Starting down the DH rabbit hole

[Perryed]

OK final assembly and set up. Will be diving with in Bonaire in late June-early July. Pool session before that.

 

[James79]

Well, too many projects, and a move later, this happened a week and a half ago:

Don't mind the forest of poor hose routing... just used what I had laying around and it left me with some weird lengths. I do have a BC hose (way to long and looping high), and a Calypso badged 1085 second for the an alternate. I tried clearing the mouthpiece both by exhaling (lungs full when flooding it) and by puffing cheeks in and out (lungs empty when flooding), and the left roll with exhale to clear the exhaust hose (all in chest deep water). Semi confident in that I took it for a lap around Vortex spring.
First thought.... this is F'n cool! A very different experience from single hose, and an absolute blast.
Next thought... I get a mild free-flow when in a fully head up orientation. I haven't had a chance (in the midst of work and other projects) to take a look at the IP, and see how to de-tune it just enough to eliminate that free flow. Any advice on that is greatly appreciated. Also, it's on an old school 72 mounted to my Deathwish Engineering prototype BPW.... advice on can positioning and if that could be a factor in free-flow would be appreciated (I suspect the can is a bit high on my back, but this is my first DH reg).
The slow leak from the Teflon taped hookah port splitter was so negligible that my dive buddy couldn't see it, so I'm calling that a win for now.
I need to spend some time in the shallow end working on emergency procedures (mouthpiece recovery, etc.) but I'm digging it so far!
respectfully,
James

 

[herman]

I would not worry too much about the slight FF when vertical and esp if you are slightly (or more) back. That is due to DH design and to be expected, just shows it's real close to proper tune. On the surface and slightly back it WILL freeflow, expect it. You have to keep the mouthpiece below the water, plug it with something or use a DSV to prevent it. That is normal for a DH and if it doesn't, it's not tuned properly.
Can't tell well from the photos but it appears the reg might be a bit high. When under water, the top of cans should be below the base of your neck and as close to the body as possible.

@couv had a photo of me showing my AK placement. It seems to be missing from the board, maybe he can repost it

 

[James79]

I would not worry too much about the slight FF when vertical and esp if you are slightly (or more) back. That is due to DH design and to be expected, just shows it's real close to proper tune. On the surface and slightly back it WILL freeflow, expect it. You have to keep the mouthpiece below the water, plug it with something or use a DSV to prevent it. That is normal for a DH and if it doesn't, it's not tuned properly.
Can't tell well from the photos but it appears the reg might be a bit high. When under water, the top of cans should be below the base of your neck and as close to the body as possible.

Thank you, Herman... I anticipated free-flow at surface (making a mouthpiece plug is on the to do list), but to make sure I understand right; vertical in the water column at depth, free-flow is normal, and indicative of being tuned just a smidge hot? And I believe you are right about the positioning of the reg, I'll double check the video for a better view to verify. Frogkicker gave me a VDH plate that I need to rig up, but I need to make MK3 of my dirt cheap wing to use with it first.... too many projects and not enough time!
Any advice on appropriate drills (e.g. mouthpiece recovery, etc.) I should work out prior to taking in other than pool like conditions?
respectfully,
James

p.s. Just re-checked the video, and can placement looks right (based on my absolute lack of experience!) Better picture:

 

[herman]

That photo looks better, it's hard to tell from photos some times.
All my regs tend to "chipmunk" me a little - the hose loop gets a little positive in pressure-when completely vertical, more so when past vertical. Unless its actually flowing some, I would not worry about it but then I tend to set the regs up pretty hot.
If its bothering you and you are using the USD second stage, you can crank it in another hole, for the HPR I would drop IP a few PSI. Either will cost you a little in cracking pressure although you can help make some of that back by increasing the venturi by blocking some of the holes (HPR)

 

[James79]

That photo looks better, it's hard to tell from photos some times.
All my regs tend to "chipmunk" me a little - the hose loop gets a little positive in pressure-when completely vertical, more so when past vertical. Unless its actually flowing some, I would not worry about it but then I tend to set the regs up pretty hot.
If its bothering you and you are using the USD second stage, you can crank it in another hole, for the HPR I would drop IP a few PSI. Either will cost you a little in cracking pressure although you can help make some of that back by increasing the venturi by blocking some of the holes (HPR)

Thanks again! It's a cyclone / HPR setup, and does go past chipmunk-ing into actual free flow when head up... So looks like I'll be dialing down the IP just a bit. If the cracking pressure changes too much, I'll look at venturi adjustment... But as it is, it damn near breathes for me!
Respectfully
James

 

[herman]

How much is the HPR out from seated? If you haven't, turn it fully in (by hand, no tools) then back out to the first big hole. That will help if it is set to light. Seems like we have had a few that needed a washer in stalled on the springs to in crease the cracking pressure. It is quite possible to set the cracking pressure of the HPR too low, less than 1/2 is possible.. Anything less than about 3/4 IWC starts to get iffy. Do the venturi changes in steps, it can get too aggressive.

You may know this but it never hurts to remind everyone. NEVER inhale directly from the can horn. The venturi can be very aggressive and serious lung damage can occur if you inhale from the horn and the venturi kicks in hard. Always use a hose loop when testing a DH cracking pressure or venturi. By the way, a large woodworking type clamp makes a great way to hold the cans together while you are setting up the second stage. A lot easier than putting the ring on and off.

 

[James79]

I'll open it up and check on Sunday, most likely. Regarding always using the loop, I did know.... But I knew from reading threads like this, so reiterating it is always good! And I'm even lower tech than woodworking clamps.... I use my sandwich clamps for quick checks, lol

 

[Couv]

....
@couv had a photo of me showing my AK placement. It seems to be missing from the board, maybe he can repost it

Late to the party and it looks like James is sorted out pretty well, but here is the picture:

 

[James79]

Yesterday I braved the depths of my pool to try the Cyclone/HPR DAAM again... I Checked the IP, and it was at 115 on a 900 PSI tank, so I left it alone. The HPR is fully seated, per Herman's advice upthread. So I tried it again as is. in one very specific position (head up, vertical in the water column) I get very minor freeflow. On my back, it chipmunks the hell out of my cheeks. I had a printed mouthpiece plug I did in ABS (because it was loaded in the machine) to Luis's drawings that wouldn't quite seal... I'll need to work on that (either material choice, print orientation, or a combination). I believe I will need to follow Herman's advice and add a washer to the HPR to give a little more adjustment range. This was also the first use of a VDH plate that was gifted to me, and MK3 of my Dirt Cheap Wing. Rigged like that, I'm using zero lead with a 3/2 shorty in freshwater.

Ignore the date stamps.... I'm too lazy/forgot to reset the date on my Faux Pro when I switched batterys.
Respectfully,
James