Horace Heffner <hheff...@mtaonline.net> wrote:
> On Oct 8, 2011, at 1:51 PM, Jed Rothwell wrote: > > This was shown in the video on the table. Lewan says this was a Termometro > a 4 canali TM-947 SD. > > 4 canali evidently means you can attach up to 4 thermocouples. > > > http://www.bergamomisure.it/parametri-ambientali/termometri/termometro-datalogger-4-canali-tm-947-con-scheda-sd.html > > - Jed > > > Not very accurate for this purpose. > > "*Risoluzione: *1°C , 1°F / 0.1°C,0.1°F" > > I take it this means 1°C absolute, and 0.1°C relative. > > This means for a 5°C delta t there could be 2°C error, or 40%. > No it does not mean that. I have used many handheld meters and K-type thermocouples in other configurations. At a normal temperature range for a 5°C Delta T, the error is less than 0.1°C. That is to say, every single meter or thermocouple you use will report the same temperature difference to the limits of the display. They may start off at different absolute temperatures, but they will all show the same change. Even the cheapest red liquid thermometer Omega offers, the GT 736590, does not have a 2°C error in precision. I have 3 of them, and they are all accurate to within a degree, and precise to 10 or 20 degrees. (That is, when 1 goes up 18 deg C, so do the other 2, and so do the thermocouples.) A thermocouple or thermometer with a 2 deg C error in the normal range of use, 0 to 100 deg C, would be absurd. It would be useless. This particular one goes much higher, and you might see a 2 deg C error at higher temperatures, but not around room temperature. Trust me, a 250 Euro instrument would never do that. I have seen and used dozens of them. - Jed
