Overview
ISO 2944:2000, "Fluid power systems and components - Nominal pressures," defines a standardized series of nominal pressures to be used when specifying, testing, labeling and marketing hydraulic and pneumatic systems and components. The standard gives a convenient pressure series (with preferred and non‑preferred values), prescribes how to express pressure units, and clarifies that nominal pressures are to be treated as gauge pressure unless otherwise stated. ISO 2944 helps ensure consistent pressure designation across product catalogs, test reports and other technical documentation.
Key topics and requirements
- Purpose: Provides a series of nominal pressure values from which other fluid‑power standards and product specifications can choose.
- Nominal pressure definition: A pressure value assigned to a component, piping or system for convenient designation and to indicate membership in a series.
- Units and expression: Pressures shall be expressed in kilopascal (kPa) or megapascal (MPa) per ISO 1000, followed by the equivalent value in bar in parentheses. Example format: “nominal pressure of … kPa (… bar)” or “nominal pressure of … MPa (… bar)”.
- Gauge pressure assumption: Unless a modifier is given, nominal pressure is assumed to be pressure above atmospheric (gauge).
- Preferred vs. non‑preferred values: The standard provides a table of nominal pressures; values shown in brackets are identified as non‑preferred to guide selection.
- Identification statement: When complying with the standard, use the prescribed wording in catalogs, test reports and sales literature:
“Nominal pressures selected in accordance with ISO 2944:2000, Fluid power systems and components - Nominal pressures.”
Applications and users
ISO 2944 is practical for organizations that need consistent pressure designations across the fluid‑power supply chain:
- Component and system designers choosing rated pressures for valves, cylinders, accumulators, hoses and piping.
- Manufacturers creating datasheets and product catalogs that must align with international conventions.
- Test laboratories and quality assurance teams reporting test results and specifying test conditions.
- Purchasing/specification engineers writing procurement documents and verifying compatibility of hydraulic/pneumatic components.
- Standards developers and technical committees referencing a harmonized pressure series in related standards.
Using ISO 2944 supports interoperability, clearer specification of operating ranges, and consistent communication of pressure ratings in both hydraulic and pneumatic applications.
Related standards
- ISO 1000 - SI units and recommendations for use of multiples
- ISO 5598 - Fluid power systems and components - Vocabulary
- See also sector standards that adopt nominal pressures, e.g., ISO 3322, ISO 4399 and ISO 5941
Keywords: ISO 2944, nominal pressures, fluid power systems, hydraulic, pneumatic, gauge pressure, pressure ratings, pressure units, kPa, MPa, bar.
