Teledyne 3300TA - Low cost trace oxygen analyzer - Manual (Page 32)

5-2
5 Maintenance Model 3300 TA
Teledyne Analytical Instruments
fuse holder will slide out. There are two fuses in use and are visible in
the clip.
4. Remove the bad fuse and replace it with a 5x20mm 0.5 A,
250 VAC, IEC time lag (T) fuse (P /N F1130).
5. Replace the fuse holder into its receptacle, pushing in firmly until it
clicks.
5.2 Sensor Installation or Replacement
5.2.1 When to Replace a Sensor
On trace analyzers the Micro-Fuel Cell will typically fail due to excessive
zero offset caused by loss of water. Large zero offsets will result in inaccurate
SPAN settings. To test for this condition, purge the sensor and sample system
with ZERO gas (typically nitrogen with less than 1ppm O
2
). It may take several
hours for the sample system and cell to return to a stable low level of O
2
if it has
been exposed to higher levels of O
2
. If the instrument will not come down to an
acceptably low reading on zero gas, then a depleted cell or a sample system leak
should be suspected. Typically offsets of 1.0 ppm or less are acceptable. A cell
failure may also be indicated by an inability to SPAN, or slow response to
changes in O
2
concentration at levels below 100 ppm.
CAUTION: Read the section Cell Warranty Conditions, below, before replac-
ing the cell.
CAUTION: After replacing the Micro-Fuel Cell, the analyzer must be
recalibrated. See Calibration in chapter 4.
5.2.2 Ordering and Handling of Spare Sensors
To have a replacement cell available when it is needed, TAI recommends
that one spare cell be purchased when the current cell 's warranty period is
approximately two thirds over.
CAUTION: Do not stockpile cells. The warranty period starts on the day of
shipment. For best results, do not order a new spare cell to soon.
The spare cell should be carefully stored in an area that is not subject to
large variations in ambient temperature (75 °F nominal), and in such a way as to
eliminate the possibility of incurring damage.
CAUTION: Do not disturb the integrity of the cell package until the cell is to
actually be used. If the cell package is punctured and air is permit-
ted to enter, cell-life will be compromised.