ISO 5884:2018
(Main)Aerospace series — Fluid systems and components — Methods for system sampling and measuring the solid particle contamination in hydraulic fluids
Aerospace series — Fluid systems and components — Methods for system sampling and measuring the solid particle contamination in hydraulic fluids
This document specifies best practice for sampling hydraulic fluid from aircraft hydraulic systems and other hydraulic systems associated with aerospace purposes.
Série aérospatiale — Systèmes de fluides et éléments constitutifs — Méthodes de prélèvement et de mesure de la contamination particulaire solide dans un fluide hydraulique
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INTERNATIONAL ISO
STANDARD 5884
Second edition
2018-08
Aerospace series — Fluid systems
and components — Methods for
system sampling and measuring
the solid particle contamination in
hydraulic fluids
Série aérospatiale — Systèmes de fluides et éléments constitutifs
— Méthodes de prélèvement et de mesure de la contamination
particulaire solide dans un fluide hydraulique
Reference number
ISO 5884:2018(E)
©
ISO 2018
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ISO 5884:2018(E)
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© ISO 2018
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ISO 5884:2018(E)
Contents Page
Foreword .iv
0 Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Sampling apparatus . 1
4.1 General . 1
4.2 Sampling apparatus characteristics . 2
4.2.1 Manual sampling apparatus . 2
4.2.2 Automated sampling apparatus . 2
4.3 Sample apparatus preparation . . 3
4.3.1 General. 3
4.3.2 Solvents . 4
4.3.3 Cleaning procedure for sampling apparatus . 5
4.3.4 Cleaning procedure for sample bottles . 5
4.3.5 Checking and controlling cleaning methods . 6
5 Sampling . 6
5.1 General . 6
5.2 Recommendations for sampling point location . 6
5.3 Sampling frequency . 7
5.4 Sampling methods . 7
5.4.1 General. 7
5.4.2 Sampling method A — Field monitor/PCM system . 7
5.4.3 Sampling method B — Sampling valve (using sample bottles) . 8
5.4.4 Sampling method C — Reservoir sampling with vacuum pump and tubing . 9
5.4.5 Sampling method D — Reservoir sampling with direct bottle dipping . 9
5.5 Sample marking .10
6 Sample analysis methods .10
7 Test reporting .10
7.1 General .10
7.2 Test report form .10
7.3 Minimum data to be included in the test report form .11
7.4 Example test report .11
Annex A (informative) Example test report template .12
Bibliography .13
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ISO 5884:2018(E)
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 (see 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 (see 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.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by 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 5884:1987), which has been technically
revised. The main changes compared to the previous edition are as follows:
— update of the document to be in line with current ISO rules;
— improved layout and clarity in definition;
— removal of sample analysis detail, with reference to relevant ISO method instead;
— improved sampling point recommendations;
— improved clarity of sampling methods and recommendations for preference.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
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ISO 5884:2018(E)
0 Introduction
0.1 General
The design of modern hydraulic equipment for aerospace purposes, its use and performance are widely
determined by the type and condition of the applicable hydraulic fluids.
The quality and serviceability of hydraulic fluids are dependent on various factors (e.g. thermal stability,
viscosity), but in particular on the level of solid particle contamination. Regular fluid contamination
testing is required to determine if the fluid is maintained within specified limits that are set by the
aircraft manufacturer or hydraulic system operator.
In order to obtain consistent and comparable test results, the test methods detailed in this document
should be used.
As a result of the rapid development and improvement of hydraulic systems and their components,
which meet critical requirements, the problem of solid particle contamination of hydraulic fluids has
steadily increased. The need for maintaining a specified standard of fluid cleanliness in hydraulic
systems requires continuous control of the number and size of the solid particle contaminants.
0.2 Solid particle contamination
Solid particle contaminants can be the cause of abrasion and wearing, thereby shortening the life of the
components in a hydraulic system.
In a hydraulic system:
a) components are subject to erosion (primarily in components with higher fluid velocities);
b) all moving parts are subject to wear by abrasion; and
c) control valves are subject to silting (settlement of fine particles on the control bore).
0.3 Causes of solid particle contamination
Solid particle contamination of hydraulic fluids can be system-generated, introduced from the outside,
in-built or maintenance-generated, for example:
a) dust particles in the air;
b) metal particles, produced during the manufacture of parts;
c) sand residues on castings;
d) abrasion of seals;
e) oxide layers on welding seams and on heat-formed or heat-treated steel parts;
f) chemical and physical changes in the condition of hydraulic fluids;
g) maintenance of hydraulic systems (e.g. fibres, secondary contamination, etc.);
h) wear of components from abrasion, adhesion and fatigue; and
i) ingress of particles via piston gland seals.
0.4 Layout of this document
This document is sub-divided into the following clauses:
— Sampling apparatus (Clause 4):
— Characteristics;
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ISO 5884:2018(E)
— Preparation;
— Sampling (Clause 5):
— Recommendations for sampling point location;
— Recommendation of sampling frequency;
— Sampling methods;
— Recommendation of sample marking;
— Sample analysis methods (Clause 6);
— Test report recommendations (Clause 7).
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INTERNATIONAL STANDARD ISO 5884:2018(E)
Aerospace series — Fluid systems and components —
Methods for system sampling and measuring the solid
particle contamination in hydraulic fluids
1 Scope
This document specifies best practice for sampling hydraulic fluid from aircraft hydraulic systems and
other hydraulic systems associated with aerospace purposes.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 3722, Hydraulic fluid power — Fluid sample containers — Qualifying and controlling cleaning methods
ISO 4021, Hydraulic fluid power — Particulate contamination analysis — Extraction of fluid samples from
lines of an operating system
ISO 4405, Hydraulic fluid power — Fluid contamination — Determination of particulate contamination by
the gravimetric method
ISO 4406, Hydraulic fluid power — Fluids — Method for coding the level of contamination by solid particles
ISO 4407, Hydraulic fluid power — Fluid contamination — Determination of particulate contamination by
the counting method using an optical microscope
ISO 11171, Hydraulic fluid power — Calibration of automatic particle counters for liquids
ISO 11218, Aerospace — Cleanliness classification for hydraulic fluids
ISO 11500, Hydraulic fluid power — Determination of the particulate contamination level of a liquid sample
by automatic particle counting using the light-extinction principle
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at https: //www .electropedia .org/
4 Sampling apparatus
4.1 General
When establishing the solid particle contamination of hydraulic fluids, the test results can be adversely
affected by not sufficiently taking account of the need for an optimum cleanliness.
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ISO 5884:2018(E)
To obtain meaningful results, reproducible at any place and at any time, it is essential to ensure that
the sampling equipment is carefully prepared and maintained throughout the sampling process to
prevent any addition of solid particle contamination to the hydraulic fluid sample taken. This is because
additional solid particle contamination can be caused by using apparatus inadequately cleaned for the
measurement.
All apparatus used for determination of the solid particle contamination level of hydraulic fluids shall
be thoroughly cleaned before use in accordance with the procedure specified in 4.3.3.
It is important that for all sampling apparatus, due consideration is given to the suitability and resistance
to both the cleaning fluid used to prepare the sample apparatus and to the fluid to be sampled. This is
especially important when considering the compatibility differences between mineral oil /synthetic
hydrocarbon and Phosphate Ester–based hydraulic fluids.
4.2 Sampling apparatus characteristics
4.2.1 Manual sampling apparatus
4.2.1.1 General
Most system fluid samples can be obtained with the use of a simple sample bottle and tubing (if
necessary) to transfer the fluid from the sampling point to the bottle.
It is preferable to purchase suitable sample bottles that meet the provisions of ISO 3722. The system
operator shall specify the required cleanliness level.
Tubing shall be pre-cleaned or purchased in a condition which is in accordance with a cleanliness level
required by the system operator.
If cleaning manual sampling apparatus is required prior to use, then refer to 4.3.
4.2.1.2 Sample bottles
The sample bottles shall be made from glass or polyethylene terephthalate (PET or PETG). They shall
have a maximum capacity of 250 ml and a minimum capacity of 100 ml. They should be sealed by means
of caps (preferably of phenolic resin with glass bottles) which do not cause contamination. Otherwise, a
non-flaking plastic film compatible with the hydraulic fluid should be used.
4.2.1.3 Sample tubing
The sample tubing (if necessary for sampling of fluid) shall be in accordance with the description given
in ISO 4021.
4.2.2 Automated sampling apparatus
4.2.2.1 General
Automatic sampling of fluid systems can be carried out using equipment such as a field monitor or
portable cleanliness monitor. These systems are preferred to bottle sampling methods as there is a
much lower possibility of contamination of the results, especially in adverse environmental conditions.
Automated sampling monitors shall be flushed prior to use. This can be completed using the system
fluid itself, or a fluid which has a similar viscosity and a cleanliness class better than the requirement
for the system fluid. The volume of fluid used for flushing should be at least twice that of the hose used
to connect the monitor to the hydraulic system.
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ISO 5884:2018(E)
4.2.2.2 Field monitors
Field monitors contain membrane filters suitable for subsequent microscopic analysis (ISO 4407) or
gravimetric analysis (ISO 4405).
The membrane filters shall be pre-installed in the field monitor in a clean environment.
During flushing, the fluid should bypass the membrane and therefore a three-way valve shall direct the
flow from the membrane. Following flushing and prior to sampling, the valve is actuated to direct the
flow to the membrane filter.
4.2.2.3 Laser particle counter systems
Portable laser particle counter systems use light extinction techniques to produce an immediate
analysis of the system cleanliness. The monitors shall be calibrated in accordance with ISO 11171. The
output from the systems is in the form of a coded cleanliness level in accordance with ISO 4406 or
cleanliness classes in accordance with ISO 11218.
NOTE SAE AS 4059 or NAS 1638 can also be taken as equivalent standards to ISO 11218.
ISO 11218 (or SAE AS 4059) should be used in place of NAS 1638, except in special circumstances where
comparison to earlier data is necessary.
These types of monitors are affected by the occurrence of water droplets or air bubbles in the sampled
fluid. Therefore, care shall be taken with the location of the sampling point (5.2).
4.2.2.4 Portable mesh blockage monitors
Portable mesh blockage monitors determine particulate contamination levels by passing a specified
flow of sample fluid through a series of calibrated mesh screens in a specified sequence. Pressure drop
build-up (or flow degradation), which is dependent on particulate contamination levels, is measured
and converted via algorithms into:
— a coded cleanliness level in accordance with ISO 4406; or
— cleanliness classes in accordance with ISO 11218.
NOTE SAE AS 4059 or NAS 1638 can also be taken as equivalent standards to ISO 11218.
ISO 11218 (or SAE AS 4059) should be used in place of NAS 1638, except in special circumstances where
comparison to earlier data is necessary.
These monitors are especially suited to systems in which the fluid is likely to contain free water or air
bubbles and can also be used to measure viscosity, temperature and fluid water content (if equipped
with a water sensor).
4.3 Sample apparatus preparation
4.3.1 General
Sampling apparatus requires careful preparation to achieve a high level of cleanliness and control
prior to use. This ensures that sampled fluid is not contaminated by background contaminant already
present on the sample apparatus itself.
Staff performing any cleaning procedures shall wear lint-free clothes (e.g. cap, smock frock, boots) to
avoid excessive secondary contamination by fibres.
The standard of the workroom shall be such as to ensure that the specified cleanliness standard can be
achieved repeatedly.
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ISO 5884:2018(E)
4.3.2 Solvents
4.3.2.1 General
Liquid solvents shall be used to ensure removal of both solid and liquid contamination of sampling
equipment.
The solvents used shall be verified as physically and chemically compatible with the sampling
equipment and shall not react with the hydraulic oil to be stored in the bottle.
The following solvents are recommended solvents. Other approved equivalents are permitted, but
should be agreed prior to use.
— Solvent Type A: Water in accordance with ISO 3696, Grade 3.
— Solvent Type B: 2-propanol (is
...
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