Check this vintage ad out...

[rx7diver]

Hmmm. Looks like the diver would be rebreathing a significant volume of expired gas, with every inhalation--unless there was some special technique used.

rx7diver

 

[happy-diver]

How's that Luis bloke, hey great buoyancy

and now for the finale from Mad magazine from the early Seventies, of which I had a copy, back then

 

[rx7diver]

Thinking some more about this, trying to imagine how it would work. Looks like: Diver inhales, which causes the "can" and corrugated hose to fill with tank air. There must be a mechanical (?) connection to hold the exhaust mechanism closed during inhalation. If diver then exhales through his/her mouth, then the mechanical connection releases so that the (new) air in the can and hose and some of the diver's exhaled breath can flush out through the exhaust port. If this indeed is how this reg works, I wonder if the diver is ordinarily supposed to exhale through his/her nose, into his mask.

rx7diver

 

[NothingClever]

You guys debating about the mechanical functions of early regulators are really getting in the way of me appreciating hot dive bunnies who pre-dated cartoonish cosmetic surgery and excessive tattoos.

 

[Akimbo]

Hmmm. Looks like the diver would be rebreathing a significant volume of expired gas, with every inhalation--unless there was some special technique used.

A lot of European pure Oxygen rebreathers in that era had one hose to the chest-mounted canister/bag. They were mostly made for combat swimmers and mine safety. I guess that Dräger borrowed the concept.

 

[Pressurehead]

I guess that Dräger borrowed the concept.

 

[Pressurehead]

 

[CT-Rich]

How it worked? Probably not very well...

Inhale and exhale into the same hose.

Drager Delpin II

View attachment 755234



View attachment 755235

Exhaust valve on the rear.

View attachment 755236


View attachment 755237

Most of the fresh air from the tank is getting pushed out the exhaust, while the stale air gets recycled. It’s kind of amazing that they thought this was a good design at any time…

It’s like the kid that thinks a four foot garden hose will make a good snorkel.

 

[JMBL]

It’s like the kid that thinks a four foot garden hose will make a good snorkel.

Kids have an excuse at least : haven't studied physics yet. But what about the engineers who designed that rig ?

 

[Luis H]

Most of the fresh air from the tank is getting pushed out the exhaust, while the stale air gets recycled. It’s kind of amazing that they thought this was a good design at any time…

It’s like the kid that thinks a four foot garden hose will make a good snorkel.

Yeah, you need to use deeper breaths, which is not a bad idea in general for diving to flush CO2.

The volume of a single (ambient pressure) one inch hose (20 inches long) is about 16 inches cubed (or 257 ml). The volume of the can is about 200 ml (a calculated approximation). For a total of about 457 ml (can and hose).

Per Wikipedia:

“Tidal volume (symbol VT or TV) is the volume of air moved into or out of the lungs during a normal breath. In a healthy, young human adult, tidal volume is approximately 500 ml per inspiration or 7 ml/kg of body mass.”

That assumes a 71kg person or 156 pounds.


So, if you do take deep breaths, you would flush must of your expired CO2 out, but not all of it.


I would multiply the numbers on the vertical scale by about 80 kg (for a 176 pound person). Adjust it as needed.