Re: [PSUBS-MAILIST] Barometers

[MerlinSub@t-online.de]

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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