ISO 8625-1:2018

INTERNATIONAL ISO
STANDARD 8625-1
Second edition
2018-03
Aerospace — Fluid systems —
Vocabulary —
Part 1:
General terms and definitions related
to pressure
Aéronautique et espace — Systèmes de fluides — Vocabulaire —
Partie 1: Termes généraux et définitions relatifs à la pression
Reference number
©
ISO 2018
© ISO 2018
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ii © ISO 2018 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
Annex A (informative) Graphical presentation of an arbitrary pressure curve .6
Bibliography . 7
Foreword
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electrotechnical standardization.
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URL: www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,
Subcommittee SC 10, Aerospace fluid systems and components.
This second edition cancels and replaces the first edition (ISO 8625-1:1993) which has been technically
revised and includes the following changes:
— Clause 2 “Normative References” has been added;
— Terms and definitions” has been moved from Clause 2 to Clause 3;
— example for a definition at the beginning of Clause 3 has been deleted;
— definitions in Clause 3 have been renumbered accordingly;
— definitions of the following terms have been revised:
— absolute pressure, ambient pressure, atmospheric pressure, burst pressure, control pressure,
dynamic pressure, flushing pressure, idling pressure, maximum pressure, minimum operating
pressure, nominal/system/rated pressure, operating pressure, peak pressure, pressure curve,
pressure drop, pressure impulse, pressure rise, pressure surge, pressure transient, pressure
head, proof pressure, static pressure, suction pressure; and
— the “Alphabetical Index” has been deleted.
A list of all parts in the ISO 8625 series can be found on the ISO website.
iv © ISO 2018 – All rights reserved

INTERNATIONAL STANDARD ISO 8625-1:2018(E)
Aerospace — Fluid systems — Vocabulary —
Part 1:
General terms and definitions related to pressure
1 Scope
This document defines general terms relating to pressure in fluid systems used in aerospace
construction.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
NOTE A graphical representation of an arbitrary pressure curve is shown in Annex A.
3.1
absolute pressure
pressure using absolute vacuum as a reference, equal to gauge pressure plus atmospheric pressure
3.2
actual pressure
pressure at a specific location, temperature and time within a system or component
3.3
ambient pressure
pressure on an object caused by its surrounding medium
3.4
atmospheric pressure
absolute pressure of the atmosphere at a specific location and time
3.5
back pressure
pressure acting against the specified direction of operation
3.6
breakout pressure
minimum pressure required to overcome static friction in a component under defined conditions
3.7
burst pressure, actual
pressure at which a component bursts or shows excessive leakage due to structural failure
3.8
burst pressure, minimum
ultimate pressure, minimum
pressure up to which no burst or rupture of components is allowed
3.9
certification pressure
authorized pressure for official acceptance tests
...