Patent ID: 8590360

Claim:
A method for diagnosis of a flowmeter, comprising: thermally coupling a first sensor unit and a second sensor unit to a fluid, the fluid having a temperature TM 0 ; actively heating or cooling the first sensor unit by applying power PM 1 to the first sensor unit such that the temperature TM 1 of the first sensor unit is different from the temperature TM 0 of the fluid, and simultaneously actively heating or cooling the second sensor unit by applying power PM 2 to the second sensor unit such that the temperature TM 2 of the second sensor unit is different from the temperature TM 0 of the fluid; determining a temperature TM 1 of the first sensor unit and the power PM 1 applied to the first sensor unit, and simultaneously determining the temperature TM 2 of the second sensor unit and the power PM 2 applied to the second sensor unit; determining at least two independent quantities related to heat transfer of the first and second sensor units, each of the at least two independent heat transfer related quantities being determined from at least one of TM 0 , TM 1 , TM 2 , PM 1 , and PM 2 ; and determining a diagnosis result by setting into relation the at least two independent heat transfer related quantities.