Re: [PSUBS-MAILIST] gauge questions

["Dan H." <JMachine@adelphia.net>]

Alec,

I was just making something for my depth gauge that may be of interest to
you.

I have my depth gauges piped in with stainless tubing from the upper part of
my sub.  The line comes thought the hull up high, through an emergency
shutoff, then down through a T,  through two primary shut offs and then to
the gauges.  I have two gauges.  One is low pressure for accurate depth
readings when diving shallow and one of higher pressure for deeper dives.
Each gauge can be shut off independently.

I live in a northern climate and was concerned with water being trapped in
the lines and freezing.  Instead of letting water get into the gauges, I've
decided to build a stainless housing that has a three inch rubber diaphragm
on it.  This diaphragm assembly screws on the outside of the through hull
that is connected to my gauges.  My diaphragm has one side totally exposed
to the water.  I'll completely fill the gauges and lines with oil.  The
housing with the diaphragm, located on the outside of the hull, will also be
totally filled with oil.

When the sea water presses against the diaphragm, the diaphragm will put
pressure on the oil and be sensed on the gauge inside the hull.  But water
will never enter the system.  It's built but I haven't tried it yet.   Hope
you can follow my description.  Water presses on the diaphragm, the other
side of the diaphragm presses on the oil, and the oil pressure works the
gauges.


Just starting my wiring.  Nothing seems to fit where I would like to have
it!!!!!  BIG wires in small spaces!

Dan H.
----- Original Message -----
From: "Alec Smyth" <Asmyth@changepoint.com>
To: "PSUBS (E-mail)" <personal_submersibles@psubs.org>
Sent: Friday, January 03, 2003 2:32 PM
Subject: [PSUBS-MAILIST] gauge questions


> Hi all,
>
> I'm getting close to finishing my electrical distribution and controls
panel, and the next one is a panel for pressure instruments, so I'm starting
to research gauges. Someone on the list must have done this before me, so I
thought I'd ask. Does anyone have any good sources or other recommendations?
For example, any advantage going with liquid filled or dry? I'm looking at
gauges for:
>
> 1) O2 HP -  I see most gauges in my catalogs say "not for oxygen use".
> 2) O2 regulated pressure - ditto.
> 3) Air HP - no problem.
> 4) Air regulated - no problem.
> 5) Depth  - the problem is my design prevents me from just mounting a
scuba pressure gauge outside the window, I need a panel instrument on the
inside. Is it OK to pipe a pressure gauge to the outside with nothing but
stainless tubing and a shutoff valve, or would you use some kind of
strainer? Is a stainless bourdon really necessary, or brass or copper OK?
Does anyone know of an industrial gauge supplier offering faces in fsw?
> 6) Altimeter - ebay?
>
> Any pearls of wisdom are much appreciated. Sorry for so many questions on
something so simple!
>
> thanks,
>
> Alec
>