the adoption of the BWM Convention, nearly 50% of the world’s ocean-going fleet has now been fitted with ballast water management systems. However, with the deadline for all existing ships’ implementation being between now and 8th September 2024 (depending upon their nextIOPP renewal survey date), there are still vessels that need to undergo the changes. When this time comes, they may find that their existing pumps are now undersized due to the extra pressure losses in the system. Castle Pumps have already helped many ship owners get their pumps in order to meet the new regulations…


Castle Pumps received an enquiry from a new shipyard customer in the UK that was upgrading a ballast water system on board a vessel in line with the Ballast Water Management D2 requirements. As part of the system, two ballast pumps were required for filling and emptying the ballast tanks.

As well as required performance specifications, the client laid out two additional criteria; the first was that these pumps would be located in an ATEX environment onboard the vessel, and the second was that they wanted the pump to be able to completely strip the ballast tank of water.


Based on the application requirements, Castle Pumps specified 2 x Azcue VM Vertical Inline Centrifugal Pumps supplied in bronze to ensure that it will not corrode overtime when in contact with seawater. Due to the large flow rates required, the pumps specified were really large with 8” discharge flanges. With that in mind, Castle Pumps specified a vertical solution which would have a smaller footprint than its horizontal equivalent, taking up considerably less space in the client’s installation.

One of the beneficial aspects of the Azcue VM centrifugal pump design is its lantern bracket. Whilst being of more compact, close coupled construction, the bracket providesspace between the pump and motor so in the event of a worn seal not being replaced, the motor will not be ruined by fluid entering it.

To allow for the complete emptying of the ballast tank when required, an additional electric priming pump was specified and installed. Both pumps’ motors and priming pumps were ATEX approved for safe use in the potentially flammable environment.

The pump was manufactured within 4 weeks of the order being confirmed and shipped to the client. Like all Azcuemodels, the pump underwent a full testing regime at the factory before being dispatched to ensure performance and reliability in an application as vital as ballast water pumping.