ISO 19973-3:2015

INTERNATIONAL ISO
STANDARD 19973-3
Second edition
2015-09-01
Pneumatic fluid power — Assessment
of component reliability by testing —
Part 3:
Cylinders with piston rod
Transmissions pneumatiques — Évaluation par essais de la fiabilité
des composants —
Partie 3: Vérins avec tiges de piston
Reference number
ISO 19973-3:2015(E)
©
ISO 2015

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ISO 19973-3:2015(E)

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ISO 19973-3:2015(E)

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
6 Test conditions . 2
6.1 General test conditions . 2
6.2 Initial condition . 3
6.3 Endurance test conditions . 3
6.3.1 Orientation . 3
6.3.2 Side loads . 3
6.3.3 Stroke lengths . 4
6.3.4 Test operating time . 6
6.4 Operating adjustments . 7
7 Test procedures . 7
7.1 Timing of checks and measurements . 7
7.2 Type and scope of checks and measurements . 7
7.2.1 Functional check . 7
7.2.2 Measurement of leakage . 7
7.2.3 Minimum working pressure test (for double-acting cylinders only) . 7
7.2.4 Stroke time test . 8
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 related to minimum working pressure . 9
8.5 Failure due to exceeding the maximum test stroke time . 9
8.6 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) Methods for calculating side load masses and related dimensions .11
Annex B (informative) Test data sheet .18
Bibliography .21
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ISO 19973-3:2015(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 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 19973-3:2007), 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.
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ISO 19973-3:2015(E)

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 cylinders with piston rod.
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.
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INTERNATIONAL STANDARD ISO 19973-3:2015(E)
Pneumatic fluid power — Assessment of component
reliability by testing —
Part 3:
Cylinders with piston rod
1 Scope
This part of ISO 19973 provides test procedures for assessing the reliability of pneumatic cylinders with
piston rod, both single-acting and double-acting, 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-point moving average
(3PMA) method, without repairs, but excluding outliers.
The lifetime of pneumatic cylinders is usually given in number of cycles or in kilometres. Therefore,
whenever the term “time” is used in this part of ISO 19973, this variable is to be understood as cycles
or kilometres.
This part of ISO 19973 also specifies test equipment and threshold levels for tests to assess the
reliability of pneumatic cylinders with piston rods.
This part of ISO 19973 is intended to be applied to pneumatic piston rod cylinders that conform to
ISO 6430, ISO 6432, ISO 15552, and ISO 21287; however, pneumatic piston rod cylinders that do not
conform to these International Standards but are used in the same range of operating conditions can be
tested in accordance with one of the classes defined in Tables 1 and 2.
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 10099:2001, Pneumatic fluid power — Cylinders — Final examination and acceptance criteria
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 these three documents, the following priority
order applies: first, ISO 19973-1; second, ISO 5598; and third, IEC 60050–191.
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ISO 19973-3:2015(E)

4 Symbols and units
Units of measurement shall be in accordance with ISO 80000-1.
NOTE Graphical symbols used in this part of ISO 19973 conform to the requirements given in ISO 1219-1.
5 Test equipment
5.1 The test circuit typically includes a pressure source, the cylinders being tested, solenoid valves,
and an adjustable flow control valve, which acts as a speed controller. See Figure 1 for a circuit diagram
of an example test circuit.
The basic circuits in Figure 1 do not incorporate all the safety devices necessary to protect against
damage in the event of component failure. It is important that those responsible for carrying out the
test give due consideration to safeguarding both personnel and equipment.
5.2 Cylinders to be tested shall be rigidly installed in the horizontal position and fixed to a secure base
to reduce vibration. They shall be fixed at both ends. If necessary, alternate the motion of the cylinders to
allow one to extend while another retracts.
Key
1 to 5 ports
6 pneumatic cylinder being tested
7 adjustable flow control valve (speed controller)
8 directional control valve
Figure 1 — Example of a test circuit for determining the reliability
of a pneumatic piston rod cylinder by testing
6 Test conditions
6.1 General test conditions
All test units shall have passed an acceptance test conducted in accordance with ISO 10099. The general
test conditions shall be in accordance with ISO 19973-1.
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ISO 19973-3:2015(E)

6.2 Initial condition
The leakage rate of new cylinders shall not exceed the values for this characteristic specified in
ISO 10099:2001, Table 1.
6.3 Endurance test conditions
6.3.1 Orientation
The cylinder being tested shall be installed in the horizontal position.
6.3.2 Side loads
6.3.2.1 No side loads shall be applied to single-acting cylinders. Test results can be related only to the
tested stroke.
6.3.2.2 For double-acting cylinders, the side load shall be mounted as follows.
a) The side load shall be tightened against the shoulder of the piston rod close to the theoretical
reference point (TRP) [see ISO 6099 and Figure 2 a)]. This mounting type should be preferred.
b) The side load masses and the distances from the TRP for double-acting cylinders shall be in
accordance with Table 1.
c) When a counter nut is required, the side load shall be mounted with a clearance LN from the TRP
[see Figure 2 b)]. However, the distance LT shall be maintained as shown in Table 1.
d) The side load shall be mounted to engage the piston rod at a distance H below the centre of gravity
(CG). Values for H are given in Table 1.
a) Figure 2a)                              b) Figure 2b)
Key
CG centre of gravity of the side load LN optional space for a counter nut
H eccentricity of the side load N counter nut (optional)
LT distance between TRP and CG TRP theoretical reference point
LM longitudinal length of the side load
Figure 2 — Distance of centre of gravity of the side load from the cylinder’s theoretical
reference point (TRP) and its eccentricity
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