"In this process you need to look at how fast the rate of flow can change."

Not a problem. The fluid is a kind of syrup and the viscosity being high, does not permit rapid changes. Hence the 1 sec sampling.

"Lastly a comment,,,what is the resolution of the flow sensor."

Its a Rosemount flow transmitter. The 4-20 mA is calibrated for 0-75 kg/hour mass flow rate. The required resolution (by client) is 1 kg/hour and I am happy as I can get away with 8 bit ADC! And due to this I feel scaling down by a factor of 60 will make matters worse ?

Raghu