[PSUBS-MAILIST] Oil expansion

[Alan via Personal_Submersibles]

Brian,
what I meant by added weight was that when the air is compressed it is
replaced by water making the sub heavier. It won't be much.
Of concern is that there will be air in the thruster that you won't be able
to get out & you may not be able to account for it in your calculations.
If you get it wrong & get water in through the tube, it will keep coming
in (being heavier than oil) until it has replaced all your oil! 
It will kill your motor. I have stuffed up a lot of electronics & batteries of late 
with sea water. 
Alan

> On 4/06/2019, at 3:06 PM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Alan,
>            The motor is outside the sub so I don't think there would be any added weight .
> 
> Once the motor with the wd40 heated up to it's maximum temp ( in my yard) then that would be the base line quantity of oil.  I would let it bleed out to the top of the ridge of the tube and spill out.  Then it would contract and I would just have to make sure the water going up the tube would not travel up as far as the top point of the tube where it heads back down to the motor.  
> 
> 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] Oil expansion
> Date: Tue, 4 Jun 2019 13:31:04 +1200
> 
> Brian,
> you could, but the narrow tube would need to be big enough to
> contain the expansion of the WD40. There is coefficient of expansion data
> on the WD40 documents, so you could work out what you need in a worst
> case scenario, then work out the compression of the air at your maximum dive 
> depth. You will become slightly heavier at depth with that method though.
> I did see a bellows type item posted by a psubber on Facebook recently but
> can't remember by whom. ( or is it "by who")
> Alan
> 
> 
> On 4/06/2019, at 12:25 PM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Alan,
>                I was thinking if the tube was pointing down into the water then as you submerged the pressure in the water would compress the air up into the tube.   To allow for deeper depths ( even though the most compression occurs initially at 33') to make sure the water traveling up the tube doesn't make the turn and head down to the motor I was thinking of putting a larger diameter pipe at the bottom so there would be more air to compress thereby compressing everything below the turn.
> 
> 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] Oil expansion
> Date: Tue, 4 Jun 2019 12:01:14 +1200
> 
> Brian,
> I wasn't thinking of it sitting in the yard!
> If you were leaving the tube open, you could just tape a plastic bag around
> the top during storage. There are probably hundreds of flexible items
> that would be suitable for a permanent solution if you didn't need 
> Over pressure, just make sure they are compatible with WD40.
> I don't think the regulator would be an option for storage as it relies on air 
> pressure from the tanks; unless you want to keep them on your sub with open 
> valves.
> Alan
> 
> 
> On 4/06/2019, at 11:14 AM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Hank,   I think in your situation where it's really cold you have less of a problem.  I have two things working against me , I have a very large volume of oil (wd40) and we have some pretty significant temperature swings here ( from 40F to 90F+)  So when my sub sits out in my yard the oil starts creeping up the expansion hose.    
> 
> Alan,   That sounds like it could be an option for me.  I'll have to check that out.
> 
>  What I'm thinking about doing in the meantime is running a hose up from the motor and then and then down to the bottom of the sub and just leave it open.   And I might put a  large diameter pvc pipe ( 1 1/2" )  at the bottom .
> 
> Brian
> 
> 
> 
> --- personal_submersibles at psubs.org wrote:
> 
> From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
> To: Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] Oil expansion
> Date: Mon, 3 Jun 2019 21:37:38 +0000 (UTC)
> 
> Brian,
> Have two oil filled motors on Gamma for vertical thrusters.  I fill them put in the plug and forget about them.  In the fall I drain the oil and refill in the spring.  KISS they work perfectly for years now.
> Hank
> 
> On Monday, June 3, 2019, 2:41:56 PM MDT, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Hi All,
>                What is everybody doing to allow for expansion and contraction of their oil filled motors?  
> 
> Brian
> 
> 
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