ISO 14085-6:2015

INTERNATIONAL ISO
STANDARD 14085-6
First edition
2015-03-01
Aerospace series — Hydraulic filter
elements — Test methods —
Part 6:
Initial cleanliness level
Série aérospatiale — Eléments filtrants hydrauliques — Méthode
d’essais —
Partie 6: Niveau de propreté
Reference number
©
ISO 2015
© ISO 2015
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ii © ISO 2015 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Summary of test method . 1
5 Materials and equipment . 1
6 Procedure. 2
7 Contaminant analysis . 3
7.1 Method of analysis . 3
7.2 Reporting of results . 3
8 Criterion for acceptance . 3
9 Identification statement . 3
Annex A (informative) Contaminant analysis methods . 4
Annex B (informative) Filter element cleanliness test data report form . 6
Bibliography . 7
Foreword
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The committee responsible for this document is ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 10, Aerospace fluid systems and components.
ISO 14085 consists of the following parts, under the general title Aerospace series — Hydraulic Filter
elements — Test methods:
— Part 1: Test sequence
— Part 2: Conditioning
— Part 3: Filtration efficiency and retention capacity
— Part 4: Verification of collapse/burst pressure rating
— Part 5: Resistance to flow fatigue
— Part 6: Initial cleanliness level
iv © ISO 2015 – All rights reserved

Introduction
In aerospace hydraulic fluid power systems, power is transmitted and controlled through a liquid
under pressure. The liquid is both a lubricant and power-transmitting medium. The presence of solid
contaminant particles in the liquid interferes with the ability of the hydraulic fluid to lubricate and
causes wear and malfunction of the components. The extent of contamination in the fluid has a direct
bearing in the performance, reliability, and safety of the system, and needs to be controlled to levels that
are considered appropriate for the system concerned.
Filters are used to control the contamination level of the fluid by removing solid contaminant particles,
typically consisting of a filter element enclosed in a filter housing. The filter element is the porous device
that performs the actual process of filtration. The complete assembly is designated as a filter.
Hydraulic fluid circuits require high levels of cleanliness which are not to be degraded by the filter
element itself when installed into the circuit. This procedure defined a test method to determine the
initial cleanliness level of a new hydraulic filter element.
INTERNATIONAL STANDARD ISO 14085-6:2015(E)
Aerospace series — Hydraulic filter elements — Test
methods —
Part 6:
Initial cleanliness level
1 Scope
This part of ISO 14085 defines a reference method for determining the level of cleanliness of new filter
elements for use in aircraft hydraulic systems, after production prior to shipment, or prior to installation
in the circuit.
It applies to filter elements used on systems requiring fluid cleanliness conditions defined in the
particular specification.
The tests data resulting from application of this part of ISO 14085 can be used to compare the cleanliness
of aerospace hydraulic filter elements.
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 3722, Hydraulic fluid power — Fluid sample containers — Qualifying and controlling cleaning methods
ISO 4405, Hydraulic fluid power — Fluid contamination — Determination of particulate contamination by
the gravimetric method
ISO 5598, Fluid power systems and components — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5598 and the following apply.
3.1
extraction liquid
test liquid extracted from the filter housing in which the filter element is installed during agitation
4 Summary of test method
The test consists of inserting the test filter element into a pre-cleaned filter housing and adding a solvent.
The filter assembly shall then be agitated to flush and collect built-in contaminant from a new filter
element. Multiple extraction liquid samples shall be used to achieve maximum contaminant removal.
The collected contaminant shall then be analysed using particle counting or gravimetric techniques,
and the amount of contamination shall be reported.
5 Materials and equipment
5.1 Test liquid: Use a suitable solvent with a viscosity less than 5 mm /s at test temperature. The test
liquid shall be compatible with all materials used in the filter, as well as with the functional liquid of the
system in which the filter will be applied. The test liquid should be compatible with all test apparatus,
including seals and filters, and filtered to the agreed initial cleanliness level.
The supplier and purchaser should agree upon the test liquid to be used in the collection process, and its
required initial cleanliness level, prior to the test. The contamination contained in the entire test liquid
volume to be used shall be less than 1 % of the presumed or allowable contamination level of the filter
element or class 1 per ISO 11218, so that it does not significantly influence the measured contamination
level. If the expected contamination level is unknown, a maximum contamination level of three particles
larger than or equal to 6 µm(c), or equivalent, per millilitre of container volume is considered appropriate.
WARNING — Exercise care when using test liquids with low flash points.
5.2 Test filter housing: Use a test filter housing (recommended by the filter manufacturer). Preferably
the housing type to be used in service can be utilized
...