Porpoise CA-1 regulator

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Fibonacci

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Location
Melbourne, Australia
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I just don't log dives
Neptune smiled on me at the start of 2019... I stumbled across a 1954 Porpoise CA-1 regulator complete with the original case and twin tank adaptor!

It is in pretty good condition, quite rare to find in Australia these days... so I'm now having fun trying to source NOS or reproduction parts to restore it back to working condition. The diaphragm had dissolved into goo and attached itself to the inside of the cover plate... but all the other parts are intact.

I already have a copy of the Historical Diving Society's excellent book detailing Ted Eldred's work developing the Porpoise line of regulators... the world's first commercially available single hose regulator!

When La Spirotechnique and Aqua-Lung were only producing twin hose scuba and had never dreamed of a single hose system, along came an Australian who changed scuba diving forever. This is the complete story of the engineering brilliance of Australia’s Ted Eldred and the development of his Porpoise scuba, which set today’s world-wide diving standard. Acknowledged by many including HDS US and HDS Australia-Pacific, as the first to mass produce the single hose, 2 stage scuba system as used by scuba divers today.

PORPOISE-BOOK-COVER.jpg


The “Porpoise” book reprint

Porpoise 1.jpeg


Porpoise 2.jpeg


Porpoise 3.jpeg


Porpoise 4.jpeg
 
WOW. Amazing pictures. The condition of some of the equipment showing its age. How old is it?
 
65 years old in 2019... it actually came up quite well after just a brief soak in 50:50 white vinegar and water... I'll post more pics as I restore it... but I think it could do with a new diaphragm as a start :D

Porpoise 6.jpeg
 
manual
 

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Picked up a couple of vintage LP tanks (surplus WWII aircraft oxygen bottles I believe) with manifold which should suit the Porpoise if I can find an adaptor!

Does anyone know the correct thread type?
Major diameter appears to be OD 22.4mm x 14 tpi so possibly 5/8" BSP?

Seem sound enough but some surface rust, will put into an electrolysis bath to stabilise it, two-pack prime and then hopefully get them hydro tested and stamped.

Interesting that back in the day, the initial testing stamp, type and serial number were all on a brass collar shrunk around the neck... no stamps into the shoulder as is current practice.

Vintage twins valve.jpeg
 
The entire second stage has now been stripped down, pickled in 50:50 white vinegar and water then ultrasonically cleaned.
Sourced a length of the correct ribbed hose, and currently chasing a NOS diaphragm... fingers crossed the Historical Diving Society may have stocks!

In the meantime, I scanned Ted Eldridge's original sectioned drawing of the second stage, traced it in CAD then scaled and rotated to create a 3D model of the Porpoise diaphragm... be nice to have a reproduction made in silicone rubber!

Porpoise Diaphragm 3D CAD section trace.JPG


Porpoise Diaphragm 3D CAD section.JPG
 
First tank out of the electrolysis bath, came up pretty well!
One good thing about the Porpoise is many of the fittings are standard oxyacetylene 5/8”-18 UNF, so rigging up an IP checker via an old LP inflator hose and a new oxygen hose connector took 2 mins and $9!

D196D5FE-6530-4767-B7FC-538EB8954FEE.jpeg


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Does anyone know the correct thread type?
Major diameter appears to be OD 22.4mm x 14 tpi so possibly 5/8" BSP?
thread looks like Oxygen thread from Germany. In Russia it known as Сп 21.8х1.81-А or just СП 21.8
fee8e208de8ef94a3d233e6e7549ef4c.jpg

or
2ac3130bedc2d33c44a3708fcfc17bc0.jpg

Here is drawing for nut.
Do you have calipers to recheck diameter?

here is drawing for connector from СП21 to DIN
a5d82558b4bf5b46428378d22c985ccd.jpg


...or it could be Whitworth thread G 5/8 BSPP Whitworth Pipe Thread DIN ISO 228 (DIN 259) aka DIN

here is some more threads Резьбы и О-ринги: Клуб любителей экзотического дайвинга: Подводный форум больных дайвингом. :)
 

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