Your result will be *much* more accurate if you accumulate the raw numbers and display the total divided by 3600. (BTW, what do you use MASSBUFF for?)

1.Set a sampling rate of 1 sec.
2.Open a register of suitable size for storing accumulated mass values (MASSVAL)- battery backed one.
2.Clear a register of suitable size (MASSBUFF)for adding 3600 values.
3.Acquire the flowmeter value.
4.Add the flowmeter value to the MASSBUFF and also to MASSVAL.
5.Display MASSVAL/3600.
6.After 3600 additions to MASSBUFF, clear it and jump to step 2.