[PSUBS-MAILIST] Rotary oil seal question

[Alan via Personal_Submersibles]

Thanks Hank,
I am using the Viton seals because they are more heat resistant,
but don't think I will be doing more than 3000 rpm & the shaft is only 10mm.
Am using brushless motors, so no problem with brush contact :)
That's a good thought re putting in a sleeve to go from the larger to smaller seal,
hadn't thought of that. I will try just press fitting from the front.
Alan


Sent from my iPad

> On 16/10/2015, at 1:40 am, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Hi Alan,
> I have used both seals that you mention, I never retained the seals, they are a press fit.  If you go with the low pressure seal first and want to change to the higher pressure seal later, you can just make a bushing to adapt your housing (I had to do that) .  Your enemy is RPM, if I recall your motors run real fast.  For that reason, I would try the low pressure seal first and I would air compensate them, that low pressure seal is perfectly happy at 3,600 RPM.  I have a feeling that high RPM will create a lot of drag in oil and your brushes will struggle to make contact.  I like oil compensating for the ease of it all, but think air compensating is better.  
> Hank
> magnetic couplers is best though
> 
> 
> 
> On Wednesday, October 14, 2015 9:11 PM, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Hi,
> am working away on my brushless thruster.
> I am looking at 2 different options for rotary oil lip seals on a 10mm shaft.
> Both are viton one is rated for 6-7psi the other is 145psi.
> They have different O.D.s so I need to machine for one or the other.
> I am either oil or air compensating, so the seal will be seeing less than the rated pressure 
> on the low pressure seal.
> My thoughts are that the H/P seal may give me a bit more longevity if it wears, & a
> comfort margin. However I am not sure whether the extra pressure on the shaft would be 
> a problem or how much the H/P seal would impede the turning of the shaft.
> Also I haven't resolved how I am going to fit it. Options are to press fit it externally from the propeller
> end with or without a circlip to retain it. Or alternatively a bolt on plate to retain it.
> If I don't go with any form of retaining & rely on the press fit, am I best to glue it in?
> The other alternative is to fit it from inside the housing against a shoulder, with an internal
> circlip retaining it.
> Any thoughts & opinions on this thanks.
> Alan
> 
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