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STANDARD
9912-2
First edition
19929 12-l 5
Agricultural irrigation equipment - Filters -
Part 2:
Strainer-type filters
Ma t&iel agricole d’irrigation - Filtres -
Partie 2: Filtres i tamis
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Reference number
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IS0 9912=2:1992(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
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, govern-
mental and non-governmental, in liaison with ISO, also take part in the
work. IS0 collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnicai standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an Inter-
national Standard requires approval by at least 75 % of the member
bodies casting a vote.
International Standard IS0 9912-2 was prepared by Technical Committee
ISO/TC 23, Tractors and machinery for agriculture and forestry, Sub-
Committee SC 18, irrigation and drainage equipment and systems.
IS0 9912 consists of the following parts, under the general title Agricul-
tural irrigation equipment - Filters:
- Part I: Classification
- Part 2: Strainer-type filters
- Part 3-- Automatic self-cleaning strainer-type filters
0 IS0 1992
All rights reserved. No part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without
permission in writing from the publisher.
for Standardiz ation
international Organization
Case Postale 56 l CH-121 1 Gen&e 20 l Switzerland
Printed in Switzerland
ii
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INTERNATIONAL STANDARD IS0 9912=2:1992(E)
Agricultural irrigation equipment - Filters -
Part 2:
Strainer--type filters
IS0 70051:1992, Metallic flanges - Part I: Steel
1 Scope
flanges.
This part of IS0 9912 specifies the general con-
IS0 7005-2:1988, Metallic flanges - Part 2: Cast iron
struction requirements and test methods for
flanges.
strainer-type filters (hereinafter called strainers) in-
tended for operation in agricultural irrigation sys-
tems.
3 Definitions
It does not cover filtration ability, efficiency and ca-
pacity (quality of filtered water, time of operation
For the purposes of this part of IS0 9912, the follow-
before strainer becomes entirely clogged, etc.), nor
ing definitions apply.
does it deal with strainer-type filters that have inte-
grated automatic self-cleaning devices (which are
3.1 strainer-type filter; strainer: Appliance contain-
covered in IS0 9912-3).
ing one or more filtering elements, used for separ-
ating suspended solids from the water flowing
NOTE 1 Requirements and methods for testing filtration
ability are under study, and will be added later. through the appliance by collecting them on the face
of the filter element.
3.2 filter element: Strainer internal component,
consisting of a perforated plate, screen, mesh, discs,
2 Normative references
or a combination of these, intended to retain solid
contaminants.
The following standards contain provisions which,
through reference in this text, constitute provisions
3.3 clogged filter element: Filter element which has
of this part of IS0 9912. At the time of publication,
collected a quantity of solid contaminants such that
the editions indicated were valid. All standards are
it cannot maintain the highest flow-rate rec-
subject to revision, and parties to agreements based
ommended by the manufacturer without exceeding
on this part of IS0 9912 are encouraged to investi-
the safe maximum pressure drop.
gate the possibility of applying the most recent edi-
tions of the standards indicated below. Members of
3.4 strainer housing: That part of the strainer that
IEC and IS0 maintain registers of currently valid
contains all the strainer components, except for the
International Standards.
control equipment.
IS0 7-1: 1982, Pipe threads where pressure-tight
3.5 strainer housing cover: Removable cover per-
joints are made on the threads - Part 1: Desig-
mitting assembly, disassembly and cleaning of the
nation, dimensions and tolerances.
strainer elements.
IS0 2859-1:1989, Sampling procedures for inspection
3.6 drain valve; flush valve: Valve normally in-
by attributes - Part I: Sampling plans indexed by
stalled at the bottom of the strainer and intended for
acceptable quality level (AQL) for lo t-by-lot in-
draining or flushing the strainer housing.
spection.
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IS0 9912-2:1992(E)
3.7 nominal pressure: Maximum static water e) arrow indicating the direction of water flow;
pressure immediately upstream of the strainer inlet
at which the strainer is required to operate. f) (optional marking) aperture size (if the strainer
is supplied with the filter element already as-
sembled). The aperture size may be marked on
3.8 clean pressure drop; Pressure drop in a clean
an adhesive label affixed to the strainer housing
strainer measured with a flow of clean water under
in a prominent position.
normal conditions.
3.9 safe maximum pressure drop: Maximum ailow- 4.2 Filter element
able difference between inlet and outlet pressures
across the strainer when the filter element has be- of manufacturer and/or registered trade-
name
4
come clogged to the extent of requiring cleaning or mark;
replacement.
b) aperture size. The size of the aperture may be
3.10 critical pressure drop before failure: Maximum indicated by a marking such as a colour that is
allowable pressure difference across each filtering defined in the manufacturer’s catalogue.
element of the strainer which will not cause failure
of the filter element.
5 Technical characteristics
3.11 range of recommended flow-rates: Range of
5.1 General
flow-rates declared by the manufacturer for proper
operation of the strainer supplied.
The strainer parts that are in contact with water
shall be of non-toxic materials, and shall be resist-
3.12 nominal size: Conventional numerical desig-
ant to or protected against degradation caused by
nation to indicate the size of the strainer. This des-
existing working conditions and types of water used
ignation equals the nominal diameter or threaded
in agricultural irrigation. The strainer housing shall
size of a pipe to which the strainer can be connected
also be resistant to environmental conditions. Com-
without intermediate fittings.
ponents belonging to strainers of the same size,
type and model, and produced by the same manu-
NOTE 2 A single number designation is adequate if the
facturer, shall be interchangeable.
inlet and outlet ports are the same size.
Plastics parts of the strainer that are exposed to
3.13 aperture size: Dimension, expressed in
ultra-violet (UV) radiation under the normal working
microns, of the aperture in the filter element, such
conditions in which the strainer operates shall in-
as the diameter of a round opening or the side of a
clude additives to improve their resistance to UV
square opening.
radiation. Plastics parts that enclose waterways
shall be opaque or shall be provided with an opaque
3.14 strainer length: Overall length between the
cover designed to block all light from reaching clear
extremities of the connecting threads of the strainer,
waterway enclosures.
the face-to-face distance between the connecting
flanges, or the distance between centre-lines of the The construction of the strainer shall be such as to
parallel inlet and oulet ports, either threaded or facilitate its proper installation in its intended lo-
cation and position.
flanged.
The strainer shall be so designed that, after as-
sembly of the filter element in the strainer housing,
4 Marking
all the water flowing through the strainer flows
through the filter element.
Each strainer shall bear a readily visible, durable
marking giving the particulars specified in 4.1 and
5.2 Strainer housing
4.2.
Where the size of a thread-connected strainer
4.1 Strainer housing
housing or its configuration does not allow for easy
handling of the housing while connecting or discon-
and/or registered trade-
name of manufacturer
a) necting pipework, the strainer housing shall be pro-
mark;
vided with a boss or with other means of facilitating
connection and disconnection of the strainer hous-
b) model identification;
ing to and from the network.
The strainer shall be so designed that contaminants
c) nominal size;
accumulated on the filter element or in the strainer
housing do not enter the supply line when cleaning
d) nominal pressure;
2
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IS0 9912=2:1992(E)
If the filters are not produced as a regular pro-
or replacing the filter element. Construction of the
duction series and the number of filters produced is
filter element should allow disassembly, cleaning
and reassembly of the filter element without removal less than 20, no requirement is stipulated as to the
sampling procedure.
of the strainer from the supply line.
The strainer housing cover shall be attached to the If the number of defective specimens in the sample
strainer housing by means of threads or bolts or in is equal to or less than the acceptance number
specified in table 2, the lot shall be considered ac-
a manner that ensures full and uniform tightness
ceptable. If the number of defective specimens in the
around the cover periphery. Means shall be pro-
sample is greater than the acceptance number, the
vided to ensure the tightness of the filter element
lot shall be rejected.
ends.
The length of strainers of the same length, size, type
Table 2 - Required number of test specimens and
and model, and produced by one manufacturer,
acceptance number
shall not deviate from the length listed in the manu-
facturer’s catalogue by more than the tolerance
Accept-
No. of test
specified in table 1.
Clause Name of test
ante
specimens
No.
Table 1 - Length tolerances
7.2 ‘1 Resistance of strainer to
3 12)
Dimensions in millimetres
internal hydrostatic press-
ure
Permissible
Length of strainer
7.3 Resistance of strainer to 3 12)
deviatiod)
internal hydrostatic press-
I
.J
ure at high temperature
< 400
zk2
7.4 Resistance of filter element 2 0
> 400
f3
to buckling or tearing
7.5 Tightness of filter element 3 0
1) The length tolerance only concerns filter housings where
7.6 Clean pressure drop 1 0
...