[PSUBS-MAILIST] Thruster

Mon Feb 6 07:16:09 EST 2023

 Seems like you could build a container around the second stage to protect it from any surge under tow but still allow pressure for activation.  For example, stick it inside a PVC pipe of appropriate size, cap one end and point that toward the front.  The open back end will allow in all the pressure you need for the diaphragm.  
Jon

    On Monday, February 6, 2023 at 01:05:27 AM EST, Rick Patton via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Alex was correct. I faced the second stage to the side so that the pressure of the water while towing would be lessened on the diaphram but I don't think that would stop it just lessen it so my friend who owns several dive shops in Seattle after hearing what I wanted to do with it suggested that I use the one with the slide mechanism on it to prevent burping. The only downside is that I have to remember to have a guy retract it while he is unhooking the tow line. 
On Sun, Feb 5, 2023 at 6:30 PM Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Thinking about it; towing may suck on the exhaust valve ( venturi effect) which is fairly sensitive & cause a free-flowing effect. I guess the only solution is to turn the air off while towing, but if you forgot to turn it on.....You would need a pressure activated switch that would give you a warning when there was no pressure on it. The unit I am making has the exhaust valve set at a couple of psi above the main diaphragm pressure, so wont be subject to that.Alan.

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  On Mon, 6 Feb 2023 at 3:59 pm, Alec Smyth via Personal_Submersibles<personal_submersibles at psubs.org> wrote:   Presumably to stop the tow wash from pressing thein  diaphragm?
On Sun, Feb 5, 2023 at 7:56 PM Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Rick,I am making a 5psi over pressure regulator.It uses a 2nd stage lever valve but has a spring loaded heavy duty diaphragm to give it 5psi over-pressure. Why do you need a slide mechanism to stop the diaphragm from depressing. I havent heard of that before.It seems like one more thing that can go wrong if you forgot to un-slide it.Alan

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  On Mon, 6 Feb 2023 at 12:09 pm, Rick Patton via Personal_Submersibles<personal_submersibles at psubs.org> wrote:   I was thinking that to start with. That would keep water ingress until the positive pressure kicks in. There are as you know a couple of smart people working on perfecting a LP regulator for people that want to air compensate.  I have a second stage located about as low as I can afford to go with a slide mechanism that keeps the diafram from depressing until I have been towed out and ready to dive. 

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On Feb 5, 2023, at 9:44 AM, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Rick,another option would be some flexible silicone that you can cut through easily if you want to take the clip off.Just a bit more insurance. Alan

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  On Mon, 6 Feb 2023 at 7:23 am, Rick Patton via Personal_Submersibles<personal_submersibles at psubs.org> wrote:   Thanks Alan, in theory, this system makes sense as I have tried some other options and they didn't work as after running one for just a very short time on the surface to make sure the rhostate was working and pulling the motor apart, one of the wires was bare to the copper strands from rubbing on the armature. I was going to tig weld a lttle clip to the inside that would capture the wires but I was afraid that the heat so close the the sealing surface would destort it enough that it would leak.I was thinking about putting something on the outside to prevent ingress of water before the sub gets down a bit but I was not sure it would hold due to the internal pressure once under water? I could use a strong bonding epoxy but I want to be able to remove the screw in the future if I have to. Again, won't know if this will be a good fix for this tight quarters problem until I dive it. 

On Sat, Feb 4, 2023 at 10:00 PM Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Looks good Rick.You could always put a skin of glue over the bolts & surrounding area (on the outside) if you are not sure it will seal. Alan

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  On Sun, 5 Feb 2023 at 2:32 pm, Rick Patton via Personal_Submersibles<personal_submersibles at psubs.org> wrote:   I threaded a 1/4” piece of SS flat bar using a #8X32 tap and used it to pull the 2 wires against the inner surface of the housing to keep it from rubbing against the armature. Sealed the threads with thick pipe dope. 
Hopefully always an external air pressure so if air does make it past the threads, it will just be a very small stream of bubbles. Will post the results when tested. 

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