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Electrical connection
HBPH probes have two wires: black and red. The red wire is to be connected to the +24 VDC terminal and
the black wire to the 24 VDC common terminal via the load in the loop.
Storage
1. Do not discard the protective cap that came with the sensor. If the sensor is removed from the
process for longer periods of time, thoroughly clean the sensor, put a piece of cotton ball with a
few drops of water into the protective cap and place it on the sensor with tape, this keeps the
junction from drying out which causes slow response when put back into operation or causes
permanent damage to the sensor. Sensors should not be left in dry lines or empty vessels for
longer periods of time.
2. Do not store the sensors in a dry or humid location. When storing, check the protective cap
regularly to make sure the cotton ball remains moist. Improper storage of sensors voids the
warranty.
Maintenance and calibration
The maintenance needed depends on your application and especially the accuracy required.
Precise measurement
If you use the sensor for a precise measurement of the pH value, you need frequent checks of the
calibration. The drift of the sensor is maximum 0.03pH per day but that is the maximum figure for a sensor
in high or low pH environments. Significant lower drift can be expected in neutral environments. Your
sensor verification frequency must reflect your needed accuracy.
Leakage detection
When used for leakage detection the required accuracy is low and annual or
biannual checks should be sufficient, especially when a warning is used. For
brines with a pH value between 6 and 8 it is easy to detect ammonia. Leakage of
1ml/l will increase the pH value from 7 to 10. Brines using NaCl or glycols will
have a pH value like water around 7 and they can be set up with a dual level
warning/alarm system.
A dual level warning /alarm system contains a warning level at which you need
to check your sensor calibration and a second level where you stop due to
leakage. If you have a base pH value of 7 it will make sense to use a warning for
pH above 8 and pH below 6. The second level can then be an alarm at pH=9.
With such a system it is not necessary to make frequent checks and calibrations,
however we recommend an annual or biannual check of the calibration.
Instructional manual- HBPH-MK2 – UK-004
Page 4
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