ISO 12584:2013

INTERNATIONAL ISO
STANDARD 12584
First edition
2013-11-01
Aerospace — Hydraulic fluid
components — Expression of
particulate contamination levels
Aéronautique et espace — Composants pour fluides hydrauliques —
Expression des niveaux de contamination particulaire
Reference number
©
ISO 2013
© ISO 2013
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ii © ISO 2013 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3  Terms and definitions . 1
4 Principle . 3
5 Characteristics of the component . 3
5.1 General . 3
5.2 Determination of the wetted volume . 3
5.3 Particulate contamination extraction . 4
6 Expression of results . 4
6.1 Required preliminary data . 4
6.2 Presentation of the results . 4
6.3 Example . 6
Annex A (informative) Relating wetted volume to wetted surface area of components.7
Annex B (informative) Typical component particulate contamination analysis report .8
Bibliography .10
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directives
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received. www.iso.org/patents
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
The committee responsible for this document is ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 10, Aerospace fluid systems and components.
iv © ISO 2013 – All rights reserved

Introduction
The reliability of fluid circuits depends largely on the quantity and size of the particles conveyed by the fluid.
The cleanliness of the operating fluid is obtained and maintained by filtration at a level consistent
with the sensitivity of the system components to particulate contamination and the life and reliability
required by the operator of the system.
The cleanliness of the system at start-up is dependent on the cleanliness of the components as delivered,
the amount of contamination added during the build process, the cleanliness of the hydraulic liquid
used to fill the system, and how successful the liquid was in penetrating the clearances. The amount of
contamination added from these processes must be controlled to minimize the damage to the system
during the initial running period. Cleanliness specifications are fundamental to this.
This International Standard defines the terminology used in and the method of reporting and
communicating the cleanliness of components used in aerospace fluid systems. This will ensure
consistent and unambiguous reporting.
It also presents a coding system which allows cleanliness data to be reported either in a shortened
manner or in a complete manner for communication purposes or for specifying cleanliness requirements.
INTERNATIONAL STANDARD ISO 12584:2013(E)
Aerospace — Hydraulic fluid components — Expression of
particulate contamination levels
1 Scope
This International Standard defines the method of reporting and communicating the contamination (or
cleanliness) level of components used in aerospace fluid systems.
It also presents a coding system which allows cleanliness data to be reported, both in a shortened manner
and in a complete manner, when communicating for reporting contamination level measurement results
and for specifying cleanliness requirements.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 11171, Hydraulic fluid power — Calibration of automatic particle counters for liquids
ISO 18413, Hydraulic fluid power — Cleanliness of parts and components — Inspection document and
principles related to contaminant collection, analysis and data reporting
3  Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
component
general term to cover a part, a subassembly, or a part assembly used on an aerospace fluid system
3.2
component cleanliness
condition of a component characterized by a level of particulate contamination
Note 1 to entry: Expression to be used preferably to set a specification.
3.3
component cleanliness code
CCC
alphanumeric expression of the particulate contamination level of a component or part for fluid circuits
3.4
particulate contamination
all undesirable particles which are in and on a component
Note 1 to entry: Expression to be used preferably to report measurements.
3.5
wetted surfaces
surface area of the component that is exposed to system liquid
EXAMPLE Hydraulic gear pump (see Figure 1).
Note 1 to entry: The wetted surface of a gear pump is the sum of the internal surfaces of the pump body (2 plates
+ 1 gear housing with 2 ports) and of the external surface of the two gear wheels. The example shown gives a
simplified illustration and does not include all surfaces wetted by the hydraulic liquid.
Figure 1 — Diagrammatic representation of the wetted surfaces of a hydraulic gear pump
3.6
wetted volume
V
c
volume of fluid contained in the component during normal operation
EXAMPLE Hydraulic gear pump (see Figure 2).
Note 1 to entry: The wetted volume of a gear pump is the volume of the gear housing minus the volume of the two
gears. The example shown gives a simplified illustration and does not include all of the volumes filled with the
hydraulic liquid.
Figure 2 — Diagrammatic representation of the wetted volume of a hydraulic gear pump
2 © ISO 2013 – All rights reserved

4 Principle
The particulate contamination of a component is expressed by a level related to the number of particles in
various size ranges and related to the wetted volume of the component. It is measured by counting particles
after they have been extracted from the component by an appropriate extraction method (see ISO 18413).
5 Characteristics of the component
5.1 General
The fluid cleanliness code of ISO 11218 has served as a basis for the drawing up of the component
cleanliness code. This fluid cleanliness code quantifies the number of particles of given sizes present in
a given volume (100 cm ) of fluid being analysed.
By definition, the contamination of a component is only present on its surfaces. Damage to components
of the fluid circuit is caused only when particles detach from their surfaces and are transferred to the
fluid in circulation. For this reason, the contamination of a component is quantified by the number of
particles of given sizes present in a given volume of the component under analysis.
5.2 Determination of the wetted volume
5.2.1 Experimental method
5.2.1.1 Ensure that the interior of the component is dry.
5.2.1.2 Blank off all ports except one or more if necessary in order to allow a complete filling.
5.2.1.3 Prepare a volume of test fluid (V ), known to within 1 %, of approximately 1,3 times the
presumed wetted volume of the component. The test fluid shall be compatible with the materials of the
component and shall have a viscosity below 5 mm /s at the test temperature.
NOTE It has proven to be practical to weigh this volume in its container, previously tarred, and to divide the
mass of test fluid by its density.
5.2.1.4 Carefully fill the component with test fluid, avoiding the trapping of air. To achieve this, move the
component gently in suitable directions so that all its parts are filled up. Add further test fluid as necessary.
5.2.1.5 Determine the volume (V ) remaining in the container of 5.2.1.3.
5.2.1.6 Determine the volume (V ) which has been required for the filling of the component:
c
VV=−V
c 12
5.2.2 Method of calculation
If the computer’s industrial drawing software possesses the function, calculate the wetted volume of
the component.
5.2.3 Relationship between wetted surface area and wetted volume
Where a cleanliness specification or a cleanliness measurement result is expressed per unit surface area
of the component, this value shall be calculated to the number of particles per unit volume of wetted
volume of the component using Annex A.
5.3 Particulate contamination extraction
Extract the particulate contamination from the component using a method detailed in ISO 18413. The
extraction method chosen shall be fully validated for the component being tested.
Analyse the extraction liquid using a technique detailed in ISO 18413 and obtain data at some or all sizes
defined in Table 1, as specified in the Inspection Document. Present the data in terms of the differential
number of particles in the relevant size ranges per component.
Wherever possible, or if otherwise specified, the complete volume of the extraction liquid shall be analysed.
The reason for this is to ensure the large particles are not ‘lost’ in the sampling and preparation processes.
6 Expression of results
6.1 Required preliminary data
The expression of the level of particulate contamination of a component according to this International
Standard requires data on its wetted volume.
6.2 Presentation of the results
6.2.1 Particle size distribution
Tabulate the data obtained in 5.3 in a suitable reporting sheet and calculate the numbers of particles per
100 cm of the component volume. A typical form is given in Annex B.
4 © ISO 2013 – All rights reserved

6.2.2 Component cleanliness code (CCC)
6.2.2.1 Table 1 specifies the maximum number of particles of each size class acceptable within
100 cm of wetted vol
...