KPH601 Online PH Sensor Signal Output: RS-485 (Modbus/RTU Protocol)
1.Signal processing and environmental influences
Calibration and control The electrode is characterized by its zero point and its slope. In
addition to the two-point calibration, other methods exist which
can monitor the performance of the electrode. For instance, a so
called one-point calibration may be performed, provided that the
slope remains constant. If a process sample is taken instead of
using the buffer solution, and its pH value is measured in the lab,
the electrode does not have to be removed from the process. The pH
transmitter can be set using the pH value obtained for the sample
in the laboratory. However, it has to be taken into consideration
that the pH value of the measured solution is a function of
different parameters such as temperature, dissolved C02 level,
completion of reaction, etc. A second possibility for controlling
the system is to determine both the zero point and the slope in the
laboratory and subsequently enter the values into the pH
transmitter.
Temperature compensation Automatic temperature compensation is generally used in industry,
except when both calibration and pH measurement occur at a constant
temperature. If the process temperature does not differ from room
temperature by more than 10°C, temperature compensation is often
not necessary, since the measuring error is less than 0.15 pH
units.
Accuracy and reproducibility of measuring values The main differences between pH measurement in the laboratory and
in industry are the frequency of calibration and the accessibility
of the pH assembly. The accuracy and reproducibility of the
measured values depend basically on the frequency of calibration
and maintenance of the electrode.
Environment Environmental influences act mainly on the cable and on the pH
transmitter. The most important factors are the surrounding
temperature, relative humidity, and electromagnetic fields. Hence,
in industry protection class IP65 should be observed, as well as a
robust design. In industry different hazardous areas may exist. The
pH transmitter has to be designed according to the requirements for
each safety zone.
Cable Since the signals are high impedance, long cables are susceptible
to disturbances. At a cable length of over 10 meters a preamplifier
is desirable; at a length of over 20 meters, indispensable. A
coaxial cable is used as an electrode connection cable. In the case
of strong electromagnetic disturbances (caused, for example, by
motors) it is wise to use a triaxial cable ( a coaxial cable with
an additional shield), for which a correct grounding of the outer
shield is needed. The outer shield should be grounded only in one
place.
Signal interpretation For signal conditioning, transmitters are galvanically isolated
between input and output to prevent ground loops. This helps to
avoid disturbances caused by potential differences between the
transmitter ground and the ground potentials in the vessel,
reactor, or in the pipe-line. These ground currents will otherwise
flow through the reference electrode and appear as a signal error
or even destroy the reference system. These kinds of disturbances
are eliminated without exception through galvanic isolation.
Digital measurement systems The development over the past decade of
digital process analytical measurement systems for pH and other
parameters,, has brought about significant improvements to sensor
operations. These include digital transmission of the measurement
signal from the sensor to the transmitter. This eliminates the
influence of the aforementioned environmental factors and cable
length on signal integrity.
2.Technical Specifications
| Model | KPH601 |
| Measuring Range | 0～14pH |
| Resolution | 0.01pH |
| Accuracy | ±0.1pH |
| Working Temperature | 0～65℃ |
| Working Pressure | ＜0.2MPa |
| Temperature Compensation | Auto temperature compensation (NTC) |
| Power Supply | 12～24VDC ±10% |
| Signal Output | RS-485(Modbus/RTU) |
| Wetted Material | POM |
| Mounting Method | Immersion mounting, 3/4 NPT thread |
| Cable Length | 5 meters, other lengths can be customized |
| Calibration | Two-point calibration |
| Power Consumption | ＜0.3W@12V |
| Protection Grade | IP68 |
3.Dimensional Drawing
Note:The sensor connector is M16-5 core waterproof joint male head.
4.Installation
Note: The sensor should not be installed upside down or
horizontally when installed, at least at an angle of 15 degrees or
more.
Contact Us
Website www.kacise.com
Phone +86-17719566736
Email sales@kacise.com
Location Tangyan South Road, High-tech Zone, Xi'an City, Shaanxi
Province, China
