AS NZS 2290.3:2018 Electrical equipment for coal mines – Introduction, inspection and maintenance
5.3.4 Corrective action
Those parts of the system failing to meet the acceptance criteria shall be immediately withdrawn from operation. This shall be done in a manner that leaves the remaining systemn an operational condition with only those system components that conform to the
acceptance criteria still in service.
5.4 TUBE BUNDLE SYSTEM MONTHLY INSPECTION
5.4.1 General
Monthly inspections will include verification of remote output readings and alarms. It will incorporate leakage testing of the sample delivery system by a suitable method.
5.4.2 Inspection/test criteria
The following shall be inspected:
(a) Comparison of analyser displayed readings with equivalent control room readings.
(b) Verification of alarm operation.
NOTES:
1 Only gas alarms that can be verified with the introduction of a known gas need to be tested. For example, the low alarm level for carbon monoxide may be set to -1 ppm, it is not possible to introduce -1 ppm of carbon monoxide gas, therefore this alarm setting need not be tested. However, the high alarm level for carbon monoxide may be set to 10 ppm, it is possible to introduce 10 ppm (or more) of carbon monoxide gas, therefore this alarm setting needs to be tested.
2 Hardware alarms that may affect the accurate analysis of gas readings need to be checked.This includes flow and vacuum alarms.
(c) Detection of any leakage in the tubes between the sample points and the gas analyser.
5.4.3 Acceptance criteria
The following apply:
(a) The equipment shall work normally with no conditions preventing continued operation until next inspection.
(b) Any alarm or out-of-normal conditions shall be logged, reported and resolved.
(c) No leaks shall be detected.
5.4.4 Corrective action
Those parts of the system failing to meet the acceptance criteria shall be-
(a) safely withdrawn from operation, which shall be done in a manner that leaves the remaining system in an operational condition with only those system components which conform to the acceptance criteria still in service; and
(b) repaired and subjected to an integrity test as per the requirements of Clause 5.5.
NOTES:
1The tube leakage test is designed only to detect obstructions and leakages in the gas sampling tubes.
2 Readings from this inspection should not be used to calibrate the analysers.