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4.0 Maintenance
4.1 General Maintenance
Once installed, the Model 610A Controller requires little or no routine maintenance, other
than periodic calibration checks. General Monitors recommends that a calibration
schedule be established and adhered to. GMI also recommends that a logbook b e kept ,
showing calibration dates and dates of sensor replacement.
General Monitors recommends that a calibration check should be conducted at least
every ninety (90) days. This is the only method of ensuring proper system operation and
response to combustible gases. More frequent calibration check s are enc ouraged t o
detect problems, such as mud collecting on the sensor heads; accidental painting over of
sensors, etc. A calibration check is def ined as the procedure of applying a known
concentration of gas to the system sensors, while observing the cont roller. The v is ual
display will indicate the gas concentration, and alarm indicators/circuits will activate in
direct relationship to gas concentration. Calibration adjustments must be made if res ults
vary (Section 3.6).
The removal of particulate matter from accessory sensor covers may be facilitated by the
use of an appropriate halogen-free solvent. Water and ethanol are examples of s ui table
solvents. Dry the sensor cover thoroughly with compressed air, if necessary, before
refitting to the sensor body. A calibration check must be made after the cleaned cover is
re-installed, because the cleaning process may increase response due to removal of dirt,
etc.
4.2 Periodic System Verification
The f ollowing system verifications should be performed annually. Verify wiring, terminal
connections and stability of mounting for all integral safety equipment including, b ut no t
limited to:
• Power supplies
• Control modules
• Field detection devices
• Signaling / output devices
• Accessories connected to field and signaling devices
Proper system operation should be verified by performing a f ul l, f unctional t est of all
component devices of the safety system, ensuring that the p roper levels of alarming
occur.
Fault/Malfunction circuit operation should be verified. Calibration intervals should be
independently established through a documented procedure, including a calibration log
maintained by plant personnel or third party testing services.
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