Corrosion inhibitors most commonly used for commercial closed loop systems
are typically combinations of nitrites, azoles and sometimes sodium
metaborate.
Nitrites offer protection for ferrous metals, Azoles for yellow metals
(copper & copper alloys). Sodium metaborate is used to buffer & stabilize
pH.
Typical concentrations for control of corrosion rates to negligible levels
are about 600-1000 ppm for Nitrites (depending on the intended service
temperature) and about 50-100 ppm for Azoles.
In solution, these chemicals all increase conductivity, defeating the
benefit of distillation. Also be aware that nitrates are food for bacteria
so system must stay sterile.
73
KM5VI
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Dr. David Kirkby
Sent: Tuesday, November 29, 2011 5:21 PM
To: amps@contesting.com
Subject: Re: [Amps] Can distilled water be used for a dummy load ??
On 11/29/11 02:05 PM, Jim Thomson wrote:
> My hb 50 ohm dummy load consists of 4 x 200 ohm globars in parallel
[type SP, glass bodied
> and suitable for oil immersion]. Each resistor is 1" diam x 12" long.
[275 W CCS in air]
> Each resistor resides inside it's own 2.875" OD x sched 40 Aluminum
tube.
> All 4 x thick walled AL tubes are heliarc welded.
>
> I heard some place that instead of xfmr oil, that distilled water can be
used instead?
> The same glass bodied type SP resistors, [50 ohm, high wattage] are used
in water cooled loads,
> the type that has the garden hose on one end, etc.
IIRC the dielectric constant of water is about 80, so it is very high
compared
to most other materials, so there is certainly the potential to increase
capacitances quite a bit, but depending on the sizes and spacing of
conductors,
as well as frequency, that might not be an issue.
I'd certainly add corrosion inhibitor. The inhibitors for central heating
systems might be a good choice, as you don't need a lot of them, so I don't
think it would significantly reduce the specific heat capacity of the
liquid.
Never tried it. I'd personally be a bit reluctant, but I can conceded there
are
cost savings and spillage is less of an issue. My Bird load has a silicon
oil,
but that stuff is expensive.
Dave
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