Why use a double hose

[rhwestfall]

Here is a really cool home made rig where a somewhat "modern single hose first stage" has been mounted to a DH can, and plumbed to a second stage (home made). With no DH "body", the two are plumbed together in a very cool way.

This guy is really talented and creative!

 

[captain]

In a 2 stage double hose, this is (most of) the first stage (this is a VDH Cyclone). You can see the lip that is the part that connects to the tank valve (yoke), just like a conventional first stage.
View attachment 582484
here is the second stage, and both are attached to a body that is attached to the cans. The diaphragm sits over this, and the exhaust can is placed over that.
View attachment 582483

Additionally, the large screw you see here above the second stage is the back side of the diaphragm first stage.

I'll add the large screw is the IP adjustment.

 

[captain]

Here is a really cool home made rig where a somewhat "modern single hose first stage" has been mounted to a DH can, and plumbed to a second stage (home made). With no DH "body", the two are plumbed together in a very cool way.View attachment 582487View attachment 582488

This guy is really talented and creative!

The only issue I see is it appears the the 2nd lever is not located at the center line of the diaphragm where ideally it should be.

 

[John C. Ratliff]

He wasn't that old in those pictures that was probably 1950's, he was say the high side of middle age then. That's when he was making the movies and doing most of the work he's known for.

Not really, as this was the last time he was diving. He was in his 80s at the time, I believe.

One other thing you need to know, he was a life-long smoker of both pipes, cigars and cigarettes, a left-over habit from WWII. He probably was suffering from some lung issues, and hence that need for the front-mount regulator.

SeaRat

 

[John C. Ratliff]

I am new to diving DH, but last weekend I spent about five minutes inverted vertical (vertical line from toes to head, head down), because I could... it breathed wonderfully, and DRY.

Respectfully,
James

People mistake the positioning of the double hose regulator. The double hose regulator is best dived with doubles, with the regulator on a center post, located between the shoulder blades. This will give optimal breathing in most positions.

Most people don't realize that a single hose regulator also has disadvantaged positions. Being vertical and looking up, or being inverted, puts the lungs much lower than the second stage, resulting in harder breathing independent of how easy the regulator's initial breaking effort.

SeaRat

 

[Scuba Lawyer]

Took a break from my Trieste and MR12 projects today and did a tune up of my Voit NAVY Phoenix HPR DBE enhanced venturi DH reg. Hoping to get out for a dive at least off the beach if our storm surf would ever stop. Got cracking pressure to less than 1/2" H2O at a stable IP of 135 psi. You think about inhaling and it anticipates your needs. Love this reg!