Flow measuring device having a first and a second flow measuring transducer operating on different operating principles for improved measurement accuracy

A measuring station, comprising:

• a first flow measuring transducer that works according to a first measuring principle;
• a second flow measuring transducer that works according to a second measuring principle;
• and
• an operating- and evaluating circuit, configured to:
• ascertain a contribution to the flowed amount based on the first measured values when these are more reliable;
• ascertain a contribution to the flowed amount based on the second measured values when these are more reliable, wherein the contribution to the flowed amount corresponding to the second measured values is ascertained based on the second measured values by means of a version of a transfer function valid when ascertaining the second measured values;
• update the transfer function when the measured values of the first flow measuring transducer are more reliable, wherein the updating includes empirically determining a constant C1, wherein the transfer function is proportional to the constant C1, and wherein the transfer function is further proportional to a first term of the form |dp|1/C3 wherein dp is a measured pressure difference and C3 is a constant having a value between 1.5 and 2.5;
• and
• correct as a function of the updated transfer function the contribution to the flowed amount earlier ascertained based on the second measured values.

A method for determining a flowed amount of a flowable medium that has flowed through a measuring station, wherein the measuring station includes:

• a first flow measuring transducer that works according to a first measuring principle;
• and
• a second flow measuring transducer that works according to a second measuring principle,
• wherein the two flow measuring transducers are adapted, in each case, to be exposed to the total flowed amount of the medium,
• wherein the flowing medium has variable states or combinations of states that influence reliability of first measured values of the first flow measuring transducer differently than second measured values of the second flow measuring transducer,
• wherein the first measured values of the first flow measuring transducer are more reliable in first states or combinations of states of the medium than the second measured values of the second flow measuring transducer, and the second measured values of the second flow measuring transducer are more reliable in second states or combinations of states of the medium than the first measured values of the first flow measuring transducer,
• the method comprising:
• ascertaining a contribution to the flowed amount based on the first measured values when these are more reliable;
• ascertaining a contribution to the flowed amount based on the second measured values when these are more reliable, wherein the contribution to the flowed amount corresponding to the second measured values is ascertained based on the second measured values via a version of a transfer function valid when ascertaining the second measured values;
• updating the transfer function when the measured values of the first flow measuring transducer are more reliable, wherein the updating includes empirically determining a constant C1, wherein the transfer function F is proportional to the constant C1 and the transfer function F has the form
• F(dp, T)=C1 G(dp) H(T) or
• F(dp, T)=C1 G(dp,T),
• wherein dp is a measured pressure difference, and G and H are functions of dp and/or T;
• and
• correcting as a function of the updated transfer function the contribution to the flowed amount earlier ascertained based on the second measured values.