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Post by duckbill on Dec 15, 2019 20:39:26 GMT -8
Here's a quiz for you: What is the difference between a US Divers Octopus 2nd stage and their standard second stage? Good Dives, Charlie Without consulting my manuals, the only thing different I can think of offhand is that the octopus regulator was detuned slightly to prevent free flow. |
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Post by nikeajax on Dec 16, 2019 8:21:30 GMT -8
The sticker, and length of the hose...
JB
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Post by cnotthoff on Dec 16, 2019 9:11:48 GMT -8
OK Jay, I can't argue with that. But, I was going for something that is unique to USD 2nd stages as far as I know. DB is close.
Good Dives,
Charlie
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Post by vance on Dec 17, 2019 8:04:11 GMT -8
Snap up that crusty DA AquaMaster for only $649.99 (free shipping!) One hose might not be completely broken. Or the one with Special Forces in the title for only $425. If it had a label they would ask for more! EDIT: I shoulda led with, "Gee, I don't know, Charlie!"  |
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Post by cnotthoff on Dec 17, 2019 11:23:09 GMT -8
You guys giving up on octopus question?
Good Dives,
Charlie
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Post by nikeajax on Dec 17, 2019 11:53:52 GMT -8
Charlie, that's as good as yer gunna get: I'm sure there are people who do know but they can't and won't be bothered with any sort of participation   Is the volcano orifice bigger: you'd think you'd want something that delivered more are than usual... JB |
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Post by SeaRat on Dec 17, 2019 12:43:59 GMT -8
It's been a very busy weekend. I have a sneakin' suspicion it's the exhaust tee color, and lack of a neck strap. I'll look at my catalogs later to see,if I'm correct.
John
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Post by cnotthoff on Dec 17, 2019 14:20:17 GMT -8
DB is correct that the Octopus needs to be detuned to prevent free flow. To the best of my knowledge, US Divers is the only manufacturer who does this by using a stronger spring.  Con2nd by Charlie will, on Flickr Good Dives, Charlie |
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Post by vance on Dec 17, 2019 14:33:36 GMT -8
Is that octopus a Conshelf second stage? Or just similar? I see the two springs listed for regular and octopus.
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Post by cnotthoff on Dec 17, 2019 15:42:15 GMT -8
Phil,
The only difference between the Octopus in the box at the start of this thread, and a standard second stage that came with a Conshelf, Calypso, or Aquarius is that spring. OK, longer hose and decal too.
Some of you may have noticed the adjustment port in the diagram. Those came along in the 90's . Since the brass second stage box bottom was only available to the military by then, they are rarely seen. US Divers second stages available to the public at that time and presently are plastic.
Back in the 70's when we started to add a second second stage so both me and my buddy could run out of air together, many divers just grabbed a spare second stage and screwed it in. Unless the standard spring was swapped out for one designed for an octopus, that second second stage tended to free flow. I suppose if some of you have altered your DA or similar double-hose to accept an Octopus, it would be important to use the octopus spring (depending on intermediate pressure).
Good Dives,
Charlie
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Post by duckbill on Dec 17, 2019 19:01:56 GMT -8
Interesting. I always thought it could be detuned via the locknut. At least that's what I've been doing on mine. Have I just been kidding myself?
I guess if the lever is too high, the elasticity of the diaphragm would put pressure on it, causing a freeflow. And if the lever is too low, the diaphragm will "find" it when acted upon by ambient pressure. So, having the lever too low does nothing more than lessen overall travel, diminishing maximum possible airflow. Am I thinking more clearly now?
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Post by cnotthoff on Dec 17, 2019 20:28:06 GMT -8
You got it DB.
If you are running it off a double-hose (two-stage of course) that may be functioning well with a lower intermediate pressure, a reg with a standard spring may be working just fine. It's all about how that sucker is breathing. You know what to do, if it ain't broke.
Good Dives,
Charlie
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Post by SeaRat on Dec 17, 2019 22:06:36 GMT -8
Charlie,
You've got a new avatar photo! Very good!
I've got a different way of dealing with the potential free-flow problem for the octopus, and it does involve a spring. I am using a Scubapro A.I.R. I in the "Pre-Dive" position on both my Sportsways Hydro-Twin and my Sportsways Pilot regulators. In the Pre-Dive position, there is about a two-inches of water pressure spring against the main lever, and so, no free-flow.
John
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Post by crabbyjim on Dec 18, 2019 6:14:48 GMT -8
This has been a most interesting and informative thread. I rarely use an octopus, so I don't have to deal with free flowing "safe seconds". When I dive with a bcd I have an octo attached to my inflator hose, otherwise I don't bother with them. I do pay attention to my dive buddy and my surroundings (air pressure, depth, time and location) as well as practicing the arcane exercise of free ascent.
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Post by cnotthoff on Dec 18, 2019 9:02:46 GMT -8
Hey Jim,
Since we didn't get to dive together during the last Monterey outing, I didn't see what rig you're using. How do you have an octo attached to your inflator hose?
Scubapro has the Air2 combination inflator and demand regulator. US Divers offered an Air Mic that could be adapted to their inflator.
Last week we were discussing how that arcane exercise of free ascent came in handy when I ran out of air inside the hold of a chip freighter back in the 70's.
Good Dives,
Charlie
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