Industrial Scientific OLDHAM 300 Series, Руководство по эксплуатации и техническому обслуживанию

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12
CO
2
CIRCUIT
Fig. 7
2. 4-20 mA analog output
For CTX 300 sensors, except for the CO
2
sensor, the 4-20 mA output current is proportional to the
gas level.
Notes:
•
The CO
2
sensor can be equipped with a linearization board.
•
MX 15 and MX 32 central controllers that integrate with the linearization of the CO
2
sensor are
available upon request
•
The MX6 2 integrates with the linearization of CO
2
sensors.
The various states of the output current include:
• ≤ 1 mA to indicate a fault
•
2 mA in “calibration” position (except for the CO
2
sensor that does not have a calibration
function)
•
between 4 and 20 mA for measurement values
•
≥ 20 mA if levels exceed measurement range
IV. Maintenance
Warning: The adjustment operations in this paragraph are reserved for authorized, trained personnel
because they may compromise detection reliability.
Gas detectors are safety devices. In consideration of this, Industrial Scientific recommends regular
testing of fixed gas detection installations. This type of test consists of injecting a standard gas of
sufficient concentration into the sensor to set off the pre-adjusted alarms. This test does not, in any
event, replace a full calibration of the sensor.
Industrial Scientific also recommends completely calibrating detectors with a known and certified
concentration of gas every three or four months.
Frequency of gas testing depends on the industrial application in which the sensors are used.
Inspection should occur frequently during the months following installation startup, later it may be
spaced out if no significant problem is observed. Time intervals between tests should not exceed
three months.