society for analytical and metrological systems


FAQ - frequently asked questions about hardness sensors

Are reagents / indicators used for measurements?
In contrast to titration or other photometric methods, no reagents and complex dosing systems are needed for analysis. This makes the process very simple and efficient.

How often is measured?
The measurements can be made continuously during the entire time of soft water extraction. This is advantageous if a complete documentation of the softening processes and / or rapid control has to take place.

How long do the measurements take?
Due to the measuring time of approx. 30 seconds continuous measurements are possible. Unlike processes based on the expansion of volumes (swelling resin sensors) or titration methods, current measurement results are quick and enable a quick intervention in the softening process.

Are there any other consumables besides the sensors?
Our devices are virtually maintenance free. Basically, the sensor has to be exchanged now and then (see "When does the sensor have to be replaced?"). When used properly, operating times of 6 to 9 months should be achieved.

Which operating conditions must be present?
The quality of the sensor is influenced by the water quality, in particular by high chlorine or brine concentrations.

required water conditions for soft water applications:
- natural raw waters up to a hardness value of 10.8 mmol/l
- water temperature: 5..30 °C
- pH range: 5 ... 9 pH
- chlorine content <500 μg / l
- germ content <5,000 cfu / ml

The water must be free from acids, alkalis, brines, surfactants, fats, oils, solvents and heavy metals.

What should be considered when handling the sensor?
The sensor tip must not be touched or damaged, and no force may be used during the sensor replacement. The sensor should not be dropped and must not be exposed to impermissible temperature or pressure jumps. It is best for the sensor if it remains with the attached protective cap in the supplied box, as long as it is not yet in operation or is suspended for a long time operation.

When does the sensor has to be replaced?
Normally, a sensor will last 6 to 9 months. The lifetime of a sensor depends on the water quality, not on the number of measurements. Sensor aging is automatically monitored and signaled if the sensor quality is too low.

When will the sensor alarm be issued?
The functioning of the hardness sensor as well as the measuring process is cyclically controlled. Detected errors are signaled as a sensor alarm in addition to any threshold alarm.

Why is there a number on the sensor?
The sensor number promotes fast processing in case of queries. Every hardness sensor has an individual sensor number that clearly identifies it. This is assigned during the production. Before delivery, the sensor quality is also checked and verified by a final inspection.

How is the sensor shipped?
For protection, the sensor is closed with a protective tube. This allows the sensor to be in an optimized environment. This ensures that the sensor can be put into operation immediately. For shipping, the sensor is packed in a special box. An undamaged delivery took place when the protective cap is firmly seated on the sensor and fogged on the inside.

How long can sensors be stored?
It is recommended to store the sensor only for a short time in the supplied box at 10 °C to 15 °C. This should be used as soon as possible to maintain the measurement quality of the sensor. It is recommended to order a sensor when the meter outputs the signal to change the sensor. A storage period of more than 8 months is not recommended.

How should the sensor be stored?
Until the sensor is used, it should remain in the supplied box. This is necessary for the protection and maintenance of the measurement quality.
Furthermore, the protective cap must remain tightly closed. Sensors without a tightly closed protective cap may not work properly or work properly after 1 to 2 days. Basically, the protective cap should only be removed immediately before using the sensor.