High Pressure Plunger Pump for Reverse Osmosis System On Board an Offshore Supply Vessel

Enquiry for a Bare Shaft High Pressure Plunger Pump

A vessel management company acting on behalf of an offshore supply vessel required a high-pressure pump for their reverse osmosis (RO) system onboard ship. The engineers had already sourced the electric motor and therefore only needed to purchase a bare shaft unit.

Reverse osmosis, also referred to as RO and desalination is a process whereby fresh water with unwanted contaminants, or sea water is forced through a filter/membrane at high pressure. As the water passes through a partially permeable membrane; any ions, salt, bacteria, unwanted molecules and large particles are removed. This process is commonly installed on marine vessels as a means of purification to produce potable water (drinking water) from sea water.

The engineers onboard had calculated that in order to produce the amount of fresh water required, they needed a pump that could produce a flow rate of around 90L/min. The pressure required to force the sea water through the filtration system was around 80 bar.

Our 2531 Cat Triplex Pump for Reverse Osmosis

We have a vast range of experience supplying pumps for reverse osmosis installations such as this. Our series of high-pressure Cat triplex plunger and piston pumps can produce flow rates up to 228 L/min and pressures up to 345 bar. For this application, we selected a 25-frame reciprocating plunger pump with 316 stainless steel manifolds, 316 stainless steel valve assemblies, solid ceramic plungers and NBR seals and O-rings. The 2531 Cat unit can achieve a maximum flow rate of 95 L/min and up to 83 bar. Due to the materials of construction, this model is excellent for high-pressure applications involving sea water or deionized water, such as reverse osmosis, desalination or boosting.

As we supplied the unit in bare shaft without motor, we advised the customer that the operating speed required is between 100 and 1025 RPM. They needed to ensure that the speed remained within these limits, either by directly coupling an electric motor or via a belt drive pulley system.

Reciprocating plunger and piston pumps produce pulsations by nature due to their design; we always recommend that customers install a pulsation dampener on the discharge side to reduce pulsations produced and to smooth the flow. For safety, we also recommend that pressure relief valves and regulating valves are installed to protect the system and operator from over pressure.

Below is the specification of the equipment that was installed: