ISO 9644:2018
(Main)Agricultural irrigation equipment — Pressure losses in irrigation valves — Test method
Agricultural irrigation equipment — Pressure losses in irrigation valves — Test method
This document applies to manually-activated valves only. This document specifies a test method for determining the pressure loss in agricultural irrigation valves under steady-state conditions when water flows through them. The scope and accuracy of the valve performance specifications presented will assist agricultural irrigation system designers in comparing pressure losses through various types of valves. The measurement of pressure losses provides a means for determining the relationship between pressure loss and flow rate through the valve. This document also describes the method of reporting pertinent test data. No attempt is made to define product use, design or applications. The test method is suitable for valves with equal inlet and outlet nominal sizes.
Matériel agricole d'irrigation — Pertes de pression dans les vannes d'irrigation — Méthode d'essai
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 9644
Third edition
2018-08
Agricultural irrigation equipment —
Pressure losses in irrigation valves —
Test method
Matériel agricole d'irrigation — Pertes de pression dans les vannes
d'irrigation — Méthode d'essai
Reference number
ISO 9644:2018(E)
©
ISO 2018
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ISO 9644:2018(E)
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© ISO 2018
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Published in Switzerland
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ISO 9644:2018(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test installation . 2
4.1 Permissible deviation of measuring devices . 2
4.2 Test equipment . 3
4.2.1 Piping . 3
4.2.2 Throttling valve . 3
4.2.3 Flow measuring device . . 3
4.2.4 Pressure differential measuring device . 3
4.2.5 Pressure taps . 3
4.2.6 Temperature sensors . 5
4.2.7 Filtration . 5
5 Test procedure . 5
5.1 Test installation . 5
5.2 Test conditions . 5
5.2.1 Permissible fluctuations in measurements . 5
5.2.2 Steady conditions . 6
5.2.3 Unsteady conditions . 6
5.3 Test bench pressure loss . 6
5.4 Test of valve . 7
6 Test results . 7
6.1 Presentation of test results . 7
6.2 Calculated valve coefficients . 8
6.2.1 General. 8
6.2.2 Flow resistance coefficient, ζ . 8
6.2.3 Valve flow coefficient, K . 8
v
6.3 Test report . 9
Annex A (informative) Measurement uncertainty .10
Annex B (informative) Evaluation of uncertainty of flow rate coefficient, K, and pressure
v
losses coefficient, ζ .14
Bibliography .19
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ISO 9644:2018(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.
This third edition cancels and replaces the second edition (ISO 9644:2008), which has been technically
revised. The main changes compared to the previous edition are as follows:
— addition of Annexes A and B.
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INTERNATIONAL STANDARD ISO 9644:2018(E)
Agricultural irrigation equipment — Pressure losses in
irrigation valves — Test method
1 Scope
This document applies to manually-activated valves only.
This document specifies a test method for determining the pressure loss in agricultural irrigation
valves under steady-state conditions when water flows through them. The scope and accuracy of the
valve performance specifications presented will assist agricultural irrigation system designers in
comparing pressure losses through various types of valves.
The measurement of pressure losses provides a means for determining the relationship between
pressure loss and flow rate through the valve.
This document also describes the method of reporting pertinent test data.
No attempt is made to define product use, design or applications.
The test method is suitable for valves with equal inlet and outlet nominal sizes.
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 https: //www .electropedia .org/
3.1
nominal size
DN
conventional numerical designation used to indicate the size of an irrigation valve
3.2
volume flow rate
flow rate
q
V
volume of water flowing through the valve per unit time
3.3
pressure loss
Δp
difference in pressure due to water flow between two specified points in a system or in part of a system
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ISO 9644:2018(E)
3.4
piping pressure loss
Δp
p
pressure loss in the upstream and downstream portions of the test bench piping between the pressure
taps, but excluding the pressure loss in the valve tested (see 5.4.4)
3.5
bench pressure loss
Δp
b
head loss between the pressure taps upstream and downstream from the measurement area without
the device being tested
3.6
valve pressure loss
Δp
v
pressure loss in the valve tested
3.7
reference velocity
ν
ref
velocity of flow through the valve calculated from the actual flow rate through the valve divided by the
reference cross-sectional area of the valve
3.8
steady-state flow
state of flow where the flow rate through a cross-section does not vary with time
3.9
valve flow coefficient
K
v
number equal to the flow rate of water, in cubic metres per hour, that will flow through a fully open
valve with a one bar pressure loss across the valve
3.10
flow resistance coefficient
ζ
coefficient used in non-dimensional presentation of valve loss
4 Test installation
4.1 Permissible deviation of measuring devices
The permissible deviation of the reading indicated on the measuring devices from the actual value shall
be as follows:
flow rate: ±2 %
differential and actual pressure: ±2 %
temperature: ±1 °C
The measuring devices shall be calibrated according to the existing calibration rules in the country
performing the test.
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ISO 9644:2018(E)
4.2 Test equipment
4.2.1 Piping
Upstream and downstream piping shall be the same diameter as that of the test valve connection. The
lengths of the straight, uniform-bore pipe shall be as specified in Figure 1. The inside surface of the
piping shall be free of flaking rust, mill scale and irregularities which might cause excessive turbulence.
In that part of the test apparatus shown within the frame, in Figure 1, the order of the fittings/devices
shown in the key and the distances between them shall be adhered to, with the exception that the
lengths indicated as 5d and 10d shall be understood to be the minimum allowable lengths.
4.2.2 Throttling valve
A downstream throttling valve shall be used to control the flow through the test specimen. There are
no restrictions on the size or type of this valve. The throttling valve shall be located downstream of the
downstream pressure tap (used for measuring bench pressure).
4.2.3 Flow measuring device
Locate the measuring device at the head of the system.
If an open measuring device (such as a calibrated volumetric tank) is used, it shall be located at the
downstream end of the assembly, i.e. downstream of the downstream throttling valve.
The flow-measuring device shall be installed in accordance with the specific installation instructions and,
where applicable, shall be installed with the required length of straight piping before and after the device.
The accuracy of the measuring device shall be ±2 %.
4.2.4 Pressure differential measuring device
Any device capable of measuring pressure differential with acceptable accuracy may be used.
4.2.5 Pressure taps
Pressure taps (see Figure 2) shall be provided on piping for measurement of static pressure, and
spaced as shown in Figure 1. The drilling centreline of the taps shall intersect the centreline of the pipe
perpendicularly, as shown in Figure 2. The diameter shall depend on the DN of the valve, see Table 1.
Table 1 — Pressure tap hole diameter
DN Minimum hole Maximum hole
diameter diameter
mm mm
<20 1,5 2
20 to 50 2 3
>50 3 5
The length, l, of the tap bore shall be not less than twice the diameter of the bore. For thin-walled pipes
where the wall thickness is less than 2d , a boss may be added to the pipe wall where the pressure taps
1
are to be located (see Figure 2).
Pressure taps shall be free of burrs and other irregularities and the inside wall of the piping shall be
machine-finished. For pipes of 50 mm diameter and larger, four taps shall be made, situated 90° ± 5°
apart on the circumference so that no tap is located on the lowest point of the pipe circumference.
For pipe diameters of less than 50 mm, two taps will suffice. All taps, whether two or four in number,
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ISO 9644:2018(E)
shall be connected by a conduit whose bore shall not be less than two pressure-tap cross-sections. The
pressure taps shall provide appropriate values of d and l, and may be made as illustrated in Figure 2.
1
a) Straight valves
b) Angle or multiport valves
Key
1 water supply 6 upstream pressure measuring point
2 flow meter 7 valve under test
3 temperature measurement 8 downstream pressure tapping point
4 regulating valve 9 regulating valve
5 upstream pressure tapping point 10 differential pressure measuring device
NOTE In subfigures a) and b), L and L ≥ 10d and L and L ≥ 2d.
1 3 2 4
Figure 1 — Test installation
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ISO 9644:2018(E)
a) Thick wall b) Thin wall
Figure 2 — Static pressure taps in thick and thin-wall piping
4.2.6 Temperature sensors
Any temperature-sensing device that is capable of measuring water temperature with acceptable
accuracy (see 4.1) shall be used. The device shall be located upstream of the throttling valve.
4.2.7 Filtration
If the valve manufacturer recommends the use of filtered water, a manufacturer-recommended filter
shall be installed upstream of the test circuit.
5 Test procedure
5.1 Test installation
Install the test specimen on a suitable test bench for testing valves, as shown in Figure 1. Ensure that
the water temperature during the test is between 5 °C and 50 °C.
5.2 Test conditions
5.2.1 Permissible fluctuations in measurements
For each quantity to be measured, the permissible fluctuation is given in Table 2 and Table 3.
If fluctuations of greater than the values in Table 2 and Table 3 are present, measurements may be
carried out by providing a damping device. The installation of the damping device shall not affect the
accuracy of the readings. Symmetrical and linear damping devices shall be used.
Table 2 — Differential pressure fluctuation
Flow resistance Δp
a
coefficient fluctuation
ζ %
ζ > 20 ±6
4 < ζ ≤ 20 ±10
1 < ζ ≤ 4 ±17
0,1 ≤ ζ ≤ 1 ±26
a
See 6.2.2.
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ISO 9644:2018(E)
Table 3 — Flowrate and pressure fluctuations
Quantity Fluctuation
%
Flow rate, q 5
V
Upstream pressure, p 5
1
NOTE More information about accuracy is given in Annex B.
5.2.2 Steady conditions
Test conditions are steady if the variations of each quantity, observed at the test operating point for at
least 10 s, do not exceed a value of 1,2 % (the difference between the largest and the smallest readings
of the quantity related to the mean value).
If this condition is met and if the fluctuations are less than the permissible values given in 5.2.1, only
one set of readings of individual quantities is to be recorded for the test point.
Record all readings only after steady flow conditions have been reached, and the flow is free from
pulsations.
5.2.3 Unsteady conditions
Test conditions are unsteady when variations exceed the limits of 5.2.2. In unsteady conditions, the
following procedure shall be followed.
At each test point, repeated readings of the measured quantities shall be made at random intervals of
time, but not less than 10 s. A minimum of three sets of readings shall be taken at each test point, with
more sets required as the fluctuation increases, as indicated in Table 4.
Table 4 — Minimum reading set requirements
Permissible difference between largest
Number of sets and smallest values of readings of each
quantity, related to mean value
%
3 1,8
5 3,5
7 4,5
9 5,8
13 5,9
>30 6,0
The arithmetic mean of all the readings for each quantity shall be taken as the actual value for the
purposes of the test.
If the excessive variation cannot be eliminated, the limits of error shall be calculated by statistical
analysis.
5.3 Test bench pressure loss
Measure the bench pressure loss, Δp , at the fully open position of the test specimen, unless specified
b
otherwise in a specific standard, or as recommended by the manufacturer in the installation and
operating instructions.
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ISO 9644:2018(E)
The bench pressure loss measured shall include the loss through the throttling valve (see 3.2.2), Δp ,
v
and the loss through the piping, Δp , of the test set-up:
p
Δp = Δp + Δp (1)
b v p
5.4 Test of valve
5.4.1 The test specimen shall be installed, opened or operated as in normal agricultural irrigation
practice. Valve to be tested at the full open position as defined by the manufacturer or inherent mechanical
limitations.
5.4.2 The pressure loss curve shall be confirmed by testing at least five flow rates within the flow range
declared by manufacturer. The test shall be conducted at an approximate pressure of at least 3 bar higher
than the pressure loss declared at a pressure rate that is higher by at least 3 bar than the pressure loss
declared by the manufacturer of the valve.
The manufacturer's published head loss should not vary by more than ±10 % from the test results.
5.4.3 Tests of pressure loss shall be conducted successively in progressive steps — first, with increasing
flow rates, followed by decreasing flow rates.
5.4.4 Calculate the valve pressure loss, Δp , of the test specimen by subtracting the piping pressure
v
loss, Δp , from the bench pressure loss, Δp , measured by the differential pressure measuring device:
p b
Δp = Δp − Δp (2)
v b p
The piping
...
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