BS ISO 8625-1:2018 pdf download – Aerospace — Fluid systems — Vocabulary Part 1: General terms and definitions related to pressure
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 by authorities
3.10
charge pressure
inflation pressure
pressure to which a component is charged or inflated
3.11
control pressure
pilot pressure
pressure required to control or move a component, respectively to move the component to a predefined position
3.12
cut-out pressure
pressure at which a cut‑out sequence of a component or system begins
3.13
differential pressure
difference in value between two pressures occurring simultaneously at different points
3.14
dynamic pressure
kinetic energy per unit volume of a fluid particle, the dynamic pressure is the total pressure minus thestatic pressure
3.15
flushing pressure
pressure required to flush a system under defined conditions
EXAMPLE At defined flow.
3.16
gauge pressure
measured absolute pressure minus atmospheric pressure
3.17
idling pressure
pressure required to maintain a system or component, or flow and/or load, at idle speed
Note 1 to entry: Also the resulting pressure when a system or component (e.g. a pump) is operated at idle speed.
3.18
internal pressure
pressure exerted inside a system or component
3.19
maximum pressure
highest transient pressure which can occur in any operational condition of a system or component
3.20
minimum operating pressure
lowest pressure at which a component or system will operate with a specified performance
3.21
no-load pressure
pressure required to maintain a system at the operating speed in the no‑load condition
3.22
nominal pressure
system pressure
rated pressure
theoretical average pressure at which a system or component operates
Note 1 to entry: This is usually used to classify a system or component and to derive limit pressures, such as
proof and burst pressure.
3.23
operating pressure
pressure at which a system or component is operated under normal operating conditions
3.24
outlet pressure
output pressure
pressure at the outlet port of a component
3.25
peak pressure
maximum pressure value measured during operation of a system or component within a given timeframe
3.26
permissible pressure
pressure up to which a system is permitted to operate for safety reasons
Note 1 to entry: Only important for maintenance reasons.
3.27
precharge pressure
pressure in portions of a component or system which results from an intended application of (external)pressure of the same or another medium, or which results from an external load
3.28
pressure
force per unit area
3.29
pressure curve
pressure variation, expressed graphically in relation to another value
EXAMPLE Time or flow.
3.30
pressure drop
difference in pressure between two points in a fluid path
3.31
pressure fluctuation
variation of pressure with time, occurring arbitrarily
3.32
pressure gain
ratio of output pressure to input pressure
3.33
pressure gradient
rate of change of pressure with distance in a steady‑state flow.BS ISO 8625-1 pdf download.