YBOD first stages

jradomski

I did specific tests on the solenoid itself, not kevin's implementation.. your mileage will vary depending on which version of the hh you use and what type of cells.. remember from rev b on the H uses a charge pump to create the voltage, and when the batteries get real low ther may not be enough current to fire the solenoid (the load presented causes a rapid voltage drop if ther source cell cant pump up the voltage) .. I found that if I use 3.6v cells the solenoid will fire beyond the time where firing the solenoid and having the display on resets the HH controller.. On my curret set of batteries I have 3 weeks of everyday diving on a single ls14500 in each handeset (I did swap the secondary and primary after two weeks)... I havent had a chance to check what the current voltage under load is...

The tests I ran on the snaptite were using a precision voltage/current source so I could see the effects.. another thing that happens on the snaptie is that once you open the valve you can drop the voltage significantly and still keep it open.. on the INSP solenoid it drops with much less a voltage drop.. I dont remember the figures but it required much more voltage than the snaptite.. If memory serves me the snaptie held up to somewhere around 3v once it was opened..

The snaptite does require the 100ma specified (more if the voltage is less), I was able to get it to fire (again if memeory servese me) down to around 70ma or so but not consistently at higher pressures.. at 10bar and up my current draw (without using current limiting) was consistently in the 100ma range, even up to 20+ bar!

I also agree with you on not too low an IP.. both designs require back pressure to properly seat them..

__________________
Joe Radomski
CCR Trimix Instructor Trainer
ANDI Instructor Trainer Director #10

All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.

jhaaja

I dived the 1st stage yesterday and before the dive I set the IP to 7,2bars. The unit worked really nice and no icing, surface water +17C and on the bottom +4C

Has enyone tested how much does the IP change on Apeks 1st stages with different tank pressures?
For example 200bars and 50bars?

JH
Finland

decoweenie

It is recommended to check the IP with 50-100 bar in the tank, not 200 bar.

Supposedly the IP rises slightly as the tank pressure drops, so need to set it on 7.5 bar on the lowest tank pressure you let the O2 go down to (i.e. 30 bar ?)

(that was sent to me by Martin Parker)

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ROB DAVIE

Phi,

Do you know the mechanism behind this process? (i.e. what makes it rise?)

Rob

ROB DAVIE

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[SIZE=2]"CC Rebreathers will become a viable part of tech diving [U]WHEN PIGS FLY[/U]!!"--GI3[/SIZE]

Simon A

I haven't delt with this for a long time (over 10 years) but as far as I remember it is due to the way the regulators work, and we used to refer to it as the "inversion ratio" of the regulator.
I seem to remember a "good" regulator would be approx 1 bar higher at 300psi input than at 3000 psi Input.
there is marginaly more info at
http://www.flowcontrolnetwork.com/Pa.../jun2000/4.asp

HTH
Simon A

ROB DAVIE

Thanks, Simon!

Rob

jhaaja

I got an official answer from Apeks and also a permission to publish the test results of the over balanced IP on DST 1st stage:

Sorry for the horrible outlook of the data...
Depth (msw)

UST
Oil filled
DST


0

9.5
9.5
9.5


10

10.4
10.5
10.3


20

11.5
11.5
11.4


30

12.5
12.5
12.6


40

13.5
13.4
13.7


50

14.5
14.4
15


60

15.5
15.4
16.3


70

16.4
16.4
17.7


80

17.5
17.4
19.1


90

18.5
18.4
20.5


95

19
18.9
21Looks like that the over balancing is not so bad. If I set IP on surface to 7bar it should be 7,4bar at 95m.


JH