EN ISO 8316:1995

SLOVENSKI STANDARD
01-avgust-1998
Measurement of liquid flow in closed conduits - Method by collection of the liquid
in a volumetric tank
Measurement of liquid flow in closed conduits - Method by collection of the liquid in a
volumetric tank (ISO 8316:1987)
Durchflußmessung von Flüssigkeiten in geschlossenen Leitungen - Verfahren der
Volumenbestimmung mit einem Meßbehälter (ISO 8316:1987)
Mesure de débit des liquides dans les conduites fermées - Méthode par jaugeage d'un
réservoir volumétrique (ISO 8316:1987)
Ta slovenski standard je istoveten z: EN ISO 8316:1995
ICS:
17.120.10 Pretok v zaprtih vodih Flow in closed conduits
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

~ ISO
INTERNATIONAL STANDARD
First edition
1987-10-01
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION
ORGANISATION INTERNATIONALE DE NORMALISATION
MEXflYHAPOflHAFI OPrAHM3A~MR n0 CTAHAAPTL43A~MM
Measurement of liquid flow in closed conduits -
Method by collection of the liquid in a volumetric tank
Mesure de d&bit des liquides dans les conduites fermees - NIethode par jaugeage d’un r&ervoir
volum4 trique
Reference number
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. Esch 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.
Draft International Standards adopted by the technical committees are circulated to
the member bodies for approval before their acceptance as International Standards by
the ISO Council. They are approved in accordance with ISO procedures requiring at
least 75 % approval by the member bodies voting.
International Standard ISO 8316 was prepared by Technical Committee ISO/TC 30,
Measurement of fluid flow in closed conduits.
Users should note that all International Standards undergo revision from time to time
and that any reference made herein to any other International Standard implies its
latest edition, unless otherwise stated.
International Organkation for Standardkation, 1987
Printed in Switzerland
ii
ISO8316:1987(E)
Contents
Paqe
1 Scope and field of application . . . . .
2 References . . .
..................... 1
3 Symbols and definitions . . . .
4 Principle . . .
................................... 2
5 Apparatus . . . . .
6 Procedure. . . . .
................................... 7
7 Calculation of flow-rate . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8 Calculation of the Overall uncertainty in the flow-rate
measurement. .
Annexes
* . . . . . . . . . . . . . . . . .
A Corrections to the measurement of filling time . . . . . . . 12
B Density of pure water at Standard atmospheric pressure
......... . . . . .
of101,325kPa. 16
C Example of a volumetric flow-rate installation
using the dynamic gauging method . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
D Example of a volumetric flow-rate installation
......... . . . . . 17
using the standing statt and finish method . . . . . . . . . . . . . . . .
E Student’s t-distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . .
Ill
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ISO 8316 : 1987 (E)
INTERNATIONAL STANDARD
Measurement of liquid flow in closed conduits -
Method by collection of the liquid in a volumetric tank
1 Scope and field of application If the installation for flow-rate measurement by the volumetric
method is used for purposes of legal metrology, it shall be cer-
This International Standard specifies methods for the measure-
tified and registered by the national metrology Service. Such in-
ment of liquid flow in closed conduits by determining the stallations are then subject to periodic inspection at stated in-
volume of liquid collected in a volumetric tank in a known time
tervals. If a national metrology Service does not exist, a certified
interval. lt deals in particular with the measuring apparatus, record of the basic measurement Standards (length, time and
the method for calculating the flow-rate
the procedure, temperature), and error analysis in accordance with this
and the assessment of uncertainties associated with the
International Standard and ISO 5168, shall also constitute
measurements.
certification for legal metrology purposes.
The method described may be applied to any liquid provided Annex A forms an integral part of this International Standard.
that
Annexes B to E, however, are given for information only.
a) its vapour pressure is sufficiently low to ensure that any
escape of liquid by vaporization from the volumetric tank
does not affect the required measurement accuracy;
2 References
b) its viscosity is sufficiently low so as not to alter or delay
ISO 4006, Measuremen t of fluid flow in closed conduits -
unduly the measurement of the level in the volumetric tank;
Vocabulary and s ymbols.
c) it is non-toxic and non-corrosive.
ISO 4185, Measurement of liquid flow in closed conduits -
Weighing me thod.
Theoretically, there is no limit to the application of this method,
but, for practical reasons, this method of measurement is nor-
ISO 4373, Measurement of liquid flow in open channels -
mally used for flow-rates less than approximately 1,5 m3/s and
Wa ter level measuring devices.
is used on the whole in fixed laboratory installations only.
However, there is a Variation of this method which uses a
I S 0 5168, Measuremen t of fluid flow - Estimation of uncer-
natura1 or artificial storage pond as a volumetric tank, but this
tainty of a flow-rate measurement.
application is not dealt with in this International Standard.
Owing to its high potential accuracy, this method is often used
as a primary method for calibrating other methods or devices
3 Symbols and definitions
for volume flow-rate measurement or for mass flow-rate
measurement; for the latter method or device, it is necessary to
know the density of the liquid accurately.
3.1 Symbols (see also ISO 4006)
Table 1
-
SI unit
Symbol Quantity Dimensions
* *
Random uncertainty, in absolute terms
eR
- -
Random uncertainty, as a percentage
ER
* *
Systematic uncertainty, in absolute terms
eS
- -
Systematic uncertainty, as a percentage
ES
MT-’ kgls
Mass flow-rate
4rn
LST-” m3/s
Volume flow-rate
qv
t Filling time of the tank T
V L3 nb
Discharged or measured volume
m
2 Liquid level in the tank L
ML-3 kg/m3
Density
e
* The dimensions and units are those of the quantities in question.

ISO 8316 : 1987 (El
3.2 Definitions One Variation of this method uses two tanks which are suc-
cessively filled (see 6.3). A further Variation, given in annex D,
uses a valve instead of a diverter mechanism to Start and stop
For the purposes of this International Standard, the definitions
the flow into a volumetric tank.
given in ISO 4006 apply. Only terms which are used with a par-
ticular meaning or the meaning of which might be usefully
a valve ins tead of a diverter that
Care shall be taken when using
restated are defined below. The definitions of some of the
the flow-rate does not Change when t he valve is operated.
terms concerned with error analysis are given in ISO 5168.
4.1.2 Dynamit gauging method
3.2.1 static gauging: A method by which the net volume of
liquid collected is deduced from measurements of liquid levels
The principle of the flow-rate measurement method by
(i.e. gauging& made respectively before and after the liquid
volumetric dynamic gauging (see figure 2 for a schematic
has been diverted for a measured time interval into the gauging
diagram of a typical installation) is
tank, to determine the volume contained in the tank.
-
to let liquid collect in the tank to a predetermined initial
level (and thus volume) , at w Nhich time the timer is started;
3.2.2 dynamic gauging: A method by which the net volume
of liquid collected is deduced from gaugings made while liquid
-
to stop the timer when a second predetermined final
flow is being delivered into the gauging tank. (A diverter is not
level (and thus volume) is reached and then to drain the
required with this method.)
liquid collected.
The flow-rate is then derived as explained in clause 7.
3.2.3 diverter: A device which diverts the flow either to the
gauging tank or to its by-pass without changing the flow-rate
during the measurement interval.
4.1.3 Comparison of instantaneous and mean flow-rates
lt should be emphasized that only the mean value of flow-rate
3.2.4 flow stabilizer: A device inserted into the measuring
for the filling period is given by the volumetric method. Instan-
System, ensuring a stable flow-rate in the conduit being sup-
taneous values of flow-rate as obtained on another instrument
plied with liquid; for example, a constant Ievel head tank, the
or meter in the flow circuit may be compared with the mean
level of liquid in which is controlled by a weir of adequate
flow-rate only if the flow is kept stable during the measurement
length.
interval, by a flow-stabilizing device, or if the instantaneous
values are properly time-averaged during the whole filling
period.
4 Principle
4.2 Accuracy of the method
4.1 Statement of the principle
uncertainty in the volumetric
4.2.1 Overall
measu rement
4.1.1 Static gauging method
The volumetric method gives a measurement of flow-rate
The principle of the flow-rate measurement method by
which, in principle, requires only level and time measurements.
volumetric static gauging (see figure 1 for a schematic diagram After the weighing method, the static gauging method in a
of a typical installation) is
volumetric tank may be considered as one of the most accurate
of all flow-rate measuring methods, particularly if the precau-
tions given in 4.2.2 are taken. For this reason, it is often used as
- to determine the i nitial volume of liquid contained in the
a Standard or calibration method. When the installation is
tank;
carefully constructed, maintained and used, an uncertainty of
k 0,l % to + 0,2 % (with 95 % confidence limits) may be
-
to divert the flow into the volumetric tank, until it is
achieved.
considered to contain a sufficient quantity to attain the
desired accuracy, by Operation of a diverter which actuates
4.2.2 Requirements for accurate measurements
a timer to measure the filling time;
The volu metric method gives an accurate measurement of
-
to determine the final volume of liquid contained in the
flow-rate provid ed that
tank. The volume contained at the initial and at the final
times is obtained by reading the liquid levels in the tank and
a) there is no leak in the flow ci rcuit and there is no
by reference to a preliminary calibration which gives the
un measured leakage flow across the diver
ter ;
level-volume relationship.
b) the conduit is running full at the measuring section and
iquid col-
The fl ow-rate is then derived from the volume of I
there is no vapour or air-leck between the measuring sec-
lected and the filling time as explain ed in clause 7.
tion and the volumetric tank;
ISO 8316 : 1987 (E)
f) the level measuring devices and the means for starting
c) there is no accumulation (or depletion) of liquid in a part
and stopping the timer achieve the required accuracies;
of the circuit by thermal contraction (or expansion) and
there is no accumulation (or depletion) by Change in vapour
or gas volume contained unknowingly in the flow circuit; g) the time required by the diverter (for the static gauging
method) for traversing is short with respect to the filling
care has been taken to avoid any leakage from or un- time, the timer being started and stopped while the diverter
d)
is crossing the hydraulic centreline (this Position shall be
wanted flow into the tank, absorption of liquid by the Walls
or their coatings, deformation of the Walls etc.; checked and adjusted, if necessary, using the methods
described in annex AI;
e) the level-volume relationship in the tank has been
h) the temperature of the liquid flowing through the
established by transferring known volumes, or by calcula-
flowmeter under test is either the same as that collected in
tion from dimensional measurements of the tank, as
the volumetric tank or it is corrected accordingly.
specified in 5.5;
Constant level
head tank
Flowmeter under
calibration Flow control valve
u
-
Alk
- _
-
Stilling weil
-
-
-
-
* --
r
Volumetric tank
Figure 1 - Schematic diagram of a volumetric flow-rate installation using the static gauging method
ISO 8316 : 1987 (E)
Timer
r
Compressed
air supply
\
-
-_
-
-_
-
-
-
Displacement
devices
Flow stabil i zer
Measuring
chamber
\
Volumetric tank
Leve I sei nsing
element
\
Storage tank
Pump
Q
Control valve
Flowmeter
Figure 2 - Schematic diagram of a volumetric flow-rate installation using the dynamic gauging method

ISO 8316 : 1987 (E)
an electrical or pneu matic actuator. The diverter shall in no way
Apparatus
influence the in the circuit during any
flow p hase o
...