[PSUBS-MAILIST] Vacuum vacuum

[Alec Smyth via Personal_Submersibles]

I always use the vacuum cleaner as a check before heading out to dive the
sub. The Nuytco guys have a portable vacuum, so they do it before launching
and as I recall actually launch the sub with a slight vacuum so they know
the O rings are all seated. In my case, as I don't have a portable vacuum I
just do it as a way to ensure the seals are in working order before I leave
my garage. I simply hold the shop vac hose over the over-pressure valve for
thirty seconds or so and watch the cabin pressure gauge through a viewport
for ten minutes afterwards. If the needle doesn't move, we'll be
watertight.

Best,
Alec

On Mon, Apr 29, 2019 at 10:15 PM Alan via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Brian,
> I am wondering if it is worth doing!
> None of the Psubs do it that I know of ( correct me if I'm wrong).
> If you pulled a vacuum & the sub stayed at that pressure then you
> would need to pressurise the hull to get out! But good test to see
> that the hatch is sealing ok.
> Alan
>
> On 30/04/2019, at 11:03 AM, Brian Cox via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi All,
>                    Tried the Vacuum cleaner , shop vac , method of pulling
> a vacuum on the sub today.   Works really great!   I pulled about neg 2 psi
> and it pulled the hatch down instantly and is holding nicely.  The large
> volume of air vacuum works a lot better than using a vacuum pump since it
> tends to pull surface area of the hatch all at once , where as when using
> the vacuum pump I remember having to sit on the hatch to make it grab.
>  I'm trying to remember Phil Nuytten's procedure after the vacuum is
> pulled, was it to bring the cabin pressure gauge dial back to zero by
> turning the dial indicator?  And with his bellows add system there was
> another adjustment I believe.
>
> Brian
>
>
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