Dräger PEX 3000 Manual Del Usuario página 38

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Operation
– In the calibration menu, navigate using the ▲ or ▼ key until the display
shows SP ("SPan") and confirm by pressing the (▲+▼) keys. The
measured signal is set to 3.4 mA to indicate the calibration mode to the
controller.
 The display shows the test gas concentration used during the previous
adjustment in % LEL.
– Use the ▲ or ▼ key to set the concentration of the test gas currently in use
between 20 and 99% LEL in 1% LEL steps.
– For the type XTR 0010, a decimal point appears, i.e. the concentration of
the test gas can be adjusted between 2.0 and 9.9% LEL in steps of 0.1%
LEL.
– Pressing the keys for a longer period activates the repeat function.
Recommended test gas concentration:
Transmitter Full scale value
Type XTR 0000 100% LEL
Type XTR 0010 10% LEL
CAUTION
The test gas must consist of the gas component to be monitored and air.
Calibration gases filled in nitrogen are unsuitable for this task!
– Press the (▲+▼) keys and – depending on the transmitter type – apply the
recommended test gas concentration (see table) at a flow rate of approx.
0.5 L/min via the calibration adapter.
– Wait until the reading has stabilised (max. 3 min) and press the (▲+▼) keys
to calculate the necessary internal amplification of the transmitter. The
display shows the measured value with the newly calculated amplification
factor; however, this has not yet been saved. The original amplification
factor is restored if the calibration function is automatically exited by waiting
for more than 4 minutes in this status.
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NOTICE
After sensor replacement, the internal amplification of the transmitter can be so
high that the measured value cannot be displayed. The display will then show
"99" or "9.9". In this case, press the keys (▲+▼) to recalculate the necessary
internal amplification, save it, and repeat the sensitivity adjustment.
– Press the (▲+▼) keys. This finally saves the newly calculated amplification.
The display shows a reference value for the sensitivity (sensitivity) of the
sensor (constantly amplified bridge signal). If this reference value is lower
than 10 it is displayed with a decimal point.
– The actual sensitivity of the sensor in mV per % LEL can be obtained by
multiplying the reference value by a factor 2 and dividing it by 100 (or for the
type XTR 0010, dividing it by 10), e.g.:
–
Test gas concentration
–
30 to 70% LEL
3 to 7% LEL
– The reference value and/or the actual sensor sensitivity should always be
recorded in mV/%LEL for test purposes.
NOTICE
If the reference value is less than half the value recorded during commissioning
of the sensor or if the measured value does not stabilise within 3 minutes, the
sensor should be replaced (see "Replacing the sensor", page 40).
– Press the (▲+▼) keys to exit the sensitivity adjustment.
– Press the ▲ key twice to return to measuring mode. The flashing point on
the bottom right is deactivated.
5.3.2.3
– The display shows the current gas concentration in % LEL and the
transmitter once again emits the concentration-dependent 4 to 20 mA
signal.
– Refit the upper part of the casing, ensuring that the atmosphere is free of
dust and fasten the cover screws.
If, after adjusting the type XTR 0000 with 52% LEL propane, a reference
value of 45 is displayed, the actual sensitivity of the DrägerSensor PR M
DQ for propane is 45 * 2 / 100 = 0.9 mV/%LEL.
If, after adjusting the type XTR 0010 with 4.4% LEL ethanol, a reference
value of 32 is displayed, the actual sensitivity of the DrägerSensor LC M
for ethanol is 32 * 2 / 10 = 6.4 mV/%LEL. This value is higher by a factor
of 5 than for the DrägerSensor PR M DQ because of the internal
amplification of the DrägerSensor LC M.
After completing the adjustment
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