Magnets said to be used to manipulate mass flow meters

North P&I Club has said that concerns had been raised on the use of magnets to manipulate bunker barge mass flow meters (MFM).

Marine fuel publication ‘Ship & Bunker’ reported evidence of flowmeter tampering having been found by an attending surveyor in Singapore while on a supplying vessel.

Neodymium magnets – a type of permanent magnet – allegedly were found attached with adhesive tape to the ‘u’ section of the barge’s mass flow meter. North said it understood that magnets could interfere with the Coriolis Effect – which is the principle of mass flowmeter operation. However. It added that it was not clear how much influence magnets had on the accuracy of mass flow meters and it was not yet known if this practice was widespread.

It advised receiving ships’ crews to remain vigilant and to pay close attention to the delivery and measurement arrangements on supplying vessels. “Avoid relying wholly on mass flow meters for bunker quantity assessments; it remains prudent to also carry out a full set of soundings on both barge and vessel before and after bunkering”, North said.