ISO 19973-2:2015

Pneumatic fluid power - Assessment of component reliability by testing - Part 2: Directional control valves

ISO 19973-2:2015 provides test procedures for assessing the reliability of pneumatic directional control valves by testing and the methods of reporting the results of testing. General test conditions and the calculation method are provided in ISO 19973-1. The methods specified in ISO 19973-1 apply to the first failure, as obtained with the three-points moving average (3PMA) method, without repairs, but excluding outliers. The lifetime of pneumatic and electro-pneumatic directional control valves is usually given as a number of cycles. Therefore, whenever the term "time" is used in this part of ISO 19973-2:2015, this variable is to be understood as cycles. ISO 19973-2:2015 also specifies test equipment and threshold levels for tests to assess the reliability of pneumatic directional control valves.

Transmissions pneumatiques — Évaluation par essais de la fiabilité des composants — Partie 2: Distributeurs

General Information

• Status: Published
• Publication Date: 31-Aug-2015
• ICS: 23.100.01 - Fluid power systems in general
• Technical Committee: ISO/TC 131 - Fluid power systems
• Drafting Committee: ISO/TC 131/WG 4 - Determination of the reliability of pneumatic components by testing
• Current Stage: 9020 - International Standard under periodical review
• Start Date: 15-Oct-2025
• Completion Date: 15-Oct-2025

Relations

• Amended By: ISO 19973-2:2015/Amd 1:2019 - Pneumatic fluid power - Assessment of component reliability by testing - Part 2: Directional control valves - Amendment 1
• Effective Date: 11-Dec-2021
• Revises: ISO 19973-2:2007 - Pneumatic fluid power - Assessment of component reliability by testing - Part 2: Directional control valves
• Effective Date: 10-Aug-2012

Overview

ISO 19973-2:2015 - "Pneumatic fluid power - Assessment of component reliability by testing - Part 2: Directional control valves" specifies test procedures, equipment and reporting methods for assessing the reliability of pneumatic and electro-pneumatic directional control valves. It complements ISO 19973-1 (general procedures) and defines how lifetime is expressed (cycles), how the three-points moving average (3PMA) method is applied to determine first failure (without repairs, excluding outliers), and the threshold levels used to judge failures.

Key Topics and Requirements

• Scope and lifetime unit: Lifetime is expressed in cycles; whenever the standard uses “time” it means cycles.
• Test equipment: Basic circuits for testing two-position (bi-stable and mono‑stable) and three‑position valves, rules for silencers, pilot supply and safety considerations.
• Connecting piping and volumes: Guidance to avoid flow restrictions; keep tubing short so volumes charge/vent within control-signal timing.
• Test conditions: Initial functional checks; cycling requirements (outlet pressures must fall below 10% and rise above 90% of supply during a cycle); actuation on/off ratio 1:1.
• Control signals: Defined patterns for mono‑stable and bi‑stable/three‑position valves to ensure reproducible cycling.
• Checks and measurements:
  • Functional checks (acoustic, visual, tactile) to detect switching failures or incomplete charging.
  • Leakage measurements (functional leakage and specific internal/external pilot leak checks depending on valve type).
  • Measurement of shifting pressures (performance change over cycles).
• Failure criteria and thresholds: Criteria for functional failure, leakage failure and shifting-pressure failure; customizable agreements allowed between parties.
• Data analysis and reporting: Use methods from ISO 19973-1 for statistical analysis and prepare a standardized test report.

Applications and Users

ISO 19973-2:2015 is intended for:

• Valve manufacturers - for design validation, production testing and reliability claims.
• Test laboratories and OEMs (machine builders) - to evaluate component reliability, set maintenance intervals, and optimize spare-part inventories.
• Reliability and quality engineers - for reliability modelling, warranty analysis and continuous improvement. Practical uses include predicting valve lifetime in cycles, establishing service schedules, and informing FMEA, design changes and production acceptance tests.

Related Standards

• ISO 19973-1 (General procedures)
• ISO 1219-1 (Graphical symbols)
• ISO 5598 (Vocabulary)
• ISO 8778 (Standard reference atmosphere)
• ISO 80000-1 (Units)
• IEC 60050-191 (Dependability vocabulary)

Keywords: ISO 19973-2:2015, pneumatic directional control valves, reliability testing, 3PMA, leakage measurement, cycling frequencies, test procedures, threshold levels.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 19973-2
Second edition
2015-09-01
Pneumatic fluid power — Assessment
of component reliability by testing —
Part 2:
Directional control valves
Transmissions pneumatiques — Évaluation par essais de la fiabilité
des composants —
Partie 2: Distributeurs
Reference number
©
ISO 2015
© ISO 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
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Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
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 Symbols and units . 2
5 Test equipment. 2
5.1 Basic test equipment . 2
5.2 Connecting piping and volume. 4
5.3 Simultaneous operation of multiple pneumatically operated valves . 4
6 Test conditions . 4
6.1 General test conditions . 4
6.2 Initial condition . 4
6.3 Cycling frequencies . 4
7 Test procedures . 6
7.1 Timing of checks and measurements . 6
7.2 Type and scope of checks and measurement . 6
7.2.1 Functional check . 6
7.2.2 Measurement of leakage . 6
7.2.3 Measurement of shifting pressures . 6
8 Failure criteria and threshold levels . 8
8.1 General . 8
8.2 Functional failure . 8
8.3 Failure due to leakage . 8
8.4 Failure due to shifting pressures . 9
8.5 Customised agreements . 9
9 Data analysis . 9
10 Test report . 9
11 Identification statement (reference to this part of ISO 19973) .10
Annex A (informative) Test data sheet .11
Bibliography .14
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 meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 131, Fluid power systems.
This second edition cancels and replaces the first edition (ISO 19973-2:2007), which has been
technically revised.
ISO 19973 consists of the following parts, under the general title Pneumatic fluid power — Assessment of
component reliability by testing:
— Part 1: General procedures
— Part 2: Directional control valves
— Part 3: Cylinders with piston rod
— Part 4: Pressure regulators
— Part 5: Non-return valves, shuttle valves, dual pressure valves (AND function), one-way adjustable flow
control valves, quick-exhaust valves.
iv © ISO 2015 – All rights reserved

Introduction
In pneumatic fluid power systems, power is transmitted and controlled through a gas under pressure
within a circuit. Pneumatic fluid power systems are composed of components and are an integral part
of various types of machines and equipment. Efficient and economical production requires highly
reliable machines and equipment. This part of ISO 19973 is intended to provide requirements and test
conditions that permit the assessment of the inherent reliability of pneumatic and electro-pneumatic
directional control valves.
It is necessary that machine producers know the reliability of the components that make up their
machine’s pneumatic fluid power system. Knowing the reliability characteristic of the component, the
producers can model the system and make decisions on service intervals, spare parts inventory and
areas for future improvements.
There are three primary levels in the determination of component reliability:
a) preliminary design analysis: finite element analysis (FEA), failure mode and effect
analysis (FMEA);
b) laboratory testing and reliability modelling: physics of failure, reliability prediction, pre-produc-
tion evaluation;
c) collection of field data: maintenance reports, warranty analysis.
Each level has its application during the life of a component. A preliminary design analysis is useful
to identify possible failure modes and eliminate them or reduce their effect on reliability. When
prototypes are available, in-house laboratory reliability tests are run and initial reliability can be
determined. Reliability testing is often continued into the initial production run and throughout the
production lifetime as a continuing evaluation of the component. Collection of field data are possible
when products are operating and data on their failures are available.
INTERNATIONAL STANDARD ISO 19973-2:2015(E)
Pneumatic fluid power — Assessment of component
reliability by testing —
Part 2:
Directional control valves
1 Scope
This part of ISO 19973 provides test procedures for assessing the reliability of pneumatic directional
control valves by testing and the methods of reporting the results of testing. General test conditions
and the calculation method are provided in ISO 19973-1. The methods specified in ISO 19973-1 apply to
the first failure, as obtained with the three-points moving average (3PMA) method, without repairs, but
excluding outliers.
The lifetime of pneumatic and electro-pneumatic directional control valves is usually given as a number
of cycles. Therefore, whenever the term “time” is used in this part of ISO 19973, this variable is to be
understood as cycles.
This part of ISO 19973 also specifies test equipment and threshold levels for tests to assess the
reliability of pneumatic directional control valves.
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 1219-1, Fluid power systems and components — Graphical symbols and circuit diagrams — Part 1:
Graphical symbols for conventional use and data-processing applications
ISO 5598, Fluid power systems and components — Vocabulary
ISO 8778, Pneumatic fluid power — Standard reference atmosphere
ISO 19973-1, Pneumatic fluid power — Assessment of component reliability by testing — Part 1:
General procedures
ISO 80000-1, Quantities and units — Part 1: General
IEC 60050-191, International Electrotechnical Vocabulary, chapter 191: Dependability and quality of service
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5598, ISO 19973-1 and
IEC 60050-191 apply.
NOTE Where a conflict of definitions exists for a term in any of t
...