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7-2.2 Calculating the K Factor for Analog
7-2.2 Calculating the K Factor for Analog
Inputs.
Inputs.
Obtain the Flow Rate value that corresponds
to the meters full scale signal. This should
be specifi ed on your device or with its paper
work.
Example:
20 mA = 200 Gal / min
The unit converts the analog input span to a
0-10000 Hz frequency. Given the full scale
fl ow rate that corresonds to the analog input
span, and the Time Factor (TF) that corre-
sponds to the equivalent fl ow rate time base,
the K-Factors can be calculated as follows:
Step-1
Calculate the equivalanet sensor K-
Factor as follows:
Equivalent Sensor K-Factor =
10000 * TF
Full Scale Flow Rate
Example:
4 to 20 mA corresponds to 0-200
Gal/min
Equivalent Sensor K-Factor =
10000 * 60
200
= 3000 pulses/gal
Step 2.
Determine the necessary DPF for
the desired total decimal point loca-
tion you wish to use in displaying
total on the instrument from the fol-
lowing table:
DPF Table
Desired Total
Decimal Location:
DPF
XXXXXX.
1
XXXXX.X
10
XXXX.XX
100
XXX.XXX
1000
XX.XXXX
10000
X.XXXXX
100000
Example: for X.X, DPF = 10
Step 3.
The Count K Factor may be computed
as follows:
Count K-Factor = Sensor K-Factor
DPF
Example:
Count K-Factor of 3000 /10 =
300
Step 4.
Enter the Count K-Factor as de-
scribed in Section 3-3 referencing
the Programming Flowchart (3-4) as
needed.
Step 5.
Determine the necessary TF (time
factor) given the fl ow rate time base
you wish to have displayed on the
device using the following table:
TIME FACTOR (TF)
TIME FACTOR (TF) TABLE
Rate Display Desired
Rate Display Desired
TF
Rate / second
1
Rate / minute
60
Rate / hour
3600
Rate / day
86400
Example:
For display of rate per minute;
TF = 60
Step 6.
Compute the Rate K-Factor from
the average sensor K-Factor and
the TF selected.
Rate K-Factor = Sensor K-Factor
TF
Example:
Rate per minute:
Rate K-Factor = 3000 = 50
60
Step 7.
Enter the Rate K-Factor as de-
scribed in Section 3-3 referencing
the Programming Flowchart (3-4) as
needed.
