What makes a Conshelf 30 different?

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The 1st stage of the Royal and Pro series always reminds me of a flying saucer. All it needs is flashing lights and little tiny green men saying “Take me to your leader!” 😁
Thank you @USdiver1! The reg 1st stage I got (an “orphan” part) was sold to me as a Conshelf SE 2. If I use the large ID hose with 1/2” fitting into the 1st stage, what fitting should I expect on the 2nd stage end? Will it be the standard one to fit my 1085 boxes? Every 2nd stage I’ve ever seen from AL had the same connector on the downstream side.
Just go here and pick out the one you want.

I went from the 31" rubber to the 40" miflex. Happy with the change. So it is a standard 9/16" female into the 2nd stage, but a 1/2" oversize male from the 1st stage. Friggin' engineers.
And so we end up with the same size inlet into the second stage... does that become a choke point after that nice 1/2” ID hose?the actual opening in a “standard” 9/16” fitting is actually pretty small. I gues the limiting factor is how much air can move through the volcano and out into the chamber. The more I learn, the “confuseder” I get!
It appears that AL found a batch of unused Con XIV seconds and just made a new purge button sticker Those I have seen don’t have the external poppet adjust of the Conshelf 14.
Not quite but near, Try this.

1. The Conshelf XIV Fourteen (14) second stage part number was 1085-30 back then hence the dash 30 was used from the original part number to make the new Conshelf 30 model number.

2. Further no one was keen on using Roman numerals anymore and Google wasn't invented yet so you couldn't look it up. (it would have been XV and could have been the next variant option)

3. In addition the Conshelf XIV "cock and balls" decal became the plane Conshelf 14 decal to save further embarrassment.

4. No external soldered cap ("Weld o let") was fitted on the metal 2nd stage Box Bottom back then. It was added a lot later.

3. The left over part as you put it was the 1st stage from the poor selling Royal range (not the 1085-30 second stage)

4. The Royal 1st stage came in either hard chrome Shiny polished or the very unpopular matt bead blasted (vapour blasted) finished that scuffed too easy and discontinued

I can answer the design brief for the enlarged 1/2" hose diameter and odd outlet angle in a later post. Iain
Black 2nd stage cap on a Chrome plated back body.
5. There was originally a military application here to tone down the bright shiny metal.
and stop the divers on the surface acting like landing lights for low flying aircraft. Iain
Having used the Conshelf SE [with 1/2 inch LP hoses] for commercial scuba work, I can confirm that it is one of the driest breathing regulators of all times. Plus it simply can not be over worked, at least not down to 200'. Of all my regulators, the Connie SE is my 'go to' workhorse when I need to guarantee lots of airflow. Definitely not a gimm

And so we end up with the same size inlet into the second stage... does that become a choke point after that nice 1/2” ID hose?the actual opening in a “standard” 9/16” fitting is actually pretty small. I gues the limiting factor is how much air can move through the volcano and out into the chamber. The more I learn, the “confuseder” I get!
A bigger (smaller) choke point, I think, is air squeezing through the second stage orifice - seat interface.
Back to the one apparently different mechanical feature… has anyone seen a difference using the large bore hose going to their primary second stage?
6. The larger bore 1/2" hose was in fact the result of a required design requirement. You need to bear in mind back then the US Navy NEDU and Royal Navy Experimental Diving Unit Alverstoke were after a 1st stage regulator to meet an improved breathing resistance at depth.

7. Consider also US Divers at around 73 to 75 owned the Kirby Morgan Band Mask manufacturing rights and tooling for the then US Divers KMB Band Mask Model Mark 9 with the Mark 10 or KMB-10 from 75 to 1988 There were others and helmet versions. The hose or umbilical was 3/8"ID internal made to a SAE100 R3 specification compared to the 1/4" bore hose used on all other scuba regulators
For comparison a surface supplied 3/8 hose can be used at a 120 meter length with air down to a depth of 50 MSW 165 FSW

8 The Royal 1st stage with the larger ports and outlet post angled towards the side block came many years later but on a band mask as a design idea the reduced kinking and strain on the end crimped fitting was a plus. Other variants on the standard Conshelf Supreme were made including a 44 inch 1/4" hose assembly for the Royal Navy as we fitted our cylinders upside down back then used one cylinder down to restricted flow then equalised allowing 50% in reserve you equalised twice before returning to service with 25% in reserve as long as you turned the cylinder off after equalising. Ideal in black water oil slicks etc for plane recovery etc. Iain
Somebody at AL must have been smoking left handed cigarettes that day. 🤪 Or was the extra large LP port for use inflating a dry suit, or some other special purpose?
9. First off who the heck is AL I trust you didn't mean Aqualung.
To get this off my chest so to speak... It was and still is in some quarter US Divers

Aqualung didn't exist back then they were some pop]xy French poodle calling themselves La Spirotechnique

The French lot didn't make a move until much later and turning US Divers into a poxy scobee doo mask fin and snorkel range. Dont get me started. Iain
The advert claimed larger bore meant you could move a larger volume of air.
10. You can it does and it has a clear mechanical engineering advantage in diving
I'm not sure if you could describe it as lyrics for another Grateful Dead song
But maybe a JJ Cale number would suit better......... Call me the Breeze

To get a flow of any kind you first need a pressure drop
With a pressure drop you get a gas velocity
The greater that pressure drop the greater the gas velocity
The greater the gas velocity the colder the gas becomes
The colder the gas becomes the greater the potency for water vapour to condense
The greater the water vapour condenses out of gas vapour the greater the water condensate droplets
The greater the condensate droplets the greater the risk of freezing
The greater the risk of freezing the more the diver moans and groans.
And so on.

Now add into the design mix the development of mechanical breathing simulators, the military requirement for easier breathing at depth and the deep diving and closed bell diving HE02 on open circuit with a 95/5 oxy helium mix.

Then going onto deep bail out in your KMB-10 on the bell stage for sticks and grins and feeling the solid dust and frozen solid dead flys blasting out into the back of your mouth at sonic velocity at minus heck knows what temperature from a pin pick of a hose out of some scuba shack. No? then increase the internal diameter lower the velocity speed and you can taste the warm wet crunch feeling of chewing the now soft fly.
It's a no brainer choice within a limited preference range. Iain
@iain/hsm, first let me thank you profusely for the wealth of information you have provided. I know I will be sifting through, rereading, and absorbing this knowledge for a while!
Second, if my tone sounded too flip or disrespectful, please forgive… I sometimes get a little carried away with some of my comments. No offense intended. I have a long-standing attachment to what is now Aqua Lung here and had US Divers gear before it became the sissified stuff it has now become. My preferred reg rig involves a 1085 box in front and one of the Conshelf series of 1st stages with a single HP and 4 LP ports on my tank behind me.
I’m an aging recreational diver, so that probably makes me enough a dilettante to sometimes stir up irritation among serious divers, but I’m just having fun while I still can… no offense intended.
Anyway, all that said, thanks again to all of you who have contributed so much to my search for information about the elusive Conshelf 30
Green 🐸 Frog

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