Re: [PSUBS-MAILIST] Msg For Dan H

[vbra676539@aol.com]

He ran all his air through a first stage scuba regulator mounted internally. About the max you can wring out of one of those is 150 psi. Moreover, they do not provide a big flow, even at that pressure. You'll be a lot happier with full high pressure. And safer at depth. The only time I have seen regulated air work successfully was on the Johnson Sea-Link variable tanks, and they used SS regulators mounted outside so that they provided the same amount of pressure over ambient. That worked just fine, but the regulators cost $1K/each. Ouch.

Vance

-----Original Message-----
From: James Frankland <jamesf@guernseysubmarine.com>
To: personal_submersibles <personal_submersibles@psubs.org>
Sent: Wed, Dec 28, 2011 7:06 am
Subject: Re: [PSUBS-MAILIST] Msg For Dan H

hmm, ok.  Good idea.  Should be easy enough to do.  I'll dump it into a water test tank as well for extra safety and hide out of the way.  I'll test it as soon as the piping arrives.

 

Strange that George only calls for 150psi pressure.  I thought it was higher than that.  Thats only just enough to blow mains at full diving depth.  Oh well, mine will be 3000psi.

James

 

 

On 28 December 2011 16:29, <vbra676539@aol.com> wrote:

I'd fill that tank with water and test it to 125% or so (at a distance, mind you). It's probably plenty strong enough, but better to know in advance.

Vance

-----Original Message-----
From: James Frankland <jamesf@guernseysubmarine.com>
To: personal_submersibles <personal_submersibles@psubs.org>

Sent: Wed, Dec 28, 2011 6:03 am
Subject: Re: [PSUBS-MAILIST] Msg For Dan H

Hi Vance,

 

Yes, understood.  They have a chart at Swagelok that tells you what wall thickness to use for the OD of the pipe and the pressure you want. 

 

i have the standard VBT design, i was going to use 1/2" SS tube for that part as per the plans (as its the vent as well) but at the correct thickness for 3000psi.  Then use thinner piping for the rest of it, again at the correct thickness for 3000psi.  Do you think that wont work now?  The through hull to the tank is sched 80, tank is as standard but with sched 80 air inlet pipe.

 

Thanks

James

On 28 December 2011 15:37, <vbra676539@aol.com> wrote:

James,

The original Kittredge design called for 135-150 psi system pressure and used 3/8" and 1/2" tubing to account for lower flow rates. If you are using a high pressure system, 1/4" SS tubing will do nicely. That said, you can't mix and match. Captain K's copper tubing system and VBT design are not strong enough for 3000 psi.

Vance

-----Original Message-----
From: James Frankland <jamesf@guernseysubmarine.com>
To: personal_submersibles <personal_submersibles@psubs.org>
Sent: Wed, Dec 28, 2011 5:28 am
Subject: [PSUBS-MAILIST] Msg For Dan H

Hi Dan,

 

Couldnt find your email so had to send this to the whole group.

 

Can you tell me what size piping you used for the HP air.  The smaller diameter one.  Looks like 3/8ths as per the plans?  With 0.032 wall?

 

Many thanks

James