Dry mounted Diesel hydraulic driven fire water pumps for use on FPSO’s and FLNG’s. Configuration depending on the required capacity with or without boost pump, all consisting of a hydraulic driven fire water (lift) pump and dedicated hydraulic power pack. Design, construction and testing according to the latest Marine Class Society Rules & Regulations.
The system uses a hydraulically driven lift pump and a direct driven boost pump. The lift pump is located below the water level. The boost pump and diesel engine are located at deck level (under deck in for example the Steering Gear room or Bosun store, optionally in an enclosure on deck).
We use horizontally split case pumps (double volute) both for lifting and boosting.
Horizontally split case pumps with double volute have two advantages:
- higher efficiency at higher flows, hence lower power requirement
- lower NPSHr , especially when compared to a mixed flow impeller
With a lower NPSHr there is more reserve left when the draught of the ship is light and/or the lift pump can be installed less deep below the water line.
Lift pump dry mounted type:
The lift pump is to be installed in a dry location, with its suction line (as short as practical possible) connected to a sea chest. The lift pump is delivered on a steel skid. The shipyard has to fixate it in a suitable location below the water line. Furthermore the yard has to connect the suction side to the sea chest and bring the water discharge line and hydraulic oil lines to deck level. Because of its dry location, the lift pump is easy to reach for inspection, service and maintenance. The lift pump can be installed in a void space, but also in for example a ballast tank. With only a minor adaptation the lift pump unit is suitable for (temporarily) submerged location
The hydraulic system is of a simple, open system. When starting up the system, the swash plate angle of the hydraulic pump is set at no flow. Once the diesel engine is at speed, the swash plate is set at a preset maximum angle. Only then the lift pump starts to run and consume power. The diesel engine speed is automatically controlled to compensate for higher/lower discharge pressures caused by draught variations.
Advantages of the dry mounted system:
- flexible installation, either new built or retrofitting/upgrading
- installation also possible in ballast tank
- lift pump + drive easy to reach for inspection, service and repair
- horizontal split case pumps, favourable efficiency and lower NPSHr
- automatic diesel engine speed control for constant discharge pressure at deck level
- cost effective compared to submerged types
Yard supply for dry mounted system:
- piping and fittings for water and hydraulics between lift pump and deck level
- supply and installation of sea chest with valve
- install and fixate lift pump skid