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Tank gauging principles

Cargo temperature monitoring

Cargo ullage

We offer a variety of radar based tank gauges (RTG) for different applications. Common for all applications is the level sensing unit located on top of the tank, connected to the dedicated signal processing unit, normally installed in the cargo control room. Our radar tank gauge employs the Frequency Modulated Continuous Wave (FMCW) concept. This patented detection method ensures reliable measurements up to 50 metres. When applied in a gas tanker, it measures the ullage of the liquefied gas emitting microwaves through a narrow still pipe that reaches from the top to the bottom of the tank. Still pipes can also be applied for oil and product tanks, when required.

Cargo temperature

Temperature is normally measured at one, two or three levels in each tank. For gas carriers five or six temperature levels are normally measured in each tank. Pt-100 or Pt-1000 temperature sensors are inserted into the tank from a connection box located at deck level. Average temperature is calculated from the sensors submerged in the liquid cargo.

Vapour pressure

Vapour pressure is measured using an accurate pressure sensor incorporated in the radar tank gauge housing.

Line and manifold pressure

Line and manifold pressure is measured using an accurate pressure sensor installed on special flanges on the deck lines and manifolds.

Line and manifold temperature

Line and manifold temperature is measured by means of accurate temperature sensors installed in sensor pockets on the deck lines and manifolds.

Level gauging in ballast and service tanks

Different applications require different tank gauging concepts. For ballast and service tanks a level gauging system based on submerged pressure sensors is normally used. Air purge systems can also be supplied as a part of the tank gauging system.

Cargo control station

Supervision and control of the cargo monitoring and control system is done from a cargo control station. This station will normally be located in the cargo control room or on bridge. Easy operation is accomplished by using standard and customized mimic diagrams.

Local operator station

Local operator stations are available for local operation or as back-up stations. For stand-alone tank gauging systems manual setting of parameters (trim, list, etc.) is possible. Information is displayed either graphically or in the form of lists. Our CAN network ensures that information is quickly updated, regardless of the size or complexity of the system.

Load calculator

An on-line load calculator communicating with the tank gauging system is normally supplied as part of the delivery.

Trim and list corrections

Trim and list corrections are required in order to calculate the correct volume of the liquid cargo. Corrections are carried out based on input from inclinometers or a combination of draught sensors and an inclinometer.

Alarms and printing

Up to 4 alarm limits can be preset. Reports are printed by the network printer(s).