[PSUBS-MAILIST] inside ballast

Sat Dec 10 13:10:54 EST 2016

Brian,I was at a hydraulic hose shop yesterday and they sell real nice 3,000 psi air hose with reusable ends.  Why not just go with your original plan to blow the tank and use a good quality line to carry the water out. Easy as pie and your doneHank 

    On Saturday, December 10, 2016 11:06 AM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Thinking of something like this as a inside ballast pump.  I think the diaphragm pumps would be better since the diaphragms are rubber and wouldn't rust;   https://www.amazon.com/100PSI-Pressure-Diaphragm-Water-Pump/dp/B00XDSJEJY   Brian

--- personal_submersibles at psubs.org wrote:

From: Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org>
To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] inside ballast
Date: Thu, 8 Dec 2016 10:18:56 -0800

Hmmm, that kind of makes a case for not using HP air to get rid of that water ballast inside the hull.  My goal was not to really have a hard ballast but I guess using HP air to rid the water pretty much makes it a hard ballast by definition.  Thanks for clarifying Sean !   I guess I wasn't thinking in terms of larger Swagelok piping since I've just been dealing with the 1/4" tubing -duh .  Sean do you know of any manual HP pumps that are available ?  The two methods for pumping out hard ballast is regardless of whether the tank is inside or out I imagine .   Thanks again, Brian

--- personal_submersibles at psubs.org wrote:

From: "Sean T. Stevenson via Personal_Submersibles" <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] inside ballast
Date: Thu, 08 Dec 2016 09:44:37 -0700

If any pressure vessel inside the personnel compartment (or its associated piping / fittings downstream of a hull shutoff valve) were to fail and release its contents into the compartment, it must not raise the internal pressure of the compartment by more than 1 ATM (demonstrated by calculations). If it does, it must go outside, no exceptions.Also, technically you're supposed to have two independent methods of emptying hard ballast tanks, so for example, pumping them out against the sea pressure with a high pressure pump (powered or manual) and simultaneously venting 1 ATM air into the tank with a check valve as one method, and opening the tank to sea and blowing it out with HP air as the second method.Sean

On December 7, 2016 4:59:02 PM MST, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
I'm routing my lines to use two scuba tanks as my internal ballast.  I estimate the total weight if they are both filled with water to be around 42 lbs.  (about 570 cu in for each, alum 80's)  .  What kind of water line does everybody use?  I was considering using soft copper but I'm not sure of it's pressure rating.  Or maybe that is not such an issue.  It could see some pressure using the HP tanks in a closed position, which then could be an issue I guess.   But I would most likely just give a little blast of HP air to push the water out.  Hmmm, wonder if I should have the option to vent outside the sub if I had some air pressure in the ballast tanks?  or I guess I could just simply let it push all the water out and then it would get expelled that way.   Are there any specific rules like that for inside ballasttanks? Brian

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