[PSUBS-MAILIST] Gauge for outside viewport?

Wed Oct 7 17:36:40 EDT 2015

I hadn't thought of that, but those cans are pretty robust, but still good point.Hank 

     On Wednesday, October 7, 2015 2:15 PM, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 One can install mechanical seals by machining the end of a Minnkota, and that's a really attractive solution for most PSUBS. But this is a 1,000 footer and will be tested deeper. I think the strength of the can itself would probably be the issue.
Best,
Alec
On Wed, Oct 7, 2015 at 2:01 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

| Alec,
I am driving Gamma with two Perry thrusters that have a simple mechanical seal. I think a Minkota could be modified with a mechanical seal. A new end cap and a shaft extension would do it. This could be a add on kit for Psubbers. I can send you pictures of the Perry seal set up.
Hank |

     From:  Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org>; 
  To:  Personal Submersibles General Discussion <personal_submersibles at psubs.org>; 
  Subject:  Re: [PSUBS-MAILIST] Gauge for outside viewport? 
  Sent:  Wed, Oct 7, 2015 2:05:54 PM 

| Alec,   BTW, that big 12" seawater depth gauge doesn't have a phosphorus dial, however it is very readable in minimal light and does have a small reflective strip which runs around the one edge of the numbers. Brian 

--- personal_submersibles at psubs.org wrote:

From: Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] Gauge for outside viewport?
Date: Wed, 7 Oct 2015 08:29:07 -0400

Just a follow-up on this. While I'm pretty sure external oil filled gauges would work outside I find the oil doesn't like staying inside them, so I ended up bringing the gauges inside the hull. In the end, the majority of my air system is outside with just the gauges and the BIBS inside the hull. Apart from hull stops, the valves for operating the sub are outside and operated via mechanical through-hulls. It's not hard because there's just three valves total. In my experience most air leaks happen in those valves that are used routinely, as opposed to hull stops that are left alone. Even using top quality Swagelok valves, you sometimes have to tighten things up because a leak develops with use. 
One recent design change is that I'm trying air compensation on the thrusters again. I had originally made them oil compensated because the thrusters are jettison-able and oil compensation meant one less connection between thruster and hull, but I'll give air a try because, with big battery banks and freeboard, I expect this sub to rack up many more hours of running time than Snoopy did using thrusters just for maneuvering. Air compensation should mean less brush maintenance.

Best,
Alec 
On Wed, Oct 7, 2015 at 6:46 AM, Steve McQueen via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Alec, while I am not 100% sure from the photo I believe these are standard ss Ashcroft pressure gauges used in industry.  They are normally oil filled to dampen the needle movement.  The oil is added through a rubber plug normally that might also act as a compensation diaphragm. Anyway maybe a vendor to start having discussion with.

Steve

On Sun, Sep 20, 2015 at 11:03 PM, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

I have an interesting thing to think about and wondered if any of the PSUBS brain trust might have a suggestion.
One of the simplifications on my new sub is that all HP air lines are external, aside from the BIBS (which is normally shut off anyway). Thus, I'm looking for a 3,000-4,000 psi gauge to mount outside a viewport, like in the Pisces photo that I'll paste below. In case my paste doesn't come through, it is the one at the top of the following article: http://www.nytimes.com/2015/09/15/science/piloted-deep-sea-research-is-bottoming-out.html?_r=1
The first thing that came to mind was to use a SCUBA submersible pressure gauge, but the problem is these are normally 1 atm dry enclosures of limited depth rating. There is generally little information posted about how deep they'll go, but what I did find was mentioned 260 feet for the plastic ones and 490 feet for the brass variety. This is a 1,000 foot sub.
The second idea was to use oil filled gauges intended for above-water use. But these generally have considerable bubbles in the oil, are not very good at keeping the oil inside, and have other hardware not intended to live long in sea water.
Any suggestions would be most welcome!

Thanks,
Alec 

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