Overview
EN ISO 15748-2:2002 - Ships and marine technology: Potable water supply on ships and marine structures - Part 2: Method of calculation - provides a standardized calculation method for planning and sizing potable water systems on ships, stationary or floating marine structures and inland waterway craft. Adopted by CEN as a European Standard (EN ISO 15748-2), it complements Part 1 (Planning and design) and is intended to determine required water quantities, storage capacities, pump sizing, water heater capacity and related hydraulic parameters.
Key topics and technical requirements
- Scope and purpose: Calculation procedures for potable water consumption, storage, component sizing and system configuration on marine installations.
- Potable water consumption: Guidance for estimating daily and peak water demand based on ship type, number of dispensing points and operational time; includes allowances for technical equipment and commissary machinery (dishwashers, coffee machines, washers).
- Storage and supply strategy: Criteria for direct supply versus pressurized reservoirs; typical limit between methods is around 30–40 m³/h peak demand.
- Pressurized reservoirs: Pre‑compression guidance (air pre-charge ≈ 0.3 bar below pump cut-in), recommended pressure difference between pump cut-in and cut-off (1–2 bar), and switching frequency guidance (typical 6–8 starts/h, not to exceed 12/h).
- Pump sizing and operation: Centrifugal pumps sized to ≈110% of calculated peak flow, reciprocating pumps 120–130%; stepped cut-in/cut-off pressures for multiple pumps; recommendations for pump suction/discharge piping.
- Hydraulics and flow rates: Suggested maximum flow velocities to limit noise and pressure transients (examples: 2.5 m/s in machinery spaces; 1.4 m/s in accommodation decks; 0.5 m/s in circulation lines).
- Supply pressure: Minimum supply pressure calculation must include geodetic head, friction and fitting losses, apparatus losses and a minimum flow pressure of 1.5 bar (plus allowance where required).
- Hot water and circulation: Methods for sizing heaters, circulation lines and circulating pumps; design temperature guidance (system design temperature 10 °C used for calculations).
- Supporting materials: Annexes with tables, figures, calculation forms and worked examples to streamline practical calculations.
Practical applications and users
This standard is essential for:
- Ship designers and naval architects sizing potable water systems
- Marine HVAC and plumbing engineers specifying pumps, tanks and heaters
- Shipyards, system integrators and contractors implementing potable water installations
- Classification societies and operators reviewing compliance and safety of onboard water systems
Use cases include passenger ships, cargo vessels, offshore platforms and inland watercraft where reliable potable water supply and correct hydraulic sizing are critical.
Related standards
- EN ISO 15748-1 - Planning and design (complements Part 2)
- ISO 5620-1 - Filling connections for drinking water tanks
- Tube and piping standards cited (e.g., ISO 1127, ISO 274, ISO 4200) for material and dimension references.
Keywords: EN ISO 15748-2:2002, potable water supply on ships, method of calculation, marine structures, pump sizing, water storage, shipboard plumbing, potable water system design.