Overview - ISO 20155:2017 (Ships and marine technology)
ISO 20155:2017 specifies a laboratory test method for determining flow induced in‑pipe noise source characteristics of a ship‑used pump treated as a two‑port sound source. The standard applies to centrifugal pumps with a diameter over 50 mm operating under steady conditions. Tests measure acoustic pressures in the inlet and outlet pipe reaches (using hydrophones) and derive both passive and active source characteristics in the frequency band approximately 10 Hz to 1 000 Hz (upper frequency limited by pipe inner diameter and plane acoustic wave propagation).
Key technical topics and requirements
- Two‑port source model: The pump is represented by inlet and outlet ports with inter‑coupling; characteristics are described by active (source strength) and passive (transmission/impedance) components. Three theoretical representations are referenced: transmission, impedance and scattering models. The impedance model is used to express radiated pressures and volumetric velocities.
- Secondary‑source method: A known secondary acoustic exciter is alternately driven at inlet and outlet while recording signals from four hydrophones to derive the 2×2 impedance matrix (Z). With Z determined, the pump’s active source parameters are obtained with the pump unexcited.
- Test rig and instrumentation: Requirements cover the test loop, test‑bed pipeline, test section for hydrophone mounting, throttling valve, secondary acoustic exciter, water tank, foundation and supports. Instrumentation includes static (pressure, flow) and dynamic (hydrophones, data acquisition) measurements.
- Data processing & evaluation: Procedures to compute passive and active characteristics, criteria for test validity, and required test reporting (overview, conditions, records, results).
- Assumptions: Plane‑wave propagation in the pipe and steady hydraulic operating conditions.
Practical applications and users
Who uses ISO 20155:2017:
- Pump manufacturers (design validation, quieter products)
- Shipbuilders & naval architects (hydraulic system integration)
- Acoustic engineers and test laboratories (characterization, certification)
- Classification societies & regulators (environmental noise assessments)
- R&D teams optimizing pump geometry and hydraulic circuits to reduce radiated noise
Practical benefits:
- Provides pump source data independent of the installed piping circuit, enabling meaningful comparison between pumps and informed design choices to reduce pipe‑borne noise, onboard radiated noise and environmental impact (e.g., marine life disturbance).
Related standards
Keywords: ISO 20155:2017, flow induced in‑pipe noise, ship‑used pump, two‑port source, centrifugal pump noise test, impedance matrix, secondary‑source method, hydrophones, plane acoustic wave.