Yokogawa RAKD - Manual (Page 64)

<A1. SAFETY INSTRUMENTED SYSTEMS INSTALLATION>
A1-2
IM 01R01B30-00E-E 5th edition February 01, 2013 -00 All Rights Reserved. Copyright © 2003, Rota Yokogawa
A1.2.2 Diagnostic Response Time
In case of a fault the limit switches will go to their safe fail state immediately.
A1.2.3 Setup
A setup of the flow meter is not required. Installation shall be done according to the manual.
A1.2.4 Proof Testing
The objective of proof testing is to detect failures within the flow meter that are not detected by the
diagnostics of the flow meter. Of main concern are undetected failures that prevent the safety instrumented
function from performing its intended function.
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 flow meter 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.
Proof test for variable area flow meter RAKD with inductive limit switches:
When all the tests listed above are executed a proof test coverage of approximately 99% of possible DU
failures in the variable area flow meter RAKD can be claimed.
The following tools need to be available to perform proof testing:
Measurement instrument to verify output status of the limit switches
The person(s) performing the proof test of the Yokogawa RAKD variable area flow meter should be trained
in SIS operations including bypass procedures, flow meter maintenance and company management of
change procedures.
A1.2.5 Repair and replacement
Maintenance information can be found in section 6, Maintenance of the User’s Manual Model RAKD Small
Metal ROTAMETER, IM 01R01B30-00E-E.
If repair is to be performed with the process online the Rota Yokogawa RAKD variable area flow meter will
need to be bypassed during the repair. The user should setup appropriate bypass procedures for that.
Contact the Yokogawa sales office if this instrument requires repair
The person(s) performing the repair and / or replacement of the Rota Yokogawa RAKD variable area flow
meter should have a sufficient skill level.
Step Action
1 Take appropriate action to avoid a false trip
2 Inspect the device for any visible damage, corrosion or contamination.
3
Force the variable area flow meter RAKD to reach a defined “MAX” threshold value and
verify that the inductive limit switch goes into the safe state.
Note: only applicable if RAKD is equipped with a “MAX” limit switch.
4
Force the variable area flow meter RAKD to reach a defined “MIN” threshold value and
verify that the inductive limit switch goes into the safe state.
Note: only applicable if RAKD is equipped with a “MIN” limit switch.
5 Restore the loop to full operation
6 Restore normal operation