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Appendix 1. Safety Instrumented Systems
WARNING
The contents of this appendix are cited from
exida.com safety manual on the AXR series
flowmeter specifically observed for the safety
flowmeter purpose. When using the AXR for
Safety Instrumented Systems (SIS) application,
the instructions and procedures in this section
must be strictly followed in order to preserve the
flowmeter for that safety level.
A1.1 Scope and Purpose
This section provides an overview of the user
responsibilities for installation and operation of the
AXR in order to maintain the designed safety level
for Safety Instrumented Systems (SIS) applications.
Items that will be addressed are proof testing, repair
and replacement of the transmitter, reliability data,
lifetime, environmental and application limits, and
parameter settings.
A1.2 Using the AXR for an SIS
Application
A1.2.1 Safety Accuracy
The AXR has a specified safety accuracy of 2%.
This means that the internal component failures are
listed in the device failure rate if they will cause an
error of 2% or greater.
A1.2.2 Diagnostic Response Time
The AXR will report an internal failure within 8
seconds of the fault occurrence.
A1.2.3 Setup
During installation the flowmeter must be setup
with engineering units parameters. This is typically
done with a handheld terminal. These parameters
must be verified during the installation to insure
that the correct parameters are in the flowmeter.
Engineering range parameters can be verified by
reading these parameters from the optional local
display or by checking actual calibration of the
flowmeter.
<Appendix1. Safety Instrumented Systems Installation>
Installation
The calibration of the flowmeter must be performed
after parameters are set.
A1.2.4 Required Parameter Settings
The following parameters need to be set in order to
maintain the designed safety integrity.
Table A1.2.1 Required Parameter Settings
Item
Burnout direction
To specify if the output should go
switch
21.6 mA or higher or 3.2 mA or lower
upon detection of an internal failure.
Write protection
The write function should be
switch
disabled.
A1.2.5 Proof Testing
The objective of proof testing is to detect failures
within the flowmeter that are not detected by the
diagnostics of the flowmeter. Of main concern
are undetected failures that prevent the safety
instrumented function from performing its intended
function. Read Table A1.2.2 for proof testing
method.
The frequency of the proof tests (or the proof
test interval) is to be determined in the reliability
calculations for the safety instrumented functions
for which the AXR is applied. The actual proof tests
must be performed more frequently or as frequently
as specified in the calculation in order to maintain
required safety integrity of the safety instrumented
function.
The following tests need to be specifically executed
when a proof test is performed. The results of
the proof test need to be documented and this
documentation should be part of a plant safety
management system. Failures that are detected
should be reported to Yokogawa.
The personnel performing the proof test of the
flowmeter should be trained in SIS operations
including bypass procedures, AXR flowmeter
maintenance, and company management of
change procedures.
A1-1
Description
IM 01E30D01-01EN
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