Name
Date
Designation
Prepared
JF 05.07.13
Service Manual BB 150
Index
Name
Date
Document No.
Page
File
50078923_04_CN
50 079 823
35/ 35
4.12.2 PERFORMING ADJUSTMENTS CO
2
METERING AND REGULATION
CIRCUIT
Performing adjustments:
The following steps can be performed for units equipped with either a thermal
conductivity or an infrared detector.
In general, a comparative measurement should be made, unless the actual value is
known, e.g., CO
2
display deviation at 0.0 % CO
2
.
Adjustment routine activation: Refer to the example in the operating instructions
(Chapter 6: Switch Function, Manual Zero-point Adjustment of the CO
2
Metering
System)
Comparative
measurement:
CO
2
regulating circuit
Perform the comparative measurement at the user's normal CO
2
concentration, e.g.,
5.0 %. Make sure the unit has adequate time to reach equilibrium before taking a
reading:
-
For test addition: No sooner than 45 min. after all regulating circuits have reached
equilibrium.
-
For units at
operating temp.,
with gas, stable
humidity:
The measurement can be made immediately.
Comparative measurement
procedure:
(Portable IR meter or hand pump w. sample
tube 0..10 % CO
2
)
Extract three gas samples through the metering opening in the gas
diaphragm/glass door.
Read and average the values, then compare with the displayed value.
Deviation:
<
±
0.5 % CO
2
No adjustment necessary.
>
±
0.5 % CO
2
Refer to Section 10.6 of the operating
instructions.
