ISO 15886-3:2021

Agricultural irrigation equipment - Sprinklers - Part 3: Characterization of distribution and test methods

This document specifies the conditions and methods used for testing and characterizing the water distribution patterns of irrigation sprinklers. The term sprinkler is used in this document in a broad generic sense and is meant to cover a wide variety of products. The specific performance measurements addressed include distribution uniformity, wetted radius, and water jet trajectory height. This document applies to all irrigation sprinkler classifications for which those three performance measurements are required to verify the design objectives as defined by the manufacturer. This document deals both with indoor and outdoor tests and with radial and full grid tests. It is organized so as to deal with conditions common to all tests first and then with conditions unique to indoor testing only and finally with conditions unique to outdoor testing only. For any given sprinkler, a wide range of nozzle configurations, operating conditions, and adjustments generate at least a theoretical need for a correspondingly large number of tests. Testing agencies and manufacturers can use interpolation techniques to reduce the number of actual test runs provided accuracy standards are still being met. This document does not address the specific performance testing required for sprinklers intended for use in frost protection. This document does not address the topic of drop spectrum measurement and characterization and the related questions of soil compaction, spray drift, evaporative losses, etc., all of which can be considerations in the design of sprinkler irrigation systems. This document is used for evaluating irrigation coverage of sprinklers that are identical and arranged in a fixed repeating geometric pattern. This document does not apply to moving systems. This document applies to part-circle sprinklers provided that the testing agency can satisfy questions of potential anomalies in performance parameters. NOTE Annex A addresses the procedures for the characterization of sprinkler pattern uniformity. Annex B addresses testing part-circle sprinklers.

Matériel agricole d'irrigation — Asperseurs — Partie 3: Caractérisation de la distribution et méthodes d'essai

General Information

• Status: Published
• Publication Date: 11-Mar-2021
• 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/WG 3 - Irrigation sprinklers
• Current Stage: 6060 - International Standard published
• Start Date: 12-Mar-2021
• Due Date: 18-Mar-2022
• Completion Date: 12-Mar-2021

Relations

• Revises: ISO 15886-3:2012/Amd 1:2016 - Agricultural irrigation equipment - Sprinklers - Part 3: Characterization of distribution and test methods - Amendment 1
• Effective Date: 23-Apr-2020
• Revises: ISO 15886-3:2012 - Agricultural irrigation equipment - Sprinklers - Part 3: Characterization of distribution and test methods
• Effective Date: 23-Apr-2020

Overview

ISO 15886-3:2021 - "Agricultural irrigation equipment - Sprinklers - Part 3: Characterization of distribution and test methods" specifies standardized test conditions and methods for characterizing the water distribution patterns of irrigation sprinklers. The standard addresses key performance metrics such as distribution uniformity, wetted radius (radius of throw) and water jet trajectory height, and covers both indoor and outdoor testing using radial and full-grid collector arrays. It applies to a broad range of sprinkler types (including pop-up and part‑circle sprinklers) used in fixed repeating geometric layouts, but does not cover moving systems, frost-protection testing, or drop-spectrum/evaporation/drift characterization.

Key topics and technical requirements

• Performance measurements: Methods to determine distribution uniformity (DU), Christiansen’s uniformity coefficient (UCC), effective radius of throw, and trajectory height.
• Collector design and arrangement: Specifications for collector receptacles, orientation, spacing and number for full-grid and radial array methods.
• Measurement accuracy: Required accuracy for flow, pressure and atmospheric condition measurements; recommendations for pressure taps and pop-up sprinkler measurement.
• Test operation: Procedures for sprinkler installation, rotation, riser height, test duration and rotation uniformity checks.
• Indoor vs outdoor testing: Conditions common to all tests, then provisions unique to indoor buildings and to outdoor sites (including atmospheric measurements and site specifications).
• Data handling: Interpolation techniques to reduce test runs while maintaining accuracy; guidance for generating distribution curves and validating results.
• Annexes: Annex A - procedures for characterizing pattern uniformity; Annex B - part-circle sprinkler testing guidance.

Practical applications and users

ISO 15886-3:2021 is directly useful for:

• Sprinkler manufacturers - product design validation, performance claims and quality control.
• Testing laboratories and certification bodies - standardized test methods for product certification and comparison.
• Irrigation system designers and consultants - selecting sprinklers based on verified coverage, wetted radius and uniformity.
• Procurement and specification writers - defining measurable performance requirements in tender documents.
• Researchers and agronomists - reproducible experimental methods for sprinkler distribution studies.

Using ISO 15886-3 helps ensure consistent, reproducible sprinkler performance metrics (distribution uniformity, wetted radius, trajectory) and supports reliable decision‑making in irrigation design, product development and quality assurance.

Related standards

• Part of the ISO 15886 series (other parts address additional sprinkler topics).
• Users should consult their national standards bodies or the ISO Catalogue for complementary parts and implementation guidance.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 15886-3
Third edition
2021-03
Agricultural irrigation equipment —
Sprinklers —
Part 3:
Characterization of distribution and
test methods
Matériel agricole d'irrigation — Asperseurs —
Partie 3: Caractérisation de la distribution et méthodes d'essai
Reference number
©
ISO 2021
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Collectors . 4
4.1 Collector design . 4
4.2 Collector orientation . 4
5 Installation of sprinklers under test. 5
6 Measurements . 6
6.1 Accuracy of measurements . 6
6.2 Pressure measurement . 6
6.3 Atmospheric conditions measurements . 8
6.4 Corrections for evaporative losses within collectors . 8
7 Collector arrangement, spacing and number . 8
7.1 Full grid collector array method . 8
7.1.1 Method . 8
7.1.2 Collector spacing . 8
7.1.3 Sprinkler location relative to grid . 8
7.2 Radial collector array method . 9
7.2.1 Method . 9
7.2.2 Collector spacing . 9
7.2.3 Location of sprinkler . 9
7.2.4 Radius of throw . 9
8 Additional tests . 9
8.1 Time of rotation . 9
8.2 Trajectory height . 9
9 Test operation . 9
9.1 Rotation of sprinkler riser . 9
9.2 Test duration .10
9.3 Other test details .10
10 Test location specifications .10
10.1 Indoor testing building specifications .10
10.2 Outdoor site specification.11
10.2.1 General.11
10.2.2 Measurement of atmospheric conditions .11
11 Characterization of distribution .11
11.1 Overview .11
11.2 Application pattern coverage and uniformity .11
11.3 Generating performance measurements from radial arrays .12
11.4 Validation of test results .12
12 Radius of throw and water distribution curve .12
12.1 General .12
12.2 Radius of throw .13
12.3 Distribution curve .13
12.4 Uniformity of rotation (for rotating sprinklers intended to rotate in a uniform manner) .14
Annex A (informative) Procedures for the characterization of sprinkler pattern uniformity .15
Annex B (informative) Testing of part-circle sprinklers .19
Bibliography .21
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 of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 23, Tractors and machinery for agriculture
and forestry, Subcommittee SC 18, Irrigation and drainage equipment and systems.
This third edition cancels and replaces the second edition (ISO 15886-3:2012), which has been
technically revised. It also incorporates the Amendment ISO 15886-3:2012/Amd 1:2016.
The main changes compared to the previous edition are as follows:
— the definitions have been updated;
— the following test methods have been changed:
— for the installation of sprinkles under test, the height of the top of the sprinkler riser has been
modified;
— for the pressure measurement, the test method for pop-up sprinklers has been modified;
— the radius of throw and water distribution curve tests have been added.
A list of all parts in the ISO 15886 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved

INTERNATIONAL STANDARD ISO 15886-3:2021(E)
Agricultural irrigation equipment — Sprinklers —
Part 3:
Characterization of distribution and test methods
1 Scope
This document specifies the conditions and methods used for testing and characterizing the water
distribution patterns of irrigation sprinklers.
The term sprinkler is used in this document in a broad generic sense and is meant to cover a wide variety
of products. The specific performance measurements addressed include distribution uniformity, wetted
radius, and water jet trajectory height. This document applies to all irrigation sprinkler classifications
for which those three performance measurements are required to verify the design objectives as
defined by the manufacturer.
This document deals both with indoor and outdoor tests and with radial and full grid tests. It is
organized so as to deal with conditions common to all tests first and then with conditions unique to
indoor testing only and finally with conditions unique to outdoor testing only.
For any given sprinkler, a wide range of nozzle configurations, operating conditions, and adjustments
generate at least a theoretical need for a correspondingly large number of tests. Testing agencies and
manufacturers can use interpolation techniques to reduce the number of actual test runs provided
accuracy standards are still being met.
This document does not address the specific performance testing required for sprinklers intended for
use in frost protection.
This document does not address the topic of drop spectrum measurement and characterization
and the related questions of soil compaction, spray drift, evaporative losses, etc., all of which can be
considerations in the design of sprinkler irrigation systems.
This document is used for evaluating irrigation coverage of sprinklers that are identical and arranged
in a fixed repeating geometric pattern. This document does not apply to moving systems.
This document applies to part-circle sprinklers provided that the testing agency can satisfy questions
of potential anomalies in performance parameters.
NOTE Annex A addresses the procedures for the characterization of sprinkler pattern uniformity. Annex B
addresses testing part-circle sprinklers.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
ambient temperature
temperature of the air surrounding a sprinkler
3.2
area of coverage
area within the wetted boundary from the sprinkler operated within the range of effective application
rates (3.9) specified in the manufacturer’s literature
3.3
Christiansen's uniformity coefficient
UCC
coefficient using deviations from the mean to characterize the uniformity of field-measured or
simulated water application from a grid of sprinklers
3.4
clean water
water processed, if necessary, so as to contain suspended particles no larger than 74 μm (200-mesh
equivalent) and to contain no dissolved chemicals known to have short-term effects on sprinklers
materials
3.5
collector
receptacle into which water is deposited during a water distribution test
3.6
critical dry area
experience-based definition of the dry area size that defines uniformity of coverage objectives
3.7
densogram
areal map utilizing the density of dots representing water application depth at locations in the area of
coverage (3.2) of a sprinkler or a grid of sprinklers
3.8
distribution uniformity
DU
coefficient using the lowest 25 % of water application depths to characterize the uniformity of field-
measured or simulated water application from a grid of sprinklers
3.9
effective application rate
application rate equal to or exceeding 0,26 mm/h for sprinklers with flow rates (3.11) exceeding 120 l/h
and 0,13 mm/h for sprinklers with flow rates equal to or less than 120 l/h
3.10
effective radius of throw
radius at which 95 % of the reconstituted volume of water discharged by a sprinkler, interpolated
between points of measurement, is applied
3.11
flow rate
volume of water flowing through a device per unit time
3.12
full grid collector array
collectors (3.5) located at the intersections of a two-dimensional geometric grid pattern sufficient in
number to give a desired statistical basis for determining water distribution uniformity (3.8)
2 © ISO 2021 – All rights reserved

3.13
inlet connection size
numerical designation used to characterize the sprinkler which is identical to the size of the connection
to the irrigation pipe
3.14
irrigation lateral
branch supply line in an irrigation system on which distribution devices are mounted directly or by
means of fittings, risers, or tubes
3.15
nozzle
aperture of a sprinkler through which water is discharged
3.16
part-circle sprinkler
sprinkler with an adjustable feature that enables it to irrigate a sector of a circular area either with or
without an attachment which enables it to be adjusted to irrigate another sector or the entire circular area
3.17
pop-up sprinkler
sprinkler designed for installation so that the sprinkler nozzle automatically raises from below ground
when the system is pressurized and automatically lowers to its original position when the system is
depressurized
3.18
pressure tap
precisely fabricated connection for communicating internal conduit pressure to an external pressure-
measuring device
3.19
radial collector arrays method
collectors (3.5)located only on a radial axis projected from the centreline of a sprinkler sufficient in
number to characterize the water distribution curve
3.20
radius of throw
wetted radius
distance measured from a centreline of a continuously operating sprinkler to the most remote point at
which the sprinkler deposits water at the minimum effective application rate (3.9), measured at any arc
of coverage except near the arc extremes for part-circle sprinklers
3.21
range of working pressure
pressures between the minimum working pressure and the maximum working pressure
3.22
rotating sprinkler
distribution device which, as a result of rotating motion around its axis, distributes water over a
circular area, part of a circular area, or a non-circular area
3.23
scheduling coefficient
SC
coefficient used to characterize the water application uniformity of sprinklers employing an analysis of
full-grid test data based on a definition of critical dry area (3.6)
3.24
sprinkler spacing
conventional designation including the distance between the sprinklers along an irrigation lateral
(3.14) and the distance between consecutive irrigation laterals
3.25
statistical uniformity coefficient
UCS
coefficient using standard deviation as a measure of dispersion in statistical theory to characterize the
uniformity of field-measured water application from a full grid of sprinklers
3.26
test pressure
pressure at the inlet of a sprinkler declared by the manufacturer as the pressure to be used for test
purposes
3.27
maximum trajectory height
maximum height above a sprinkler of the trajectory of the water stream discharged from the sprinkler
nozzle operating under the nominal test pressure (3.27)
3.28
water application rate
mean depth of water applied per unit time
3.29
distribution curve
graphical plot of water application depth as a function of distance from a sprinkler along a specified radius
3.30
wind speed
speed of the wind at a test site averaged over the time required for a sprinkler distribution uniformity
(3.8) test
3.31
working pressure
water pressure recommended by the manufacturer to ensure proper operation of a sprinkler
4 Collectors
4.1 Collector design
All collectors used for any one test shall be identical. They shall be designed to minimize water splashes
in or out and distortions of the catchment volume as may be caused by wind currents.
The height of a collector shall be at least twice the maximum depth of the water collected during the
test, but not less than 150 mm.
The collectors shall have a circular opening with sharp edges free from deformities. The diameter shall
be between 1/2 to 1 times the height, but not less than 85 mm.
Alternative collector designs may be used, provided that their measuring accuracy is not less than of
those described above.
The catchment from a collector shall be quantified from a direct reading of mass, depth, or a volumetric
determination provided that the required accuracy standard is met.
4.2 Collector orientation
The openings of all collectors shall be in a common horizontal plane with a slope not exceeding 2 % in
any direction. The difference in height between any two adjacent collectors shall not exceed 20 mm.
For indoor testing, collector height is not critical. For outdoor testing, the collector height shall be
sufficient to ensure that vegetation does not interfere with jet access to the collectors.
4 © ISO 2021 – All rights reserved

5 Installation of sprinklers under test
The sprinkler selected for testing shall be representative of general production capabilities particularly
as relates to the speed of rotation. New sprinklers shall be operated before the test for a period sufficient
to demonstrate that the time per revolution has stabilized to ±5 %.
Mount the sprinkler on a riser with the same nominal size designation as the sprinkler inlet connection
size. Ensure that the riser is fixed rigidly vertically, and that it does not vibrate sufficiently to cause a
visual effect on the sprinkler operation, bend or deviate from the vertical during the test. The maximum
allowable deviation from the vertical during the test shall not exceed 2°.
A steel pipe riser is recommended to provide the required mechanical strength and facilitate the
installation of a standard pressure tap.
The sprinkler nozzle height above the collectors should simulate the conditions under which the
sprinkler is normally used. For example, with the turf sprinklers the top of the sprinkler body should
coincide with the top of the collectors.
For agricultural sprinklers used under a variety of field conditions, the following height requirement
applies:
— The height of the top of the sprinkler riser above the openings of the collectors shall be according to
the manufacturer's specifications.
— If the manufacturer does not provide specification, the relevant data shall be selected from Table 1,
with a tolerance of ±0,05 m.
Table 1 — Sprinkler height
Sprinkler flow rate Top of the sprinkler riser height above the
collector
(l/h)
(m)
Pop-up 0
(in a non-pressurized state)
0 to 300 0,3
301 to 1 500 0,5
1501 to 2 500 1,0
>2 500 1,5
If the manufacturer specifies any special test-related conditions, for example, testing with straightening
vanes, they shall be used if such items are provided as standard equipment with the sprinkler.
For a sprinkler that is not riser-mounted as described in above, the test mounting shall be as specified
by the manufacturer.
For single leg distribution patterns, a shelter may be used around the sprinkler to contain jet action
provided the following conditions are met:
— The shelter is large enough and so constructed as to trap the water jets and not let them interfere
with the sprinkler’s operation or contribute to the collector catchment.
— The shelter is designed to allow air circulation to develop around the jets.
— The shelter provides a minimum sector for unrestricted jet operation of 45° centred on the collector
radius. If the testing agency uses an angle less than 45°, it shall demonstrate that the integrity of
the results is not compromised. Special attention shall be put to sector size, to avoid interception of
projections (spoon spit) generated by the impact arm.
— The shelter is designed so that no jet deflection or splash is directed into the collectors.
6 Measurements
6.1 Accuracy of measurements
The accuracy required for all measurements not specifically addressed in this document is ±3 %.
Water depths within collectors shall be measured with an accuracy of ±3 %.
Pressure shall be measured with an accuracy of ±1 %.
Flow rate through the sprinkler shall be measured with an accuracy of ±2 %.
Time shall be measured with stop watches accurate to ±0,1 s.
Temperature shall be measured with an accuracy of ±0,5 °C.
6.2 Pressure measurement
The test pressure shall be measured at the height of the main nozzle. The pressure tap construction
details are shown in Figure 1. There shall be no flow obstructions between the pressure tap and the
sprinkler base. The bore of the pipe containing the pressure tap shall be clean and smooth. The pressure
tap shall be located at the medium point of the riser pipe.
For pop-up sprinklers the pressure shall be measured in the main pipe at a distance of 3D (main pipe)
to the sprinkler base.
6 © ISO 2021 – All rights reserved

a) Thick wall
b) Thin wall
Key
1 pressure gauge
2 pressure tap
D riser pipe nominal diameter/ main pipe nominal diameter for pop-up sprinklers
L riser pipe length
Figure 1 — Pressure tap location and construction details
Figure 1 a), l ≥ 2,5d, where d = 3 mm to 6 mm or 1/10 pipe diameter, whichever value is smaller.
Figure 1 b), l ≥ 2d; r ≤ d/10.
6.3 Atmospheric conditions measurements
Relative humidity and ambient temperature shall be measured at the start, midpoint, and end of the
test. For indoor testing, changes in temperature and humidity during the test shall not exceed ±5,0 % of
the pre-test ambient conditions.
Air conditioning systems may be required to ensure that the testing facilities meet this requirement.
6.4 Corrections for evaporative losses within collectors
Under some conditions, evaporative losses within collectors are known to result in measurement
errors that exceed the required accuracy of ±3,0 %. Under these conditions, a c
...