Level measurement of anhydrous chlorine

Application Note | Chemical

  • Non-contact level measurement in VCM production
  • Dual seal
  • Measurement redundancy


A chemical company produces chlorine from salt and stores it horizontally in several cylindrical reservoirs for the production of VCM (vinyl chloride monomer), used in the composition of PVC (polyvinyl chloride). This intermediate product is extremely dangerous and requires special attention when storing.

Measurement requirements

A French site uses a KROHNE BM 12 special (float) and a chlorine type BM 100 (TDR guided wave) to measure the level of chlorine. One BM 12 with dual casing, featuring a pressure release plug in the dual casing, and one BM 100, also equipped with a pressure release plug between the dual seal, allow for simultaneous chlorine measurement and detect leaks in the first safety enclosure. The chemist can thus plan to empty this reservoir and repair the safety enclosure without worrying about a chlorine leak.

KROHNE Solution

KROHNE's proposal to replace the BM 12 and BM 100 with a non-contact solution impressed the chemist. A special dual seal design featuring metaglass and a pressure release plug between the two seals guarantees the same functionality as the dual casing of the BM 12 and the dual seal of the BM 100. The OPTIWAVE 7300 C (chlorine type) was thus proposed, tested and validated by this chemist.

Customer benefits

By combining the signal dynamics with the FMCW radar technology, the customer obtains accurate and reliable measurements. Because it measures the distance to the surface of the product and not the density of the product, this radar device is immune to variations in density, unlike pressure sensors. The antenna, and all wetted parts are made of Hastelloy C 22 in order to prevent any risk of corrosion due to the presence of humidity. The radar is easy to set up and use, thanks to the installation wizard.

Products used


Radar (FMCW) level transmitter for liquids in agitated process applications

  • Continuous, non-contact measurement of level, distance, volume, mass and reflection
  • 24 GHz radar, Horn or Drop antennas
  • 0.2…80 m / 0.7…260 ft
  • -50…+200°C / -58…+392°F; -1…100 barg / -14.5…1450 psig