[PSUBS-MAILIST] Compensating oil

[hank pronk via Personal_Submersibles]

Alan,No clue on brand, there is substantial  thrust protection because the motor sits vertical and the weight of the armature is always on the thrust mechanism.   If I recall, they have bushings not bearings.  If you can add reverse and speed control, you have a winner.  I just have no expertise in that area.Hank 


    On Saturday, December 12, 2015 8:22 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
 

 It should be relatively easy to add reverse, but I presume they are either on or off, so you would need the addition ofa 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


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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..... "Whatdoes reduce an oil filled motor’s efficiency is the energy loss due to oilcirculation within the stator housing. As a rule of thumb, this circulationrequirement reduces efficiency by about 1.5% when compared to an air filledmotor. "
   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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