Re: [PSUBS-MAILIST] Barometers

[MerlinSub@t-online.de]

No Alan, thats its no problem. 

All crew members are divers. And we have scuba regulator conected to the main air bus are in all conpartments. 
In the case that we end at the bottom of the harbour, flooded boat and hatch open:
We have a emergency protocol for that. 

00) First check on checklist that the hatch is really open and the boat is really flooded
01) One diver goes out and surface. 
02) The other crew members close the hatch from inside, open the bottom flood vale or diver exit bottom hatch 
    and blown the boat empty. 
03) If the boat later surface we start to dry everything and the first diver should be manage 
    in time to be back from the harbour pub with fresh beer.. 

As you can easy see this protocol save you the alarm switch and light. 
And it cleans the boat automaticly from trash and works even if this alarm parts fails..

vbr Carsten


"Alan James" <alanjames@xtra.co.nz> schrieb:
> That's timely thanks Cliff,
> I just looked at a Youtube video of the working parts of an aneroid barometer & thought the mechanism could easily be adapted to 
> push
> a tilt valve for additional O2. At a guess more accurate than an air filled bellows.
> http://www.youtube.com/watch?v=O55hhntGh1A
> There are a few safety alarms you've got that I hadn't thought of. You've been quite innovative in what you've done.
> Will print this email.
> Sounds like Carsten needs a "Hatch open on dive alarm". With the pre dive beers he was talking about it would be a pity if the 
> Euronaut
> ended up on the bottom of the harbor because one of his mates went for some more beers & forgot to lock down the hatch.
> Alan
>   ----- Original Message ----- 
>   From: Cliff Redus
>   To: personal_submersibles@psubs.org
>   Sent: Thursday, December 30, 2010 11:43 AM
>   Subject: Re: [PSUBS-MAILIST] Barometers
> 
> 
>   Like Sg. Peppers, the R300 is a small boat.  In early years I to had some pesky O2 and air leaks which I eventully sorted out. 
> Initially I tried to control my O2 makeup valve using the measured cabin pressure with a barometer (700 to 1100 mBar).  I found 
> this quite problematic.  I changed to controlling off the O2 concentration measurement rather than cabin pressure.  This worked a 
> lot better for me.  When the O2 level drops below 18% the PLC opened the O2 makeup solenoid valve until the O2 concentration 
> reaches 23% then it cuts off.  It takes about 1 minute for the O2 makeup value to cycle from closed to open to closed. In additon 
> to the automatic O2 makeup system, I have a backup manual metering needle valve with a simple direct reading medical flow rate 
> gage.  I added a cabin pressure gage that is 0-30 psia that I use to trigger overpressure alarms.   I had this alarm sound on one 
> dive when a hair line crack developed in O2 regulator high pressure fitting.  The high O2 alarm also went off.  At that point I 
> surfaced the boat.  After blowing my MBTs, I began relasing my hatch latches.  After releasing the first one, the other released 
> poping the hatch open to releave the 5 psi overpressure in the boat.  This sudden release of cabin air was enough to unseat my 
> hatch o-ring. I was very nervous for about a minute until I reseated this o-ring as I could not close the hatch and my freeboard 
> is quite small.   Needles to say, my diving was over for the day and I did not dive the boat again until I found and fixed the 
> source for the high pressure leak and installed a hull equlization valve for the hatch.  I also have a high CO2 alarm which 
> triggers when the CO2 partical pressure exceeds 5000ppm (0.5%). This happens when the CO2 absorbent becomes saturated. Normal air 
> has about 300 ppm of CO2.  I did quite a few 4-8 hour "garage" dives to make sure the environmental controls were working and to 
> sort out the CO2 scrubber fan size. Acturally they are a lot of fun but a bit boring. Garage dives are a great way to debug 
> systems.  The 15 alarms on the R300 are:
> 
>   High Oxygen Level, > 23%
> 
>   Low Oxygen Level, < 18%
> 
>   High CO2 Level, > 5000ppm
> 
>   Hatch Open on Dive
> 
>   High Main Current, > 300 Amps
> 
>   High Aux Current, >20 Amps
> 
>   Low pressure in Air Tank, <750 psia
> 
>   Low pressure in O2 Tank, < 550 psia
> 
>   Depth Exceeds 300 ft
> 
>   Low Cabin pressure , < 12 psia
> 
>   High Cabin pressure , > 20 psia
> 
>   Motor field winding > 248 F
> 
>   Seal Barrier Fluid Outlet Temp >200 F
> 
>   Low Main Battery Voltage, <110Vdc
> 
>   Low Aux Battery Voltage, <22Vdc
> 
> 
>   Cliff
> 




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