[Amps] SS amps watercooling - was PowerGenius XL

donroden at hiwaay.net donroden at hiwaay.net
Mon Mar 6 14:08:18 EST 2017

Use a large enough radiator and flow that the fluid never rises above 150F.

Quoting Al Kozakiewicz <akozak at hourglass.com>:

> There are waterless coolants used in automotive applications. Evans  
> seems to be the main manufacturer in NA. The main advantage is that  
> its boiling point is way higher than water + antifreeze. This means  
> that the operating pressure is near atmospheric and allows operation  
> at temperatures that would cause overpressure issues with water  
> based coolants.
> Whether it is useful for this application is unknown to me.
> Al
> ________________________________________
> From: Amps <amps-bounces at contesting.com> on behalf of Jeff DePolo  
> <jd0 at broadsci.com>
> Sent: Monday, March 6, 2017 1:32 PM
> To: amps at contesting.com
> Subject: Re: [Amps] SS amps watercooling - was PowerGenius XL
>> ##  IF conductivity is NOT an issue, then Id suggest using
>> what is already
>> being used in car eng radiator setups.  Distilled water + a
>> corrosion inhibitor.
>> Typ a 50-50 mix of glycol + distilled water is used.  The
>> glycol offers the
>> inhibitor properties, and also raises the boiling point by a
>> bunch, to typ 265 deg F,
>> IF under  typ pressure of 10-15 psi.  Less, with lower
>> pressure, but still  more than
>> 212 deg F.  That 50-50 mix  will also lower the freezing
>> point to aprx  -40 deg F.
>> You can also buy the 50-50 premixed, just pour it in.
> I agree.
> In liquid-cooled broadcast transmitters (both tube and solid-state), the
> thermal transfer fluid is typically a 50/50 mix of distilled water and
> Dowtherm SR-1.  SR-1 is ethylene glycol with corrosion inhibitors.  There
> are a few manufacturers that recommend or specify something else; Rohde and
> Schwarz comes to mind - they spec DEX-COOL for some of their rigs (and,
> yeah, I know all of the GM DEX-COOL horror stories, though I've never
> experienced any problems myself either in broadcast transmitters nor in my
> own GM vehicles).
> 50/50 is a good all-around mix ratio for SR-1.  It provides freeze
> protection down to around -35 degrees F, yields a healthy concentration of
> corrosion inhibitors, and prevents bacterial growth/contamination.
> Unless there is some anomaly that occurs during the life of the coolant that
> results in contamination, the primary reason to replace coolant at regular
> intervals is due to the natural change in pH.  When the system is initially
> filled, the pH of the 50/50 glycol mix is about 9.3.  As the glycol ages,
> and as the copper and aluminum in the plumbing and system components leach
> into the coolant, the pH slowly falls.  We usually do a flush when the pH
> falls below 8.0, and we never ever let it go below 7.5.  You don't want to
> let it turn acidic.  While you can try to extend the lifespan of the coolant
> by adding KOH to raise the pH, by the time the pH starts gets down near 8.0,
> the corrosion inhibitors are likely nearing depletion anyway.
> You can send a fluid sample out to a lab for testing of all the main
> indicators of the health of the coolant (glycol concentration, pH, inhibitor
> concentration, contaminants, etc.) -- probably overkill for ham amplifiers.
> Dow will even do it for free if your system is large enough (as I recall, if
> the volume of coolant in the system is over 200 gallons they do it for
> nothing).  But, for home/ham use, I think that if you just do a visual on
> the coolant to confirm it's the proper color and free of contaminants, and
> you check the pH every few months and when it falls below 8.0 do a flush and
> re-fill, you would be fine.
> By the way, cleaning the system real well before the first fill is very
> important.  A solution of a few percent TSP in distilled water is typically
> used, and then flushed twice with distilled water before filling the system
> with the 50/50 mix.
> The usual disclaimers apply regarding the toxicity of ethylene glycol, the
> proper disposal of the same, yada yada yada.
>                                         --- Jeff WN3A
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