Tracy
wrote:
Bottom line is, if you need very accurate readings, learn to calibrate the EM2 if that is what you are using. To do this, you need a good reference. The easiest way is to use a non-contact (infra-red) thermometer. Harbor Freight and others are now selling inexpensive ones for about $10.00. No reason for any airplane builder not to have one. Be sure to paint the test points on the part to be measured with a spot of flat black paint to eliminate emissivity errors
Be careful; though. I haven't seen one for $10; but I did go to Harbor Freight about a month ago, and bought one that was on sale for $39.95 (marked down for $59). I wanted to double check the temps in and out of the oil cooler. It didn't take me long to realize it was not reading correctly. I have a lab grade thermometer that I then checked it against. It was off about 10 degrees or more at room temp on any surface. At higher temps it was off by more (30 – 40 F at about 180) on any surface with emissivity less than about .9. It was very accurate pointed at the cooler core (essentially a 'black body' – emissivity very close to
1.0). I returned it for a refund. Maybe you'll have better luck.
I had previously borrowed one from a friend which was quite accurate, and used it to calibrate coolant and oil temps. Air temp sensor and CHT TC channels I calibrated using ice water and hot water with the lab thermometer in it. I used pressure gauges to calibrate MAP and fuel and water pressure. Yes, my MAP calibration data is different than
Tracy
's (I guess the pressure variation is different in FL J
.)
FWIW,
Al