Value of 4th Cell & Computer

dive*ski · 5th October 2007, 13:16

How many people are using a 4th cell hooked up to an external computer eg VR3.

Are you getting any value from it ?

**sfldiver** · 5th October 2007, 14:26

Hi dive*ski,

I recently completed training for a Dive Rite Optima I purchased. Initially, I only went with the 3 cells the unit comes with. After completing several dives and seeing how the values of particular cells can often fluctuate during a dive, I decided to go ahead and add a VR3 w/the 4th independent cell.

It was a very expensive backup/safety feature, but I sleep very well at night knowing that I have that little extra edge!

Abbo · 5th October 2007, 14:53

Because the Meg does not have a built in deco computer I bought a 4th cell and special counterlung to connect a 4th cell up. If you're not careful in calibrating it you can get a significantly different reading from the other 3 cells, in which case I disconnect it and use the default fixed setpoint I've plugged in on the VR3. Though the larger cells on the Meg will hold their calibration for a week, this little fourth cell quickly gets out of line. I don't really trust it enough to calibrate the night before, so I have to calibrate straight before the dive, when there are time pressures, so sometimes I dive without it. There's quite a run around getting the cell and cable sent to you from Delta P, then sending them to ISC for connection to a special counterlung. Apecs 3.0 will obviate the need for this, and the 4th cell will be a backup system.

bourskov · 5th October 2007, 15:17

Quote: (Originally Posted by sfldiver)

Hi dive*ski,

I recently completed training for a Dive Rite Optima I purchased. Initially, I only went with the 3 cells the unit comes with. After completing several dives and seeing how the values of particular cells can often fluctuate during a dive, I decided to go ahead and add a VR3 w/the 4th independent cell.

It was a very expensive backup/safety feature, but I sleep very well at night knowing that I have that little extra edge!

How do you know, that your 4th cell isn't fluctuating?! I mean, 3 cells if fluctuation, why isn't the fourht doing it!?

Anyway, because the Boris comes with a build-in VR3 it calculates deco/no-stop "on-the-fly" and compared to my stand-alone VR3 on the other arm with fixed setpoint calculation, it turns out, that my stand-alone VR3 is giving me shorter no-stop-times, and/or longer deco-stops...

Cheers
Bo Urskov

diver1369 · 5th October 2007, 15:34

I have a Shearwater hooked up to fourth cell in IH counterlung - as backup to my Hammerhead deco on the three primary cells. It does give me the redundancy I want, and the K-1D calibration/recalibration issue is moderated by the ease with which the Shearwater calibrates (just pull the little sensor assembly off the CL and pop it into a little plastic baggie with an O2 feed ala the Meg Head only cal kit.)

What is interesting is to watch the O2 values in the IH CL against the O2 values in the head during the dive. When I inject O2 manually into the CL, the Shearwater shows the spike - its what I'm actually breathing. (I know, I know, I should be plumbing the O2 feed into the EH CL...) And with the same GF factors, the Shearwater gets me out of the water just a bit more quickly because of the sometimes higher O2.

My only problem is that its the 'old' Shearwater (how quickly we forget the wonder of a really excellent deco computer - now it's 'old'...) with no screen flip, so I have to wear it as 'jewelry', can't put it on either wrist...

john

**sfldiver** · 5th October 2007, 15:43

Quote: (Originally Posted by bourskov)

How do you know, that your 4th cell isn't fluctuating?! I mean, 3 cells if fluctuation, why isn't the fourht doing it!?

You are absolutely correct, I do not know which cells are fluctuating; however, the fourth cell is directly providing my VR3 with my P02 information, which the VR3 is using for decompression calculation purposes. As a safety procaution, I always clear my HH handsets and my VR3 before leaving the water, even if one ends up being considerable more conservative than the other.

By adding that additional cell, I am adding one other variable into the equation. When dealing with variables, the probability of a higher number of variables being off is lower than that of fewer variables

Therefore, logic would dictate that, under normal conditions, you are safer by adding the fourth cell (more variables), than by not adding it - higher safety factor.

Like I said, personally, I sleep better at night knowing I have that fourth cell.

With regard to the calibration issues that Abbo indicated he has, I have not experienced the same thing. I calibrate my handsets the night before, when I am assembling my Rebreather, and I have yet to notice any major variance in my calibration the next morning.

**Fun Under Pressure** · 5th October 2007, 18:13

Hi,

i use a shearwater and and a narked at 90 4th cell holder. But i have connect the 3 cells from my classic to the shearwater. So i have online deco and when the electronic fails i can fly my unit manually, and the shearwater reads all 3 cells !! It is a safety option for me.

Cheers Markku

Mikel-Deko · 5th October 2007, 18:25

Hi
I've a 4th cell holder from narket at 90 and a rEvodream in my Classic inspi.

The best inprove that i've made to my Rebreather.

Best
Mikel

Depth-junkie · 5th October 2007, 19:10

I run a VR3 and 4th cell with a narked@90 cell holder with my vision inspo.

I like it, it tracks inline perfectly with the standard 3 cells. And it gives me 2 things:-

1:independant intergrated real time deco
2: & Most importantly a redundant PO2 meter, incase of main elec failure, enables me to still run the unit manualy even in the case of a total electronic failure.

Was not a cheap mod, cost around £360 all in all, with cell holder, x-func PIN for VR3 and extra cell. But it is the only major mod i have made and IMHO a very good one.

ATB
Gareth

***Beanie*** · 5th October 2007, 22:58

Well I did get a cell holder designed so I have to say it is worth it

It is nice to have another PPO2 read out.

5th October 2007, 13:16	#1 (permalink)
diveski RBW Member Current Rebreather/s:* Inspiration Classic Other Rebreather/s: Inspiration Classic Join Date: Nov 2005 Location: Australia Posts: 32	Value of 4th Cell & Computer How many people are using a 4th cell hooked up to an external computer eg VR3. Are you getting any value from it ?
(Offline)

5th October 2007, 14:26	#2 (permalink)
sfldiver S.C.R.U.B.'S Photographer Current Rebreather/s: Optima Other Rebreather/s: Join Date: Jul 2007 Location: Pompano Beach, FL Posts: 819	Re: Value of 4th Cell & Computer Hi diveski, I recently completed training for a Dive Rite Optima I purchased. Initially, I only went with the 3 cells the unit comes with. After completing several dives and seeing how the values of particular cells can often fluctuate during a dive, I decided to go ahead and add a VR3 w/the 4th independent cell. It was a very expensive backup/safety feature, but I sleep very well at night knowing that I have that little extra edge! __________________ Currently piloting & shooting...* Dive Rite O2ptima FX Rigged w/ a Dsix Custom Aluminum Frame, Nomad Wing, Transpac Harness and VR3 Computer w/ VPM-B/E & a 4th Cell Sensor Link.* Canon PowerShot G9 Digital Camera *Rigged in a Patima-PDCH 2008 G9 Aluminum Housing w/ an Inon UWL-100 Achromat Wide Conversion Lens, 2 Inon UCL-165M67 Close-Up Lenses and 2 Inon Z-240 Strobes.
(Offline)

5th October 2007, 14:53	#3 (permalink)
Abbo Nicholas Smith Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Aug 2006 Location: Tokyo Posts: 460	Re: Value of 4th Cell & Computer Because the Meg does not have a built in deco computer I bought a 4th cell and special counterlung to connect a 4th cell up. If you're not careful in calibrating it you can get a significantly different reading from the other 3 cells, in which case I disconnect it and use the default fixed setpoint I've plugged in on the VR3. Though the larger cells on the Meg will hold their calibration for a week, this little fourth cell quickly gets out of line. I don't really trust it enough to calibrate the night before, so I have to calibrate straight before the dive, when there are time pressures, so sometimes I dive without it. There's quite a run around getting the cell and cable sent to you from Delta P, then sending them to ISC for connection to a special counterlung. Apecs 3.0 will obviate the need for this, and the 4th cell will be a backup system.
(Offline)

5th October 2007, 15:17	#4 (permalink)
bourskov New Member Current Rebreather/s: Ouroboros Other Rebreather/s: Inspiration Classic Join Date: Nov 2006 Location: Denmark Posts: 92	Re: Value of 4th Cell & Computer Quote: (Originally Posted by sfldiver) Hi dive*ski, I recently completed training for a Dive Rite Optima I purchased. Initially, I only went with the 3 cells the unit comes with. After completing several dives and seeing how the values of particular cells can often fluctuate during a dive, I decided to go ahead and add a VR3 w/the 4th independent cell. It was a very expensive backup/safety feature, but I sleep very well at night knowing that I have that little extra edge! How do you know, that your 4th cell isn't fluctuating?! I mean, 3 cells if fluctuation, why isn't the fourht doing it!? Anyway, because the Boris comes with a build-in VR3 it calculates deco/no-stop "on-the-fly" and compared to my stand-alone VR3 on the other arm with fixed setpoint calculation, it turns out, that my stand-alone VR3 is giving me shorter no-stop-times, and/or longer deco-stops... Cheers Bo Urskov
(Offline)

5th October 2007, 15:34	#5 (permalink)
diver1369 RBW Member Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: Maryland, USA Posts: 87	Re: Value of 4th Cell & Computer I have a Shearwater hooked up to fourth cell in IH counterlung - as backup to my Hammerhead deco on the three primary cells. It does give me the redundancy I want, and the K-1D calibration/recalibration issue is moderated by the ease with which the Shearwater calibrates (just pull the little sensor assembly off the CL and pop it into a little plastic baggie with an O2 feed ala the Meg Head only cal kit.) What is interesting is to watch the O2 values in the IH CL against the O2 values in the head during the dive. When I inject O2 manually into the CL, the Shearwater shows the spike - its what I'm actually breathing. (I know, I know, I should be plumbing the O2 feed into the EH CL...) And with the same GF factors, the Shearwater gets me out of the water just a bit more quickly because of the sometimes higher O2. My only problem is that its the 'old' Shearwater (how quickly we forget the wonder of a really excellent deco computer - now it's 'old'...) with no screen flip, so I have to wear it as 'jewelry', can't put it on either wrist... john
(Offline)

5th October 2007, 15:43	#6 (permalink)
sfldiver S.C.R.U.B.'S Photographer Current Rebreather/s: Optima Other Rebreather/s: Join Date: Jul 2007 Location: Pompano Beach, FL Posts: 819	Re: Value of 4th Cell & Computer Quote: (Originally Posted by bourskov) How do you know, that your 4th cell isn't fluctuating?! I mean, 3 cells if fluctuation, why isn't the fourht doing it!? You are absolutely correct, I do not know which cells are fluctuating; however, the fourth cell is directly providing my VR3 with my P02 information, which the VR3 is using for decompression calculation purposes. As a safety procaution, I always clear my HH handsets and my VR3 before leaving the water, even if one ends up being considerable more conservative than the other. By adding that additional cell, I am adding one other variable into the equation. When dealing with variables, the probability of a higher number of variables being off is lower than that of fewer variables Therefore, logic would dictate that, under normal conditions, you are safer by adding the fourth cell (more variables), than by not adding it - higher safety factor. Like I said, personally, I sleep better at night knowing I have that fourth cell. With regard to the calibration issues that Abbo indicated he has, I have not experienced the same thing. I calibrate my handsets the night before, when I am assembling my Rebreather, and I have yet to notice any major variance in my calibration the next morning. __________________ *Currently piloting & shooting...* Dive Rite O2ptima FX Rigged w/ a Dsix Custom Aluminum Frame, Nomad Wing, Transpac Harness and VR3 Computer w/ VPM-B/E & a 4th Cell Sensor Link.* Canon PowerShot G9 Digital Camera *Rigged in a Patima-PDCH 2008 G9 Aluminum Housing w/ an Inon UWL-100 Achromat Wide Conversion Lens, 2 Inon UCL-165M67 Close-Up Lenses and 2 Inon Z-240 Strobes.
(Offline)

5th October 2007, 18:13	#7 (permalink)
Fun Under Pressure Supporting Member Current Rebreather/s: Megalodon Other Rebreather/s: Inspiration Classic Join Date: Nov 2006 Location: Germany Posts: 811	Re: Value of 4th Cell & Computer Hi, i use a shearwater and and a narked at 90 4th cell holder. But i have connect the 3 cells from my classic to the shearwater. So i have online deco and when the electronic fails i can fly my unit manually, and the shearwater reads all 3 cells !! It is a safety option for me. Cheers Markku
(Offline)

5th October 2007, 18:25	#8 (permalink)
Mikel-Deko RBW Member Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Other CCR Join Date: Jul 2005 Location: Basque Country -Sp- Posts: 476	Re: Value of 4th Cell & Computer Hi I've a 4th cell holder from narket at 90 and a rEvodream in my Classic inspi. The best inprove that i've made to my Rebreather. Best Mikel __________________ Mikel-Deko Basque Country www.olatu.net "DIR is the nanny state for divers who cannot think on their own" Ron Micjan
(Offline)

5th October 2007, 19:10	#9 (permalink)
Depth-junkie 10/52 Psycho Current Rebreather/s: Inspiration Vision Other Rebreather/s: Join Date: Aug 2005 Location: Wrexham Posts: 298	Re: Value of 4th Cell & Computer I run a VR3 and 4th cell with a narked@90 cell holder with my vision inspo. I like it, it tracks inline perfectly with the standard 3 cells. And it gives me 2 things:- 1:independant intergrated real time deco 2: & Most importantly a redundant PO2 meter, incase of main elec failure, enables me to still run the unit manualy even in the case of a total electronic failure. Was not a cheap mod, cost around £360 all in all, with cell holder, x-func PIN for VR3 and extra cell. But it is the only major mod i have made and IMHO a very good one. ATB Gareth
(Offline)

5th October 2007, 22:58	#10 (permalink)
*Beanie* Gallery Administrator Current Rebreather/s: Inspiration Classic Other Rebreather/s: Inspiration Vision Join Date: Jan 2005 Location: In da house! yeah baby! Posts: 3,312	Re: Value of 4th Cell & Computer Well I did get a cell holder designed so I have to say it is worth it It is nice to have another PPO2 read out. __________________ Beanie Gallery Admin & Library Assistant. www.outlawdivers.org.uk www.beandiving.co.uk www.beanengineering.co.uk
(Offline)

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode