SIST EN ISO 15212-2:2002

Oscillation-type density meters - Part 2: Process instruments for homogeneous liquids (ISO 15212-2:2002)

The standard specifies metrological and other requirements for modular and non-modular density meters of the oscillation type, which are used inline or online in process for homogeneous fluids. A method for adjustment and calibration is given.

Dichtemessgeräte nach dem Schwingerprinzip - Teil 2: Prozessgeräte für homogene Flüssigkeiten (ISO 15212-2:2002)

Dieser Teil von ISO 15212 legt messtechnische und Anforderungen unter anderem an Dichtemessgeräte nach dem Schwingerprinzip und für deren Funktionseinheiten fest (siehe 4.2), die in Prozessen für alle Arten von homogenen Flüssigkeiten angewendet werden. Dies schließt verflüssigte Gase mit ein. Auch werden Anweisungen und Methoden zur Vorjustierung, Justierung und Kalibrierung der Prozessgeräte gegeben. Die Geräte sind entweder vollständige Systeme oder Funktionseinheiten, die zu einem vollständigen Messsystem kombiniert werden können.
Dieser Teil von ISO 15212 beschreibt nicht die Anwendung der Prozessdichtemessgeräte für besondere Anwendungen oder Produkte, zum Beispiel für Mineralölprodukte oder Getränke. Diese Anwendungen können durch zuständige Institutionen wie ISO oder durch verantwortliche Behörden festgelegt werden.
Es gehört auch nicht zum Anwendungsbereich dieses Teils von ISO 15212, Gerätespezifikationen für besondere Anwendungsgebiete festzulegen; diese können in den entsprechenden Verfahrensnormen gefunden werden.
Dieser Teil von ISO 15212 richtet sich an Hersteller von Dichtemessgeräten und an Stellen, die die Normenkonformität von Dichtemessgeräten prüfen und zertifizieren. Diese Internationale Norm gibt auch Empfehlungen für Justierung und Kalibrierung von Prozessdichtemessgeräten.
Für Labordichtemessgeräte nach dem Schwingerprinzip gilt Teil 1 dieser Internationalen Norm.

Densimetres a oscillation - Partie 2: Instruments industriels pour liquides homogenes (ISO 15212-2:2002)

La présente partie de l'ISO 15212 spécifie les exigences métrologiques et autres relatives aux densimètres à oscillation et à leurs unités fonctionnelles, utilisés dans des processus industriels pour tous types de liquides homogènes, y compris les gaz liquéfiés. Elle donne également des instructions et des méthodes d'installation, de préréglage, de réglage et d'étalonnage d'instruments industriels. Ces instruments sont soit des systèmes complets, soit des unités fonctionnelles pouvant être combinées pour former un système de mesurage complet.  La présente partie de l'ISO 15212 ne spécifie pas la méthode d'utilisation des densimètres industriels pour des applications ou des produits particuliers tels que les produits pétroliers ou les boissons. De telles méthodes 'utilisation peuvent être définies par les institutions compétentes comme I'ISO ou les organes gouvernementaux responsables.  La présente partie de l'ISO 15212 n'établit de spécification sur les instruments pour aucune application particulière.  Pour cela, il convient de se reporter à la norme correspondante, traitant de la méthode d'utilisation.  La présente partie de l'ISO 15212 s'adresse aux fabricants de densimètres et aux organismes chargés de la vérification et de la certification de la conformité des densimètres. De plus, la présente partie de I'ISO 15212 donne des recommandations pour le réglage et l'étalonnage de densimètres industriels par l'utilisateur.  Les densimètres à oscillation pour laboratoires sont traitées dans l'ISO 15212-1.

Denzimetri - oscilacijski tip - 2. del: Procesni instrumenti za homogene tekočine (ISO 15212-2:2002)

General Information

• Status: Published
• Publication Date: 31-Aug-2002
• ICS: 17.060 - Measurement of volume, mass, density, viscosity
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Sep-2002
• Due Date: 01-Sep-2002
• Completion Date: 01-Sep-2002
• Ref Project: EN ISO 15212-2:2002 - Oscillation-type density meters - Part 2: Process instruments for homogeneous liquids (ISO 15212-2:2002)

Relations

• Corrected By: SIST EN ISO 15212-2:2002/AC:2009 - Oscillation-type density meters - Part 2: Process instruments for homogeneous liquids (ISO 15212-2:2002/Cor 1:2008)
• Effective Date: 01-May-2009

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 15212-2:2002
01-september-2002
'HQ]LPHWULRVFLODFLMVNLWLSGHO3URFHVQLLQVWUXPHQWL]DKRPRJHQHWHNRþLQH
,62
Oscillation-type density meters - Part 2: Process instruments for homogeneous liquids
(ISO 15212-2:2002)
Dichtemessgeräte nach dem Schwingerprinzip - Teil 2: Prozessgeräte für homogene
Flüssigkeiten (ISO 15212-2:2002)
Densimetres a oscillation - Partie 2: Instruments industriels pour liquides homogenes
(ISO 15212-2:2002)
Ta slovenski standard je istoveten z: EN ISO 15212-2:2002
ICS:
17.060 Merjenje prostornine, mase, Measurement of volume,
gostote, viskoznosti mass, density, viscosity
SIST EN ISO 15212-2:2002 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 15212-2:2002

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SIST EN ISO 15212-2:2002
EUROPEAN STANDARD
EN ISO 15212-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2002
ICS 17.060
English version
Oscillation-type density meters - Part 2: Process instruments for
homogeneous liquids (ISO 15212-2:2002)
Densimètres à oscillation - Partie 2: Instruments industriels Dichtemessgeräte nach dem Schwingerprinzip - Teil 2:
pour liquides homogènes (ISO 15212-2:2002) Prozessgeräte für homogene Flüssigkeiten (ISO 15212-
2:2002)
This European Standard was approved by CEN on 1 March 2002.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2002 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 15212-2:2002 E
worldwide for CEN national Members.

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SIST EN ISO 15212-2:2002
EN ISO 15212-2:2002 (E)
CORRECTED  2002-04-17
Foreword
This document (ISO 15212-2:2002) has been prepared by Technical Committee ISO/TC 48
"Laboratory glassware and related apparatus" in collaboration with Technical Committee
CEN/TC 332 "Laboratory equipment", the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication
of an identical text or by endorsement, at the latest by September 2002, and conflicting
national standards shall be withdrawn at the latest by September 2002.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy,
Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the
United Kingdom.
Endorsement notice
The text of the International Standard ISO 15212-2:2002 has been approved by CEN as a
European Standard without any modifications.
NOTE  Normative references to International Standards are listed in annex ZA (normative).
2

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SIST EN ISO 15212-2:2002
EN ISO 15212-2:2002 (E)
Annex ZA
(normative)
Normative references to International Publicationswith their relevant
European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text, and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions
of any of these publications apply to this European Standard only when incorporated in it by
amendment or revision. For undated references the latest edition of the publication referred to
applies (including amendments).
NOTE  Where an International Publication has been modified by common modifications,
indicated by (mod.), the relevant EN/HD applies.
Publication Year Title EN/HD Year
ISO 15212-1 1998 Oscillation-type density meters - Part EN ISO 15212-1 1999
1: Laboratory instruments
3

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SIST EN ISO 15212-2:2002

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SIST EN ISO 15212-2:2002
INTERNATIONAL ISO
STANDARD 15212-2
First edition
2002-03-01
Oscillation-type density meters —
Part 2:
Process instruments for homogeneous
liquids
Densimètres à oscillation —
Partie 2: Instruments industriels pour liquides homogènes

Reference number
ISO 15212-2:2002(E)
©
ISO 2002

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SIST EN ISO 15212-2:2002
ISO 15212-2:2002(E)
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Printed in Switzerland
©
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SIST EN ISO 15212-2:2002
ISO 15212-2:2002(E)
Contents Page
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Principle and functional units . 2
4.1 Measuring principle . 2
4.2 Functional units . 2
5 Density sensor . 4
5.1 Sensor material . 4
5.2 Sensor design . 4
6 Requirements and tests . 4
6.1 General . 4
6.2 Density measuring transducer . 4
6.3 Liquid temperature measurement . 6
6.4 Display and output of results . 7
6.5 Auxiliary units and data transfer . 7
6.6 Safety requirements . 8
6.7 Electromagnetic compatibility . 8
7 Preadjustment and adjustment . 8
7.1 Preadjustment of process density meters . 8
7.2 Preadjustment of density measuring transducers . 8
7.3 Adjustment of installed density measuring transducers . 8
7.4 Adjustment of processing units . 8
8 Calibration . 9
8.1 Laboratory calibration . 9
8.2 In-situ calibration . 11
9 Process density meter accuracy . 13
9.1 Accuracy requirements . 13
9.2 Laboratory conformity test . 13
9.3 In-situ tests . 14
9.4 Test procedure and conformity assessment . 14
10 Installation . 15
11 Operating manual . 15
12 Marking . 16
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SIST EN ISO 15212-2:2002
ISO 15212-2:2002(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this part of ISO 15212 may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 15212-2 was prepared by Technical Committee ISO/TC 48, Laboratory glassware and
related apparatus, Subcommittee SC 4, Density measuring instruments.
ISO 15212 consists of the following parts, under the general title Oscillation-type density meters:
— Part 1: Laboratory instruments
— Part 2: Process instruments for homogeneous liquids
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SIST EN ISO 15212-2:2002
ISO 15212-2:2002(E)
Introduction
Density values of pure water at different temperatures and information on how to calculate the density values at
different pressures can be found in ISO 15212-1:1998, annex A.
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SIST EN ISO 15212-2:2002

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SIST EN ISO 15212-2:2002
INTERNATIONAL STANDARD ISO 15212-2:2002(E)
Oscillation-type density meters —
Part 2:
Process instruments for homogeneous liquids
1 Scope
This part of ISO 15212 specifies metrological requirements, among others, for oscillation-type density meters as well
as for functional units (see 4.2) of oscillation-type density meters, which are used in process for all kinds of
homogeneous liquids. This includes liquified gases. Instructions and methods for installation, preadjustment,
adjustment and calibration of process instruments are also given. The instruments are either integral systems or
functional units, which can be combined into an integral measuring system.
This part of ISO 15212 does not describe the method of use of process density meters for particular applications or
products, e.g. petroleum products or beverages. Such methods of use can be defined by relevant institutions such as
ISO or responsible Government agencies.
This part of ISO 15212 does not define an instrument specification for any particular application. For this information
reference should be made to the relevant standard covering the method of use.
This part of ISO 15212 is addressed to manufacturers of density meters and to bodies, testing and certifying the
conformity of density meters. This part of ISO 15212 also gives recommendations for adjustment and calibration of
process density meters.
Oscillation-type density meters used in laboratories are addressed in ISO 15212-1.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this part of ISO 15212. For dated references, subsequent amendments to, or revisions of, any of these publications
do not apply. However, parties to agreements based on this part of ISO 15212 are encouraged to investigate the
possibility of applying the most recent editions of the normative documents indicated below. For undated references,
the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of
currently valid International Standards.
ISO 15212-1:1998, Oscillation-type density meters — Part 1: Laboratory instruments
IEC 61010-1, Safety requirements for electrical equipment for measurement, control and laboratory use — Part 1:
General requirements
IEC 61326-1, Electrical equipment for measurement, control and laboratory use — EMC requirements
Guide to the Expression of Uncertainty in Measurement (GUM). BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, OIML
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SIST EN ISO 15212-2:2002
ISO 15212-2:2002(E)
3 Terms and definitions
For the purposes of this part of ISO 15212, the terms and definitions given in ISO 15212-1 and the following apply.
3.1
preadjustment
〈process density meter〉 adjustment performed in a laboratory environment before installation
NOTE Adjustment, see 3.1 of ISO 15212-1:1998.
3.2
laboratory calibration
〈process density meter〉 calibration for the intended entire working range of the instrument performed in a laboratory
environment before installation
NOTE Calibration, see 3.2 of ISO 15212-1:1998.
3.3
in-situ calibration
〈process density meter〉 calibration of the installed instrument for its actual working conditions in a process
environment
4 Principle and functional units
4.1 Measuring principle
The sensors used in density meters are electrically or mechanically induced oscillating systems, whose oscillation
frequencies or periods are a function of the liquid density. Depending on the sensor design, the liquid can either flow
through the sensor or the sensor can be immersed in the liquid. Instrument constants of the adjusted density meter
are used to calculate the sample density from the oscillation frequency or oscillation period and from associated
measurements, e.g. temperature or pressure.
4.2 Functional units
Oscillation-type process density meters shall consist of the following functional units:
a) a density sensor through which the liquid flows or which is immersed in the liquid;
b) a device to determine the density sensor temperature;
c) a device to condition and/or preamplify the density sensor signal;
d) a device to condition and/or preamplify the temperature sensor signal;
e) a unit for signal processing, output of results and functional monitoring.
Optional functional units of process density meters may be:
f) a temperature transducer to measure the liquid temperature (see item 6 in Figure 1);
g) a pressure transducer to measure the liquid pressure (see item 7 in Figure 1).
The functional units a) to d) are often referred to as density measuring transducer (see item 8 in Figure 1). The unit e)
can be referred to as processing or indicating unit (see item 5 in Figure 1) and may accept additional signals or
process parameters, e.g. from a flow meter.
The functional units, items 5 and 8 in Figure 1, can be integrated into a single instrument or can be separate units.
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SIST EN ISO 15212-2:2002
ISO 15212-2:2002(E)
Key
1 Density sensor [see 4.2 a)]
2 Temperature sensor [see 4.2 b)]
3 Density sensor signal preamplification [see 4.2 c)]
4 Temperature sensor signal preamplification [see 4.2 d)]
5 Processing or indicating unit [see 4.2 e)]
6 Temperature transducer [see 4.2 f)]
7 Pressure transducer [see 4.2 g)]
8 Density measuring transducer
9 Liquid to be measured
10 Output (display, printer, interface)
Figure 1 — Functional units of a process density meter
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SIST EN ISO 15212-2:2002
ISO 15212-2:2002(E)
5 Density sensor
5.1 Sensor material
Density sensor materials can be, for example, metal, metal alloys, coated metals or glass. The material is considered
to be suitable if it is compatible with the process liquids to be measured at the process conditions and with the
cleaning agents to be used in the density meter. Erosion, abrasion as well as special forms of corrosion shall be
considered in this respect since they have an impact on the accuracy of the instrument. The manufacturer shall
provide certificates about the sensor material on request.
5.2 Sensor design
Density sensors can be designed as straight, U-formed or omega-formed tubes. Other designs are tuning-forks,
cylinders, bells or membranes. All designs which conform with the functional principle in accordance with 4.1 can be
constructed.
6 Requirements and tests
6.1 General
All the tests of this clause are intended to be type tests.
6.2 Density measuring transducer
6.2.1 Drift
◦
6.2.1.1 Within 30 days, the drift of the measured density ∆ρ at a temperature of 20 C, at a pressure of 0,1 MPa
30
1)
to 0,2 MPa (1 bar to 2 bar) and at a typical flow rate specified in the manual shall not exceed 20 % of the maximum
permissible error specified by the manufacturer for the instrument.
If the working range of the density meter does not include the above mentioned conditions, the drift at the typical
measuring conditions of the density meter shall not exceed 40 % of the specified maximum permissible error.
6.2.1.2 The test for the drift determination shall be performed as follows:
— install the instrument, preadjusted by the manufacturer, to a liquid circulation system; suited liquids can be for
example water or mineral oil;
— switch on the instrument and attemper it for 24 h;
◦
— circulate the liquid through the instrument and record the density at least three times at (20± 0,1) C within
30 min;
— record the mean value ρ of the density measurement;
1
— repeat the density measurement (without a new adjustment) and mean value calculation ρ after a minimum of
2

30 days.
5 2
1) 1 bar= 10 N/m = 0,1 MPa.
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SIST EN ISO 15212-2:2002
ISO 15212-2:2002(E)
Instrument, liquid circulation and thermostating device shall be in operation during the whole test.
During the minimum time period of 30 days between the two density measurements, the instrument shall be run at
◦ ◦
least 2 days at a temperature of (10± 1) C and another 2 days at a temperature of (30± 1) C.
To calculate the drift, ∆ρ , use the following equation:
30
ρ −ρ
1 2
∆ρ =
(1)
30
∆t
where ∆t is the difference in days between the two threefold measurements.
◦
If the density measuring transducer is not designed for a measuring temperature of 20 C, testing shall be performed
at the mean measuring temperature of the density measuring transducer. The increased and decreased temperature
◦ ◦
between the two density measurements shall be +10 C and −10 C from this mean measuring temperature.
6.2.2 Effect of liquid properties
6.2.2.1 The density measuring transducer shall be constructed in such a way, that the maximum permissible errors
are in accordance with the requirements given in 9.1 when measuring liquids with different sound velocities and,
where appropriate, having different viscosities.
6.2.2.2 For testing, use Newtonian liquids with known densities and sound velocities as well as, where appropriate,
known viscosities. They shall cover the intended application range of the density meter specified by the manufacturer
with regard to sound velocity and viscosity. Testing shall be performed in accordance with 9.2.
6.2.3 Deviation between liquid and sensor temperatures
6.2.3.1 The density measuring transducer shall be designed to minimize the deviation between liquid temperature
and sensor temperature. The density deviations due to this temperature deviation at constant flow and temperature
shall not exceed 50 % of the specified maximum permissible error of the density measuring transducer.
6.2.3.2 Testing shall be performed by comparing the densities determined by the density measuring transducer with
the actual densities of a suitable test liquid of known density at three different temperatures, being approximately the
lower, upper and mean value of the specified liquid temperature range. Ambient temperature shall be kept constant
◦
to within ± 1 C of the mean value for the specified ambient temperature range of the density measuring transducer.
For this test
— switch on the density measuring transducer and circulate the test liquid for at least 1h at a temperature as
specified above and at a suitable flow rate;
— determine the actual liquid temperature as mean value of the temperatures at the inlet and outlet of the density
transducer, measured by suitable thermometers;
— calculate the deviation between the actual density of the test liquid of known density at the actual liquid
temperature and the density displayed by the density measuring transducer;
— repeat the test at the two other temperatures specified above.
Ethanol, n-nonane or mineral oil are suitable test liquids for this test.
6.2.4 Effect of instrument parts oscillations
6.2.4.1 Measurement deviations arising from parasitic resonances of instrument parts on the density measuring
transducer shall not exceed 35 % of the maximum permissible error over the whole measuring range, specified for
the density measuring transducer by the manufacturer.
6.2.4.2 For testing, examine the oscillatory characteristics of the built-in density sensor provided by the
manufacturer. This test may not show any parasitic resonant points (see 3.3 of ISO 15212-1:1998) whose effects
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SIST EN ISO 15212-2:2002
ISO 15212-2:2002(E)
exceed 35 % of the maximum permissible error specified for the density measuring transducer by the manufacturer
over the whole density measurement range.
6.2.5 Effect of instrument positioning
6.2.5.1 Unless otherwise specified by the manufacturer, the maximum permissible errors, in accordance with
Table 2 or in accordance with the manufacturer's specifications (see 9.1), shall not be exceeded if the position of the
◦
instrument is turned 90 from the vertical and horizontal sample flow direction.
6.2.5.2 Testing shall be performed in all three positions in accordance with 9.2 at constant temperature, pressure
and density.
6.3 Liquid temperature measurement
6.3.1 Built-in temperature sensor
6.3.1.1 If the process density meter is equipped with a built-in liquid temperature measurement, the temperature
sensor shall be fitted in such a way, that a good thermal contact with the liquid is guaranteed. The deviation between
the displayed and actual liquid temperatures shall not be greater than the maximum permissible error of the density
◦ −1 3
measuring transducer multiplied by the factor 0,2 C× kg × m .
−3 −1
NOTE This factor has been defined by assuming an extreme thermal density deviation of 2,4 kg× m K .
If the application range of the density measuring transducer is limited to aqueous liquids and water-containing
◦ −1 3
mixtures, the factor to be multiplied by the maximum permissible error can be increased to 0,5 C× kg × m .
6.3.1.2 Testing shall be performed by comparing the temperature determined by the built-in temperature sensor
with the actual liquid temperature at three different temperatures, i.e. approximately the lower, upper and mean value
◦
(preferably 20 C) of the specified liquid temperature range. Ambient temperature shall be kept constant to within
◦
± 1 C of the mean value for the specified ambient temperature range of the density measuring transducer. For this
test
— switch on the density measuring transducer and circulate water, or, if water is not suitable, a typical test liquid, for
at least 1h at a temperature as specified above and at a suitable flow rate;
— determine the actual liquid temperature as the mean value of the temperatures at the inlet and outlet of the
density measuring transducer, measured by suitable thermometers;
— calculate the deviation between the actual liquid temperature and the temperature displayed by the density
transducer.
The calculated deviations shall not exceed the maximum permissible error specified for the density measuring
◦ 3 −1 ◦ 3 −1
transducer multiplied by the factor 0,2 C× m × kg or 0,5 C× m × kg (see 6.3.1.1) at all three
temperatures.
6.3.2 Separate temperature transducer
If the processing unit of the density meter (see item 5 in Figure 1) is intended to indicate the liquid temperature
measured by an external temperature transducer (see item 6 in Figure 1), its error of measurement shall not exceed
◦ 3 −1
the maximum permissible error of the density measuring transducer multiplied by the factor 0,2 C× m × kg or
◦ 3 −1
0,5 C× m × kg (see 6.3.1.1).
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SIST EN ISO 15212-2:2002
ISO 15212-2:2002(E)
6.4 Display and output of results
6.4.1 Display of results
The display of results shall be designed in such a way that
— the density is displayed in kilogram per cubic metre or gram per cubic centimetre together with the measurement
unit;
— the resolution of the density display on a digital scale the values given in Table 1;
— one scale interval on an analogue scale is equal to the maximum permissible error of the process density meter
1mm
and the spacing of the scale marks is minimum .
Table 1 — Resolution and maximum permissible errors
Maximum permissible error Resolution Factor
3 3
kg/m kg/m
1,0 0,1 1/10
0,5 0,1 1/5
0,20 0,01 1/20
0,10 0,01 1/10
A display may be part of a separate ind
...