AMC AMC-360-IREP Manuel d'instructions - Page 13

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AMC-360-IREP 0-100% LEL Methane Sensor/Transmitter

5.2.2 TRANSMITTER CALIBRATION / VERIFICATION SET-UP PROCEDURE

The calibration procedure may cause the monitoring equipment to give a false alarm, therefore

appropriate precautions should be taken. Refer to Figure 5 for the following procedure.

1. Remove cover from transmitter housing

2. Connect "Remote Calibration Lead" to multimeter.

BLACK lead to negative or common (–).

RED lead to positive (+).

3. Switch ON multimeter and select the 200 mA DC milliamp range to allow readings

greater than 20 mA full scale.

4. Insert plug end of "Remote Calibration Lead" fully into CAL jack on transmitter cover

plate. This will block the outgoing signal, causing a "fail" at the monitor.

5. With the sensor in clean air or zero gas, check for a stabilized zero signal of

approximately 4.0 mA.

6. Apply a Span gas sample delivered at a flow rate of 0.5 to 1 litre per minute. Since the

transmitter output range is 4 to 20 mA, a full-scale concentration should register 20 mA

after a few moments exposure. Proportionately, a half-scale concentration of gas should

5.2.3 ADJUSTMENTS (STANDARD CALIBRATION)

For full recalibration adjustments, follow the set-up procedure steps 1 to 6 inclusive. There are

two adjustments to be made for recalibration, Zero and Span.

•

ZERO: When there is no gas present (clean air), the transmitter signal should be 4 mA.

This is obtained by adjusting the zero trimmer on the transmitter. It is possible, with

certain conditions, that the "zero" current will go below 4.0 mA.

•

SPAN: When the sensor is exposed to the calibration gas sample, adjust the span

trimmer on the transmitter to set up the output current proportional to the gas

concentration applied.