I agree with Alec 100 % when he says
“Simple is Safe”.
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Smyth, Alec
Sent: Thursday, April 19, 2012
9:43 AM
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST]
Questions and update
Snoopy will be
diving for the first time tomorrow with a revised HP air system. I’ll let
you know how it goes, but here’s what it consists of:
-
Two
SCUBA tanks are carried outside and connected with fill whips.
-
Swagelok
instrumentation ball valves are used as hull stops.
-
The
two tank lines feed into the ends of a manifold made from a six inch length of
hex SS bar. They have check valves, so the air can feed into the manifold
but not back out. This means if a tank blows its O ring or some such problem,
the system will not lose pressure. There is no longer any need for crossover
tubing (to blow any tank from either supply source) as the manifold takes care
of that.
-
The
manifold has a pressure gauge and three valves on it for blowing Snoopy’s
three MBT tanks (forward, saddle, aft).
I think this is
about as simple a system as one can come up with, and I really like dispensing
with the regulators. There’s no moving parts, except for the bare minimum
of valves, and no issue of maintaining regulators, max depth limitations, etc.
Simple is safe.
On the topic of the
vent valves, I’m also doing something copied from Greg’s sub. I had
trouble with the original Kittredge design weeping, because the valves were
bolted onto the tower and sealed with nothing more than RTV. Not dangerous
trouble, just a nuisance little drip. The current system uses flange valves
mounted on tabs, and a SS shaft going through the tower wall, sealed with O
rings. See project page for details.
Best,
Alec
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of James Frankland
Sent: Thursday, April 19, 2012
5:13 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST]
Questions and update
WIth regards to the tubing and pipework questions. Ive just been
over all this myself and with help from the group, i think i know whats needed
now.
The captains plans show copper tubing which is a low pressure
system. General concensus is to ditch this idea and go for
stainless steel as Jon says.
Also, people tell me that a high pressure system is better as you get
faster blowing of tanks. But, the high pressure port on a standard scuba
reg is not big enough to deliver a decent amount of air.
So, i have ordered all my parts and expecting them to arrive
tomorrow. I'lll post a pic on my website of it all as soon as it arrives.
I am using 2x scuba tanks piped via whips into a manifold
block. Then i have a reducing regulator into the system so i
can dial up whatever pressure i want, up to full tank pressure. The
pipes are all parker 350bar stainless pipes with swaged joints. Most
of the pipe is 6mm but does change to 1/2inch for the vbt parts. After
that the actual configuration of the pipe system is the same as the plans.
However, Emile has a system that i believe is better an you may be able
to use this. He has tanks mounted outside. The system uses a low
pressure ports on standard scuba 1st stages but as its outside, is always
delivering correct ambient pressure. The advantage is tanks outside out
of the way, and also only pressure you actually need in the pipework.
Correct me if im wrong there Emile!
On 19 April 2012 07:03, Jon Wallace <jonw@psubs.org>
wrote:
Hi Scott,
Sorry to hear about your accident. I got hit by a car while riding my
motorcycle back in 2003 and can vouch that it's not fun.
I believe conventional wisdom is to forgo the copper and use stainless
steel. The K-600 has SS plumbing throughout.
The problem you're going to have with putting the vent valves internal is
requiring two penetrations for each valve (inlet and outlet for air) instead of
the one penetration for the valve stem. I personally do not care for
K-boat vent configuration and am going to try to come up with an electric or
compressed air modification. Vance Bradley was working on a ballast tank
vent design at one time but I haven't heard anything about it for a while.
I like the DC breaker box idea. I might think about that myself.
200psi is 449 feet sea water. Since the K-350 is only rated for 350 feet,
using the 200psi first stage shouldn't be a problem. However, yes if you
drop to 500 feet then water would infiltrate the system and you won't be able
to use your ballast tanks because the outside pressure is stronger than the
first stage. There's a very simple technique to prevent getting in this
situation however, just don't dive in any area in which the water depth exceeds
350 feet.
Not sure what you mean regarding the motor pods since the plans call for 1-ATM
housings not oil-filled housings. We definitely could use a good
white-paper or photo-journal that describes how to do it. It's fairly
simple but I can sympathize with you, when you aren't familiar with it the
concept can be confusing exactly how to perform it. I have some photos of
JimK's Bionic Guppy motors which are oil filled. Let me find them and
post them and it should help.
We're scheduled to go to Muskegon
Michigan for the convention this
year and I'm working out the final plans. However, I sent out a request
for speakers and got no response. Unless we get 3 or 4 people to present
topics there won't be any need for technical sessions. That leaves the
potential for sub diving but with the exception of some local folks in the area
I suspect gas prices are going to curb any subs that might have otherwise
considered the trip. Unfortunate since the facility has the resources to
support us for diving. In any event, I'll be sending out notice in a week
or so for registration. If we get to end of May without speakers or subs
then we'll cancel this years event and wait until more people are willing to
participate.
Jon
On 4/18/2012 11:31 PM, Scott Waters wrote:
Hey everybody,
I've been pretty quiet on the pusubs form. A little update on myself and KW350
Trustworthy. For those of you who remember I got ran over and suffered a really
bad leg injury. I went though surgery in November to remove peices of my ankle
and reshape my cartilage and was doing better, but am having complications
again, so surgery again may be comming soon. I haven't let that stop
me (just slow me down), but I have been making good progress on my sub. I'll be
uploading pictures soon. I also got engauged just recently! I proposed 35 feet
under water while scuba diving in Key
West. Good thing is my girlfriend is a excellent
welder and scuba cert, so I might actually be getting more done on my sub
rather than less with a wife. haha. I have ran into a few questions though and
I though I would ask everyone. Here they are:
*For the copper tubing on the blueprints is it best to use compression fittings
or flare fittings?
*Is there anything wrong with running the vent controls internaly so the ball
valve is on the inside rather than a trough hull with the valve on the outside?
*I planning on putting in a DC breaker box on the inside of the sub so you can
reset circuts (in the rare ocasion) rather than fuses in the battery
pods. Does anyone see any problems with this?
* The blueprints call for "1st stage Dacor 200 Regulator" to
take the pressure down from 3000psi out of the scuba tanks. I believe that
means it brings the pressure down to 200psi. What happens if the sub has an
accedental drop to say 500 feet where the pressure is greater than 200psi?
Wouldn't the water rush in rather than air go out? Maybe I'm missing something.
*The blueprints for the oil compensated motor pods confuse the heck out of me. I
have them built, but am pretty much lost as far as how to make the things
work. I'm hoping to see some of your subs at the next conference or
something and perhaps I'll get it then. I think seing them completely finished
and filled with "oil" would help me. would help me alot. Any help on
this would be really appriciated. This reminds me, are we having a psubs
conference this year? I've heard about lake Michigan, but besides discussion,
haven't heard much. If help is needed putting it on, I'd love to help.
Thanks in advance for the help!
Scott Waters