Hach Ultra MET ONE 227, User Manual

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Section 5 Maintenance
DANGER
Only qualified personnel should conduct the tasks described in this section of
the manual.
DANGER
Electrocution hazard. Always disconnect the power to the instrument before
making any electrical connections.
WARNING
Harmful radiation exposure. Do not use the controls or adjustments or
performance of procedures other than those specified.
CAUTION
Electrostatic discharge (ESD) can damage or destroy electronic components. All
work inside the particle counter should be done at a static-safe workstation.
5.1 Maintenance guidelines
A static-safe workstation can be created by doing the following:
• Use a grounded conductive table mat and resistor-isolated wrist-strap combination.
• Earth-ground all test instruments to prevent a build-up of static discharge.
Important Note: The laser diode in this device is extremely sensitive to static charges and
out-of-tolerance voltage variations.
Important Note: Never connect or disconnect the sensor cable from the counter when the
counter is on.
5.2 Clean the sensor
To clean the sensor:
1. Remove the four screws (two on each side) from the MET ONE 227 particle counter.
2. Remove the two screws from the bracket on the top end of the MET ONE 227
particle counter.
3. Open the two halves of the unit apart. Pull the back of the unit slightly downward to
enable the sensor inlet to have an opening at the top of the counter.
4. Remove the four nylon screws that hold the sensor to the case.
5. Disconnect the tubing from the sensor.
6. Disconnect the sensor cable from the sensor circuit board.
7. Insert two #2-56 machine screws into the two threaded holes in the reflector. Use
these screws as a handle to remove the reflector with a pulling and twisting motion.
8. Clean the reflector and photo detector with cotton swabs dipped in a small amount of
reagent grade Acetone. Wipe the optical surfaces with a dry swab. Blow the dust out
of the interior surfaces with clean dry air.
9. Perform steps 1 to 8 in the reverse order to assemble the MET ONE 227
particle counter.