Hach Met One 6000 Series, User Manual, Page: 45 / 70

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Section 5 Maintenance
Important Note: Do not disassemble the particle counter for maintenance. If the internal
components require cleaning, contact the nearest Hach Company authorized service
representative.
5.1 Maintenance schedule
Complete the maintenance tasks according to the schedule in Table 14 to keep the
particle counter operating efficiently. The maintenance tasks are described in the
following sections.
5.2 Cleaning the instrument
Important Note: Moisture will damage the unit. If the sampling point is in a clean room
where wash downs occur, install the units outside of the room, or remove the units before
each wash down.
5.2.1 Wipe down
Wipe the external surface with a soft cloth lightly moistened with isopropyl alcohol (IPA).
The isokinetic probes can be autoclaved for cleaning.
5.2.2 Zero counting
Zero counting is a process for removing contaminants such as particles, lint, or dust from
the inside of the counter. Zero counting uses a near-absolute filter to block any external
particles from entering the counter. Over time, particles are removed from the inlet tube
and other internal areas and counted. When the count reaches zero, the counter is
considered clean.
Prerequisites:
• Standard purge filter assembly (refer to Parts and accessories on page 47 ).
Procedure:
Perform zero counting as follows:
1. Attach a standard purge filter assembly to the sensor inlet tube.
2. Start the count cycle and run for at least 30 minutes.
3. Start sampling data in 5-minute intervals and continue until the count reaches zero.
4. When the count is zero and no alarms are on, the counter is functioning correctly. If
the count does not reach zero after nine or ten 5-minute sampling periods, purge the
sensor overnight.
Table 14 Maintenance schedule
Maintenance task As needed 6 months Annually
Calibrate
1
X
Clean instrument
2
X
Inspect sample tubing X
Purge X
Wipe down X
1
Refer to section 5.4 on page 44 .
2
Refer to section 5.2 .