Re: [PSUBS-MAILIST] Barometers

I agree that automatic hatch shower is a good open hatch alarm!

For a small sub this is kind of overkill but I sure like seeing my hatch status light go from red to green when the hatch closes and I get ready to flood the tanks. Also I kind of like having all my flood ballast tank controls being locked out if the hatch status is open.

Happy 2011.

From: "MerlinSub@t-online.de" <MerlinSub@t-online.de>
To: personal_submersibles@psubs.org
Sent: Wed, December 29, 2010 4:59:00 PM
Subject: Re: [PSUBS-MAILIST] Barometers

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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