[PSUBS-MAILIST] right side up compensator

Fri Mar 27 23:24:58 EDT 2020

Brian,
because of the volume of the reservoir being semi replaced with water on
the first dive. On the second dive there is less area to compress before it gets to
the bend to the motor, so chancing getting water in the motor unless you do
your calculations right.
As far as going to the beach is concerned; I had previously been in contact with a 
senior Sgt regarding clothes I had found on a cliff & a bad smell in a cave below it.
We smelt the smell 10 days after a Chinese student had disappeared at that beach.
I contacted her today to get permission to drive to this beach to check the cave
out on a super low tide. But no luck. She agreed that I was 1000 times more likely
to contact CV 19 at the local supermarket, but those are the rules. No driving
anywhere non essential. If our govt had have payed attention to what was going
on in the rest of the World & monitored our borders & people supposedly
isolating, then we wouldn't have to do this.
Alan

> On 28/03/2020, at 3:11 PM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Jon,
>               I have a drain at the bottom of the reservoir , you're right about the reservoir being filled after one deep dive, upon surfacing the expanding air bubble would push the water out of the hose open to the sea, so then at that point you would have only the air in the hose as a compression region.   You could still go back down to 300' and that volume would just get compressed.
> 
> Alan -  Why can't you go on the beach?   As long as you stay a distance form people I don't see the problem.   Things are pretty crazy here as well.   Time to isolate at -30 feet !
> 
> 
> 
> Brian
> 
> 
> 
> --- personal_submersibles at psubs.org wrote:
> 
> From: Jon Wallace via Personal_Submersibles <personal_submersibles at psubs.org>
> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] right side up compensator
> Date: Fri, 27 Mar 2020 23:29:07 +0000 (UTC)
> 
> Brian, what is the max depth you are trying to achieve?
> 
> At 300 feet, if the reservoir is full, a 5 foot hose will only give you about .652 inch air gap.  Not much of a buffer between oil and water.  I ran some volume numbers based upon 3x24 reservoir and there will be plenty of  air gap the first dive but it sounds like Alan has a good point regarding multiple dives.  Have you thought about using a smaller diameter hose and coiling it so you increase the air gap size but in a compact manner?
> 
> I'm curious about something else.  If oil gets from the motor into the reservoir you end up with a mix of oil and water, which makes it a "sacrificial" system rather than one in which you can transfer the oil back to the motor after dive ops.  Would a check valve be appropriate on the oil hose to combat this?
> 
> Jon
> 
> 
> On Friday, March 27, 2020, 06:28:04 PM EDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Brian,
> yes, but depending on your depth & ascents, descents within your dive
> profile, the reservoir will fill with water defeating it's purpose. If you do
> a second dive there is no way of clearing it of water so you may as well
> just have a hose.
> In my pool experiments with my home made thruster, I was observing the 
> compensating oil moving up the oil hose by a few inches every time I
> turned on the motor & I have a minuscule volume of oil. In other words the
> motor is acting like a pump & throwing the oil out. So one reason to
> have some over pressure is to keep the oil in the housing. It is critical for me 
> as I have a high powered small motor that relies on the oil for cooling.
> Maybe you could take the hose off the reservoir on the motor side, fill the 
> hose to a couple of inches from the top & turn the motor on to check this,
> as if this is happening then that will be something else you need to factor in.
> Got a nation wide shut down at the moment but allowed to walk to the beach
> not sure that I can even go fishing there. No boats allowed out. :(
> Alan
> 
> 
> On 28/03/2020, at 10:12 AM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Alan, 
>            Assume the oil goes all the way up to the high point of the oil tube, and then assume the water goes all the way up the water side tube and fills the reservoir all the way up to the top.  Then the only air remaining in the system is at the very top of the reservoir .  That would be the condition at maximum depth.    No? 
> 
> Brian
> 
> 
> 
> --- personal_submersibles at psubs.org wrote:
> 
> From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] right side up compensator
> Date: Sat, 28 Mar 2020 09:59:43 +1300
> 
> Brian,
> that would work to 30ft at the most. 
> If the volume in the reservoir was 1 litre & the volume in the hose going
> down in to the water was half a litre, then at 30ft the volume would be compressed 
> to half. So the reservoir needs another half a litre to achieve this. And that 
> would mean that the half a litre in the hose would move in to the reservoir &
> the hose would fill up with water.
> The main problem is you haven't worked out how much the oil might expand.
> If you did that you would have a ball park figure to work on.
> You may find that a hose without a reservoir would suffice.
> Or hose with small bladder on the end.
> Cheers Alan
> 
> 
> On 28/03/2020, at 8:20 AM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Here it is right side up hopefully 
> <IMGr_1522.jpg>
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