ISO 3857-2:1977

Overview

ISO 3857-2:1977 - Compressors, pneumatic tools and machines - Vocabulary - Part 2: Compressors is an international vocabulary standard that defines terms and bilingual (English/French) definitions specifically for compressors. Published by ISO/TC 118 in 1977 as Part II of the ISO 3857 series, this standard establishes consistent terminology covering basic compressor concepts, measurement points, and parameters used across design, testing and procurement.

Key topics

The standard focuses on vocabulary and definitions rather than prescriptive performance limits. Major technical topics and defined terms include:

• General compressor terms: swept volume, displacement (volume rate), clearance (clearance volume), relative clearance volume, volume factor.
• Measurement points: standard inlet point and standard discharge point; standard inlet and discharge conditions.
• Temperatures: inlet temperature, discharge temperature (total temperatures at standard points).
• Flow rates: actual volume rate of flow, standard (reference) volume rate of flow.
• Pressures and ratios: inlet pressure, discharge pressure, total pressure ratio, stage and overall stage pressure ratios.
• Dynamic-compressor characteristics: tip Mach number, pressure coefficient (stage and overall).
• Powers and thermodynamic references: theoretical required power (isentropic, isothermal, polytropic reference processes), indicated power, internal power.
• Compression process definitions: ideal multi‑stage compression and reference thermodynamic processes (isothermal, isentropic, polytropic).

These entries are supplied in both English and French, ensuring consistent multilingual use.

Applications

ISO 3857-2:1977 is a foundation document used to:

• Standardize terminology in technical specifications, test reports and certification documents for compressors and pneumatic machinery.
• Support engineers and designers when documenting compressor performance (flow rates, pressures, temperatures, efficiencies).
• Help testing laboratories and acceptance testing to reference clearly defined measurement points and conditions.
• Assist manufacturers and procurement professionals in drafting unambiguous product data sheets and contracts.
• Provide translators, technical writers and standards developers with authoritative bilingual terms for documentation and regulatory use.

Keywords: ISO 3857-2:1977, compressor vocabulary, compressor terminology, swept volume, clearance volume, inlet/discharge conditions, pressure ratio, indicated power, polytropic/isotropic processes.

Related standards

• ISO 3857-1 - Part 1: Basic concepts, symbols and units (companion document covering symbols and units).
• ISO 3857-3 - Part 3: Pneumatic tools and machines (covers other pneumatic equipment; noted as in preparation in the original document).
• Work developed by ISO/TC 118 (Compressors, pneumatic tools and machines).

Use ISO 3857-2:1977 when consistent, internationally accepted compressor terminology is required in design, testing, procurement and documentation.