[PSUBS-MAILIST] Cornelius compressors

Sat Jun 11 07:19:10 EDT 2016

Thanks Antoine,some good information there. I am intending to have a constant flow system that is toppedup via a re-breather style metering device. If the factory settings of the re-breather computercan't be changed then plan 2 is to use a PLC to do the work. This may be the better optionas I could then have O2 level displays & alarms on one main HMI.As for the problem of remembering to turn the O2 on; I think I will have a switch under the pilotschair, activated by the weight of the pilot. This will activate an alarm or warning if the O2 valve isn't open.Alan 

      From: Antoine Delafargue via Personal_Submersibles <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
 Sent: Saturday, June 11, 2016 6:09 PM
 Subject: [PSUBS-MAILIST] Cornelius compressors

hi AlanYou re right in a small cabin if Something is wrong in the oxy you have less time to react before o2 level drops too low or goes too high, so rb automatic systems can help and keep you alive if you fall unconscious. But:-one of the main failures rb systems are designed to address is much less present in subs:  o2 cells age fast at high oxygen partial pressures and fail to record high oxygen partial pressures which can trick into injection of too much oxy-oxy variations in rb are much larger than in a small 1atm sub-statistics of rb accidents tend to say that the automatic systems with solenoids are not safer than manual add systems. They might induce more complacency and have divers forgeting to check things. manual add on (like reabreather ´adv' system which can be also used to make a bellow add type ) systems coupled with constant flow (pediatric regulator) to cover minimal rate make you alert while giving you more time to react and perhaps decrease the chance you forget to turn o2 on which has been a cause of several rb deaths.  -it would be easy to use rb equipment in a sub, although some factory settings for O2 level alarms may have to be changed. But it is difficult to find spare parts if you do not own a unit and certification, other than on second hand market like cave diving forums. parts on rb accessory shops like tecme.de or golem are an option but can be expensive.The good thing with rb stuff though is their o2 cells have hydrophobic membranes for keeping condensed water away and give PpO2 on a large range or absolute pressure and O2.stand alone monitors like revo dream coming with HUD display could be good.Doing some rb diving course with the system you want to use can be very helpful... I did it with APdiving rb. 

Regardsantoine
On Saturday, June 11, 2016, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Yes.Cliff has a system that reads off one O2 sensor & seems to work fine, but Iwant the redundancy I will get with three O2 sensors as per a rebreather. It is a bitmore complicated as if one O2 sensor is reading out of sync with the other twoit will take the measurements from those two as Gospel. So I want to use a rebreather module that already has the algorithm for that. The bellows add system relies on cabin pressure which can fluctuate for reasons other than a variation in the O2 levels. And because my sub is so small anyatmospheric conditions are going to fluctuate more quickly than a larger sub,hence the need for a reliable system that responds to changes quickly.There is a bit of a blurb on the system AP developed for James Cameron here.James Cameron's Deepsea Challenge. Marianna Trench Trip Report Mar 2012

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James Cameron's Deepsea Challenge. Marianna Trench Trip Report Mar 2012
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 Cheers Alan

      From: Al Secor via Personal_Submersibles <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
 Sent: Saturday, June 11, 2016 12:28 PM
 Subject: Re: [PSUBS-MAILIST] Cornelius compressors

Isn't that what people are basically doing already?  Whether you are using a flow meter, needle valve, mpu controlled solenoid valve or bellows add system ala Dr Phil, you are basically adding O2 at your metabolic rate the same as a rebreather would do...

Al Secor

--------------------------------------------
On Fri, 6/10/16, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: Re: [PSUBS-MAILIST] Cornelius compressors
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Date: Friday, June 10, 2016, 6:34 PM

 Thanks
 Steve.How
 easy would it be to adapt a rebreather O2 feed system to a
 submarine?I
 believe APdiving in the UK did this for James Cameron's
 sub.I'm
 building a one person sub about the size of Cliff's R300
 & because of the small size,wanted
 a system that responded quickly to O2 deviations.I
 envisage the system as having a constant flow of O2 at a
 rate just below my minimumconsumption,
 with a top up from readings off 3 O2 sensors.Cheers
 Alan

  From: Stephen Fordyce
 via Personal_Submersibles
 <personal_submersibles at psubs.org>
  To: Personal
 Submersibles General Discussion
 <personal_submersibles at psubs.org> 

 Sent: Friday,
 June 10, 2016 4:26 PM
  Subject:
 [PSUBS-MAILIST] Cornelius compressors

 Hi
 all,I
 know Hank uses a Cornelius compressor and I think others
 have enquired after them.  In a nutshell, it's a
 small/lightweight (~60lb?) high-pressure compressor no
 longer made, originally used by the US Air Force in aircraft
 - so it's pretty well spec'd.  Also by default
 runs off nominal 27VDC - so highly suitable for install in
 a PSUB, if you can handle the current draw, noise and 2cfm
 flowrate.
 Well
 in the course of my business, I sold a SCUBA nitrox mixing
 stick to a guy in Canada who mounted it on a Cornelius
 compressor - see a picture of the final setup he sent me (if
 the recent discussions of email vs Facebook haven't put
 you off!):https://www.facebook.com/tfmengineeringaust/photos/a.754931991306953.1073741830.754476911352461/858648047602013/?type=3&theater
 Anyway, we
 got to talking and he said he got the compressor from a
 bloke in Florida.  I made contact and discovered this
 bloke has a whole lot of them that he is slowly setting
 up and selling as fully functional breathing air compressors
 (they are old but apparently well preserved and have only a
 few hours - he runs them in).  He also has parts as well
 for anyone like Hank who already has a unit.  I'm
 contemplating bringing a few into Australia to
 on-sell.
 In case
 anyone is interested, his name is Paul Deverell, with email
 pauldeverell at ymail.com
 and phone number +1 786-367-3365
 Cheers,Steve
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