S
ERVICE AND
M
AINTENANCE
34
December 2000 Rosemount Analytical 748221-L
Model 7D Thermal Conductivity Analyzer
T
HERMAL
F
USE
The fuse opens at temperatures above 72
°
C. Check continuity with ohmmeter.
6.2.5 D
UAL
A
LARM
M
ODULE
(O
PTIONAL
)
This module is not user-serviceable. If problems occur, contact Rosemount Analytical
service.
The module has Zero and Span potentiometers that set the 0 to 5 V input. To check
these, adjust the analyzer for zero gas, set the Low Alarm (ALARM 1 on the front
panel) set point to 0 %, and turn the Deadband counterclockwise. Adjust the Zero pot
to trigger the alarm. Do the same for High Alarm (ALARM 2 on the front panel). The
alarm span should agree with the analyzer meter span. Readjust the deadbands to
the desired level. (See Figures 2-7, 2-8.)
6.3 SUPPRESSED ZERO ADJUSTMENT
If the instrument has suppressed-zero ranges and does not calibrate properly, adjust
the potentiometers located on the Master Board (see Figure 2-6). Follow the startup
procedure in Section 3.3. After the analyzer has stabilized, use appropriate calibration
gases to make the following adjustments. Refer to Section 2.2.2 for information on
selecting appropriate gases.
Note
For instruments with more than one range, RANGE 1 is the most sensitive
range; it must be set for the highest gain. This range should be used for the
smallest span. Always start procedure with RANGE 1 (i.e., RANGE 1 ... 95 to
100%, RANGE 2 ... 90 to 100%, RANGE 3 ... 60 to 80%).
1. Set the front panel ZERO and SPAN pots to their midpoints (five turns).
2. If the instrument has a Range Switch, set it to RANGE 1.
3. Connect a digital voltmeter between TB3-1 and TP1 (polarity does not matter).
4. Flow downscale calibration gas through the sample inlet of the analyzer. Adjust R8
until the reading on the voltmeter is zero. The front panel meter should also read
zero.
5. Flow upscale calibration gas through the sample inlet of the instrument. Adjust R4
until the front panel meter reads 100 % (fullscale).
6. Repeat steps 4 and 5 above until no adjustment is required.
If the analyzer has more than one range, repeat steps 2 through 6 with the following
alterations:
Содержание 7D
Страница 12: ...PREFACE P6 December 2000 Rosemount Analytical 748221 L Model 7D Thermal Conductivity Analyzer NOTES ...
Страница 30: ...INSTALLATION 18 December 2000 Rosemount Analytical 748221 L Model 7D Thermal Conductivity Analyzer NOTES ...
Страница 34: ...INITIAL STARTUP 22 December 2000 Rosemount Analytical 748221 L Model 7D Thermal Conductivity Analyzer NOTES ...
Страница 36: ...OPERATION 24 December 2000 Rosemount Analytical 748221 L Model 7D Thermal Conductivity Analyzer NOTES ...
Страница 54: ...REPLACEMENT PARTS 42 December 2000 Rosemount Analytical 748221 L Model 7D Thermal Conductivity Analyzer NOTES ...