I’m doing incubator validation at 37 degree set point . Thermocouples were inserted into 15 mL tubes with 10 mL water inside, the thermocouples readings were stable from 3rd hour to 34 hours around 35.9 to 36.8 degree, looks never reach 37, but once removed from the water and left to the chamber air, the readings are around 37 to 37.5. Can anyone explain the reason? I think the equilibrium time is long enough.
the set point is 37 C, with +/- 1 C range according to manufacturer’s manual, the volume is 153L. Around 120 tubes of 15 mL with 10 mL water and 80 tubes of 50 mL with 40 ml water were loaded into the chamber, thermocouples were inserted selectively into the corner tubes at each level. Before the PQ, an empty chamber temperature mapping was performed, all locations were close to 37 degree. Looks like the loaded temperature is lower than air temperature for at least half degree.