GF PORTAFLOW 330, Инструкция по эксплуатации

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Operating Procedures Instruction manual
38
6. Press the ENTER key when done.
4-20mA Signal scaling
The 4-20mA can be set to represent a particular flow range. It is also possible to enter a
negative figure for the minimum output and this would enable a reverse flow to be monitored
7. With the instrument operating in the FLOW
READING mode, press the 4-20mA function
key. This will access the 4-20mA OUTPUT
screen.
8. Select Flow at max. output and enter a value
of the flow rate that you want to associate with
a 20mA output.
9. Select Flow at min. output and enter a value of
the flow rate that you want to associate with a
4mA output. This could be ‘0’.
10. Select Output mA for error and enter a value (default is 22mA) that you want the 4-
20mA output to produce in the event of an error (e.g. if the flow-rate is outside the set
range).
11. Upon completion press the ENTER key to return to the FLOW READING screen.
Converting the measured current to flow rate
Assume the maximum flow rate is F
max
(l/min) and the minimum flow rate Fmin is ‘0’ (l/min),
as shown.
To calculate the flow rate (l/min) for a measured current I(mA) then:
0-20mA 0-16mA 4-20mA
Flow rate =
I x (F
max
− F
min
)
20
+ F
min
Flow rate =
I x (F
max
− F
min
)
16
+ F
min
Flow rate =
(I − 4) x (F
max
− F
min
)
(16)
+ F
min
NOTICE