Calibration; Maintenance - Sensor Electronics SEC Millenium Series Instruction And Operation Manual

IV. CALIBRATION
SEC MILLENIUM
The SEC MILLENIUM is factory calibrated zeroed and spanned. Unlike other types of sensors it does not
require routine span gas calibration to ensure proper operation.
The SEC MILLENIUM is required to be spanned with gas only one time with CO2. Typically this is done at
the factory, but it is possible to field span the device by connecting the SEC MILLENIUM to a computer and
using a software package provided by SEC. Please contact the factory for further details.
A typical field calibration only requires the use of 99.99% nitrogen.
There is a fitting on the bottom of the sensor for a 1/8" ID tubing connection.
Before beginning calibration use the SEC MILLENIUM Insulation Tube to cover outer cylinder holes and
connect a 99.99% nitrogen source to the sensor's calibration port for a minimum of 3 minutes. To enter into
the calibration mode the calibration wire must be connected to negative (common of the power supply) for
ten (10) seconds, upon release the sensor will automatically enter the zero calibration routine. The
electronics will automatically adjust the sensor's signal to the new zero reference level. (Applying span gas
is not necessary because of the SEC MILLENIUM's unique software algorithms). During the zero
calibration routine, the current output of the SEC MILLENIUM will go to 2.2 mA. Although this can be
accomplished manually, installation of a switch (contact closure) can accomplish the zeroing procedure. It is
recommended that this switch be a momentary type switch to prevent it from inadvertently being left in the
calibrate position. If after 20 seconds the calibration lead has not been removed from common, the SEC
MILLENIUM will ignore the signal and continue operation as normal.
V. MAINTENANCE
The SEC MILLENIUM does not normally require cleaning of the optics. However if the unit is operating in a
very dirty or dusty environment the optical path might become obscured. If the obscuration is severe enough
to affect the unit's accuracy, the unit will activate an "Optics Fault" will. To clear an Optics Fault, first try a
calibration. If the calibration does not correct the fault condition, try to clean the optics. The outer barrel
(tube with two sets of holes) can be removed (unscrewed) to inspect the cleanliness of the hydrophobic
filter. The hydrophobic filter is a Teflon coated stainless steel mesh that keeps moisture and particulates out
of the optical path. A setscrew holds the filter to the MILLENIUM's housing. Once the hydrophobic filter is
removed, the internal waveguide tube should be inspected for cleanliness. The waveguide and waveguide
collar can be removed by inserting rigid instruments such as Allen wrenches into one hole of the waveguide
and one hole of the collar. Turning the two instruments in opposite directions will loosen the waveguide
allowing the collar to be screwed down on to the waveguide until it can be removed from the SEC
MILLENIUM housing. This will allow the windows of the SEC MILLENIUM to be cleaned. Dust can be
removed using compressed air. Hard or oily deposits can be removed using Isopropyl alcohol and cotton
tipped swabs. Wipe any film or residue or film left by the alcohol on the windows with a clean dry cotton
swab. The internal electro polished wave-guide tube can be cleaned the same way. Be careful not to leave
any particles of the cleaning swab in the waveguide. The waveguide holes can collect pieces of the
cleaning swab. After reassembling the unit (the waveguide and collar should be very tight to both ends of
the SEC MILLLENIUM housing after installation. Once the unit is completely reassembled and power is
reapplied, the SEC MILLENIUM must be calibrated. Refer to the calibration section of this manual.
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