SBP Superflow hoses vs other’s?

[Angelo Farina]

I saw a regulator that was only finger tight blow off the hose. It was a real eye-opening experience. I think our instructor did it on purpose.

When my regs are pressurized there is a strong axial force on the threads, making it impossible to unscrew the nut by hand, and very hard with the wrench. The nut becomes easy to unscrew only when not pressurised. So the risk that the nut self-unscrews underwater is zero even if hand-tightened.
The risk is that the nut was already almost completely unscrewed before pressurising the reg.
Of course checking the nuts (completely screwed in, but not overtightened) before pressurising the regs is a standard procedure for divers who, as me, hand screw the second stage.
On the first stage end, instead, the situation is very different. The O-ring is static and there is no swivel. An hand-tightened hose can effectively extrude the O-ring, as it is not designed for allowing rotation. This end of the hose is designed for being properly tightened with a torque-measuring wrench.

 

[rhwestfall]

And that is why a double-hose is so superior for extreme conditions. Large brass surface area.... Heat transfer (and dry second stage). And why metal is desirable in ice... You are very smart and educated, but you are in left field if you believe the spline nuts were for the benefit and non-standard approach of hand tightening....

 

[Angelo Farina]

And that is why a double-hose is so superior for extreme conditions. Large brass surface area.... Heat transfer (and dry second stage). And why netal is desirable in ice... You are very smart and educated, but you are in left field if you believe the spline nuts were for the benefit and non-standard approach of hand tightening....

As said, I did think the spline nut was about hand tightening simply because this is what any engineer has been taught...
It is a normal association, such as seeing a Phillips head on screws designed for NOT being routinely removed and reinstalled during service, and a Posidrive, Hex or Torx head on screws which instead should be unscrewed and screwed again...

 

[BoundForElsewhere]

The wrench is a tool for loosening the finned nut. Not for tightening. The wrench cannot be used with a torque meter, hence it is not designed for tightening.
Any mechanical engineer's handbook contain a phrase saying something as "splined nuts are designed for hand tightening".
Any engineer, as me, seeing for the first time the SP splined nut thinks immediately that it is for hand tightening...
As this is what is written in his manual!
Regarding heat exchange: some finned nuts are effectively designed for improving heat exchange. But this is typjcally done for air cooling. The air-to-metal heat exchange coefficient, in natural convection, is very low, typically just 5-10 W/(m2s).
In water, instead, the natural convection heat transfer coefficient is much larger: 2000÷5000 W/(m2s). Hence a finned nut gives no practical benefit to heat transfer, underwater.

I love having kick-ass engineers in our midst.

 

[rhwestfall]

Additionally, their factory servicing videos clearly show the spline wrench utilized (removal and replacement), and demonstrate "special" techniques to address a tight spline nut so as not to rotate the air barrel and damage internals of the regulator. Nowhere in their literature or videos do they ever show hand tightening of the hose to the regulator. Their adoption of a universal spline nut (a plastic one exists in their "economy fleet") is obviously standardization, and you would be correct to state it provides no thermal benefit, and it is frequently securing a polymer air barrel. Those regulators are specifically identified an not "cold water" regulators.

 

[rhwestfall]

and another tidbit:

 

[Angelo Farina]

Usually (and unfortunately) service manuals are not written by the same engineer who designed the device.
Said that, my opinion is that the SP splined nut, accompanied by its protective sleeve, (which avoids the risk of unwanted self-unscrewing) was designed for being perfectly safe to be hand-tightened.
Of cours it can also be wrench-tightened, but MODERATELY, as the manual states clearly.
The risk here is over-tightening the nut, not tightening too gently...
This is obtained easily using just your fingers, if your hands have a decent force.
If your hands are weak, then you use that special wrench, but very gently...

 

[Pearlman]

That being said, certain models of SP second stage regulators not only have the splined nut on the hose, but also on a second nut that secures the air barrel in the regulator. So, if you are intending to self-service, you will be needing the spline wrench (unless you can locate/secure an aftermarket jam nut).....

The nut for the hose (blue arrow) is under that shroud, and the red is the air barrel nut. Both are spline nuts....View attachment 709113
There are different philosophies regarding how hoses are attached, but you don't "finger tight" the air barrel nut, and do snug it up.....

Looks like they changed the design a bit? Here is my latest purchase that arrived yesterday. The nut looks different and a single piece - if it is really two separate nuts I can’t make out which one is the barrel nut and which one for the hose. The hose rotates 360 degrees. The Scubapro Tool I got only fits the outer spline only. I need to change to an Apeks 2.1 mtr hose I will get tomorrow.

Any tips? (I am not yet ready to do a maintenance course and open to fiddle with the innards until I dive a few dozen dives over this year - I just want to change the hose ).

 

[rhwestfall]

Looks like they changed the design a bit?

nope..

(maybe prettier?)

(the 260 is a cold water reg, so the splines are exposed for heat transfer - here we go again)

I can’t make out which one is the barrel nut and which one for the hose

I need to change to an Apeks 2.1 mtr hose I will get tomorrow.

Any tips?

Until they seize, you only need the single wrench to remove the hose..... The hose isn't attached with gorilla force. It is however more than finger tight (and it continues)...

Once the hose is removed, the wrench also removes the air barrel retainer nut....

 

[Pearlman]

upnope..View attachment 712897 (maybe prettier?)

(the 260 is a cold water reg, so the splines are exposed for heat transfer - here we go again)


View attachment 712894




Until they seize, you only need the single wrench to remove the hose..... The hose isn't attached with gorilla force. It is however more than finger tight (and it continues)...

Once the hose is removed, the wrench also removes the air barrel retainer nut....

My fear is about rotating the air barrel inside. I don’t want to do that disturb the careful tuning that came from factory or a future servicing, everytime I change a hose. Is there a risk and a special technique to keep the air barrel in its original position while turning the nut? So the secret is that only after removing the hose if I use the wrench the air barrel will turn?

Edit: I did it just now. Whew! The joint was hidden and recessed under the larger splines barrel and the O-ring showed itself the moment I loosened the nut. The worry kept me up a few nights as I was shopping and researching regs to buy. It makes such a huge difference to have gear in hand to play with rather than see it for the first time just moments before you head to the boat with rental gear …

Thanks a Ton!