The Seli GmbH Company developed the SMW device - the very first digital fill level limit switch. Due to the very considerable stresses to which the material is exposed during the processes, VICTREX® PEEK™ polymer was specifically selected.

As a result of the exclusive use of pure PEEK for the sensors, the highest possible standard of safety for the food and pharmaceutical areas has been achieved because the material from VICTREX PEEK complies with the most stringent FDA requirements in every respect.

The sensor is exposed to extreme temperature and chemical conditions associated with corresponding plant operations as the PEEK sensor heads are constantly in contact with the medium to be monitored. The excellent resistance of VICTREX PEEK to all common solvents, acids and bases makes it the perfect material for sensors.

To this must be added the outstanding mechanical properties of VICTREX PEEK such as tensile strength, bending and creep characteristics as well as impact strength. 

The SMW capacitive fill level limit switch can be incorporated in the common process connections of the given industry (TriClamp, BioControl, Varivent, APV, DRD Flange, Milchrohr and Seli Socket System).

The sensor can be used to monitor filling levels in containers or pipelines, and as a limit switch, depending on the medium for phase separation.

It is insensitive to foam and adhesions. The response time is in the order of milli-seconds. The Seli probe features a switch in the connecting head to adjust the switch delay and switch output.

The process can be monitored via an interface and the corresponding software. It is also possible to modify the configurations directly at the device or alternatively at the PC. Moreover complete process monitoring can be implemented with a PC. The feature that makes the sensor so unique is the ability to freely adjust the limit values and hysteresis.

The operating conditions are as diverse as the actual processes in which the fill level limit switch can be installed. The sensor’s continuous operation temperature ranges from -10°C to 150°C.

The VICTREX PEEK material resists temperatures of up to 260°C which is why the sensor can be exposed to prolonged sterilisation at approx. 150°C at up to 6 bar. Complete encapsulation of the sensor with PEEK material eliminates the need for seals, thereby significantly extending the service life of the sensor.

About Victrex
Victrex plc is the sole manufacturer and supplier of VICTREX PEEK polymer and APTIV film worldwide. Read more information about APTIV™ film, made with VICTREX® PEEK™ polymer, and on the high performance PEEK-backed tapes made with Victrex APTIV film visit the Covalence Adhesives.

About Seli
The SELI automation technology company was founded in 1990 with the aim of creating an alternative supplier for automation technology components. Right from the outset prominence was also given to the development of products and special solutions for manufacturers of food processing equipment. Today, the company with a workforce of more than 30 staff, is one of the top-ranking system vendors for automation technology with products setting standards in terms of quality and technologies.

Within a very short period Seli advanced to a competent and renowned manufacturer of sensors for the pharmaceutical industry on account of its innovative approach and flexibility. This also means that the highest priority is accorded to quality assurance. All Seli sensors are subject to a 100% test and can be supplied with the following certificates: Material Certificate 3.1. B, Surface Roughness, Delta-Ferrit Measuring Protocol and Electropolishing Confirmation.

Another major element of the standards is the control of inspections, measuring and testing equipment as well as the calibration of sensors and measuring instruments. Competent personnel and partners ensure effective international and national sales and service. The representatives and staff are trained for the given products in the parent company.