Increased onboard safety through the KRAL AG pump upgrade project. As a trial and return project, KRAL has been offering hermetically sealed pumps for booster-modules to ship owners and operators.

Defects of screw pumps in marine booster-modules are some of the most frequent incidents affecting lifecycle-costs and ship availability. The competence of KRAL in magnetic coupling technology helps lower the costs for ship owners. Several years ago the magnetic coupling was developed as an alternative for pumps with shaft seals.

To make the decision easy, KRAL offers not only the hermetically sealed magnetic coupling pump but also an upgrade project. The test is cost free and KRAL service technicians are available if necessary to assist with the installation and during start up.


Normally, the cost premium total leak free sealing is obtained with the cost amortized over three years. Magnetic couplings insure that a pump is hermetically sealed, thus leaks are nonexistent. These couplings are maintenance free, only the ball-bearing has a much extended maintenance interval of 40.000 hours, compared with 10.000 hours for a mechanical seal design. KRAL pumps typically used for fuel transfer are available with flow rates of up to 660litres/min, and can easily handle heated fuel oils with temperatures of up to 180 °C.


The rotation of the electric drive motor is transferred through the magnetic coupling to the pump without contact, friction or wear. If an overload situation occurs, the motor will decouple from the pump to prevent damage. Once the motor is stopped, the magnetic coupling will synchronize and the pump can be restarted. The development of rare earth magnets made it possible to produce economical magnetic couplings. This minimizes the containment can volume, reducing costs substantially.

As a result of the smaller coupling size, standard pump/motor brackets were able to be utilized for further cost savings. The advantage for these pump types is high efficiency, small design and near pulsation free flow. Also, mechanically sealed versions of our pumps can easily be converted to magnetic couplings using a special kit.

Visit us at the Seatrade Cruise Shipping Convention in Miami booth 149.