"Standard" corrugated tube diameter on BCD?

[Luky1]

I have an IST BCD that I bought new 8 or 9 years ago and has served me well for 60-70 recreational dives, mainly in warm water Cozumel, and a few dive trips here in SoCal. I am planning a trip to Puerto Galera Philippines for late May and I decided to get an AIR2 (5th gen) to add to my BCD (and no I don't want to go into discussions on pro's/con's; I have read several of the threads on here and understand what I am getting in to. I will probably leave my octo on until I get to practice with the AIR2 and learn the limitations.)

I was trying to install it on my BCD tonight and removed the original inflator. It was then that I found the corrugated hose was too small in diameter to fit. I measured the "nipple" on the inflator and found it was only 19.3mm at the root under the barbs (25.4mm = 1"). The nipple on the AIR2 is about 24.9mm in diameter, so closer to 1". My question is whether there is a "standard diameter" corrugated tube used in most BC's or are they proprietary per manufacturer? Might I find one that is 1" on one end and ~3/4" on the other? I have found multiple replacement corrugated tubes on-line, but they only list length and not diameter.

Divegearexpress.com offers a "Dive Right" 16" corrugated tube that says:

• Compatible with most 1-inch diameter power inflators and BC Integrated second stages
• 
  
  Corrugated Hoses

They also offer a Dive Right remote exhaust elbow that says it will fit a 1.75" opening so it should fit my application (if it has the same collar threads as my BCD).
https://www.divegearexpress.com/dive-rite-elbow-remote-exhaust-w-nut-w-pull-cable

Am I reaching trying to do this? I also just bought a lightly used Atomic B2 reg and still need to take it in for service so I don't really want to look at buying a different BC before my trip. It seems I could get the new tube, shoulder exhaust valve, and clamps for about $50... If I try to go this route should I go for the 22" length since I may be using it as a safe second? (my current corrugated hose is 16").

 

[runsongas]

standard is 1 inch. 3/4 inch is what oceanic liked to use on their bcds. you probably would have to get the full assembly including the elbow and hose because the adapter hose from NESS would be too short when using the air2 as an actual backup.

12'' Corrugated Adapter Hose

 

[g1138]

runsongas pretty much answered your question above. I'll add and say the adjustment in corrugated hose length is dependent on the diver. Wear your BC adjusted as you would UW and put the inflator in your mouth. Make sure you can look up still without ripping the infiltrator from your mouth. Looking to your right & top right is slightly important but depending on comfort and preference you can give yourself a tiny blindspot at the benefit of not having a 22in corrugated hose dangling in the sand below you and fouling the Air 2.

I was able to stick with the 16in on my stock BC's when using an Air 2.
A longer corrugated hose will give you full range of head movement when using the Air2 but it also can create tension, pushing the Air2 out of your mouth when you keep your head neutral.

 

[Luky1]

standard is 1 inch. 3/4 inch is what oceanic liked to use on their bcds. you probably would have to get the full assembly including the elbow and hose because the adapter hose from NESS would be too short when using the air2 as an actual backup.

12'' Corrugated Adapter Hose

That's an awesome find! Thanks for sharing. Yeah, too bad it is only 12" as 16" would have been perfect for my application! I am going to dig a bit more to see if they make a 16" one...

G1138 thanks for the input. It's one of the things I had considered with a 22". A review for the replacement tubes said they were quite a bit softer than the originals so I thought that might help alleviate the side pressure issue from a longer corrugated hose.

My BCD also has a right shoulder dump valve (and right buttock) so being able to control my ascent while using the AIR2 is not a concern for me. I have good technique to release just a little air at a time so I might be able to swap out the inflator dump elbow for a standard elbow... I guess I will need to check out a couple of the LDS to see if they have something I might be able to try the fit before I buy it.

 

[Luky1]

I found this corrugated AIR 2 adapter hose by Hollis that is 16", but it says 1" x 1/2". Is anyone familiar with Hollis equipment to know if they really only use a 1/2" hose barb on their gear? (seems like that would be pretty small to me.)

Corrugated Adapter Hose 16”, Air 2 (1” x 1/2” hose)

 

[Umuntu]

I measured the "nipple" on the inflator and found it was only 19.3mm at the root under the barbs (25.4mm = 1"). The nipple on the AIR2 is about 24.9mm in diameter, so closer to 1".

You will also need a specific Scubapro AIR2 LP Inflator hose for the AIR2. The diameters are much larger than a standard LP Inflator hose because it requires a higher gas flow if you are breathing on it.

 

[g1138]

I found this corrugated AIR 2 adapter hose by Hollis that is 16", but it says 1" x 1/2". Is anyone familiar with Hollis equipment to know if they really only use a 1/2" hose barb on their gear? (seems like that would be pretty small to me.)

Corrugated Adapter Hose 16”, Air 2 (1” x 1/2” hose)

Hollis uses 1in at both ends. I don't know what they're measuring; they're annoyingly vague.
Before you go further, did you measure the Elbow diameter connecting to your BC?
I think your elbow is probably 3/4in meaning you'll need both an elbow & a corrugated hose to attach your Air 2. Might as well buy them as a package deal.
Northeast Scuba Supply & Dive Gear Express will be your cheapest options.

The nut holding the elbow for generic brands will be 46mm inner thread diameter for reference (measured with a ruler not calipers so +/- 1mm for human error.)
If you find you can't replace your whole assembly with a generic, you'll have to go with the corrugated hose adapter at Northeast Scuba Supply. It's the only one on the market.


I don't know if IST/Oceanic/old Seaquests use a different elbow/nut fitting with their 3/4in corrugated hoses.

 

[Luky1]

Hollis uses 1in at both ends. I don't know what they're measuring; they're annoyingly vague.
Before you go further, did you measure the Elbow diameter connecting to your BC?
I think your elbow is probably 3/4in meaning you'll need both an elbow & a corrugated hose to attach your Air 2. Might as well buy them as a package deal.
Northeast Scuba Supply & Dive Gear Express will be your cheapest options.

The nut holding the elbow for generic brands will be 46mm inner thread diameter for reference (measured with a ruler not calipers so +/- 1mm for human error.)
If you find you can't replace your whole assembly with a generic, you'll have to go with the corrugated hose adapter at Northeast Scuba Supply. It's the only one on the market.


I don't know if IST/Oceanic/old Seaquests use a different elbow/nut fitting with their 3/4in corrugated hoses.

I had measured the port on the BCD for the shoulder elbow. It was about 1 3/4" at the threads so around 44/45mm. I figured if I took it in to an LDS I might be able to compare it or test fit parts off of some other BCD's (maybe rentals) to get a better idea if another brands elbow may work.

I called Northeast Scuba Supply and he said they only make the 12" long adapter hose now; Sounds like they used to offer a 16" but no longer.

I also tried to find the Hollis corrugated adapter tube 1" x 1/2", but difficult to find on-line. It may be discontinued even though it's showing on their website (probably need to call them). Leisurepro shows a 16" hollis hose, but no diameter info. I on-line chatted with a person but they could not find any info on the the ID. They suggested I call the store (when they are open) to see if someone can measure it for me. I did find a 2013 Hollis catalogue online that shows their part number for this adapter hose as 208-1066-016 (the standard 1" ID Hollis 16" is 2018-1065-016) so I may pursue that tomorrow.

I was also considering seeing if I could fabricate a "sleeve" (maybe with a section of bicycle inner tube) to fit over the existing elbow fitting to increase the diameter so I can clamp a 1" ID hose (really 0.950" ID) onto it and have it seal. I could test in in our pool to make sure it does not leak. I am sure I could make it work, but I would prefer a factory fit solution...

And to Umuntu, thanks, the AIR 2 came with the correct LP hose with QD fitting in the box.

 

[Luky1]

I just confirmed Hollis no longer makes the 1" x 1/2" x 16" AIR 2 adapter hose.