Patent ID: 8485046

Claim:
A method of operating an ultrasonic gas flow meter, the ultrasonic gas flow meter including at least one signal evaluation unit, at least one memory, a piping through which gas can flow, at least one pair of ultrasonic transducers disposed on opposite sides of the piping and separated by a path inclined to a flow direction of the piping, wherein each ultrasonic transducer is connected to an electronic circuit to selectively act as an ultrasonic transmitter and an ultrasonic receiver, wherein the ultrasonic gas flow meter is adapted to detect a flow velocity of the gas flowing through the piping on the basis of differences between propagation times (T 1 , T 2 ) of ultrasonic signals transmitted and received between each pair of transducers and propagating in opposite directions along the path, wherein the method comprises a test procedure for verifying the operation of electronics associated with the ultrasonic gas flow meter wherein, when the test procedure is activated, test signals (PX 1 , PX 2 , PY 1 , PY 2 , PZ 1 , PZ 2 ) are triggered which replace the propagation times (T 1 , T 2 ) with predefined propagation times associated with an assumed gas flow velocity and the output of the evaluation unit is detected to see how the calculated gas flow velocity compares to the assumed gas flow velocity, characterized in that the test signals comprise electric circuit test signals (PY 1 , PY 2 ) which are configured as representative signals output from the transducer electronics to obtain test values for electric circuits arranged between the transducer electronics and the evaluation unit, to obtain test values for the electric circuits at the output of the evaluation unit for comparison with expected test values and/or, characterized in that the test signals comprise evaluation unit test signals (PZ 1 , PZ 2 ) which are configured as representative signals input into the evaluation unit to obtain test values for the evaluation unit at the output of the evaluation unit for comparison with expected test values.