A common issue with on-line water monitoring optical systems is the long term drifting of the signal due to deposits created in the flow cell. Many diverse cleaning procedures were developed by the producers of on-line process photometers to suppress this phenomenon, for instance by ultra-sonic cleaning or cleaning with compressed air. Both approaches however didnâ€™t perform perfectly in the removal of sample specific deposits from the flow cell and cannot be used for low absorption measurements.
Skalar recently introduced its new On-line Photometer with automated mechanical flow cell cleaning at the Austrian company Lenzing AG, world leader in cellulose fiber production. The new On-line Photometer with automated mechanical flow cell cleaning is very efficient for the removal of deposits from the flow cell and shows excellent stability in handling low absorption values.
Lenzing AG is paying a great attention to the protection of the environment. The companyâ€™s waste water treatment plant is monitoring itâ€™s effluent for many parameters to prevent any pollution of the bypassing river. One of the parameters to monitor is the absorption of the effluent at 420 nm, a typical parameter for the paper & pulp industry which should be reported to the governmental water inspection authorities. Skalar supplied Lenzing AG with its robust double beam on-line photometer with mechanical cleaning of the flow cell which has been successfully used for many years for the measurement of turbidity in water monitoring stations. Lenzing AG confirmed that the stability of the new on-line photometer is excellent in routine daily operation without any maintenance requirements.
The on-line photometer consists of three parts: The control unit with a simple keyboard and a display, the optical unit and the automatic cleaning device on top of the optical unit. The optical unit and the electronic control unit can be located up to 1 km apart. The photometer does not require any maintenance and the cleaning time interval can be preprogrammed according to customer requirements. The optical and the cleaning units can be disassembled within 1 minute for inspection, exchange of the cleaning rings, manual cleaning or recalibration of the unit if desired. The process photometer in Lenzing AG works with an LED emitting specifically at 420 nm as a light source. For water turbidity measurement an IR diode is used instead. For the total dissolved organic matter, i.e. Specific UV Absorbance (SUVA) at 254 nm according EPA 415.3, and turbidity monitoring a four beam photometer with a low pressure mercury lamp is available. All models are provided with 4-20 mA outputs and can be completed with relays, RS data communication, data logger, PID controller etc.
For more information on the Skalar Analyzers or other Skalar products, please contact Skalar Analytical BV.