Servomex NanoTrace DF-760E, Instruction Manual

Page: 132 / 182

128 DF-760E Service
For best performance at initial start or anytime the electrolyte is changed, it
is important to allow the sensor to sit with electrolyte in it for 60 minutes
before the gas is allowed to flow through the sensor, or power is connected.
NOTE
When an Analyzer is operating at low ppb levels, adding solution to the
electrolyte level may result in a temporary increase in the oxygen reading
due to the presence of dissolved oxygen in the solution and the introduction
of oxygen due to agitation. More frequent additions (using smaller
quantities of solution), and adding solution with minimal disturbance to the
electrolyte in the reservoir, minimizes this effect and the resulting potential
temporary interruptions in service.
9.3.5 Moisture Cell Maintenance
None required.
9.3.6 Vacuum Pump Maintenance
If equipped, the vacuum pump requires periodic maintenance every 6 – 12 months in order
to maintain proper pressure and individual installations will ultimately determine the
appropriate maintenance interval. A good working pump will pull down to approximately
120 torr or less when the moisture cell is isolated. But when pump performance degrades
to the point that proper pressure cannot be attained a significant improvement in
performance can often be achieved by simple cleaning of the cylinder and piston assembly.
A rebuild kit is available from Servomex to return the pump to original specifications. See
the list on page 133 for cleaning fluid and rebuild kit part numbers.
9.3.6.1 Cleaning Vacuum Pump Piston and Cylinder Assembly
1. Disconnect power and vent all lines
2. Remove head bolts, head, gasket and valve plate assembly (note orientation of
head)
3. Remove cylinder and shims.
4. Clean residue from walls using a soft cloth and non-petroleum, non-oil based
solvent.
5. Replace cylinder including all shims. Be sure to orient the shims exactly the same
as they were removed.
6. Install valve plate, head gasket and head
7. Install head bolts and torque to 80 in-lbs.
9.3.7 Gas Purifier Maintenance
The Gas Purifier removes oxygen from typical trace level sample gas stream to provide
sub-ppb oxygen concentrations for use as a zero reference gas during Analyzer calibration.