The pilot is already in the sub before you commence vacuum test.
Re: 'Underwater Robotics' book - yes, I know the authors and had imput
into a couple of the sections. Vickie Jensen is a long-time friend and I also
provided info on several of her books on Northwest Coast First Nations art and
culture. Co-incidental that she should become interested in U/W
technology!
----- Original Message -----
Sent: Tuesday, January 04, 2011 11:53
PM
Subject: Re: [PSUBS-MAILIST] Pre-dive
Vacuum
Thanks Phil,
Presume there's some way of equalizing the pressure so you can
get in afterward?
I was thinking maybe leave a valve open inside the hull but closed at an
external bottle.
Have just ordered the book, "Underwater Robotics: Science, Design & Fabrication"
& noted there were some Deep Worker
photos in the preview. Did you have input into this
book other than the photos?
Regards Alan
----- Original Message -----
Sent: Wednesday, January 05, 2011 7:15
PM
Subject: Re: [PSUBS-MAILIST] Pre-dive
Vacuum
We use a small shop vac or a battery operated car vac. The
over-pressure relief valve is located externally and has smooth
barrel/cylinder casing over it - the vac hose end has a machined plastic
nozzle with an internal o ring groove and o ring. The vac is slipped onto
the pressure relief valve and a light vacuum quickly sucked - the tech
watches the cabin pressure guage through the dome and the pilot watches it
also. At a couple of pounds neg, the vac is stopped and the gauge
watched to make sure it stays steady with no leakage. The nozzle is easily
pulled off and the sub is ready to launch. Prior to pulling the vacuum, the
bellows on the O2 system is backed off so that the neg pressure doesn't
cause the O2 make-up system to function and add oxygen.
Phil
----- Original Message -----
Sent: Tuesday, January 04, 2011 8:14
PM
Subject: Re: [PSUBS-MAILIST] Pre-dive
Vacuum
Phil & Dean,
This is intriguing. What
pressure differential do you pump it to? Do you use the
over-pressure relief or another port? What's the whole
procedure?
Best regards,
Jim
Hi
Dean,
have you piped the intake to the tyre inflator to use it as a
vacuum pump from the outside of the sub.
Or do you sit inside &
pump air out from there.
Regards Alan
From: "Recon1st@aol.com"
<Recon1st@aol.com>
To:
personal_submersibles@psubs.org
Sent: Wed, 5 January, 2011 3:46:33
AM
Subject: Re:
[PSUBS-MAILIST] Pre-dive Vacuum
Jim on my sub I installed a small air
pump I made from these small 12v
auto tire inflator. It works very
well.
Dean
In a message dated 1/2/2011 6:14:19 P.M. Central Standard Time,
JimToddPsub@aol.com writes:
Phil,
That's certainly worth putting on a pre-dive
checklist. It will definitely go on mine. How do you go
about it?
Thanks,
Jim
In a message dated 1/2/2011 1:51:25 P.M. Central Standard Time,
phil@philnuytten.com writes:
We never dive any of our subs unless they've held vacuum for
several minutes immediately prior to launch - this procedure tests
and 'sets' the o rings and avoids a nasty surprise at the end of a
large air-gap launch!
Phil