ISO 9635-3:2014

Agricultural irrigation equipment - Irrigation valves - Part 3: Check valves

ISO 9635-3:2014 specifies construction and performance requirements and test methods for check valves, intended for operation in irrigation systems with water at temperatures not exceeding 60 °C, which can contain fertilizers and other chemicals of the types and concentrations used in agriculture. It is applicable to hydraulically operated check irrigation valves of DN 15 diameter or greater, designed to operate in the fully open and fully closed positions, but which can also operate for extended time periods in any intermediate position.

Matériel agricole d'irrigation — Vannes d'irrigation — Partie 3: Clapets antiretour

General Information

• Status: Published
• Publication Date: 13-Nov-2014
• ICS: 65.060.35 - Irrigation and drainage equipment
• Technical Committee: ISO/TC 23/SC 18 - Irrigation and drainage equipment and systems
• Drafting Committee: ISO/TC 23/SC 18 - Irrigation and drainage equipment and systems
• Current Stage: 9093 - International Standard confirmed
• Start Date: 04-Sep-2025
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 9635-3:2006 - Agricultural irrigation equipment - Irrigation valves - Part 3: Check valves
• Effective Date: 24-Dec-2011

Overview

ISO 9635-3:2014 - Agricultural irrigation equipment - Irrigation valves - Part 3: Check valves - specifies construction, performance requirements and test methods for hydraulically operated check valves used in agricultural irrigation systems. The standard applies to valves of DN 15 and larger, designed to operate fully open and fully closed (and capable of remaining in intermediate positions), with water temperatures up to 60 °C and exposure to fertilizers and agricultural chemicals.

Key topics and technical requirements

• Scope and definitions: clear definitions for check valves and flow-coefficient (Kv) used for performance claims.
• Design requirements: compliance with ISO 9635-1 general requirements (orientation, maintainability, marking of flow direction).
• Mechanical strength: tests for shell and pressure-containing parts and for obturator resistance to differential pressure; post-test function must not degrade by more than 10% versus manufacturer-declared values.
• Resistance to bending: bending moment tests defined as a function of DN to simulate in-line loads.
• Watertightness and seat tightness: internal and external pressure leak tests and seat tightness tests at high and low differential pressures.
• Hydraulic characteristics: head-loss or Kv must match manufacturer data; when measured per ISO 9644:2008, head loss shall not exceed 1.1× the declared value.
• Chemical resistance: materials and lubricants in contact with water must resist fertilizers/chemicals used in agriculture.
• Endurance: valves must withstand 2 500 opening/closing cycles (Annex A procedure) at approximately 1 m/s flow velocity and still pass leak tests; endurance testing not required for DN > 300.
• Conformity assessment: type tests, production control and quality-system requirements referenced to ISO 9635-1.

Practical applications

• Use ISO 9635-3:2014 to develop technical specifications for manufacturing, type-testing, and quality control of irrigation check valves.
• Aid procurement teams and irrigation system designers to select valves verified for chemical resistance, hydraulic performance and durability.
• Provide acceptance criteria for independent test laboratories and certification bodies performing leak, strength and endurance tests.
• Support maintenance teams by clarifying expected performance limits and required markings (e.g., flow direction) and recommending valve designs that permit in-line repair.

Who should use this standard

• Valve manufacturers and product engineers
• Irrigation system designers and agricultural engineers
• Test laboratories and conformity assessment bodies
• Procurement/specification writers for agricultural and landscape irrigation projects
• Maintenance and asset managers of irrigation networks

Related standards

• ISO 9635-1:2014 (General requirements for irrigation valves)
• ISO 9635 (Parts 1–5 covers isolating, check, air and control valves)
• ISO 9644:2008 (Pressure losses in irrigation valves - test method)

Keywords: ISO 9635-3:2014, check valves, irrigation valves, agricultural irrigation equipment, DN 15, endurance test, Kv, seat tightness, chemical resistance.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 9635-3
Second edition
2014-11-15
Agricultural irrigation equipment —
Irrigation valves —
Part 3:
Check valves
Matériel agricole d’irrigation — Vannes d’irrigation —
Partie 3: Clapets antiretour
Reference number
©
ISO 2014
© ISO 2014
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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the requester.
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Published in Switzerland
ii © ISO 2014 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Design requirements . 1
5 Performance requirements . 2
5.1 Mechanical strength . 2
5.2 Watertightness and airtightness. 3
5.3 Hydraulic characteristics . 4
5.4 Resistance to chemicals and fertilizers . 4
5.5 Endurance . 4
6 Conformity assessment . 4
6.1 General . 4
6.2 Type tests . 4
6.3 Control of production process and quality system . 4
7 Marking . 5
8 Packaging . 5
Annex A (normative) Test method for endurance of check valves . 6
Bibliography . 7
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 23, Tractors and machinery for agriculture and
forestry, Subcommittee SC 18, Irrigation and drainage equipment and systems.
This second edition cancels and replaces the first edition (ISO 9635-3:2006), which has been
technically revised.
ISO 9635 consists of the following parts, under the general title Agricultural irrigation equipment —
Irrigation valves:
— Part 1: General requirements
— Part 2: Isolating valves
— Part 3: Check valves
— Part 4: Air valves
— Part 5: Control valves
iv © ISO 2014 – All rights reserved

INTERNATIONAL STANDARD ISO 9635-3:2014(E)
Agricultural irrigation equipment — Irrigation valves —
Part 3:
Check valves
1 Scope
This part of ISO 9635 specifies construction and performance requirements and test methods for check
valves, intended for operation in irrigation systems with water at temperatures not exceeding 60 °C,
which can contain fertilizers and other chemicals of the types and concentrations used in agriculture.
It is applicable to hydraulically operated check irrigation valves of DN 15 diameter or greater, designed
to operate in the fully open and fully closed positions, but which can also operate for extended time
periods in any intermediate position.
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 9635-1:2014, Agricultural irrigation equipment — Irrigation valves — Part 1: General requirements
ISO 9644:2008, Agricultural irrigation equipment — Pressure losses in irrigation valves — Test method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
check valve
valve which is opened by the flow of water and closed by the weight of a check mechanism or by
mechanical pressure caused, for example, by a spring, permitting flow in one direction only and
preventing reversal of flow
3.2
flow coefficient
K
v
proportionality factor equal to the flow rate, in cubic metres per hour, of water at a temperature between
5 °C and 50 °C, passing through a fully open valve and causing a loss of static head of 1 bar
Note 1 to entry: QK= Δp , where Q is the flow rate in cubic metres per hour (m /h), and Δp is the pressure
v
2 2
across the valve in bar or kilopond/kilogram-force per square centimetre (kp/cm , kgf/cm ).
Note 2 to entry: 1 bar = 0,1 MPa = 105 Pa; 1 MPa = 1 N/mm .
Note 3 to entry: Adapted from EN 736–3.
4 Design requirements
Check valves shall be designed in accordance with ISO 9635-1:2014, Clause 4.
Check valves
...