Product catalogue

Viscosity control unit

System description

Barthel's Viscobarth system is used to monitor and control the viscosity of homogenous liquids. This system, which has been successfully established on the market for over thirty years, has been continuously further developed to its present design. One of the Viscobarth's main jobs is to monitor the viscosity of heavy fuel oils (HFOs) on seagoing vessels. However, any other Newtonian liquid can also be measured by this system. To guarantee trouble-free operation, precise adjustment of viscosity is indispensable for today's diesel engines. In doing so, the Viscobarth excels with its high degree of measuring accuracy. This is especially important considering the influence temperature has on the viscosity of heavy fuel oil. Temperature fluctuations of just  +/- 1° C can cause the viscosity value to change by as much as 2 cSt.

Range of application

  • Viscosity measurement and controlling the correct injection viscosity (12 cSt) for main and auxiliary engines (Engine-Viscobarth). For mass flow rates of up to 45 m³/h and more.
  • Monitoring viscosity during the filling of bunkers (Bunker-Viscobarth) in the bypass for the main mass flow. This measurement is made using an SPS to register and record all the important parameters, such as differential pressure, temperature and viscosity based on
    50° C.

The measuring principle

The measuring system employed by the Viscobarth is based on the way the capillary viscometer functions.
The system allows accurate measurement from approx. 2 - 100 cSt, or 100 - 700 cSt, depending on the type of job.

The design

The medium to be measured flows through a capillary. The differential pressure that develops is recorded and converted into a signal. The differential pressure is determined by an evaluation using a transmitter with a control unit connected (with temperature display, alarm and three-point stepped triggering system for the control valve). To ensure that the medium to be measured flows through the capillary, a gear pump is also installed on the side of the Viscobarth. The capillary is adjusted to a differential pressure transmitter, which together with the gear pump form an adjusted unit. If one part has to be replaced, then a readjustment has to be carried out. Also the temperature is ascertained using a PT100. In addition, the Viscobarth also has a local visual temperature display.

Comes with:

  • Differential pressure transmitter
  • PID controller
  • Gear pump
  • PT100
  • Visual temperature display

Optional accessories

  • Control valves


All the components are designed for installation in engine rooms. The system will be pre-adjusted to the viscosity desired on a test stand at Barthel's plant. Connecting flanges as per DIN (ANSI or JIS available on request).


The system has been certified by the Institute of Ship Operation Technology in Flensburg. The respective class only requires a certificate for the transmitter. The transmitter meets all the requirements made for automation. The Viscobarth itself does not require any acceptance by class. Confirmed by: DNV GL, Lloyd's Register and RMRS.

Viscobarth [PDF 328 KB]

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