ProSoft Technology MVI56-AFC - Manual (Page 260)

Diagnostics and Troubleshooting MVI56-AFC ♦ ControlLogix Platform
User Manual Liquid and Gas Flow Computer
Page 260 of 316 ProSoft Technology, Inc.
February 25, 2011
Alarm Message Description Solution
Orifice
Characterization
error
The orifice parameters (Meter
Configuration / Orifice button) are
invalid. Check the orifice and meter
parameters. The following conditions
should be true:


Orifice diameter > 0

Tube diameter > 0

Orifice diameter < Tube diameter
The beta ratio between the orifice
and tube diameters should follow the
AGA Standard.
Alarm Code values:


0 = No alarm

1 = Orifice diameter non-positive

2 = Orifice not narrower than
pipe

3 = Beta ratio less than 0.10
(adjusted by tolerance)

4 = Beta ratio greater than 0.75
(adjusted by tolerance)

5 = Pipe diameter less than 2.0
inches (adjusted by tolerance)

6 = Orifice diameter less than
0.45 inches (adjusted by
tolerance)
The "tolerance", fixed by the AFC
firmware, allows the AGA limits to be
exceeded by up to 75% towards the
physical limit. For example, while
AGA restricts pipe diameter to 2.0
inches or greater, the AFC allows it to
be as small as 0.5 inch.
Orifice Pressure
Exception
Configuration and process input for
an Orifice Meter are such that the
effective downstream pressure is less
than vacuum. For calculation,
upstream pressure is raised by the
amount necessary to raise absolute
downstream pressure to zero.
Check the process inputs for Gauge
Pressure and Differential Pressure,
and the configured Barometric
Pressure and Static Pressure Tap
Location. Also check any performed
vapor pressure calculations to ensure
that all are reasonable.
Pressure correction
error
The pressure correction calculation
resulted in an error according to the
standard.
Alarm Code values:
0 = No alarm
1 = Density outside range of API
Chapter 11.2
2 = Temperature above near critical
limit
3 = Temperature outside range of
API Chapter 11.2.1
4 = Temperature outside range of
API Chapter 11.2.2
5 = Non-convergence of Cpl-density
iteration