ISO 19973-2:2007

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

ISO 19973-2:2007 provides test procedures for determining the reliability of pneumatic directional control valves by testing and the methods of reporting the results of testing according to the general test conditions and the calculation method provided in ISO 19973-1. 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 ISO 19973-2:2007, this variable is understood as cycles. ISO 19973-2:2007 also specifies test equipment and threshold levels for tests to determine the reliability of pneumatic directional control valves.

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

General Information

• Status: Withdrawn
• Publication Date: 29-Jul-2007
• Withdrawal Date: 29-Jul-2007
• 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: 9599 - Withdrawal of International Standard
• Completion Date: 01-Sep-2015

Relations

• Revised: ISO 19973-2:2015 - Pneumatic fluid power — Assessment of component reliability by testing — Part 2: Directional control valves
• Effective Date: 10-Aug-2012

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 19973-2
First edition
2007-08-01

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 19973-2:2007(E)
©
ISO 2007

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ISO 19973-2:2007(E)
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ISO 19973-2:2007(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 . 4
7 Test measurement periods . 6
8 Test measurement requirements . 6
9 Threshold levels. 8
10 Data analysis . 9
11 Test report . 9
12 Identification statement (reference to this part of ISO 19973). 9
Annex A (informative) Determination of threshold values for leakage rates. 10

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ISO 19973-2:2007(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 19973-2 was prepared by Technical Committee ISO/TC 131, Fluid power systems.
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
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ISO 19973-2:2007(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. Within the ISO 19973 series, this Part 2 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-production
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 is possible when products are operating and data on their failures are
available.

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INTERNATIONAL STANDARD ISO 19973-2:2007(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 determining 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 part 1 of ISO 19973. The methods specified in that part of ISO 19973 apply
to the first failure without repairs, but exclude 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 be understood as
cycles.
This part of ISO 19973 also specifies test equipment and threshold levels for tests to determine the reliability
of pneumatic directional control valves.
2 Normative references
The following referenced documents are indispensable for the application 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 1000, SI units and recommendations for the use of their multiples and of certain other units
ISO 1219-1, Fluid power systems and components — Graphic symbols and circuit diagrams —
Part 1: Graphic symbols for conventional use and data-processing applications
ISO 5598, Fluid power systems and components — Vocabulary
ISO 6358, Pneumatic fluid power — Components using compressible fluids — Determination of flow-rate
characteristics
ISO 8778, Pneumatic fluid power — Standard reference atmosphere
ISO 19973-1, Pneumatic fluid power — Assessment of component reliability by testing — Part 1: General
procedures
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. 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 19973-2:2007(E)
4 Symbols and units
4.1 Units of measurement are in accordance with ISO 1000.
4.2 Graphic symbols used in this part of ISO 19973 conform to the requirements of ISO 1219-1.
5 Test equipment
5.1 Basic test equipment
Basic test equipment shall conform to the requirements given in Table 1 and Figure 1. Any silencers fitted to
exhaust ports shall not restrict the valve’s flow rate.
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.

a)  Two-position bi-stable valves
Figure 1 — Basic test equipment requirements (continued)
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ISO 19973-2:2007(E)

b)  Two-position monostable valves with spring or air return

c)  Three-position valves
Key
1 to 5 ports 9 valve being tested
6 control signal: electrical, pneumatic, or pilot-operated 10 volume at working ports
7 spring or air-spring return 11 supply pressure to port 1
8 spring return to centre position
The pilot supply can be either internal or external as long as it has the capability described in 8.3.
Figure 1 — Basic test equipment requirements
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ISO 19973-2:2007(E)
5.2 Volume at working ports
The volume at the working ports depends on the valve’s sonic conductance, C, as determined in accordance
with ISO 6358. The volumes shall meet or exceed the minimum values given in Table 1.
CAUTION — During testing, the volumes at working ports can become hot. It is necessary to take care
to protect personnel.
Table 1 — Minimum volume at the working ports, based on valve’s sonic conductance
Sonic conductance Minimum volume at working ports
C

ml
3
dm /(s·MPa)

C u 4
2
4 < C u 40
10
40 < C u 120
25
120 < C u 200
50
200 < C u 400
100
C < 400 200
5.3 Recommended tube sizes for supply line
5.3.1 Connect the volume to the working ports of the test units either directly or by means of sections of
tubes, in a manner that does not restrict flow.
5.3.2 Tubes in the connecting lines shall be kept as short as possible so that the volumes can be charged
and vented within the times provided by the control signal.
5.4 Simultaneous operation of multiple pneumatically operated valves
When testing pneumatically operated valves, several test units may be operated simultaneously from one
control valve. In doing so, the control pressure described in 6.2.1 shall be applied to all test units.
6 Test con
...