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
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