[Beowulf] 96 cores in silent and small enclosure

Lux, Jim (337C) james.p.lux at jpl.nasa.gov
Wed Apr 7 11:39:40 PDT 2010

> -----Original Message-----
> From: beowulf-bounces at beowulf.org [mailto:beowulf-bounces at beowulf.org] On Behalf Of Gerald Creager
> Sent: Wednesday, April 07, 2010 10:52 AM
> To: Hearns, John
> Cc: beowulf at beowulf.org
> Subject: Re: [Beowulf] 96 cores in silent and small enclosure
> Hearns, John wrote:
> >
> > I'd guess having vats of cooking oil in an office environment is a no-no
> > - what oil do radio hams etc. use for cooling dummy loads for high power
> > RF work?
> I remember when I could get a bucket of transformer oil from the light
> company, but that was laced with PCB, and is no longer available,
> responsible or legal. 

That wasn't oil, anyway.. askarels most likely.

Or, used oil that was drained from something that had previously been filled with PCBs, and is now "contaminated".  It's not the actual PCBs in the askarel that's the problem, of course, it's the inevitable dioxin (another PCB) trace contaminant that is the issue.

 Now, mineral oil. Clean, uncontaminated, mineral
> oil. Filtered mineral oil.

The tesla coil world spends an inordinate amount of time trying to find substitutes for the real thing, which is available for about $5-10/gallon in 5 gallon pails.  (the price varies surprisingly, and doesn't always track crude oil/gasoline prices.. mostly because the jobber has some amount of stock, so they tend to charge you what they paid for it, which might have been some months back).

If you have an agricultural supply (feed and farm type thing) they sell USP white mineral oil as an animal laxative in gallon bottles.  It's not the driest in the world, so I wouldn't use it for HV, but it is clean and filtered.  The important thing you want to avoid in non-electrical mineral oils is contamination with Poly Aromatic Hydrocarbons (PAH), which don't cause problems for things like using oil for machining, but do cause health issues for other uses. If the oil ever got hot, it "cracks", forming PAHs. USP oil has very low PAH.

Hydraulic fluid is another possibility, but watch the additives that get put in.  Something that helps keep your pumps, valves, and cylinders from rusting may not be the best thing for your PC board.

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