Optidew User’s Manual
36 97551 Issue 1, February 2018
OPERATION
4.3.2 First Time Operation
Before using the instrument, please read through the Installation, Operation and
Maintenance sections of this manual. This instruction assumes that all recommendations
within these sections have been followed, and that the control unit and sensors are
physically installed and all electrical connections complete.
1. Ensure that all sample connections are in good condition, of appropriate
materials and are leak-tight
2. Clean the mirror according to the instructions in section 5.1
3. Control the fl ow rate to within 0.1 to 2Nl/min (1l/min optimal)
4. Power on the instrument
NOTE: if the dew point sensor has been swapped, refer to section 5.2
4.4 Operational Functions
4.4.1 DCC Function
Dynamic Contamination Control (DCC) is a system designed to compensate for the loss
of measurement accuracy which results from mirror surface contamination.
During the DCC process the mirror is heated to a default temperature of 20°C above the
dew point to remove the condensation which has formed during measurement.
The surface finish of this mirror, with the contamination which remains, is used by
the optics as a reference point for further measurements. This removes the effect of
contamination on accuracy.
After switch-on, the mirror is assumed to be clean, therefore the instrument will only run
a DCC for 2 minutes to quickly establish a clean mirror reference point. By default, every
subsequent DCC is 4 minutes in duration and will automatically occur every 4 hours.
At certain times it may be desirable to disable the DCC function in order to prevent it
from interrupting a measurement cycle, e.g. during a calibration run. This is achieved
by setting ‘Mode’ to ‘Manual’ in the DCC menu. See section 3.2 for further details.
A manual DCC can be initiated or cancelled by touching the DCC button on the Main
Screen. The DCC button is context sensitive, i.e. if DCC is on, the Main Screen shows
DCC OFF as being selectable. Similarly if DCC is off, DCC ON is shown.
It is possible to change the parameters relating to the DCC cycle on the DCC Setup
Screen, refer to Section 3.2.
DCC Plus
DCC Plus is a feature designed to further control the build-up of contaminants on the
mirror surface without physical intervention from the operator. The function operates
immediately prior to either a scheduled automatic DCC or a manual DCC, by cooling the
mirror for a few seconds before heating it.
This cooling causes additional condensation on the mirror, which dissolves water-soluble
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