[TowerTalk] oil vs distilled water cooling.

[Jim Thomson]

Date: Mon, 13 Apr 2015 07:46:17 +1200
From: Steve Wright <stevewrightnz at gmail.com>
To: amps at contesting.com
Subject: Re: [Amps] Amps Digest, Vol 148, Issue 15



On 13/04/15 00:10, amps-request at contesting.com wrote:
> The anode air cooler could be removed. In its place, a small copper (or
> aluminum) liquid cooling block --considerably smaller than the original air
> cooler-- could be made in a machine shop in a couple of hours.
The cooling will be worse than air cooling, not better, as the ceramic
and other parts of the tube have no cooling at all, unless I add a fan,
which I dont want to do.  I want a fully integrated low-maintenance system.


> I would use distilled water, and replace it regularly. It's cheap, readily
> available, and is a better coolant.
>
And its a pain in the butt tocks always having to jigger with the amp. 
I build things so that I am more a liability to them than the other way
around.

Steve

##  so exactly what is the issue with oil vs distilled water ???   Distilled water
can be found in 4 litre jugs, cheap, at any grocery store.  To the best of my knowledge,
distilled water will extract heat a lot faster / better than oil.   I only saw 1-2 small tubes in the
entire Eimac catalog that used oil cooling.  All their big commercial broadcast tubes are either
air, or water, or vapor phase cooled tubes.  Or multi-phase cooled.... which is a combo of
water cooled and vapour phase cooling. 

##  at least if you had a leak..with distilled water,  you wont get a mess like with oil. 
If it was me, Id use a combo of distilled water  +  water wetter.  The water wetter,
added to the distilled water, stops bubbles  forming.  Water wetter is sold at any
automotive parts stores.   I use it in both my engine radiator.....and also in my roots
type  supercharger on my mustang  V8...  ( intercooler-heat exchanger- pump-degas loop). 

##  At the local race track, they will not allow the use of glycol mixed in with distilled
water in any engine radiator.   They will only allow distilled water + water wetter. 
Distilled water + water wetter is a proven winner.  It will reduce engine coolant temps
by at least 20 deg F.   Water wetter is sorta like soap, reduces surface tension. 
A lot of the water wetter products have a rust inhibitor included in their formulation. 

##  last year, I tested distilled water  vs  tap water  with just a fluke 87 dvm.  The
dc resistance of distilled water is sky high compared to tap water. Distilled water is
a superb insulator.   Dunno what happens to the dc resistance once  water wetter is
added to the distilled water.  I should re-run the test.   For a tube cooling application
it’s a moot point, since it’s a closed loop anyway. 

##  Viscosity of distilled water + water wetter is going to be a lot less vs  oil.  Distilled
water should flow easier through the tube, plumbing and any external  pump + radiator.

## However, the xfmr oil  I used in my dummy load is low viscosity stuff.  It sloshes around
just like water.   For a closed loop setup, oil or water will work of course.  The big advanatge
to oil is its boiling point will be a helluva lot higher vs water.   In a closed loop system, under
just 5-15 psi of system pressure, plus water wetter being used, the boiling point of water
will be a lot higher than the  normal 100 deg C.  

Jim   VE7RF