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...8 STARTUP
8) Reset the range selector switch on the gas monitor to
position 2. The top display continues to indicate NOT IN
USE.
9) The bottom display indicates the selected measurement
parameter – percentage by volume of hydrogen in carbon
dioxide (%H2 IN CO2) – on the lower line. The upper line
indicates a value for the parameter.
10) With carbon dioxide continuing to pass through the sample
system, the upper line of the bottom display unit should
stabilize within a few minutes to read 0.0.
11) If necessary, refer to Section 10.2.3 for a full calibration
sequence.
Note.
No
adjustment
potentiometer is necessary. As any adjustment required will
already have been made while calibrating the 'air in carbon
dioxide' range.
8.3.2 Hydrogen
Warning. Test for leaks in accordance with the
requirements of the responsible authority after making any
hydrogen connections.
1) Arrange to pass calibration quality hydrogen gas through the
(H2) Katharometer Unit on the appropriate katharometer
analyser panel, at the normal working pressure of the sample
gas system. This should give the correct flowrate of gas, as
set previously.
2) Power up the monitor unit, and the hydrogen katharometer
unit by switching on the appropriate power supply unit.
3) If fitted, set the range selector switch on the monitor unit to
position (1).
4) The hydrogen display unit indicates the measurement
parameter – percentage by volume of hydrogen in air (%H2
IN AIR) – on the lower line. The upper line indicates a value for
the parameter.
5) If fitted, the purge gas display unit indicates NOT IN USE.
6) With hydrogen calibration gas passing through the sample
system at the normal flowrate, the upper line of the top
display should stabilize within 2 hours to read 100.0.
7) If necessary, refer to Section 10.1.3 for a full calibration
sequence.
Note. A remote zero adjustment facility is available at
the top 'zero' potentiometer. Adjustment is made by
inserting a screwdriver through the hole behind the small
escutcheon plate.
24
of
the
bottom
zero
9 OPERATION
9.1 Normal
During normal operation the Model 6553 Gas Analyser System
is used to indicate the purity of hydrogen used as a coolant. The
displays shows the percentage of hydrogen in air, which should
be safely in excess of the explosive limit at the hydrogen rich
end.
There are no routine adjustments required to the gas analyser
system after completion of start-up procedures and putting on-
line in monitoring mode. The system only requires minor
adjustments to the metering valve to maintain the required
flowrate and the carrying out of safety routines.
A summary of the functions and status of the system for the
different range selector switch positions is shown in Table 9.1.
9.1.1 Purging of Hydrogen Coolant Gas
Initially, inert purge gas (carbon dioxide) is introduced into the
system. When the hydrogen concentration is safely below the
explosive limit, air is introduced into the system to completely
displace the other two gases.
The Model 6553 Gas Analyser System provides all the
necessary indications and output signals to enable this
operation to be carried out safely.
In respect of the operation of the gas analyser system(s), the
procedures are as follows:
Warning. Suitable safety procedures apply to the
operation of gas cooling and sample systems.
1) Select position (2) of the range selector switch on the
monitor unit. This causes the display units to indicate and
have the functions given in Table 9.1.
2) Commence the purging operation.
3) When the changeover to introduce air into the application
plant is made, select position (3) of the range selector switch
on the monitor unit. This causes the display unit to indicate
and have the functions given in Table 9.1.
9.1.2 Filling with Hydrogen Coolant Gas
This procedure is a reversal of the purging procedure.
Initially, inert purge gas (carbon dioxide) is introduced into the
application plant until the air content is safely below the
explosive limit for air in hydrogen. When this limit is reached,
hydrogen is gradually introduced into the system to displace the
other two gases.
With respect to the operation of the gas analyser system, the
procedure is as follows:
Warning. Suitable safety precautions will apply to
the operation of the gas cooling and sample systems.
Note. For reasons of accuracy it is recommended that
the filling operation commences within 24 hours of carrying
out the calibration procedure.
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