Checking And Fine-Tuning Measuring Accuracy; Taking Account Of Barometric Altitude; Checking The Indicating Accuracy - Bosch ETT 008.31 Repair Instructions

6

Checking and fine-tuning measuring accuracy

! Before commencing testing or fine-tuning work as described in Sections 6.2 or 6.3, the analyzer must be warmed up for a period
of 10 minutes. The cover of the device must be closed during this time.
It is essential to note the instructions in Section 6.1 before checking and fine-tuning measuring accuracy.
Please observe the propane factor of 0.5 for checking or fine-tuning the HC measuring channel.
Observe safety regulations when working with toxic gases.
6.1

Taking account of barometric altitude

Before checking or fine-tuning measuring accuracy, using a barometer read the current air pressure at the site in which testing or
adjusting is taking place.
In addition, find out what altitude is stored in the analyzer in input mode to Section 4.1.7.
If the analyzer is equipped with an air-pressure gauge (and this has been activated as described in Section 4.1.6), then check the
following:
- Does the altitude stored in the analyzer correspond to a mean air pressure which does not deviate by more than +50 mbar from the
currently measured air pressure? If there is a difference of 50 mbar or more, set the altitude in the analyzer to the current value.
If the analyzer is not equipped with an air-pressure gauge, the altitude in the analyzer must be set to the value which most accurately
corresponds to the current air pressure.
After you have finished checking or fine-tuning the device, set the altitude at which the device is to be used by the operator.
Altitude for mean air pressure
Altitude in m Mean air pressure
above sea
level in torr
-700 825
-600 815
-500 806
-400 797
-300 787
-200 778
-100 769
0 760
100 751
200 742
300 733
400 724
500 716
600 707
700 699
800 691
900 682
1000 674
1100 666
6.2

Checking the indicating accuracy

The pump must be switched off. Select analysis mode with the "Select" button (press 10 x) and activate with the "Enter o"
button.
Introduce a flow of test gas no. 4 into the device via the calibration-gas inlet.
Read the displayed values of the CO, CO
Maximum permitted indicating error = 5% from certified test-gas value.
If the value of one of the measuring channels exceeds the maximum permitted error, re-tune the measuring channel in ques-
tion to Section 6.3.
in Hpa (mbar)
1099
1087
1074
1062
1049
1037
1025
1013
1001
989
977
966
955
943
932
921
909
899
888
and HC measuring channels and compare with the certified test-gas values.
2
Altitude in m Mean air pressure
above sea
level in torr
1200 658
1300 650
1400 642
1500 634
1600 627
1700 619
1800 611
1900 604
2000 596
2100 589
2200 582
2300 574
2400 567
2500 560
2600 553
2700 547
2800 539
2900 533
3000 526
in Hpa (mbar)
877
867
856
845
836
825
815
805
795
785
776
766
756
747
737
729
719
711
702
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