Re: [PSUBS-MAILIST] Shelsol D60 experiment

[JimToddPsub@aol.com]

Hi Alan,

 

Now that you mention it I recall the issue with the brushes lifting.  As with most areas in life, everything seems to be a trade off.  I'll stay tuned to the search for the perfect fluid. 

 

It would be interesting to know the coefficient of thermal expansion for various fluids at the temperatures generated by the motors in our operating environments.  It seems there would be several variables:  continuous and intermittent run time, cooling effect of the water, etc.  Perhaps there isn't enough expansion variation from fluid to fluid to even be concerned with it.  One can over-think these things.

 

Thanks,

Jim

 

In a message dated 12/23/2010 5:59:18 P.M. Central Standard Time, alanjames@xtra.co.nz writes:

Hi Jim,

I started off using a mineral oil in my small DC brushed linear actuator motors.

This was too viscous & created (as Phil describes it) a "herky Jerky" movement due to it's centrifugal motion

causing the brushes to lift temporarily. Possibly larger motors would be OK.

Another option I looked at was WD40 wich is used by Psubbers for motor compensation & is also mainly mineral spirits.

The WD40 can degrade some plastics quickly due to the levels of aromatics & although people have used it successfully in motors,

my application was primarily for inside linear actuators that have electronics, so didn't want to chance it.

I couldn't track down a silicone with a low enough viscosity & if I had it probably would have cost a fortune.

The Shelsol D60 was recommended to me by a chemical importer, as it had a low viscosity & was highly refined with a

low level of aromatics. It also has a higher flash point than WD40.

Regards Alan

 

 

----- Original Message -----

From: JimToddPsub@aol.com

To: personal_submersibles@psubs.org

Sent: Friday, December 24, 2010 11:31 AM

Subject: Re: [PSUBS-MAILIST] Shelsol D60 experiment

Hi Alan,

 

Interesting to hear how the various plastics stood up to D60.  Why would you use mineral spirits (a solvent) instead of light mineral oil as a compensating fluid?

 

Jim

 

In a message dated 12/23/2010 2:31:22 P.M. Central Standard Time, alanjames@xtra.co.nz writes:

Hi,

A couple of months back I posted that I was experimenting with Shelsol D60 for use as a

compensating fluid for my motors & linear actuators.

This is a low viscosity, low aromatic mineral spirit.

http://www.scdynamiccontent.shell.com/Files/aliphaticmineralspirits_shellsold60_americas.pdf

I left polystyrene, acrylic, & bits & pieces of household plastic soaking in it.

I just noticed that after 2&1/2 months the polystyrene had shriveled slightly & sunk.

This was a good result compared with WD40 wich did this to the polystyrene in less than a

day.

The Shelsol also caused some of the cheap plastics to become brittle. The Acrylic, acetate

& some other plastics (not sure what they were) were unchanged.

I haven't tried running my submarine motors in it. But one of my very small linear actuator motors wich

had been soaking in it for the same time frame works fine.

Although the result was great compared with WD40, it's still degrading some plastics & I'll have

to rethink what I'm doing with my actuators as there are electronics inside them that may be affected.

Alan