National foreword

This British Standard is the UK implementation of ISO 23309:2020. It supersedes BS ISO 23309:2007, which is withdrawn.

The UK participation in its preparation was entrusted to Technical Committee MCE/18/-/6, Contamination control.

A list of organizations represented on this committee can be obtained on request to its secretary.

This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 May 2020.

Foreword

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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).

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This document was prepared by Technical Committee ISO/TC 131, Fluid power systems, Subcommittee SC 6, Contamination control.

This second edition cancels and replaces the first edition (ISO 23309:2007) which has been technically revised.

The main changes compared to the previous edition are as follows:

identifies the shortfall of the Reynolds formula when it's used in isolation;
identifies the importance of flushing oil velocity, temperature, and viscosity;
identifies to the practitioners who perform flushing procedures that if they only consider the Re value the flushing velocity could be much less than the system oil flow within the system and what it will be subjected to in normal service;
raises awareness and importance of the factors other than the Re valve that affect the effectiveness, efficiency and reliability of any flushing process.

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.

Introduction

In hydraulic fluid power systems, power is transmitted and controlled through a liquid under pressure within an enclosed circuit.

The initial cleanliness level of a hydraulic system can affect its performance and useful life. Unless removed, particulate contamination present after manufacturing, assembly, component failure and repair of a system can circulate through the system and cause damage to the system components. To reduce the probability of such damage, the fluid and the internal surfaces of the hydraulic fluid power system needs to be flushed clean to a specified level.

Flushing of lines in a hydraulic system needs to be viewed as one means of removing in-built and residual contamination and should not be the sole method for cleaning such systems unless other methods are impractical.

1 Scope

This document specifies the procedures for flushing particulate contamination from the hydraulic lines and components of hydraulic fluid power systems which is:

residual in the components after manufacture;
introduced into the system during the assembly of a new system; or
introduced into the system after system failure, maintenance or modification of an existing system.

The aim of flushing the system is to quickly remove this contamination to reduce the amount of wear and damage that results if these particles are allowed to circulate around the system.

This document is not applicable to:

the chemical cleaning and pickling of hydraulic tubes;
the cleaning of major system components (this is covered in ISO/TR 10949).

2 Normative references

3 Terms and definitions

4 Principle of flushing

5 Flushing lines in a hydraulic system

5.1 Initial factors to consider

5.2 System layout

5.3 Component cleanliness level

5.4 Anti-corrosion agents

6 Treatment of lines

6.1 Preparation of lines during fabrication

6.2 Surface treatment

6.3 Storage of lines and connectors

7 Installation of piping systems

7.1

7.2

8 Flushing requirements

8.1 Flushing document

8.2 Flushing criteria

8.3 Flushing parameters

8.4 Filters and separation of particles

8.5 Monitoring the progress of flushing

8.6 Flushing procedures

9 Identification statement (reference to this document)

Bibliography

BS ISO 23309:2020

Hydraulic fluid power systems. Assembled systems. Methods of cleaning lines by flushing

Current

Published:

31 May 2020