From ballast tank emptying to engine cooling to marine fuel transfer, it doesn’t go unknown that the marine market reliesheavily on reliable pumping solutions for vessel operations. When sourcing a pump, it is essential to understand that a pump that works is not necessarily the best solution. It is about total cost of ownership, including the lifespan of the pump and the availability of spare parts. After almost 15 years representing Azcue type approved pumps in the UK, Castle Pumps understand how the right pump is in the detail of the application…


Castle Pumps received an enquiry from a marine propulsion engineering company. They were building a new seawater engine cooling system test bench at their facilities, which required a high flow rate pump for circulating seawater around the system at up to 530m³h.

After discussing the application in detail with the engineer, the client advised that in order for genuine cooling applications to be replicated on the test bench, the pump would be regularly required to run for long periods of time.


There were several key things Castle Pumps needed to consider when selecting the right solution; the corrosive nature of seawater, the size of a pump capable of handling such high flow rates and the fact that the pump would be under regular, continuous duty.

Based upon all of the application requirements, Castle Pumps specified an Azcue LN Vertical Inline Centrifugal Pump in bronze with a Stainless Steel shaft for compatibility with seawater. Bronze is a great alternative to casting in Stainless Steel as it is more cost effective whilst still not affected by the salt content in the water. Azcue cast their pumps in bronze in their own refinery, allowing quicker lead times to also be met.

One of the key benefits of the Azcue LN centrifugal pump is its lantern bracket. Whilst being of more compact, close coupled construction, the bracket provides space between the pump and motor so if the seal ever wears, fluid will not enter the motor and ruin it.

To meet the flow rate requirements of 530m³h, the pump in question was going to be quite sizeable. 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. To put it into perspective, the supplied solution weighed a massive 720kg.

Considering that the pump would be run for long periods of time, Castle Pumps specified the pump to be fitted with a 4-pole motor running at 1750 RPM. The slower motor speed reduces the wear on the pump in the long-term making themideal for continuous running applications like this, as opposed to adhoc fluid transfer requirements.

The pump was manufactured within 4 weeks of the order being confirmed and shipped to the client. Like all Azcuemodels, the supply of spares is guaranteed for 15 years from model discontinuation for long term servicing, saving the customer from ever having to prematurely replace the pumpon their test bench if it just needs maintenance.