ISO 9635-4:2014

Agricultural irrigation equipment - Irrigation valves - Part 4: Air valves

ISO 9635-4:2014 specifies construction and performance requirements and test methods for air 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 air irrigation valves of DN 15 diameter or greater, designed to be directly operated, i.e. the force is applied to the obturator by the float, either directly or via a mechanical linkage. The valves can be operated by a force applied through an adjustable pilot valve.

Matériel agricole d'irrigation — Vannes d'irrigation — Partie 4: Vannes de purge d'air

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: 9020 - International Standard under periodical review
• Start Date: 15-Oct-2025
• Completion Date: 15-Oct-2025

Relations

• Revises: ISO 9635-4:2006 - Agricultural irrigation equipment - Irrigation valves - Part 4: Air valves
• Effective Date: 24-Dec-2011

Overview

ISO 9635-4:2014 - Agricultural irrigation equipment - Irrigation valves - Part 4: Air valves specifies construction, performance requirements and test methods for air valves used in agricultural irrigation systems. It applies to hydraulically operated, float-type air irrigation valves of DN 15 or greater, designed for water temperatures up to 60 °C and for use with fertilizers and typical agricultural chemicals. Valves covered include those with air release, air intake (vacuum relief) and air venting functions, operated directly by floats or via mechanical linkages or adjustable pilot valves.

Key topics and technical requirements

• Scope and applicability
  • Float-operated (single- or double-float) air valves for irrigation pipelines.
  • Suitable for water containing agricultural fertilizers and chemicals at normal concentrations.
• Design requirements
  • Design to the general provisions of ISO 9635‑1; optional integrated isolating devices to ISO 9635‑2.
• Performance and testing
  • Mechanical strength and pressure resistance per ISO 9635‑1 methods.
  • Watertightness / seat tightness: tested with water; leakage class rate A; type tests minimum duration specified.
  • Airflow characteristics: manufacturer curves (airflow vs inlet pressure) must be validated; type tests in Annex A (air release) and Annex B (air intake); catalogue values must agree within ±10% at representative points.
  • Air venting (continuous): verify small-orifice area and sonic-flow capability using the AWWA M51 approach; measured results within ±10% of catalogue data.
  • Chemical resistance: tested for resistance to fertilizers/chemicals as per ISO 9635‑1.
  • Endurance:
    • Air intake/release: 250 cycles (filling/draining) per Annex C.
    • Air venting: 2 500 cycles of venting.
    • Long-term unseating test: accelerated test at 50 °C and 1.2× allowable operating pressure for five days, followed by verification of normal operation and watertightness.
• Conformity assessment
  • Type tests, production control and quality-system requirements following ISO 9635‑2 clauses.
• Marking & packaging
  • In accordance with ISO 9635‑1.

Practical applications and users

ISO 9635‑4:2014 is essential for:

• Irrigation equipment manufacturers specifying design, materials and test procedures for air valves.
• Test laboratories and certification bodies performing conformity and type testing.
• Irrigation system designers, specifiers and procurement teams who need validated performance data (air release/intake/venting) and compliance criteria.
• Quality and maintenance engineers ensuring long-term reliability in agricultural systems handling fertilized water.

Keywords: ISO 9635-4:2014, air valves, irrigation valves standard, agricultural irrigation equipment, air release, air intake, air venting, DN 15, test methods, endurance testing.

Related standards

• ISO 9635‑1:2014 - General requirements for irrigation valves
• ISO 9635‑2:2014 - Isolating valves
• ISO 9635‑3 / ISO 9635‑5 - Other parts in the ISO 9635 series (check ISO catalogue for full list)

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 9635-4
Second edition
2014-11-15
Agricultural irrigation equipment —
Irrigation valves —
Part 4:
Air valves
Matériel agricole d’irrigation — Vannes d’irrigation —
Partie 4: Vannes de purge d’air
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
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
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Tel. + 41 22 749 01 11
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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 . 2
5 Performance requirements . 2
5.1 General . 2
5.2 Mechanical strength . 2
5.3 Watertightness . 2
5.4 Airflow characteristics . 3
5.5 Resistance to chemicals and fertilizers . 4
5.6 Endurance . 4
6 Conformity assessment . 5
6.1 General . 5
6.2 Type tests . 5
6.3 Control of production process and quality system . 5
7 Marking . 6
8 Packaging . 6
Annex A (normative) Test method for airflow characteristics of valves with air release function .7
Annex B (normative) Test method for airflow characteristics of valves with air intake function .9
Annex C (normative) Test method for endurance of valves with air intake and/or air
release functions .12
Bibliography .14
Foreword
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bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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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).
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Any trade name used in this document is information given for the convenience of users and does not
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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 9635-4:2006) 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 9635-4:2014(E)
Agricultural irrigation equipment — Irrigation valves —
Part 4:
Air valves
1 Scope
This part of ISO 9635 specifies construction and performance requirements and test methods for air
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 air irrigation valves of DN 15 diameter or greater, designed
to be directly operated, i.e. the force is applied to the obturator by the float, either directly or via a
mechanical linkage. The valves can be operated by a force applied through an adjustable pilot 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 any amendments) applies.
ISO 9635-1:2014, Agricultural irrigation equipment — Irrigation valves — Part 1: General requirements
ISO 9635-2:2014, Agricultural irrigation equipment — Irrigation valves — Part 2: Isolating valves
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 9635-1:2014 and the following
apply.
3.1
air valve
float-type purger
self-operating float-type valve for the evacuation of air from, or the ingress of air into water pipelines
Note 1 to entry: Such valves can be single-float or double-float and can fulfill one or more or the following
functions: air release, air intake.
3.2
air release function
discharge of air from a water pipeline or appliance
3.3
air intake function
vacuum relief function
admittance of air to a water pipeline or appliance
3.4
air venting function
continuous acting air vent function
purging of entrapped air from a water pipeline in service under pressure
4 Design requirements
Air valves shall be designed in accordance with ISO 9635-1:2014, Clause 4. In addition, these valves may
be fitted with an integrated isolating device which shall be in accordance with ISO 9635-2:2014.
5 Performance requirements
5.1 General
Perform all tests on the valve as delivered to the test facility.
5.2 Mechanical strength
5.2.1 Resistance of shell and all pressure-containing components to internal pressure
Carry out testing in accordance with ISO 9635-1:2014, 5.2.1. For double-float valves, the obturators may
be tested simultaneously or separately.
Test results shall comply with the requirements of ISO 9635-1:2014, 5.2.1.
5.2.2 Resistance of obturator to differential pressure
Tested within 5.2.1.
5.2.3 Resistance of valves to bending
Not applicable. However, testing of bending resistance may be an optional requirement for air valves, if
bending resistance is specified by the customer.
5.2.4 Resistance of valves to operating loads
Not applicable, except for any integrated isolating device, which shall be in accordance with
ISO 9635-2:2014, 5.2.4.
5.3 Watertightness
5.3.1 Watertightness of shell and all pressure-containing components
5.3.1.1 Internal pressure
The requirement of watertightness to internal pressure is fulfilled by compliance with 5.2.1.
5.3.1.2 External pressure
Not applicable, except for any integrated isolating device, which shall be in accordance with
ISO 9635-2:2014, 5.3.1.2.
5.3.2 Seat tightness
5.3.2.1 Seat tightness at high pressure
Carry out testing in accordance with ISO 9635-1:2014, 5.3.2.1, using water as the test fluid. The leakage
rate shall be rate A. For a type test, continue the test for at least 10 min. For double-float valves, the
obturators may be tested simultaneously or separately.
Test results shall comply with the requirements of ISO 9635-1:2014, 5.3.2.1.
2 © ISO 2014 – All rights reserved

5.3.2.2 Seat tightness at low pressure
Carry out testing in accordance with ISO 9635-1:2014, 5.3.2.2, using water as the test fluid. The leakage
rate shall be rate A. For a type test, continue the test for at least 10 min. For double-float valves, the
obturators may be tested simultaneously or separately.
Test results shall comply with the requirements of ISO 9635-1:2014, 5.3.2.2.
5.3.3 Maximum operating torque (MOT) for operation and tightness
Not applicable, except for air valves with an integrated isolating device which shall be in accordance
with ISO 9635-2:2014, 5.3.3.
5.4 Airflow characteristics
Test results shall comply with the requirements of ISO 9635-1:2014, 5.4.
The characteristics given by the manufacturer in the form of a graph or table shall be the airflow as a
function of inlet pressure. When this is measured according to the conditions defined hereafter in the
relevant subclauses of this part of ISO 9635, the flow shall be not less than 90 % of the value indicated by
the manufacturer at a minimum of three points on the curve, these points being indicative of the range
and functions of the valve.
Show the performance data at standard conditions of temperature and barometric pressure.
5.4.1 Air release function
Conduct the type test as set ou
...