Fluid density variation compensation for fluid flow volume measurement

A method at least partially implementable in a computer to compensate fluid flow volume measurements in a fluid pipeline for fluid density variations, the measurements being performed by a meter which provides an output electrical signal at a frequency corresponding to the fluid flow rate therethrough, the meter being coupled to said computer which is arranged to receive the output signal provided by the meter and calculate fluid flow volume through the meter, the method comprising the steps of:

• a) providing a differential pressure sensor coupled across said meter, said sensor being operative for generating a pressure signal corresponding to the differential fluid pressure across said meter;
• b) proving the meter by providing a plurality of fluids each with a different density and for each of said plurality of fluids
• b1) causing said each fluid to pass through said meter at each of a plurality of predetermined flow rates;
• b2) for each of said plurality of predetermined flow rates tabulating the frequency of the meter output signal and the differential pressure measured by the sensor;
• b3) constructing a look-up table indexed by meter output signal frequency and containing the measured differential pressure and a volume factor corresponding to the predetermined flow rate;
• and
• b4) storing the table in a non-volatile memory of the computer;
• c) installing the meter in the fluid pipeline;
• d) on a repetitive basis providing to said computer the meter output signal and the sensor pressure signal;
• e) comparing, for the frequency corresponding to the provided meter output signal, the corresponding differential pressure measurement stored in each of the tables constructed for each of said plurality of fluids with the sensor measured differential pressure corresponding to the provided sensor pressure signal;
• f) selecting the table with the closest comparison;
• and
• g) updating the calculated flow volume by utilizing from the selected table the stored volume factor corresponding to the provided meter output signal frequency.