Re: [PSUBS-MAILIST] pressure compensation

["Dale" <heinzind@cadvision.com>]

-----Original Message-----
From: Sean T. Stevenson <sts@telus.net>
To: personal_submersibles@psubs.org <personal_submersibles@psubs.org>
Date: Sunday, June 23, 2002 1:00 PM
Subject: Re: [PSUBS-MAILIST] pressure compensation


>>>I am pressure compensating at ambient..
>>
>>dale.
>
>Would it not make sense to compensate these spaces at higher than ambient
pressure?
> I can see this having a couple of advantages:
>
>1)  This prevents water (bad) or sea water (very bad) from entering
whatever
>it is you're trying to protect.  If you compensate just to ambient, water
can
>pass freely through a leak in the system.
>
>2)  By compensating to higher than ambient, you are alerted to the presence
>of any leaks in the system because the compensating oil volume will
decrease,
>giving you time to surface before the pressure reaches ambient and water
can
>enter.
>
>-Sean


  Yes, I agree with you, but didn't go over ambient for a couple of reasons.
first,  I only carry a fixed ammount of air with me, any large leak  in the
compensation system, would soon deplete my air supply  (if you have a valve
to shut the air supply off when you get a bad leak, then you are down to the
second uncompensated option anyways) with this in mind, and the knowledge
that the motors will still function fully flooded, I decided I would rather
put up with possible small leaks, and just check the motors .  I am not
using a scuba regulator, but am using a regulator I modified to act in the
same way.  (it is inside the sub with me ,and takes pressure from the depth
gauge line.)  I have also taken Carstens advise, and sprayed the inside of
the motors with a spray lube, to keep minor rust from forming with
condensation etc,  then compensate only with air (no oil inside or
anything)... For the depths I am working at, I think this is a good option.
I have had no leaks yet.  This is different than George called for in the
plans, but I can always go that way later if this doesn't work.

dale.