[PSUBS-MAILIST] Compensating oil

[Alan via Personal_Submersibles]

It should be relatively easy to add reverse, but 
I presume they are either on or off, so you would need the addition of
a speed controller anyway. It would be interesting to pull one apart.
There might not be much in the way of a thrust bearing, as the pump impeller 
wouldn't have an axial load on the shaft like a propeller.
What brand was it again?
Alan



Sent from my iPad

> On 13/12/2015, at 2:35 am, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Alan,
> I am still in favour of pump motors except I do not know how to reverse them.  As far as I can tell they are not reversible.  The efficiency in oil comes from the extremely smooth interior of the motor.  If you could reverse them, they would be perfect, they are cheap at about 200 dollars for a small 120v and they would be pretty easily modified to take a prop.  Oh ya, and they already have  thrust bearings.   The oil inside was real stinky, kinda like antifreeze.
> Hank
> 
> 
> 
> On Saturday, December 12, 2015 3:24 AM, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Hank, 
> what ever happened to your idea of using a submersible pump as a thruster?
> Have just been doing a bit of reading on oil compensation of submersible pumps.
> In this article....
> http://www.pumped101.com/oilvsair.pdf
> it states that with oil compensation there is only a loss of about 1&1/2% efficiency 
> over an air compensated motor.....
>  "What does reduce an oil filled motor’s efficiency is the energy loss due to oil circulation within the stator housing. 
> As a rule of thumb, this circulation requirement reduces efficiency by about 1.5% when compared to an air filled motor. "
>    Of interest was that they base this on the use of an oil "Shellflex 210" which has a viscosity of 20.3 cst at 40C.
> I was recently trying to track down a silicone oil of 3cst thinking that I would need a really low viscosity to get reasonable efficiency.
> A chemist I spoke to said at that low a viscosity it would be flammable.
> Alan
> 
> 
> 
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