Chapter 1. Installation
14 DigitalFlow™ GF868 Startup Guide (1 and 2-Channel)
1.7.6 Wiring a 0/4-20 mA Analog Inputs Option Card
To calculate standard volumetric flow and mass flow of Flare Gas, the GF868 must have temperature and pressure data
from the measurement site. Transmitters installed in the flowcell send this information to the analog input card. This
card provides two isolated 4-20 mA inputs (A and B) with 24 VDC supply for loop-powered transmitters. You can
assign the temperature and pressure inputs to A and B as desired.
Note: To enter programming data during meter operation, you should know which input is assigned to which process
parameter. Enter the connections in Appendix B, Data Records.
The analog inputs, which have an impedance of 118 ohms, should be connected with standard twisted-pair wiring.
Temperature and pressure inputs require two or four wires, depending on whether the GF868 will provide power to the
transmitter. If desired, INLO and RTN can use the same wire.
Wire the analog input terminal block in accordance with the pin number assignments shown in Figure 9 on page 18.
The analog inputs on the option card(s) can be calibrated with the Model GF868’s built-in analog outputs. However, be
certain that the analog outputs have been calibrated first. See Chapter 1, Calibration, in the Service Manual for the
appropriate procedures.
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