YOKOGAWA WE440, Руководство пользователя

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<4. Analyzer Hardware Configuration and Calibration>
4-1
IM 12Y18A04-01EN 1st Edition : Oct. 04, 2019-00
4. Analyzer Hardware Configuration
and Calibration
Each analyzer is setup at the factory, and shipped ready to be commissioned for on-line analysis.
This section describes the hardware setup in case maintenance or other post calibration
adjustment after service is required.
The WE440 Phosphate Analyzer is based on colorimetric detection principles. The analyzer uses
optical components that require initial setup at the factory and can be further tuned or recalibrated
by a trained technician.
This section describes the operation and calibration of the following assemblies: Optics, Heater,
Pumps and Analog Outputs.
4.1 Optics Calibration
WE440 Phosphate Analyzer optics consists of a LED light path and a photo-detector. The
analyzer is capable of driving three LEDs and the intensity of each of the LED can be individually
varied. The light path is preset in the reaction cell sample chamber. The photo detector receiving
the light energy is connected to an amplifier with programmable gain. The output of the photo
detector amplifier is digitized and measured in mV. Optics calibration in the analyzer is done in
two stages. In the first stage, the level of stray light is recorded. The LED light source is switched
off and the output of the photo detector is recorded. The second stage of calibration consists of
adjusting the intensity of the LED and the gain of the photo detector amplifier to get an optimum
level of output close to a fixed reference level. This is optimized for the specific LED and the
results of the calibration are stored.
The reaction cell sample chamber must be clean and filled with de-ionized water for proper optics
calibration cycle.
4.2 Optics Calibration Steps
For proper optics calibration the cell must be clean and filled with de-ionized water. Press the
MENU key and navigate to CALIBRATE OPTICS:
MAIN MENU → SERVICES → HARDWARE SETUP → CALBRATE OPTICS
The prompts remind the user to add de-ionized water in the reaction cell, and then allows them to
proceed for optics calibration upon confirmation.
The optics calibration is an automated sequence that also detects fault conditions. Once a fault
is detected, the sequence is aborted. For example, the optics calibration of stray light is aborted
if the stray light measured is greater than the factory allowed set reference value. The optics
calibration optimizes the light from the LED present in the system along with tuning the front-end
detection to maximize the signal levels with de-ionized water in the cell. The system stores all the
parameters for the application.
The calibration results are available for editing. From the MAIN MENU, follow the sequence:
MENU → SERVICES → HARDWARE SETUP → EDIT CALIBRATED VALUES
The stray light measurement is listed as OPTICS DARK; the optimum light level is listed as
OPTICS xREF for the LED specified in the MEASUREMENT METHOD.