ABB 266 MODBUS User Manual page 49

Validating DP measurement system
This procedure can be used to validate the differential pressure measurement system. Use Figure 33 for valve identification.
1. Verify the high and low pressure tap valve connections on the stream are closed to shut off the process flow (Figure 33,
item L and H).
2. Open the low and high side equalizer valves (items A and B).
3. Vent the high (+) and low (-) side of the manifold to atmosphere by opening the manifold vent valve (item C).
4. Verify the device is reading the differential pressure as zero.
5. Close the high side equalizer valve (item B).
6. Attach the low pressure calibration tool to the high side manifold vent/test port.
7. Apply the pressure corresponding to the requirements of the application.
8. The applied pressure will be visible on the device display.
IMPORTANT NOTE: If the differential pressure measurement changes beyond the limit documented in the
device specification, this is an indication of a leak in the system. If the value is increasing positively the leak
will be located on the low side of the system. For a increasing negative value the leak will be located on the
high side of the system.
9. Record the validation data necessary to satisfy the requirements of the application.
IMPORTANT NOTE: The 266 MODBUS
10. Continue with the validation until all the requirements have been met.
®
multivariable transmitter does not store validation data.
266 MODBUS® multivariable transmitter User manual 2105216 Rev. AB | 41
4 Transmitter start up