Re: Fw: [PSUBS-MAILIST] Re: Ballast Tank design

[Ray Keefer <Ray.Keefer@Sun.COM>]

Hi Tom,

On the simpler PSUBS they are controlled manually. The top of the
ballast tanks are piped into the hull where the valves are.  From the
valve a second pipe goes out for venting the ballast tank. The
operation is to manually turn the valve open and the ballast tanks
flood as the air comes up the pipe, passed the valve, and out.  To work
the valve and exhaust piping have to be arranged higher then the top of
the ballast tank so are usually located in the conning tower.

To blow the tanks dry a second valve is piped from your compressed air 
(HPA) source and tee'ed into the pipe from your ballast tank.

                               | <- vent pipe
                          _____|____
                          |    |   |
                   _______|____O   |<- hull/conning tower
                __|__     |  |     |
               |     | ^  |  O     |
               |     | |     |
               |__ __| |     |___HPA       O = valves
                       |
                ^ ^    |____pipe
                | |____ flood hole
                |______ ballast tank  
                
Safety concerns are:

1. The piping inside the hull needs to be able to handle the pressure 
   differential between the outside ambient pressure and the inside 1atm
   pressure. Else a pipe could burst, the interior floods, the hull
   gets more negatively bouyant, sinks and you die.
   
2. Each hull penetration of a pipe should also have a stop cock valve just
   inside the hull. This is in case a valve or pipe springs a leak. Allows
   you an opportunity to shut it off.
   
3. The high pressure air needs to be reduced from the 3000lbs/cu in its
   tank to some acceptable intermediate pressure that is 50 - 200 lbs/cu in
   over the ambient pressure. Else you could burst pipes, over pressurize
   your interior, pop out your view ports, flood, sink and you die.
   
   So reduce your HPA and/or beef up the piping and valves that you use.
                
Regards,
Ray

> From: Floridarobots@aol.com
> Date: Sun, 2 Sep 2001 08:01:19 EDT
> Subject: Re: Fw: [PSUBS-MAILIST] Re:  Ballast Tank design
> To: personal_submersibles@psubs.org
> 
> Carten
> 
> Thanks for the reply I will look up the items you mentioned. I will also post 
> my design up here in JPG or DXF. By the way thanks for the compliment on our 
> boats....Im proud. My design will be a metal ship, I dont think its feasible 
> to even try a 1000 foot ship with FRP. Another ballast question:
> How are the majority of submersibles designed as far as Ballast control? I 
> mean how are the ballast tank valves opened and closed ? Manually? Air 
> controlled? Please advise.... I am not talking about controlling the 
> trim,yaw,pitch, but specifically what type controls actually open the valves 
> themselves....
> Tom Mitzlaff