DEZA measures up with Krohne

01 November 2007

DEZA, Czech benzol and tar processor, claims to have improved accuracy and reliability of naphthalene measurement with a radar level meter.

The company installed an Optiflex 1300 TDR radar level meter, from Wellingborough based Krohne, to measure the substance that is used in chemical production.

At DEZA’s plant, liquid naphthalene is contained in a 3.3 metre cylindrical horizontal tank. Here, it is heated to 100°C before being used in production processes. The substance has a very low dielectric constant, around 2.2 at 100°C, which makes it difficult to measure.

DEZA said it needed an instrument, with two-wire connection and local indication, to improve accuracy and reliability of level measurement in the tank. Furthermore, any instrument that could cope with harsh conditions within the plant, and operate within the hazardous area, must be of robust design.

Technicians from Krohne specified an Optiflex 1300 TDR level meter with a single 8mm rod. This configuration is designed to be resistant to the liquid naphthalene, and its vapours, and also allows the length of the sensor to be modified if required.

Krohne claims the instrument has a measurement accuracy of ±3mm at a maximum allowable flange temperature of 200°C. The actual flange temperature is 150°C.

The instrument also has a local indicator and a protection cover which protects the converter from the harsh conditions. It is loop-powered (providing 2-wire connectivity) and is flameproof to ATEX EEx d standard.

During final installation the upper flange of the tank was insulated to prevent naphthalene depositions forming on the sealing system.

Engineers at DEZA evaluated the instrument over a two-month period and said they were pleased with its operation.

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