly, over here we tend to use the term 'stage' and 'deco' cylinder interchangeably.

.

On this side of the pond, my budies and I do as well. We're not cave divers and we don't use bottom stages for our dives. If we did, I can see where mixing the terminology would be a bad thing. As it is, we all know what we're talking about when we discuss our dive plan.

 

[Divin'Papaw]

You may look above and ask why the technical community accepts the use of safety bottles, but not pony bottles. My answer to that is pony bottles are often used as an equipment solution to a skills problem- " I don't trust my buddy", or used when someone really should be using a properly redundant configuration but chooses not to.

Some of us who are part of the “technical community” do consider a pony bottle a “properly redundant configuration” for [U]recreational[/U] diving. It’s a completely philosophical disagreement and to use the term “technical community” as if it speaks with one voice on this subject is just not true. That horse has been whipped but yet the beatings continue.