Upgrade to a longer primary hose

[dmaziuk]

Hi Nemrod,
I have been following along with this topic because of my interest in it.Was wondering though,why do you just recommend the right angle connector,only, for the longer primary hose?

Think of the angles between the mouthpiece and the hose during normal use -- if this is what you're asking:

• The long hose plugs into the side of 2nd stage and goes down. There's a 90-degree angle between "side" and "down". An elbow in there will make it easier to hold it in your mouth for extended periods.
• The short[-er] hose goes out of the side and to the side above and around your shoulder. There isn't much of an angle there so a bent connector is not only not needed, it'll likely make the reg less comfortable to hold.
• The "traditional" octopus is supposed to be not used 99% of the time, not used for long when it is used, and when it's used by another diver, the angles are different. So you won't gain much, if anything, by adding an elbow.

 

[Nemrod]

Think of the angles between the mouthpiece and the hose during normal use -- if this is what you're asking:

• The long hose plugs into the side of 2nd stage and goes down. There's a 90-degree angle between "side" and "down". An elbow in there will make it easier to hold it in your mouth for extended periods.
• The short[-er] hose goes out of the side and to the side above and around your shoulder. There isn't much of an angle there so a bent connector is not only not needed, it'll likely make the reg less comfortable to hold.
• The "traditional" octopus is supposed to be not used 99% of the time, not used for long when it is used, and when it's used by another diver, the angles are different. So you won't gain much, if anything, by adding an elbow.

Yes, very good explanation. As an actual minimalist diver and not one that just pays it lip service, if it is not actually needed then I prefer not to have it. For me, based on my diving and my gear, I find that if I am going to breath from the long hose as primary (under the shoulder routing, 36 to 42 inch hose) then I need the 90/60 degree fitting there. But for a traditional long(er) hose octopus the benefit is questionable and likely to be used so rarely (though we should occasionally practice) that I cannot justify it really.

And what he said!

N

 

[waterduck]

Yes, very good explanation. As an actual minimalist diver and not one that just pays it lip service, if it is not actually needed then I prefer not to have it. For me, based on my diving and my gear, I find that if I am going to breath from the long hose as primary (under the shoulder routing, 36 to 42 inch hose) then I need the 90/60 degree fitting there. But for a traditional long(er) hose octopus the benefit is questionable and likely to be used so rarely (though we should occasionally practice) that I cannot justify it really.

And what he said!

N

Thanks guys

 

[fiziks]

I have to tear into this; with respect:
I have the digital Bench test read outs to prove that this is absolutely false.
The change is minimal enough to not be detected on Scuba Instrument's Digital Bench Test platform.

If your explanation were true, Your 1st stage and 2nd stage would negate this as is their job for something that's not even a mm difference in orfice size. But the matter is there is no narrowing or restriction of orfice size or airflow with Omni Swivels or Angle adapters. The only difference is the angle change, which will not affect airflow perceivable on any analog gauge.
My readouts show that Angle Adapter, Swivel, or no adapters, it's all the same readouts in regards to airflow and Magnehelic.

Swivels that are at a 180 degree angle will, by your definition flow better than an angle adapter.
Their setup is the same, Omni or Generic, and it is simply an orb shaped chamber with a eyeballed-measure same entry/exit orifice size, sealed by orings to keep the pressure from escaping. There is no narrowing of the orfice from the hose connection to the swivel orb.

Thank you for doing the bench tests... As I said before, there is little difference using the elbows. If you want to get into specifics, Scubapro sells, or used to sell, a 70 degree elbow and claimed that it had no affect on breathing resistance. The rep, who taught my regulator repair tech class, said they had done bench tests and that they were able to see a difference in breathing resistance under load for some elbows. He did not mention specific brands. This was over 15 years ago. It would not surprise me if that is no longer the case. Elbows are pretty simple devices.

As for swivels, your tests were specifically with the Omniswivel (according to what you said), and I said that the Omniswivel was better than most of the cheap ones and that I couldn't tell the difference between using an elbow and not using one (to be fair, I should have edited my post to say also that I couldn't tell the difference between the Omniswivel, the elbow or neither, but I could definitely tell with the cheap swivel, although I only compared the cheap swivel to the elbow). So I can't see what you are taking exception to. Did you test some $15 swivels (not elbows) from different sources and find they perform as well as the Omniswivel? Ocean Reef sells a swivel for use with their FFMs and we've found that to perform well. But I have seen two of the cheap swivels literally fall apart while the diver was assembling his equipment. What if that happens during the dive?

 

[g1138]

Thank you for doing the bench tests... As I said before, there is little difference using the elbows. If you want to get into specifics, Scubapro sells, or used to sell, a 70 degree elbow and claimed that it had no affect on breathing resistance. The rep, who taught my regulator repair tech class, said they had done bench tests and that they were able to see a difference in breathing resistance under load for some elbows. He did not mention specific brands. This was over 15 years ago. It would not surprise me if that is no longer the case. Elbows are pretty simple devices.

As for swivels, your tests were specifically with the Omniswivel (according to what you said), and I said that the Omniswivel was better than most of the cheap ones and that I couldn't tell the difference between using an elbow and not using one (to be fair, I should have edited my post to say also that I couldn't tell the difference between the Omniswivel, the elbow or neither, but I could definitely tell with the cheap swivel, although I only compared the cheap swivel to the elbow). So I can't see what you are taking exception to. Did you test some $15 swivels (not elbows) from different sources and find they perform as well as the Omniswivel? Ocean Reef sells a swivel for use with their FFMs and we've found that to perform well. But I have seen two of the cheap swivels literally fall apart while the diver was assembling his equipment. What if that happens during the dive?

If I can nitpick, your original description was taken to an extreme. Blind testing you won't notice anything different.
That's the main point I wanted to rebuttal with.

I have heard stories of generic swivels falling apart because of an inferior screw. Omni Swivel also had this problem early on in 2007. For the most part that is corrected for both brands in current productions.
However the generic swivels still have a reputation to fail earlier in service intervals than Omni Swivel. That is to say they will develop leaks and require oring service replacement earlier than Omni Swivel, more times than not. That is their reputation and it probably comes down to Omni's having tighter tolerances than generic, which is why they're more expensive (I'm guessing from memory, I can't prove that).

I have also digital benched tested the generic swivels. No perceivable difference. There will always be minute differences even testing the same gear multiple times on a digital bench. That is because of the human error affecting airflow and the rate air is input into the test run.
The differences are negligible.
For non-digital bench tests, you can drastically affect your Magnehelic reading both consciously and subconsciously, especially if you know what you're testing and have a preconceived perception.

Even with that said, if there were a difference in breathing resistance or flow, a tech can tune any of the configurations to breath better or worse to each other; it only takes minute adjustments on 2nd stage spring tension or orfice to make a correction.
On a relevant example you'll get the same minute difference in flow from a 22in hose VS a 9ft hose using the same 2nd stage. Mathematically there can be big difference in flow depending on how small a unit of measure you choose to use (say nano-cubic feet per minute; if we were able to measure in that). But this can be negated by tuning your 2nd stage.

The point I'm getting at is I still say there's no perceived difference in flow or breathing resistance if you were to reconfigure without re-tuning.