
Manual CWD 2005
Important Information
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Manual CWD2005.doc
11
When planning the installation, local site conditions must be taken into account. The
instrument has a small open flame inside so consult any hazardous area regulations
for applicability. If supplied the analyzer shelter may require an air purge system to
conform to hazardous area regulations.
Note:
A purge system can also be useful for installations in very dusty areas.
A small source of air for combustion is necessary, generally you must ensure that
flue gas is not allowed to accumulate the inside of the shelter (CO, H
2
and H
2
S may
be present) and that any combustion heat is discharged so that the analyzers thermal
stability remains unchanged. Any outside vent needs protection from wind to avoid
back flow of flue gases into the unit and the possibility of unstable readings.
The analyzer is fitted with numerous safety features and instrument ignition can only
occur with the door closed. In the event of failure of gas or cooling air supply, the gas
solenoid valve will close and after a short interval the solenoid will reopen and the
instrument will enter an ignition cycle. If the ignition cycle or online measurement
function is aborted due to flame out or power failure, the gas supply solenoid reverts
to its normally closed position and the small amount of sample gas flow is instantly
terminated. User intervention is then necessary to resolve the problems source.
Calibration is only possible if a calibration gas cylinder is available and contains the
correct certified gas. The mixture will normally be similar to the major process gas
components with a value around 80% of the analyzers range.
CWD 2005 gas consumption is between 8 and 200 liters per hour and the quantity
will depend on the characteristics of the process gas. When designing an outdoor
shelter the use of a gas flow restrictor is recommended since it will limit the
„potential
to release‟ in case of any accidental damage to the sample gas tubing inside.
An air purge system will ensure the LEL inside the enclosure remains well within the
allowable limits of the standards defined by local or national electrical codes.