AW Gear Meters EMO-500 - Manual (Page 28)

EMO-500
Operation and Programming Manual
27
6. Units for Total.
This variable determines the Engineering Units for Total displayed after the totalizer value. It too is a
“display only” function and does not perform the actual conversion of total impulses to the correct
value. The KFT handles those calculations.
Enter the two-digit number for the desired Units for Total:
00 - cc 04 - revolution
01 - liter 05 - gram
02 - gallon 06 - lb
03 - ounce 07 - kg
08 - impulses
7. Sample Size (Default 200)
To determine the ratio, the EMO-500 separately counts the total number of pulses from both flow
meters until one of them reaches the programmed Sample Size. The number of pulses from flow meter
A is then divided by the number of pulses received from flow meter B. The accuracy and response time
of the ratio calculation are therefore dependent on the Sample Size.
To determine a reasonable number to program for Sample Size, the main factor is the flow meter with
the lowest pulse rate, but with at least 100 pulses before the Ratio calculation. If 100 pulses are counted
on the slowest moving totalizer then the accuracy of the ratio calculation should be about 1%.
The pulses counted are straight from the flow meter, not scaled engineering unit values.
The display screen #7 (Status Display 2) is a useful guide in this selection. The lower line shows the
incoming raw pulse count. For example, if the Sample Amount is 1000, the ratio display updates each
time the fastest total increments by 1000. Also by this method, the slower pulse count can be observed.
Default value is 200.
8. Gate Time (Default 1.85 sec.)
The gate time (in seconds) is the amount of time pulses are accepted before the EMO-500 performs flow
rate calculations. The accuracy and response time of the flow rate display are dependent on the gate
time. To achieve a 1% flow rate accuracy, the lowest pulse rate should produce 100 pulses before the
device performs the rate calculation. In display #7 (Status Display 2), the lower line indicates incoming
flow meter impulses, an estimate of the time elapsed for 100 pulses, to be accumulated by the slowest
meter, which gives a good approximation of the minimum recommended gate time.
Notice