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4.0 Maintenance
4.1 Replacing the gas filter element
The Model 450H comes equipped with a gas filter on the ozone inlet. These filters
accept 25mm diameter glass fiber elements. Only filter elements of borosilicate glass or
quartz fibers should be used. When the instrument is first installed, the sample filters
should be checked at least once a week for particulate loading and replaced if necessary.
Once the replacement frequency is determined, a regular schedule for filter replacement
should be instituted.
For replacement 25mm filter elements, please contact Teledyne API’s sales department
and request part number 02851.
Filter Replacement Procedure:
1. First ensure that the gas delivery line is not under pressure and has been purged of
ozone.
2. Remove the four nuts securing the gas filter assembly.
3. Remove the bottom half of the filter housing
4. Examine the internal sealing o-ring and replace if necessary.
5. Pull out the stainless steel screen securing the filter element.
6. The element can now be removed and replaced. When re-assembling filter, make
sure that the top stainless steel screen is pushed into the filter cavity, securing the
element in place.
7. After re-assembly, the gas line should be pressurized with oxygen or dry air and
checked for leaks using a bubble solution.
4.2 Cleaning Exterior Surfaces of the M450H
If necessary, the exterior surfaces of M450H can be cleaned with a damp cloth. Do not
attempt to clean any of the other surfaces of the instrument. Do not submerge any part of
the instrument in water or cleaning solution.
4.3 Cleaning the Optical Cell
Over long periods of time the optical cell windows in the sensor assembly may become
dirty and affect the operation of the instrument. Each time a zero calibration is done, the
instrument can detect changes in the light transmission through the windows and will
issue a warning when this value drops to an unacceptable level. The warning message
“Optical Cell Warning” will be issued on the front panel and the “Cell Dirty” status
output(See Section 1.6.3) will be turned on. The cell assembly should then be cleaned to
avoid any degradation in measurement accuracy of the M450H.
P/N 02826B1 Teledyne API Model 450H O
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Monitor Instruction Manual - Page 39