Flowmeter proving device and method

A flow meter proving device for use in proving a flow meter in situ under operating conditions, comprising:

• first and second Coriolis based mass flow meters which have been calibrated to a predetermined accuracy specification;
• means connecting the fluid outlet of the first flow meter to the fluid inlet of the second flow meter to connect said flow meters in series;
• supply and return conduits respectively connected to the fluid inlet of the first flow meter and to the fluid outlet of the second flow meter to enable the device to be connected to a fluid flow line containing a flow meter which is to be proved such that fluid flowing in the flow line will flow in series through said flow meter to be proved and said first and second flow meters of the proving device;
• and
• control means for connection to said first and second flow meters and to said flow meter to be proved to receive flow measurement signals therefrom, said control means being operative to use one of said first and second flow meters as a master meter to check the accuracy of the flow meter to be proved and the other of said first and second flow meters as a check meter for said master meter.