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RE: [PSUBS-MAILIST] on-board air.
Hi Jay,
I am a fan of the words "or equal".
sample:
Oxygen bottle should be storage outside - if possible.
If not possible a equal solution should be found - like the main vale of the bottle inside is easy reach by the pilot.
> The fan should be powered by a small
> independent, dedicated battery system sized to meet the duration of your
> scrubber.
Or the fan should be powered by the main battery - in case of a failture with the main battery it should be switch together with other main emergency systems to the emergency battery. In this case the mainbattery should by have a offline switch close to the cable troughull. To reach 48 or more hours a manual scrubber breathing hose is common (and cheap ;-) ).
Fire and flooding are the two
> major causalities that ever submariner should fear and the immediate action
> should be an emergency surfacing.
Thats right: Fire or just smoke ! Leaking or Flooding and catching a net or rope underwater.
But in case of a major leak I would say the first thing you should do is to
check or make the boat in "dive condition" ! Major leak means in general:
Hatch not sealed, flood- or other vales not tight or in wrong position.
Most leaks I have seen on subs are: Open engine exhaust vale, not tight hatches..
A real leak because of a broken something is.. - ..rarely
In case of smoke or fire inside the hull:
- First stop breathing for some seconds and grab the scuba regulator
(cable fire exhaust can put you out of action with one breath!)
- second grab the scuba mask
- battery main switch offline (I think most fire are electrical powered)
- blow tanks.
- close o2 main vale
best regards Carsten
"Jay K. Jeffries" <bottomgun@mindspring.com> schrieb:
> Frank,
>
> Your concern over the issue of entanglement is VERY valid but should be easy
> to minimize with a little forethought. Fiberglass shrouds over exterior
> protuberances blending external gear into the hull should alleviate most of
> the snags and make the sub look more professional. Joe has started this
> with the Alvin Jr. and we have discussed further covers for the battery pods
> and external gas tanks.
>
>
>
> You are going to find in most PSUBs that there is little room to carry a
> bunch of tools and room to shift around to reach things in the hull
> difficult due to the already cramped space. 99.9% of the emergency repairs
> will occur on the surface and as for the other 0.1%, ever effort should be
> made to engineer the issue away prior to a potential failure. By keeping
> the sub's system as simple as possible the opportunity for failure is
> minimized. As complexity increases the opportunities for failure do not
> increase linearly but in an exponential mode. Fire and flooding are the two
> major causalities that ever submariner should fear and the immediate action
> should be an emergency surfacing.
>
>
>
> With a simple PSUB, there are few subsystems that are critical that could
> potentially be worked on within the sub (all other systems or components are
> non-critical):
>
> 1. Hull integrity
> 2. MBT blow
> 3. MBT vent
> 4. Electrical propulsion
> 5. Life support
> 6. Drop weight retaining mechanism
> 7. Steering (while often thought of as critical, is not needed in most
> emergencies other then entanglement).
>
>
>
> Let us consider each of these for contingencies and reparability underwater:
>
> 1. Hull Integrity - minor leak around a packing or shaft gland (few
> drips per minute) should be able to be resolved with tightening the gland
> night with an adjustable wrench, if not abort the dive. If it is a
> mechanical seal, there should be no leakage and this is a portent of things
> getting worse so immediate dive abortion should occur. Small main hatch
> leak should abate with depth due to increased pressure on the hatch, if not
> abort. This should have been found as part of the pre-dive checks by
> partially flooding down, increasing cabin pressure slightly over ambient,
> and observing for any escaping bubbles. Any major leak should be cause for
> immediate abortment of the dive. If the hull rapidly floods, the immediate
> response should be to go to an emergency swimming free ascent
> 2. MBT Blow - if the tanks are inside, there initially appears to be
> options for repair but is balanced by the loss of internal space and the
> possibility of a catastrophic HP air accident (loss of valve to tank neck
> seal or more likely a blowout disk failure). With two tanks and two
> regulators you have the opportunity to recover from the loss of a regulator
> or hose by cross connecting (or just running off of one tank). With the
> tanks outside of the hull increased internal space is available, a
> catastrophic HP air failure will not result in immediate personal injury,
> and with the addition of a remotely operated valve (with valve stem or valve
> stem extension protruding into the hull) the loss of a regulator or failed
> piping can be mitigated.
> 3. MBT Vent Valve - a failure here can not be worked on within the hull
> without causing massive flooding. Mitigation for this causality - motor to
> the surface and blow what ballast you can. To reduce the magnitude of the
> causality, increase reserve buoyancy so that there are 3 MBTs instead of two
> thus if one is loss, the other two will bring the sail far enough above
> water to allow the operator to exit the boat without it scuttling. See
> Joe's Alvin Jr's saddle tank amidships. This is a departure from the
> standard K-boat design but 30% reserve buoyancy should be the minimum
> acceptable design.
> 4. Electrical Propulsion - Loss of power should be immediate cause for
> aborting the dive. Loss of the main thruster (in a K-boat styled design)
> would allow continuance of the dive under reduced propulsion of the
> thrusters. Loss of a thruster would only potentially cause steering issues.
> Any motor lost due to flooding should be removable from the electrical bus
> by unbolting the power leads from the buss bar with an adjustable wrench or
> a closed-end wrench to mitigate a short. Better would be a Guest-styled
> battery switch capable of isolating a defective motor. If the insulation is
> smoking due to a short, this is cause for immediate dive termination. With
> internal batteries you potentially have the capability of removing a faulty
> battery from the battery bank with a wrench (pre-dive checks should have
> found this issue). Internal batteries have the hazard of forming chlorine
> gas and releasing acid with a severe flooding incident. The chlorine will
> burn the skin and damage the eyes and lung lining (just had to deal with a
> gaseous chlorine incident Friday, fortunately not in a sub.NOT FUN!).
> 5. Life Support - A 72 hr. emergency life support capacity is the goal
> but 48 hrs. is probably the norm for those PSUB operators that are cautious.
> This means sufficient oxygen, scrubber material (usually slaked calcium
> carbonate), and dedicated scrubber fan batteries to keep the number of
> occupants alive for 48 hrs. with minimal movement. Often not considered s
> the need for thermal insulation for the occupants in the majority of
> operational areas for PSUBs (even Florida). Carrying O2 inside the hull
> should not be an option for two reasons related to tank failure: the rapid
> pressure spike could be injurious and O2 at higher partial pressures
> resulting from a leak can be very poisonous. If the scrubber is properly
> designed and there is a failure of the atmosphere-driving fan, you should be
> able to switch to lung-powered mode. The fan should be powered by a small
> independent, dedicated battery system sized to meet the duration of your
> scrubber. If the scrubber becomes wet due to a flooding incident, the
> scrubber material will become ineffective and even caustic. Not much here
> that can be fixed underwater.
> 6. Drop Weight Retaining Mechanism - Simple 90 degree twist handle or a
> threaded rod that will take multiple turns for emergency release of the drop
> weights. Not much that can go wrong here other than a hang of the external
> weight holding tray. Should be regularly lubricated and tested. Other than
> whacking the release mechanism inside with a small sledge (or one of your
> lead trim weights) to try to dislodge a hung tray, there is not anything
> repairable here.
> 7. Steering - Loss of steering can be mitigated with using the
> thrusters under proportional control. If a mechanical steering mechanism is
> frozen, slightly loosening of the packing gland nut with an adjustable
> wrench might free it. This issue should have been found on pre-dive checks.
> If the steering is fouled outside, there isn't much the operator can do.
>
>
>
> I am also a side-of-the-rode mechanic; unfortunately the motorcycle analogy
> doesn't work very well with PSUBs. The safest option is to abort the dive
> and return to the surface. This response to emergencies has been well
> tested in the technical diving world which shares many similar hazards to
> those encountered in PSUBs.if the dive is not going to plan, TERMINATE! (I
> have to admit to taking apart a regulator underwater and performing a quick
> repair inside the Control Room of the USS Bass SS-164 in 165 fsw).
>
>
>
> My analysis is not definitive and I would appreciate comments of others.
> Contingency planning is something that should be given more thought to in
> the PSUB community.
>
> R/Jay
>
>
>
> Respectfully,
>
> Jay K. Jeffries
>
> Andros Is., Bahamas
>
>
>
> It is the mark of an educated mind to be able to entertain a thought without
> accepting it.
> - <http://www.quotationspage.com/quote/1152.html> Aristotle
>
>
>
>
>
>
>
>
>
> _____
>
> From: owner-personal_submersibles@psubs.org
> [mailto:owner-personal_submersibles@psubs.org] On Behalf Of
> ShellyDalg@aol.com
> Sent: Sunday, February 25, 2007 2:38 AM
> To: personal_submersibles@psubs.org
> Subject: Re: [PSUBS-MAILIST] on-board air.
>
>
>
> Vance and all.... I see the subs with batteries, tanks, and all the rest,
> bolted to the outside of the pressure hull, but what do you do if something
> goes wrong?
>
> Maybe you get slammed against a rock outcropping, or maybe snagged on a
> submerged cable, or maybe a tank line or fitting fails. If the problem is
> outside.....How can I fix it?
>
> I like the idea of having all my stuff inside.
>
> With a set of tools onboard, I can re-route air lines, re-do electrical
> connections, jury rig something so I can get to the surface, save my self
> and passenger, and maybe even the sub.
>
> Another point is entanglement.
>
> I would like to keep my hull as smooth as possible. No hooks, corners, or
> snag points.
>
> I ride a dinosaur motorcycle, and I carry tools. That baby always gets me
> home. It's the chrome bikes that go in the truck.
>
> I can re-build damn near everything on the side of the road, and I expect
> the same sort of problems with my sub.
>
> Shit happens, and you can't anticipate everything, but you can be prepared
> to improvise.
>
> Frank D.
>
>
>
>
>
> _____
>
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>
>
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