ISO 9912-4:2018

Agricultural irrigation equipment — Filters for microirrigation — Part 4: Granulated media filters

This document specifies construction requirements and test methods for pressurized granulated media filters, hereinafter referred to as media filters, intended for operation in agricultural irrigation systems. It is applicable to both manual cleaning media filters and automatic self-cleaning media filters, used as single unit or in batteries (two or more units working in parallel). This document covers the operation and performance of a media filter, together with all related valves, back flushing mechanism, underdrains, manifolds and other related accessories necessary for the operation of the filter. This document is applicable to three configurations of a filter. a) An empty filter vessel (tank) housing. b) A filter vessel filled with media filter material(s), complete with valves, connections, air release and/or other accessories. This configuration, when connected to and controlled by a flushing control device, is a complete operating single filter unit, usually positioned as a part of a filtration station. c) A filtration station, called "filter battery". Annex A provides information on types of irrigation media filters. Annex B provides information on granulated media.

Matériel agricole d'irrigation — Filtres pour micro-irrigation — Partie 4: Titre manque

General Information

• Status: Published
• Publication Date: 08-Aug-2018
• 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 10 - Filters
• Current Stage: 9020 - International Standard under periodical review
• Start Date: 15-Jul-2023
• Completion Date: 15-Jul-2023

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 9912-4
First edition
2018-08
Agricultural irrigation equipment —
Filters for microirrigation —
Part 4:
Granulated media filters
Matériel agricole d'irrigation — Filtres pour micro-irrigation —
Reference number
ISO 9912-4:2018(E)
©
ISO 2018

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ISO 9912-4:2018(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2018
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
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Published in Switzerland
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ISO 9912-4:2018(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Design and construction requirements . 2
4.1 General . 2
4.2 Inlet and expansion space chamber . 5
4.3 Media chamber . 5
4.4 Collection (underdrain) and back flushing unit . 5
4.5 Prefiltration element. 5
4.6 Back flushing control . 6
4.6.1 Mandatory requirements . 6
4.6.2 Optional features . 6
5 Resistance of the filter to internal hydrostatic pressure . 6
5.1 General . 6
5.2 Preparation . 7
5.3 Static pressure test . 7
5.4 Cyclic pressure test . 7
5.5 Collection (underdrain) and back flushing unit resistance to buckling or tearing . 8
6 Clean pressure drop test . 9
6.1 General . 9
6.2 Flow rates and test sequence . 9
6.3 Filter media . 9
6.4 Prescreening . 9
6.5 Inlet and outlet pressures. 9
6.6 Test duration . 9
6.7 Report .10
7 Back flushing tests .10
7.1 Back flushing parameters .10
7.2 Media escape test .10
8 Automatic back flushing and controller .11
8.1 Back flushing initiation .11
8.2 Flushing control mechanism test .11
8.2.1 Mechanism activated by pressure drop .11
8.2.2 Mechanism activated by duration of operation .11
8.2.3 Mechanism activated by volume of filtered water .11
8.2.4 Mechanism activated by another physical quantity .12
8.3 Operation of the protective device .12
9 Information to be supplied by the manufacturer .12
9.1 General .12
9.2 Filter data .13
9.3 Back flushing controller .13
Annex A (informative) Types of irrigation media filters .14
Annex B (informative) Granulated media .15
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ISO 9912-4:2018(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.
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 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 the following
URL: 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.
A list of all parts in the ISO 9912 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.
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INTERNATIONAL STANDARD ISO 9912-4:2018(E)
Agricultural irrigation equipment — Filters for
microirrigation —
Part 4:
Granulated media filters
1 Scope
This document specifies construction requirements and test methods for pressurized granulated
media filters, hereinafter referred to as media filters, intended for operation in agricultural irrigation
systems.
It is applicable to both manual cleaning media filters and automatic self-cleaning media filters, used as
single unit or in batteries (two or more units working in parallel).
This document covers the operation and performance of a media filter, together with all related valves,
back flushing mechanism, underdrains, manifolds and other related accessories necessary for the
operation of the filter.
This document is applicable to three configurations of a filter.
a) An empty filter vessel (tank) housing.
b) A filter vessel filled with media filter material(s), complete with valves, connections, air release
and/or other accessories. This configuration, when connected to and controlled by a flushing
control device, is a complete operating single filter unit, usually positioned as a part of a filtration
station.
c) A filtration station, called “filter battery”.
Annex A provides information on types of irrigation media filters.
Annex B provides information on granulated media.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 9644, Agricultural irrigation equipment — Pressure losses in irrigation valves — Test method
ISO 9912-1, Agricultural irrigation equipment — Filters for micro-irrigation — Part 1: Terms, definitions
and classification
ISO 9912-2:2013, Agricultural irrigation equipment — Filters for microirrigation — Part 2: Strainer-type
filters and disc filters
ISO 9912-3, Agricultural irrigation equipment — Filters for microirrigation — Part 3: Automatic flushing
strainer-type filters and disc filters
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ISO 9912-4:2018(E)

3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 9912-1, ISO 9912-3 and the
following 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
granulated media filter
media filter
permeable granulated media, such as sand, gravel, crushed granite or synthetic material, with a specific
gravity higher than water and used for filtration, provided the granules can be fluidized during back
flushing
3.2
clogged filter element
filter element that has collected a quantity of residue such that it cannot maintain the highest flow rate
recommended by the manufacturer without exceeding the safe maximum pressure drop (3.6)
3.3
flush valve
valve through which back flushing water is discharged from the filter
3.4
nominal pressure
p
nom
numerical designation equal to the maximum working pressure specified by the manufacturer at which
a device will operate at a water temperature of 23 °C ± 3 °C
3.5
clean pressure drop
pressure drop in a clean filter measured with a flow of clean water
3.6
safe maximum pressure drop
maximum allowable difference between inlet and outlet pressures across a filter, when the filter
element has become clogged to the extent of requiring cleaning or replacement, as specified by the filter
manufacturer
3.7
range of recommended flow rates
q to q
min max
range of flow rates declared by the manufacturer for proper operation of a filter
3.8
nominal size
conventional numerical designation, the same as the nominal diameter of the pipes to which the ‎filter
can be connected directly, indicating the size of the filter connections
4 Design and construction requirements
4.1 General
A complete media filter system includes the following connections:
a) an inlet: the point of entry for unfiltered supply water;
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ISO 9912-4:2018(E)

b) an outlet: the point of exit for filtered water going to the irrigation network;
c) a back flush outlet: the point of exit for water and residue that are flushed out during the back
flushing stage;
d) a command power source: for the activation of an automatic back flushing operation, normally
hydraulically-operated by filtered water (can also be pneumatically-operated or electrically-
operated).
Components belonging to filters of the same nominal size, type and model, and produced by the same
manufacturer, shall be interchangeable.
Filter parts that are in contact with water shall be made of non-toxic materials, and shall be resistant
to, or protected against, degradation caused by existing working conditions and types of water used in
agricultural irrigation. The filter housing shall be resistant to environmental conditions in the intended
application.
Plastics parts of a filter that are exposed to ultraviolet radiation under normal working conditions in
which the filter operates in the intended application shall include additives to improve their resistance
to UV radiation. Plastics parts that enclose waterways shall be opaque or shall be provided with an
opaque cover that blocks all light from reaching clear waterway enclosures.
The construction of the filter shall facilitate its proper installation in its intended location and position.
The construction of the filter body shall permit dismantling for maintenance, according to
manufacturer’s instructions.
In most cases, a filtered flush stream is supplied by other filter units of the battery that are in the
filtering stage. In case other options are used to supply flush water, the supplier shall guarantee that it
is in accordance with this document.
The back flushing flow rate shall be high enough to vigorously fluidize and agitate the entire media, yet
low enough so that only residue is washed from the tank and not the filter media itself.
Typical media filter constructions are shown in Figure 1. Two operational modes of a media filter are
shown in Figure 2.
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ISO 9912-4:2018(E)

Key
1 inlet
2 outlet
3 service port
4 backflush valve
Figure 1 — Typical media filter construction
a) Filtering mode b) Flushing mode
Key
1 opened
2 closed
Figure 2 — Two operational modes of a media filter
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ISO 9912-4:2018(E)

4.2 Inlet and expansion space chamber
The inlet and expansion space chamber shall be able to accommodate expansion of the media during
back flushing. The expansion volume shall be at least one third of the media volume.
The chamber shall have a cover to enable media filling and visual inspection. Filter covers operating
under pressure shall be supplied with a safety mechanism to protect the operator in case of a
catastrophic failure. The filter vessel shall provide for the relief of internal pressure before opening
any internal access ports. All access ports shall be secured to the filter vessel with suitable fasteners to
prevent harm when attempting to loosen or remove covers or lids.
A hydraulic inlet distributor that evenly distributes incoming flow across media surface is recommended.
4.3 Media chamber
The media chamber is the main part of the filter.
Total volume, surface area and the depth of the filtering layer shall be clearly indicated on the filter
body. If a rough media support layer is used, its dimensions shall be deducted from the active media
parameters.
If the filter tank shape is not a cylinder, the surface area as a function of media level shall be indicated in
the manufacturer’s documentation.
Both ends of the filter media chamber shall have large, accessible service ports: at the top for checking
and for media filling, and at the bottom for media replacement and underdrain service.
Parameters pertaining to specific granular media shall be supplied by the manufacturer.
4.4 Collection (underdrain) and back flushing unit
This component collects the filtered water, while not allowing media leakage. In the back flushing stage,
it distributes reverse water flow used for back flushing.
There are several possible configurations for this unit:
a) a diffuser system assembled on a collection piping (“spider web”);
b) a diffuser system mounted on top of a plate, which separates the filtering chamber from the
collection chamber (“underdrain plate”);
c) other variations of patterns.
Diffuser placement shall ensure even distribution of back flushing water over the whole granular media
surface area.
The filter’s underdrain shall be designed to retain the media sand and resist clogging by fine
particle matter.
The size of the underdrain slot shall be no more than half the size of the smallest media grain.
4.5 Prefiltration element
a) The design of a prefiltration element, its filtering area, the size of water passages and their shape
should be appropriate for the water quality for which the filter is intended.
NOTE 1 The prefiltration element is an optional component.
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ISO 9912-4:2018(E)

b) When a prefiltration element exists, the maximum pressure drop across it shall be less than the
safe maximum pressure drop of the prefiltration element.
In case of no prefiltration pressure drop indication, the total pressure drop across it and the filter
assembly shall be less than the safe maximum pressure drop.
c) The prefiltration element shall be an integral part of the filter while being tested. (This element is
not intended to be tested separately.)
NOTE 2 The prefiltration element is not automatically flushed.
4.6 Back flushing control
4.6.1 Mandatory requirements
The construction of an automatic self-cleaning filter shall conform to the following requirements.
a) The flushing control system shall either be part of the filter assembly, supplied by the manufacturer
together
...