ISO 14540:2013

Hydraulic fluid power - Dimensions and requirements for screw-to-connect quick-action couplings for use at a pressure of 72 MPa (720 bar)

ISO 14540:2013 specifies dimensional and performance requirements for hydraulic screw-to-connect quick-action couplings designed to be used at pressure of 72 MPa (720 bar) in static conditions as an interface between a hydraulic power unit and a tool. Typical applications for these couplings are related to hydraulic jacks, rams, clamping devices, hand tools, and cylinders. ISO 14540:2013 covers two types of such couplings: the "P" type, which has a poppet valve, and the "S" type, which has a spherical valve.

Transmissions hydrauliques — Dimensions et exigences des raccords rapides de type à visser pour usage à une pression de 72 MPa (720 bar)

General Information

• Status: Published
• Publication Date: 14-Mar-2013
• ICS: 23.100.40 - Piping and couplings
• Technical Committee: ISO/TC 131/SC 4 - Connectors and similar products and components
• Drafting Committee: ISO/TC 131/SC 4 - Connectors and similar products and components
• Current Stage: 9092 - International Standard to be revised
• Start Date: 05-Sep-2025
• Completion Date: 13-Dec-2025

Overview

ISO 14540:2013 is an international standard specifying the dimensions and performance requirements for screw-to-connect quick-action couplings used in hydraulic fluid power systems. These couplings are designed to operate safely and reliably at extremely high static pressures of up to 72 MPa (720 bar). The standard serves as a key reference for manufacturers and users of hydraulic quick-action couplings, particularly where high-pressure interfaces between hydraulic power units and tools are involved.

The couplings covered by ISO 14540:2013 are critical components in various hydraulic applications such as jacks, rams, clamping devices, hand tools, and cylinders, ensuring secure fluid connections under demanding conditions. Two primary coupling valve types are addressed: the “P” type with a poppet valve and the “S” type with a spherical valve.

Key Topics

• Dimensional Specifications
  The standard defines exact dimensional requirements including thread sizes (1-18 UNS inch threads), sealing diameters, and other critical dimensions necessary to ensure compatibility and interchangeability across manufacturers. Detailed dimensional tables and drawings are provided to guide design and inspection.

• Performance Criteria
  ISO 14540:2013 establishes rigorous performance parameters including:

  • Working pressure of 72 MPa (720 bar)
  • Minimum burst pressures up to 216 MPa (2160 bar) depending on valve type and condition
  • Rated flow capacities for different coupling sizes (e.g., 12 to 23 liters per minute)
  • Maximum pressure drop limits at rated flow to ensure efficient fluid transmission
  • Limits on fluid loss during disconnection to reduce environmental release and system contamination
  • Restrictions on residual static pressure during coupling connection to enhance safety

• Testing and Verification
  The standard references test methods per ISO 7241-2, detailing pressure impulse testing, burst pressure evaluation, flow rate verification, and fluid loss measurement to ensure couplings meet or exceed all safety and reliability requirements.

• Best Practices for Use and Safety
  ISO 14540 emphasizes providing users with comprehensive guidance on safe operation, correct connection procedures, and maintenance to prevent accidents associated with high-pressure hydraulic components. It highlights that these couplings are not designed for connection/disconnection under full working pressure and stresses the importance of using suitable personal protection and safety devices.

• Marking and Identification
  Permanently marked manufacturer identification and clear designation referencing ISO 14540 ensure traceability and conformity in the supply chain.

Applications

ISO 14540:2013 couplings are indispensable in sectors where high-pressure hydraulic equipment is standard, including:

• Industrial maintenance and manufacturing, utilizing hydraulic jacks, presses, and clamping tools
• Construction and heavy machinery, connecting hydraulic cylinders and rams
• Automotive repair where hand tools powered by hydraulic units require quick, secure connections
• Engineering and assembly lines requiring reliable fluid power transmission under challenging pressure conditions

These couplings enable quick, safe connections between hydraulic power sources and hydraulic tools or devices, reducing downtime and improving operational efficiency while ensuring safety at high pressures.

Related Standards

ISO 14540:2013 closely aligns with the following standards, forming a comprehensive framework for hydraulic fluid power connectors:

• ISO 7241-2: Hydraulic quick-action couplings - Test methods, providing standard testing protocols referenced in ISO 14540
• ISO 4397: Fluid power connectors and associated components – Nominal outside diameters and hose sizes, offering standardized size designations
• ISO 5598: Fluid power systems and components – Vocabulary, standardizing terminology used throughout ISO 14540
• ISO 725 and ISO 5864: Specifications for ISO inch screw threads and tolerances, defining thread dimensions vital for screw-to-connect couplings

Together, these standards support the design, testing, and safe use of hydraulic quick-connect couplings ensuring interoperability and compliance across international markets.

---

Keywords: ISO 14540, hydraulic fluid power, quick-action couplings, screw-to-connect coupling, high-pressure hydraulic fittings, hydraulic coupling dimensions, hydraulic coupling performance, poppet valve coupling, spherical valve coupling, hydraulic safety standards, ISO hydraulic connectors.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 14540
First edition
2013-03-15
Hydraulic fluid power — Dimensions
and requirements for screw-to-
connect quick-action couplings for use
at a pressure of 72 MPa (720 bar)
Transmissions hydrauliques — Dimensions et exigences des raccords
rapides de type à visser pour usage à une pression de 72 MPa (720 bar)
Reference number
©
ISO 2013
© ISO 2013
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
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Dimensional requirements . 1
5 Performance requirements . 3
6 Best practice . 3
7 Designation . 4
8 Marking . 4
9 Identification statement (reference to this International Standard) . 4
Annex A (normative) Basic dimensions of the 1-18 UNS inch screw thread .5
Bibliography . 6
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. 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. 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.
The committee responsible for this document is ISO/TC 131, Fluid power systems, Subcommittee SC 4,
Connectors and similar products and components.
iv © ISO 2013 – All rights reserved

Introduction
In hydraulic fluid power systems, power is transmitted and controlled through a liquid under pressure
within an enclosed circuit.
Screw-to-connect quick-action couplings conforming to this International Standard are designed to join
or separate fluid conductors ensuring, at the same time, sufficient resistance and safety in applications
characterized by very high working pressures up to 72 MPa (720 bar).
INTERNATIONAL STANDARD ISO 14540:2013(E)
Hydraulic fluid power — Dimensions and requirements
for screw-to-connect quick-action couplings for use at a
pressure of 72 MPa (720 bar)
1 Scope
This International Standard specifies dimensional and performance requirements for hydraulic screw-
1)
to-connect quick-action couplings designed to be used at pressure of 72 MPa (720 bar ) in static
conditions as an interface between a hydraulic power unit and a tool. Typical applications for these
couplings are related to hydraulic jacks, rams, clamping devices, hand tools, and cylinders.
This International Standard covers two types of such couplings: the “P” type, which has a poppet valve,
and the “S” type, which has a spherical valve.
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 amendments) applies.
ISO 725, ISO inch screw threads — Basic dimensions
ISO 5598, Fluid power systems and c
...