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Hi David, I've been thinking about installing a digital or normal SCUBA type dive gage and perhaps air pressure gage inside and outside my sub. Since I'm configuring my sub to be a wet exit training sub I need to make every thing so it can get wet and take the pressure, or be easily removed for training sessions. I thought since these instruments are designed for just that, why reinvent the wheel. Using one internally might not work properly when the subs interior is not flooded, as has been mentioned. Perhaps you could mount your dive watch just outside one of the subs viewports, and have some small LED dive light on it some how. Some SCUBA dive computers have there own lighting system, some even glow, but I don't know how long they can stay on. I've seen gages outside the subs front viewing area on the Uboat Worx subs, as well as the Deep Flight Aviator. The oil filled type gages might also work well for me, inside or out. But I have not done any real research on them to know what's, what. For are hyperbaric chambers, we have a pressure gage that is mounted out side the chamber, and facing right at one of the viewports, so there is no pressure on the exterior of the gage. Perhaps there is a oil filled type, that we can use internally, or perhaps a digital one that will sense the air pressure in a low range. Your resident pipe dreamer ;)' Regards, Szybowski From: dbartsch2236@hotmail.com To: personal_submersibles@psubs.org Subject: RE: [PSUBS-MAILIST] bubble pressure Date: Sun, 7 Sep 2008 16:59:37 -0400 Jay, I have installed this "watch" depth indicator within a small housing. The window thru which I view this gage has a magnifier so that this gage is more easily seen. Two small 12vdc lamps add illumination to this gage and consume little power. A additional watch (I do love spare parts) is as was delivered and I will attempt to attach a picture of this one to you tonight. You and Jens have been very helpful and informative to me and I give you my thanks. David Bartsch From: bottomgun@mindspring.com To: personal_submersibles@psubs.org Subject: RE: [PSUBS-MAILIST] bubble pressure Date: Sun, 7 Sep 2008 14:53:33 -0400 Jens, I did not read through your earlier email carefully (didn’t have my mug of morning tea yet) and unfortunately it is gone now. There are two types of air/hydraulic column depth gages that I know of, one very simple and economical and the other a little more involved but very dependable. I am not sure where your Papenberg gage falls into these descriptions: 1. Capillary gage is a tube with one end closed and so arranged that a column of air is trapped within. With an increase with depth the air column is compressed but not linearly. At 33 fsw ( 2 atmos.) the column of air is ½ of its original length, at 66 fsw the length is ⅓, 99 fsw the length is ¼, etc. They are most accurate in shallow water and loose accuracy as you increase in depth. They are subject to error from clogging of the inlet. 2. The pneumo-fathometer is used in the measurement of large tank levels and very accurate determination of depth for commercial divers. Air is injected into a tube (or hose in the case of divers) that is open to the sea at one end and the pressure increased until it levels off. At this point the air is bubbling out of the end of the tube and measuring this air pressure gives a direct indication of depth. The measure of the air pressure still needs to have care taken to insure the gage is measuring psia and not psig.
We get back to the argument of what is the minimal safe solution for the application. After reading David’s last email that he qualified the depth gage as being watch-styled and not necessarily embedded in a watch. If this is so, then he may indeed be using a straight diving depth gage. These come in two varieties (the capillary gages are no longer found generally due to the accuracies and hazard issues associated with this type): there is the electronic depth gage that depends on contact with water to be turned on and remain operating in depth mode and there is the oil-filled Bourdon tube gage (which measures psia). The Bourdon tube gage is economical, simple, dependable, and readily available…this is what I would recommend for this application. In addition, this analogue and very easy to read in many more conditions than the electronic digital gage.
Review of the web finds little information on the Papenberg gage but several pages concerning U-boats point to its use in determining the height of some other area of the sub in relationship to the waterline. In particular it was used to determine the height of the periscope. Would need more information to make the determination of being atmospheric independent since it was located in the Control Room of the sub which was at or near 1 atmosphere of pressure.
Looks like the formal evacuation of the island was called off today so have to fly back to Andros tomorrow. Ike veered further south and will be hammering Cuba instead. R/Jay
Jay K. Jeffries Andros Is., Bahamas
A skimmer afloat is but a submarine, so poorly built it will not plunge…
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Jay
I hope you do agree that the Papenberger is not a differential type gauge. The way I see it, this hydraulic type gauge should be quite independent from any local influences, i.e. from various local atmospheric pressure conditions inside the boat.
regards, Jens
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