Danfoss, group 2
I am going for one of these with Aluminium body and poss make plastic gears however the one that was in it was not corroded.
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of ojaivalleybeefarm @dslextreme.com
Sent: Tuesday, 15 February 2011 4:30 a.m.
Ah ! a gear pump, of course, That sounds like a great system. the great things about it are the fact that you can just use seawater, and that you can dump or ad water to the system depending on your wieght, the larger your tanks the more flexibility you would have. Any suggestions on a brand of gear pump?
Brian
On Mon, Feb 14, 2011 at 3:25 AM, Hugh Fulton <hc.fulton@gmail.com> wrote:
Brian, Pump is a gear pump and can run backwards or forwards developing over 1000 psi pressure. A relief valve is set for 20% over maximum dive depth and the air can be compressed in the tanks or vented. For the 2 tanks you need 4 x 2-way valves or 2 x 3-way valves also 2 x 3-way vales for air blow or vent and you have a system. Hope that helps. Hugh
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of ojaivalleybeefarm @dslextreme.com
Sent: Monday, 14 February 2011 6:23 p.m.
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Trim Tanks
Hugh, Is the pump actually reversible ie , you change the polarity on the motor or is it valves that are changed? what do they do about the compressing air in the tanks?
Brian
On Sun, Feb 13, 2011 at 8:48 PM, Hugh Fulton <hc.fulton@gmail.com> wrote:
Hi Brian,
You can do two tanks with one pump but it needs to be reversible. This will transfer between the two for fore/aft adjustment. The Comsub uses a hydraulic pump for the purpose. Chs, Hugh
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of ojaivalleybeefarm @dslextreme.com
Sent: Monday, 14 February 2011 4:52 p.m.
To: personal_submersibles
Subject: [PSUBS-MAILIST] Trim Tanks
Hi All,
I've been thinking about my various options for variable ballast / trim tanks. I'm thinking of having fore and aft hard ballast trim tanks where I transfer seawater back and forth. I think it would take two separate pumps, unless there is a pump that's reversible, since most pumps just pump one way. With some plumbing I could pump seawater from the outside and vice versa. I'm wondering if it would be necessary to evacuate the airspace in the tanks, that way I could fill the entire tank without the pump having to pressurize the air in the tank. The hard tanks would have equal straight as the pressure hull. The pumps would need to be strong enough to pull a vacuum on either of the tanks and would need to hold the water, which could be accomplished by check valves.
Brian
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