System Description; Intended Use - Burkert 8201 Manuel Utilisateur

2. System description

2.1 Intended use

pH sensor Type 8201 is used to ascertain the pH value of aqueous liquids (proportion of water > 1%)
in tubes or containers in industrial facilities. The sensor must be completely rinsed clear of product to
ensure reliable measuring.
Medium temperature and medium pressure have a considerable influence on the measuring range
and corrosion resistance of the sensor.
The temperature dependency of the measuring range is depicted in Diagram 1. For example, at a
medium temperature of +20 °C the measuring range is between pH 0 and pH 10.
The permitted range for medium pressure is -1 to 6 bar.
For medium temperatures above +100 °C, medium pressure must be above the vapour pressure as
otherwise the medium boils and this has a highly corrosive effect on the pH enamel.
No reliable pH value measurement is possible at temperatures below zero °C.
The range of high resistance can be viewed in Diagram 2.
Important! Comply with the permitted areas of application depicted in Diagrams 1 and 2.
The measuring principle, the materials used, the precision of the measurements, the low drift tendency
and the special built-in features (CIP and SIP ability) of the sensor make it particularly suitable for use
in the pharmaceutical and foods industry.
The sensor is mounted in the facility using an adaptation set. A permanent supply of a special pressur-
ised electrolyte is required during continuous operation. The electrolyte pressure must be at least 0.5
bar above medium pressure.
If the probe is subject to process pressure inside the reactor or the pipeline, it must be ensured
that the pressure inside the electrolyte system is permanently at least 0.5 bar above the process pres-
sure. Otherwise, there is a risk of product entering the probe through the diaphragm gap and clogging
or contaminating the electrolyte line.
The pH value-proportional measurement signals (electrical voltages) given off by the sensor are
extremely low-energy. They are conducted to a transducer via lines which are as short as possible
and transformed there into a standard signal (current signal).
The sensor must be conditioned before commissioning, sterilised during sterile applications and in
every case must be calibrated.
4- 8201