Hach 51 Series User Manual page 20

High level adjustment
Note: Before using this option, ensure a zero calibration has been successfully completed first.
This calibration exposes the sensor to a gas or a liquid sample with a known gas concentration. You
also have the option to reset the sensor's calibration parameters to factory settings (from drop-down
list for Cal. sample).
Press Start to start the calibration. The process is then the same as for the Zero calibration
described previously.
Barometric pressure calibration
Note: The barometric pressure sensor has been factory calibrated but should be periodically verified with a
precision certified barometer. The barometric pressure is necessary for the O2 sensor calibration. Make sure that
the barometric pressure is correct before the sensor calibration. If necessary, calibrate the barometric pressure.
The upper box shows the barometric pressure as measured by the instrument.
Using a precision certified barometer measure barometric pressure in the location where the
measuring instrument is used. Compare the values and if they are the same press Cancel, otherwise
enter the new barometric pressure value in the lower box and press Validation to validate the new
setting.
Other menus
For information on setting up relays and analog outputs refer to the full user manual (Inputs/Outputs
menu).
For information on setting up RS485, PROFIBUS-DP, USB, HTTP/TCP-IP and attached PRINTER
links refer to the full user manual (Communications menu).
For information on setting up products and global configurations refer to the full user manual
(Products and Global Configuration menus).
Maintenance
Instrument maintenance
Personal Injury Hazard. Any instrument maintenance should be carried out by a qualified Hach Service
Technician. Please contact your local representative should you feel any maintenance or instrument adjustments
are required.
Sensor maintenance
The sensor spot needs to be replaced about once a year. The procedure is very simple and takes no
more than a couple of minutes. Based on the measurement range of oxygen, the sensor lifetime can
be shorter and the maintenance—and calibration—frequency increased. If there are bleaching
compounds and strong oxidants (e.g., ClO
Equipment required
1. A replacement sensor spot
2. The maintenance tool delivered with the sensor
3. O-ring supplied with the sensor spot
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C A U T I O N
) in the sample, the sensor lifetime can also be shorter.
2