[PSUBS-MAILIST] Gauge for outside viewport?

Mon Sep 21 09:24:41 EDT 2015

Hi Hank,

That is indeed the workaround I had in mind. I could use the same
penetrator as the BIBS with a teed gauge after the hull stop and a second
valve between T and BIBS.  But if I can keep all but the BIBS outside it is
my preferred solution. External HP lines will self-indicate leaks, are
easier to work on, and any leaks won't cause cabin pressure increases.

Thanks,

Alec

On Mon, Sep 21, 2015 at 8:29 AM, hank pronk via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Alec,
> Why wouldn't you just have the gauge inside the hull mounted directly to
> a shut off valve that is screwed into the hull, a simple tee in the line
> running down the hull.
> Hank
>
>
>
> On Monday, September 21, 2015 6:20 AM, Alec Smyth via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Hi James,
>
> 1) I have a bunch of oil filled gauges lying around, but if they are left
> in any position other than with the rubber caps at the top, they leak all
> over the place. The shelf they live on is covered with oil, so I'm just not
> confident they will keep the oil inside in the field.
>
> 2) Yes, SCUBA tank gauges have a tiny orifice in their hose fittings for
> just that purpose, to prevent a broken instrument from emptying your tank
> too quickly. That is good and I plan to use it on the sub as well. However,
> the problem still persists that SCUBA gauges can only be taken to under 500
> feet. I came across tech diver accounts of gauge issues such as the plastic
> faces buckling and pinning the needle, or the whole enclosure imploding at
> about 400 feet.
>
>
> Thanks,
>
> Alec
>
>
>
> On Mon, Sep 21, 2015 at 5:03 AM, James Frankland via Personal_Submersibles
> <personal_submersibles at psubs.org> wrote:
>
> Hi Alec,
>
> I have a couple of thoughts.
>
> 1.  The gauges I have are chemical protected, so they have an oil filled
> diaphragm separating the inlet line from the gauge internals.  Then there
> is a small vent hole at the top of the gauge.  You could attach a rubber
> hose\bladder to this vent hole, top it up with glycerine or whatever the
> gauge is filled with and have a fully compensated valve with a bladder.
>
> 2.  How about using just a normal scuba gauge which will probably be
> perfectly fine.  But, just make a small adapter that screws onto the gauge
> and has only a tiny little orifice to allow the input air.  That way if the
> gauge did ever fail, it would only bleed out air slowly and you'd have time
> to blow tanks.  If you are using a scuba 1st stage and piping from the HP
> port (I assume your not and are plumbing straight into tanks) then the
> scuba HP already has this small hole for the same reason.
>
> Also, it would be easy enough to test a gauge.   Find somewhere deep
> enough and take a fishing rod and a packed lunch!
>
> Im fairly sure Emile has external gauges on his sub and its a 200m diver.
> He could maybe advise?
>
> Just a thought.
> Kind Regards
> James
>
>
>
> On 21 September 2015 at 06:51, Brian Cox via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi Alec,    New sub ?  I must have missed that !    do you have any
> details?    BTW, I received that big gage !  It's huge !  I hope I can get
> it in through the hatch !   As it is designed for sea water I assume all I
> have to do is plumb it in, will salt water getting into the tubing cause
> any problems?
>
> Brian
>
> --- personal_submersibles at psubs.org wrote:
>
> From: Alec Smyth via Personal_Submersibles <
> personal_submersibles at psubs.org>
> To: Personal Submersibles General Discussion <
> personal_submersibles at psubs.org>
> Subject: [PSUBS-MAILIST] Gauge for outside viewport?
> Date: Sun, 20 Sep 2015 23:03:02 -0400
>
> I have an interesting thing to think about and wondered if any of the
> PSUBS brain trust might have a suggestion.
>
> One of the simplifications on my new sub is that all HP air lines are
> external, aside from the BIBS (which is normally shut off anyway). Thus,
> I'm looking for a 3,000-4,000 psi gauge to mount outside a viewport, like
> in the Pisces photo that I'll paste below. In case my paste doesn't come
> through, it is the one at the top of the following article:
> http://www.nytimes.com/2015/09/15/science/piloted-deep-sea-research-is-bottoming-out.html?_r=1
>
> The first thing that came to mind was to use a SCUBA submersible pressure
> gauge, but the problem is these are normally 1 atm dry enclosures of
> limited depth rating. There is generally little information posted about
> how deep they'll go, but what I did find was mentioned 260 feet for the
> plastic ones and 490 feet for the brass variety. This is a 1,000 foot sub.
>
> The second idea was to use oil filled gauges intended for above-water use.
> But these generally have considerable bubbles in the oil, are not very good
> at keeping the oil inside, and have other hardware not intended to live
> long in sea water.
>
> Any suggestions would be most welcome!
>
>
> Thanks,
>
> Alec
>
> [image: Inline image 1]
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