|
Great info! Thanks. David Bartsch To: personal_submersibles@psubs.org Subject: Re: [PSUBS-MAILIST] tanks Date: Tue, 6 Jan 2009 07:48:40 -0500 From: vbra676539@aol.com David, Internal tankage (ie. soft tanks) require a positive displacement pump with sufficient umph to push against external pressure. Standard bilge pumps will not be sufficient. We used baby piston pumps from the commercial car wash industry, as I recall. As a side note, they were cheap and had bronze sleeves with SS pistons, so corrosion was never a problem. We didn't even bother to flush them out after diving (except for storage or overhaul periods). As for pumping the bilges (small quantities only, as Perry and Hyco subs don't actually have bilges, as such) we used a smallish tygon line. You could attach it down near the suction inlet on the pump, if you like, isolated with a ball valve. Mostly, we just mopped up the condensation after a dive. The only time I can remember pumping seawater out was after an overflow of VBT water in PC-8 via a valve left partly open (accidently). However, PC-1201 had an A-frame tear off the deck during a recovery sequence and went to the bottom with ten tons of steel on top. The pressure hull tail cone got a dent the size of your head in it, which disturbed the O-ring in the main hull spool piece flange. The sub landed upright, and was otherwise intact (if you don't count all that bent aluminum around the main propeller). The pilot was able to keep the sub from flooding by pumping that leak water overboard via the VBT system every half hour or so until rescue came. In other words, it's always good to have every to ol available that you can. If you are going to have soft tanks and a pump, then you certainly ought to have a spare suction hose, just in case. Think wet vac on steroids. Vance -----Original Message----- From: David Bartsch <dbartsch2236@hotmail.com> To: personal_submersibles@psubs.org Sent: Tue, 6 Jan 2009 5:00 am Subject: RE: [PSUBS-MAILIST] tanks
Vance,
Would a regular bilge have enough power to overcome the outside sea pressure? Do you need a special type of pump? Is this soft tank pumped at specific depths? David Bartsch To: personal_submersibles@psubs.org Subject: Re: [PSUBS-MAILIST] tanks Date: Tue, 6 Jan 2009 05:43:58 -0500 From: vbra676539@aol.com You pump overboard. Vance -----Original Message----- From: David Bartsch <dbartsch2236@hotmail.com> To: personal_submersibles@psubs.org Sent: Tue, 6 Jan 2009 3:44 am Subject: [PSUBS-MAILIST] tanks
Frank has me thinking again...
Lets see if I understand this as I should... The hard ballast tank is a tank outside of the pressure hull that is subjected to the forces of the outside ambient pressure. To surface, one blasts air into this tank with the vent valves closed. This forces the water down and out thru ballast tank vents allowing the sub to become more bouyant and it bobs to the surface... Soft tanks are such as buckets within the sub subjected but to cabin pressure and are used to fine tune the bouyancy and for trim adjustments. Water is pumped from one tank to another (If more than one is available) to control trim angle. How does one remove this water from these soft tanks on a small psub? &nb sp; David Bartsch Send e-mail faster without improving your typing skills. Get your Hotmail® account. = Life on your PC is safer, easier, and more enjoyable with Windows Vista®. See how = It’s the same Hotmail®. If by “same” you mean up to 70% faster. Get your account now. |