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Caution:
The actions described in this paragraph may affect the reliability of detection and must only be carried
out by authorised and trained personnel.
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Gas detection instruments are potential life -saving devices. Recognizing this fact, Industrial Scientific Corporation
recommends that a functional "bump" test be performed on every fixed gas-monitoring instruments as part of a regular
maintenance program. A functional test is defined as a brief exposure of the detector to a concentration of gas(es) in
excess of the lowest alarm set-point for each sensor for the purpose of verifying sensor and alarm operation and is not
intended to be a measure of the accuracy of the instrument.
Industrial scientific further recommends that a full instrument calibration be performed using a certified
concentration(s) of calibration gas(es) quarterly, every 3 months.* Calibrations may be necessary more or less
frequently based, for example, on application, field conditions, exposure to gas, sensor technology, and environmental
conditions. The frequency of calibration is best determined by company policy or local regulatory agencies.
If an instrument fails to operate properly during any functional "bump" test, a full instrument calibration should be
performed successfully prior to use.
These recommendations are based on safe work procedures, industry best practises, and regulatory standards to ensure
worker safety. Industrial scientific is not responsible for setting safety practices and policies.
* For new installations it may be prudent to carry out bump tests frequently at first (perhaps weekly), increasing the
time intervals (to, perhaps, monthly or more) as confidence grows with experience in the installation concerned, on the
basis of the maintenance record.
1.1.
Calibration
Calibration is necessary in the following cases:
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Start-up
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Replacement of the sensor block of any electronic circuit
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Constant zero drift
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Periodic test.
Items required for calibration:
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Gas calibration kit (bottle of standard reference gas and its accessories)
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IR20 remote control: non-intrusive setting (access to the maintenance menu)
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Knowledge of the procedure.
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Check that the facility is operating correctly
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Set up the gas intake system (6331137 or 6331141) depending on the gas (see Page 23)
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Connect the kit pipe to the calibration pipe
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Inject air or standard reference gas from the bottles at a rate of 1 l/mn for explosive gases and 0.5 l/mn for other
gases.
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The concentration of standard reference gas must usually be at least 50% of the measurement range.
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Use the IR20 remote control to carry out the actions.
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Check that only clean air is present in the detector, otherwise purge with cylinder of clean air to set up zero.
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Using the remote control unit:
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Validate (1) the Calibration menu (see Section III.1)
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If necessary change the value of the standard reference gas ("+", "-", "Enter" keys on the remote control unit)
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Initialise (1) the Zero function
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Wait for the measurement to stabilise
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Validate (1)
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Initialise (1) the Sensitivity function
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Inject the standard reference gas and wait for the measurement to stabilise
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Validate (1) and confirm (1)
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Finally, stop gas injection and remove the kit from the detector
(1)
ENTER key
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Calibration procedure
Preparation
Calibration
18
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