SIST ISO 4406:2022

SLOVENSKI STANDARD
01-marec-2022
Nadomešča:
SIST ISO 4406:2001
Moč hidravličnega fluida - Fluidi - Metoda za označevanje stopnje onesnaženosti s
trdnimi delci
Hydraulic fluid power - Fluids - Method for coding the level of contamination by solid
particles
Transmissions hydrauliques - Fluides - Méthode de codification du niveau de pollution
particulaire solide
Ta slovenski standard je istoveten z: ISO 4406:2021
ICS:
23.100.60 Filtri, tesnila in Filters, seals and
onesnaževanje tekočin contamination of fluids
75.120 Hidravlični fluidi Hydraulic fluids
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 4406
Fourth edition
2021-01
Hydraulic fluid power — Fluids
— Method for coding the level of
contamination by solid particles
Transmissions hydrauliques — Fluides — Méthode de codification du
niveau de pollution particulaire solide
Reference number
©
ISO 2021
© ISO 2021
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ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Code definitions. 1
4.1 General . 1
4.2 Basis of code . 2
4.3 Allocation of scale numbers . 2
4.4 Determination of code using automatic particle counter analysis . 3
4.5 Determination of code using microscope sizing . 4
5 Identification statement (reference to this document) . 4
Annex A (normative) Graphical presentation of the code number . 5
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
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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).
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iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 131, Fluid power systems, Subcommittee
SC 6, Contamination control.
This fourth edition cancels and replaces the third edition (ISO 4406:2017), which has been technically
revised.
The main change compared to the previous edition is as follows:
— the use of Particle Contamination Monitors (PCMs) can also be utilized for the determination of the
ISO 4406 contamination code (see subclause 4.4.1) and PCM is referenced throughout this document.
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.
iv © ISO 2021 – All rights reserved

Introduction
In hydraulic fluid power systems, power is transmitted and controlled through a liquid under pressure
within an enclosed circuit. Solid particle contaminant is always present in the hydraulic fluid and the
amount needs to be determined because the contaminant can cause serious problems.
The ISO 4406 cleanliness code has gained world-wide acceptance as a means of communicating the
cleanliness of a hydraulic fluid. Most hydraulic component manufacturers require a certain ISO
cleanliness level for warranty purposes, to ensure proper function and for a long, trouble-free life.
INTERNATIONAL STANDARD ISO 4406:2021(E)
Hydraulic fluid power — Fluids — Method for coding the
level of contamination by solid particles
1 Scope
This document specifies the code to be used in defining the quantity of solid particles in the fluid used
in a given hydraulic fluid power system.
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 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 11500, Hydraulic fluid power — Determination of the particulate contamination level of a liquid sample
by automatic particle counting using the light-extinction principle
ISO 21018-3, Hydraulic fluid power — Monitoring the level of particulate contamination of the fluid —
Part 3: Use of the filter blockage technique
ISO 21018-4, Hydraulic fluid power — Monitoring the level of particulate contami
...