In order to verify accuracy of commonly found and affordable K-Type Thermocouple I made small calibration chamber in which temperature is controlled by heater and attached regulator and temperature reading is compared to reference Fluke 289 Thermocouple reading.
On figure below there's whole setup. Temperature controlled heater plate with calibration chamber and two Thermocouple probes each connected to separate measuring instrument(one reference connected to Fluke DMM, other connected to my AKG regulator).
Calibration chamber is made of two aluminium cubes, smaller in which thermometers are placed, is fitted into larger one. There is air space between them making thermal insulation for convection heat transfer. All surfaces are polished making heat radiation (losses) low. Th design is very similar to insulated drink bottled - thermos bottles.
After few measurements conclusion can be made: stationary temperature within chamber can be accomplished within 20-25 mins (talking about reaching 200-250°C from starting 6°C).
Thermocouple used with AKG regulator is quite accurate, specially on higher temperatures. It only differs significantly from Fluke measurements on lower (room) temperature. Here 30°C is read as 6°C on AKG:
But higher values are within 5-6°C which don't require any calibration:
It should be said that AKG use proven and well established chip for thermocouple temperature measurement MAX6675. Anyway, there's possibility to calibrate temperature readings on AKG device if readout turn out to be inaccurate, for any reason. Linear calibration can be performed as described on page 10 of this manual.
Since lower temperature readings on AKG regulator show some difference compared to Fluke, I made calibration to eqalize readings on full scale 0-300°C.
On figure below there's whole setup. Temperature controlled heater plate with calibration chamber and two Thermocouple probes each connected to separate measuring instrument(one reference connected to Fluke DMM, other connected to my AKG regulator).
Calibration chamber is made of two aluminium cubes, smaller in which thermometers are placed, is fitted into larger one. There is air space between them making thermal insulation for convection heat transfer. All surfaces are polished making heat radiation (losses) low. Th design is very similar to insulated drink bottled - thermos bottles.
After few measurements conclusion can be made: stationary temperature within chamber can be accomplished within 20-25 mins (talking about reaching 200-250°C from starting 6°C).
Thermocouple used with AKG regulator is quite accurate, specially on higher temperatures. It only differs significantly from Fluke measurements on lower (room) temperature. Here 30°C is read as 6°C on AKG:
But higher values are within 5-6°C which don't require any calibration:
Since lower temperature readings on AKG regulator show some difference compared to Fluke, I made calibration to eqalize readings on full scale 0-300°C.
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