I tested in boiling water and boiling 100% antifreeze the VERY cheap oil
temp gauge Spruce sells. Accuracy was very good (ie as close as could be
read from the few graduations on the scale)..
Less so their Type K pyrometers which were out by 10%.
Duncan McF.
On Friday, September 13, 2002 2:37 AM, Fred Fillinger
[SMTP:fillinger@ameritech.net] wrote:
> In noting discussion re temps, I am wondering if anyone is testing
> their temp gauges for accuracy, before drawing conclusion and doing
> mods.
>
> From experience in designing digital readouts from the type sensors on
> the Rotax, the issues aren't trivial. If you look at the
> resistance/temp chart in the manual, it's nonlinear, with very low
> resistance at high temps of critical interest. Ways around that can
> be crude, in a temp gauge at the low prices they sell for. I have a
> high-end automotive temp gauge, with a separate electronics module,
> and a sensor of different characteristics which should mitigate the
> problems. It's still only sort of close in accuracy.
>
> The best way I found to check them is a digital meat or candy
> thermometer, like only $11.46 at Wal-Mart, but fast acting and very
> accurate. Heat up a small deep-fat fryer to above temp needed,
> disconnect from wall current, and immerse (and stir) with the sensor
> near the digital probe. Observe both readings as the oil cools down.
>
> I'm curious if others have tested gauge accuracy to see if the various
> experimental-aircraft-only temp gauges, with Rotax sensors, are
> accurate within a reasonable definition of the word.
>
> Best,
> Fred F.
> N3EU
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