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Re: [PSUBS-MAILIST] Barometers
I imagine a hatch interlock alarm would indicate whether or not the hatch was
dogged, as opposed to whether it was physically open. The idea being that any
event which might create positive pressure within the sub will not cause the
hatch to open on its own prior to surfacing.
-Sean
On Wednesday 29 December 2010 14:59:00 you wrote:
> Cliff, you have a alarm for "hatch open" during diving in this small sub???
>
> That is something I have not. Just high level water alarm in the bilge.
> Works also fine as indirect "hatch is still open" indicator..
> But the full automatic hatch shower is also a good indicator..
>
> smile..
>
> vbr Carsten -by the way many subs sunk because a hatch was still open or
> not real close-
>
> "Cliff Redus" <cliffordredus@sbcglobal.net> schrieb:
> > 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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