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Level Applications


Measuring differential pressure on a crude oil filter, without capillary separators

The application

When pumping and filtering crude oil, the equipment is subject to regular build up. To check the efficient operation of the pump and filter to optimise cleaning, a differential pressure sensor system is normally used. It is fitted with remote capillary chemical seals mounted to measure the pressure losses across the pumps and filter. This arrangement requires careful set up to reduce the influences of external temperature changes and ensure reliability of the measurement. The capillary diaphragms need to be flush to the pipe to avoid clogging, so they require mechanical protection from damage and wear. The resulting cost of this measurement is quite high, in equipment, installation and on-going maintenance/repairs. If one side is damaged, the whole system has to be replaced.

The process data

Medium: Water / Crude Oil
Container: Filter monitoring
Process Pressure: 13 bar maximum
Differential Loss: 1 bar
Process Temperature: 20°C ... 70°C
Outside Temperature: -20°C ... 40°C

The solution

To simplify installation, set up and minimise the cost of ownership, an electronic measuring differential pressure (e-DP) has been implemented. Two flush mounted ceramic, highly robust pressure sensors are connected upstream and downstream of the filter. The capillaries are replaced by a single electrical cable that connects the two sensors together. The ‘master’ upstream sensor, subtracts the ‘slave’ downstream pressure and then transmits the  4 ... 20 mA/HART/Profibus or FF signal of differential pressure across the filter. This system could be a viable alternative for any abrasive or adhesive product or troublesome application for a DP system.

User benefits

  Easy to implement and very robust
  No capillaries solve problems of installation, mechanical protection and build up. No capillaries/insulation removes temperature influence
  Easy set up, simply set desired measurement. The sensor calculates the Delta-P
  E-DP sensors are installed directly on the pipes, avoiding the offset of the sensor relative to the process


Example-eDP-Filter rdax 184x116 100
Differential pressure measurement upstream / downstream of the filter

Photo-BAR82 rdax 100
Flush, abrasion and impact resistant ceramic diaphragm with screwed or flanged connection

Photo-BR83 Slave rdax 184x135 100
Pressure sensor e-DP single cable connection front-flush diaphragm

Non-contact level measurement, wireless transmission of measurement data

The application

Leatransa operates a transshipment storage facility for chemicals in the Spanish Mediterranean port of Castellón de la Plana. Liquid and aggressive products such as sulphuric and phosphoric acid are among the products temporarily stored there. The tank farm consists of eight tanks with heights of 10, 15 and 30 m. To control the filling and emptying of these tanks accurately and cost-efficiently, a suitable level measuring system had to be found.
The challenging aspect of this measurement lies in the differing tank sizes as well as the changing media and their measurement properties. What is more, installation of the required signal lines is hampered by streets and buildings located between the storage tanks and the control room.


The process data

Container: Storage tanks
Medium: Chemicals such as sulphuric or phosphoric acid
Material: Steel, neoprene-coated
Height: 10, 15 and 30 meters
Ambient temperature: -20 ... +50° C

The solution

Leatransa opted for an all-inclusive solution. It consists of non-contact level measurement, on-site indication with overfill alarm and wireless transmission of measured values.
The complete system was realized with VEGAPULS 61 and 63 radar sensors (depending on the medium and size of the individual tank), VEGAMET 381 signal conditioning instruments and PLICSRADIO T61/R61 transceiver units. PLICSRADIO C62 signal conditioning units were also installed to collect the measurement data and make it available to networks for remote enquiry and visualisation.
This solution ensures intelligent control of the logistics processes and efficient operation of the tank farm. It allows the inventory to be precisely measured and optimally utilised. The cost and time saving installation of the measuring system was a factor that made the decision much easier. The sensors could be simply mounted on the tanks without having to empty them first. And thanks to wireless data transmission, no cables had to be laid.


industry chemical rdax 200x100

Evaporator in a distillation column

The application

In a petrochemical research facility, an evaporator (reboiler) heats the liquid from the bottom of a distillation column together with different additives, so-called catalysts, and splits it into its constituent parts. The temperature in this vessel is about 350° C. The different types of benzol released are then extracted in the fractionation process.

The level in the evaporator must be continuously monitored and kept constant during the process. In addition, a point level measuring system is needed to reliably detect when the maximum level is reached, regardless of the mixing ratio of the raw materials.
The different catalysts cause large fluctuations in the density and dielectric constant of the measured medium. These variations and the extreme thermal process conditions place particularly high demands on the measurement technology used.



The process data

Medium: Benzol
Vessel: Evaporator (reboiler)
Process temperature: + 350 °C
Process pressure: 20 bar
Process conditions: Extreme temperatures and high pressures, fluctuating density and dielectric values

The solution

The high temperatures and changing conditions in the evaporator require a robust and reliable measurement technology.
The vibrating level switch VEGASWING 66 is ideal for point level measurement in liquids with extreme temperatures up to +450° C and pressures up to +160 bar.
VEGASWING 66 detects the maximum permissible level of the crude oil in the distillation column and reliably prevents overfilling of the container.

The TDR level sensor VEGAFLEX 86, which is also ideal for use in hot media, measures the actual level in the evaporator. With its operating range of -196° to +450° C and 400 bar, VEGAFLEX 86is quite suitable for extreme applications. The applied TDR sensor is also SIL2 qualified (IEC 61508) and has all required approvals for use in hazardous areas.

The dependable level control system and fail-safe overfill protection device are installed in the evaporator (reboiler), which is located at the bottom of the column in the petrochemical research facility. Together, they ensure constant recirculation of product and thus effective operation of the entire distillation column.


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Instrumatics is a supplier of quality field instrumentation, offering a wide range of technology and more than 35 years in the business.
Our dedicated team of experienced engineers are able to specify appropriate instrumentation for given requirements.






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PO Box 22-671
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