[PSUBS-MAILIST] right side up compensator

Fri Mar 27 19:29:07 EDT 2020

 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 diveprofile, the reservoir will fill with water defeating it's purpose. If you doa second dive there is no way of clearing it of water so you may as welljust 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 Iturned on the motor & I have a minuscule volume of oil. In other words themotor is acting like a pump & throwing the oil out. So one reason tohave 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 beachnot 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 goingdown 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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