FprEN ISO 8655-6

Piston-operated volumetric apparatus - Part 6: Gravimetric reference measurement procedure for the determination of volume (ISO/FDIS 8655-6:2021)

This document specifies a gravimetric reference measurement procedure for the determination of volume of piston-operated volumetric apparatus (POVA). The procedure is applicable to complete systems comprising the basic apparatus and all parts selected for use with the apparatus, disposable or reusable, involved in the measurement by delivery (Ex) or contained (In).

Volumenmessgeräte mit Hubkolben - Teil 6: Gravimetrisches Referenzprüfverfahren zur Bestimmung des Volumens (ISO/FDIS 8655-6:2021)

Dieses Dokument legt ein gravimetrisches Referenzmessverfahren zur Bestimmung des Volumens von Volumenmessgeräten mit HubkolbenN1 fest. Das Verfahren gilt für vollständige Gerätesysteme, bestehend aus dem Grundgerät und allen für die Verwendung ausgewählten Zubehörteilen, die mehrfach verwendbar oder für den einmaligen Gebrauch bestimmt sind und mit denen die Messung auf Ablauf (Ex) oder auf Einguss (In) erfolgt.

Appareils volumétriques à piston - Partie 6: Méthode gravimétrique de mesurage de référence pour la détermination du volume (ISO/FDIS 8655-6:2021)

Le présent document spécifie un mode opératoire de mesure gravimétrique de référence pour la détermination du volume des appareils volumétriques à piston (AVAP). Le mode opératoire est applicable aux systèmes complets comprenant l’appareil de base et toutes les parties sélectionnées pour être utilisées avec l’appareil, à usage unique ou réutilisables, impliqués dans le mesurage par procédé de distribution (Ex) ou de prélèvement (In).

Volumetrične naprave, delujoče na bat - 6. del: Gravimetrični referenčni postopek merjenja za določanje prostornine (ISO/DIS 8655-6:2020)

General Information

• Status: Not Published
• ICS: 17.060 - Measurement of volume, mass, density, viscosity
• ICS: 71.040.20 - Laboratory ware and related apparatus
• Technical Committee: CEN/TC 332 - Laboratory equipment
• Drafting Committee: CEN/TC 332/WG 1 - Glass and plastics devices including volumetric instruments
• Current Stage: 6055 - CEN Ratification completed (DOR) - Publishing
• Due Date: 13-Feb-2022
• Completion Date: 13-Feb-2022
• Ref Project: kSIST FprEN ISO 8655-6:2020 - Piston-operated volumetric apparatus - Part 6: Gravimetric reference measurement procedure for the determination of volume (ISO/DIS 8655-6:2020)

RELATIONS

• Revised: EN ISO 8655-6:2002 - Piston-operated volumetric apparatus - Part 6: Gravimetric methods for the determination of measurement error (ISO 8655-6:2002)
• Effective Date: 11-Apr-2018
• Revised: EN ISO 8655-6:2002/AC:2009 - Piston-operated volumetric apparatus - Part 6: Gravimetric methods for the determination of measurement error (ISO 8655-6:2002/Cor 1:2008)
• Effective Date: 11-Apr-2018

Standards Content (sample)

SLOVENSKI STANDARD
oSIST prEN ISO 8655-6:2020
01-oktober-2020

Volumetrične naprave, delujoče na bat - 6. del: Gravimetrični referenčni postopek

merjenja za določanje prostornine (ISO/DIS 8655-6:2020)
Piston-operated volumetric apparatus - Part 6: Gravimetric reference measurement
procedure for the determination of volume (ISO/DIS 8655-6:2020)

Volumenmessgeräte mit Hubkolben - Teil 6: Gravimetrisches Referenzprüfverfahren zur

Bestimmung des Volumens (ISO/DIS 8655-6:2020)
Appareils volumétriques à piston - Partie 6: Procédure de mesure de référence
gravimétrique pour la détermination du volume (ISO/DIS 8655-6:2020)
Ta slovenski standard je istoveten z: prEN ISO 8655-6
ICS:
17.060 Merjenje prostornine, mase, Measurement of volume,
gostote, viskoznosti mass, density, viscosity
71.040.20 Laboratorijska posoda in Laboratory ware and related
aparati apparatus
oSIST prEN ISO 8655-6:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 8655-6:2020
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oSIST prEN ISO 8655-6:2020
DRAFT INTERNATIONAL STANDARD
ISO/DIS 8655-6
ISO/TC 48 Secretariat: DIN
Voting begins on: Voting terminates on:
2020-07-29 2020-10-21
Piston-operated volumetric apparatus —
Part 6:
Gravimetric reference measurement procedure for the
determination of volume
ICS: 17.060
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 8655-6:2020(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO 2020
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oSIST prEN ISO 8655-6:2020
ISO/DIS 8655-6:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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ii © ISO 2020 – All rights reserved
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oSIST prEN ISO 8655-6:2020
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Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 2

4 General requirements ..................................................................................................................................................................................... 2

5 Test equipment....................................................................................................................................................................................................... 2

6 Test liquid .................................................................................................................................................................................................................... 3

7 Test Conditions ....................................................................................................................................................................................................... 3

7.1 General ........................................................................................................................................................................................................... 3

7.2 Test room ..................................................................................................................................................................................................... 4

7.3 Evaporation ................................................................................................................................................................................................ 4

7.4 Test cycle time ......................................................................................................................................................................................... 4

8 Procedure..................................................................................................................................................................................................................... 4

8.1 General ........................................................................................................................................................................................................... 4

8.1.1 Test volume........................................................................................................................................................................... 4

8.1.2 Number of measurements ....................................................................................................................................... 5

8.1.3 Weighing procedure ...................................................................................................................................................... 5

8.1.4 Test conditions during weighing procedure ............................................................................................ 5

8.1.5 Dispensing of samples ........................................................................................................................................... ...... 5

8.2 Preparation ................................................................................................................................................................................................ 5

8.3 Single-channel air displacement pipettes (in accordance with ISO 8655-2) .................................... 6

8.3.1 General...................................................................................................................................................................................... 6

8.3.2 Test cycle ................................................................................................................................................................................. 6

8.4 Multi-channel pipettes (in accordance with ISO 8655-2) .................................................................................. 7

8.5 Positive displacement pipettes (in accordance with ISO 8655-2) .............................................................. 8

8.6 Burettes (in accordance with ISO 8655-3) ..................................................................................................................... 8

8.7 Dilutors (in accordance with ISO 8655-4) ...................................................................................................................... 8

8.7.1 General...................................................................................................................................................................................... 8

8.7.2 Test cycle ................................................................................................................................................................................. 9

8.8 Dispensers (in accordance with ISO 8655-5) ............................................................................................................... 9

8.9 Syringes (in accordance with ISO 8655-9) ..................................................................................................................10

8.9.1 General...................................................................................................................................................................................10

8.9.2 Test cycle ..............................................................................................................................................................................10

9 Evaluation .................................................................................................................................................................................................................10

9.1 Calculation of mass loss ...............................................................................................................................................................10

9.2 Calculation of the corrected mass of each quantity delivered ....................................................................10

9.3 Conversion of the corrected mass to volume .............................................................................................................10

9.4 Systematic error ..................................................................................................................................................................................13

9.5 Random error ........................................................................................................................................................................................13

9.6 Uncertainty of mean delivered volume ...........................................................................................................................13

10 Reporting of results ........................................................................................................................................................................................13

Annex A (normative) Calculation of volumes from balance readings .............................................................................15

Bibliography .............................................................................................................................................................................................................................17

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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 48, Laboratory Equipment, Working

Group WG 4, Piston- operated instruments.

This second edition cancels and replaces the first edition (ISO 8655-5:2002 and ISO 8655-5:2002/

Cor 1:2008), which has been technically revised.
The main changes compared to the previous edition are as follows:

— Expanded uncertainty of measurements in Table 1 and 2 has been revised in conjunction with

ISO/TR 20461;
— Annex B was deleted;
— new Clause 4 “General requirements” is added;
— a new volume formula was added based on ISO 4787.
A list of all parts in the ISO 8655 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.
iv © ISO 2020 – All rights reserved
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Introduction
ISO 8655 addresses the needs of:

— manufacturers, as a basis for quality control including, where appropriate, the issuance of

manufacutrers’ declarations;

— calibration laboratories, test houses, users of the equipment and other bodies as a basis for

independent calibration, verification and routine checking.

The tests specified in the ISO 8655 series are intended to be carried out by trained personnel.

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oSIST prEN ISO 8655-6:2020
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oSIST prEN ISO 8655-6:2020
DRAFT INTERNATIONAL STANDARD ISO/DIS 8655-6:2020(E)
Piston-operated volumetric apparatus —
Part 6:
Gravimetric reference measurement procedure for the
determination of volume
1 Scope

This part of ISO 8655 specifies a gravimetric reference measurement procedure for the determination

of volume of piston-operated volumetric apparatus (POVA). The tests are applicable to complete

systems comprising the basic apparatus and all parts selected for use with the apparatus, disposable or

reusable, involved in the measurement by delivery (Ex) or contained (In).

NOTE General requirements and definitions of terms for piston-operated volumetric apparatus are given

in ISO 8655-1. For the metrological requirements, maximum permissible errors, requirements for marking and

information to be provided for users for piston-operated volumetric apparatus, see ISO 8655-2 for pipettes,

see ISO 8655-3 for burettes, see ISO 8655-4 for dilutors, see ISO 8655-5 for dispensers, and see ISO 8655-9

for manually operated precision laboratory syringes. The photometric reference measurement procedure

for the determination of volume of piston operated volumetric apparatus is given in ISO 8655-8. Alternative

measurement procedures or the determination of volume are described in ISO 8655-7.

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 3696:1987, Water for analytical laboratory use — Specification and test methods

ISO/DIS 8655-1:2020, Piston-operated volumetric apparatus — Part 1: Terminology, general requirements

and user recommendation
ISO/DIS 8655-2:2020, Piston-operated volumetric apparatus — Part 2: Pipettes
ISO/DIS 8655-3:2020, Piston-operated volumetric apparatus — Part 3: Burettes
ISO/DIS 8655-4:2020, Piston-operated volumetric apparatus — Part 4: Dilutors
ISO/DIS 8655-5:2020, Piston-operated volumetric apparatus — Part 5: Dispensers

ISO/DIS 8655-7:2020, Piston-operated volumetric apparatus — Part 7: Alternative measurement

procedures for the determination of volume

ISO/DIS 8655-9:2020, Piston-operated volumetric apparatus — Part 9: Manually operated precision

laboratory syringes

ISO/TR 20461, Determination of uncertainty for volume measurements made using the gravimetric method

ISO/IEC Guide 2:2004, Standardization and related activities — General vocabulary

ISO/IEC Guide 99:2007, International vocabulary of metrology — Basic and general concepts and

associated terms (VIM)

ISO/IEC Guide 98:2008, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in

me a s ur ement (GUM: 1995)
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ISO/IEC Guide 98:2012, Uncertainty of measurement — Part 4: Role of measurement uncertainty in

conformity assessment (JCGM 106:2012)

ISO 4787:2010, Laboratory glassware — Volumetric instruments — Methods for testing of capacity

and for use
3 Terms and definitions

For the purposes of this part of ISO 8655, the terms and definitions given in ISO/DIS 8655-1:2020,

ISO/IEC Guide 2 and ISO/IEC Guide 99 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/
4 General requirements

When performing calibrations according to the reference measurement procedure described in this

standard, all provisions and requirements of this standard shall be followed. If one or more of those

requirements are not followed, conformity to ISO 8655-6 shall not be claimed.
5 Test equipment

Measurements by the following equipment (balance, thermometers, hygrometer, barometer) shall be

traceable to the International System of Units (SI), as shown through careful evaluation according to

ISO/TR 20461.

5.1 Analytical balance or equivalent weighing device. The balance used for testing shall be chosen

according to the specified minimum requirements of Table 1, depending on the nominal volume of the

apparatus under test. The balance parameters are defined so that the expanded uncertainty in use is less

than one-fourth of the maximum permissible systematic error of the apparatus.
Table 1 — Minimum requirements for balances
Nominal volume of appa- Expanded uncertainty in
Readability (d) Repeatability (s)
a, b
ratus under test (V) use U (k = 2)
mg mg mg
0,001 0,006 0,012
0,5 µl ≤ V < 20 µl
0,01 0,03 0,06
20 μl ≤ V < 200 μl 0,01 0,025 0,05
200 μl ≤ V ≤ 10 ml 0,1 0,2 0,4
10 ml < V ≤ 1 000 ml 1 2 4

The repeatability and expanded uncertainty in use value, in this table, apply when testing single channel apparatus.

When a balance is used exclusively for testing multichannel pipettes the repeatability and expanded uncertainty in use

values are double the values of this table.

Expanded uncertainty in use can be estimated according to EURAMET CG-18 [2] at the value of the nominal volume.

Expanded uncertainty in use shall include non-corrected errors as well as possible drift and environmental effects

to balance sensitivity. Regular sensitivity adjustments (e.g. daily) are recommended to improve balance sensitivity.

Expanded uncertainty in use may be taken from the balance calibration certificate or calculated separately (see example in

ISO/TR 20461). If expanded uncertainty in use is not available, then the expanded uncertainty of calibration may be used.

Single-channel balance

Multi-channel balance, only valid for multi-channel pipettes. Multi-channel balances of 0,01 mg readability may be

used to test multi-channel pipettes with nominal volumes below 20 µl only if the expanded uncertainty in use is less than

one-fourth of the maximum permissible systematic error of the apparatus.
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Table 1 (continued)
Nominal volume of appa- Expanded uncertainty in
Readability (d) Repeatability (s)
a, b
ratus under test (V) use U (k = 2)
mg mg mg
1 000 ml < V ≤ 2 000 ml 10 10 40

The repeatability and expanded uncertainty in use value, in this table, apply when testing single channel apparatus.

When a balance is used exclusively for testing multichannel pipettes the repeatability and expanded uncertainty in use

values are double the values of this table.

Expanded uncertainty in use can be estimated according to EURAMET CG-18 [2] at the value of the nominal volume.

Expanded uncertainty in use shall include non-corrected errors as well as possible drift and environmental effects

to balance sensitivity. Regular sensitivity adjustments (e.g. daily) are recommended to improve balance sensitivity.

Expanded uncertainty in use may be taken from the balance calibration certificate or calculated separately (see example in

ISO/TR 20461). If expanded uncertainty in use is not available, then the expanded uncertainty of calibration may be used.

Single-channel balance

Multi-channel balance, only valid for multi-channel pipettes. Multi-channel balances of 0,01 mg readability may be

used to test multi-channel pipettes with nominal volumes below 20 µl only if the expanded uncertainty in use is less than

one-fourth of the maximum permissible systematic error of the apparatus.

5.2 Liquid reservoir, with sufficient capacity for all the test liquid likely to be required for the

complete series of tests.

The liquid reservoir should minimize temperature difference between the test liquid and room

temperature.

5.3 Weighing vessel, for the selected test procedure according to Clause 8. Care shall be taken

regarding the evaporation loss of water during delivering and weighing procedure.

5.4 Measurement devices

The minimum requirements for each relevant measurement device are described in Table 2.

Table 2 — Minimum requirements for the measurement devices
Expanded uncertainty of meas-
urement
Parameter Readability
(k = 2)
Thermometer for liquids 0,1 °C 0,2 °C
Thermometer for room air 0,1 °C 0,2 °C
Hygrometer 1 % rel. humidity 5 % rel. humidity
Barometer 0,1 kPa 1 kPa
Timing device 1 s not applicable
6 Test liquid

Use distilled or deionized water conforming to grade 3 as specified in ISO 3696, degassed or air

equilibrated. The water temperature shall be within ±0,5 °C of ambient air temperature (see 7.2).

7 Test Conditions
7.1 General

All equipment used to test the POVA shall be operated as specified in the supplier's operation manual.

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7.2 Test room

The test shall be carried out in a draught-free room with a stable environment. The test room shall have

a relative humidity (RH) between 45 % and 80 % and a temperature of (20 ± 3) °C with a maximum

variation of ±0,5 °C during the test. Prior to the test, the apparatus to be tested, all test equipment, and

test solutions shall have stood in the test room for a sufficient time to reach equilibrium with the test

room conditions, the temperature variation of the room during this time should not be more than 0,5 °C

per hour.

The environmental conditions, air temperature and air humidity, shall be within the specified limits for

room and test conditions for at least 2 hours before starting the test (minimum equilibration time) and

during the test itself.

NOTE It is unlikely that this equilibration time will be less than 2 h and could be considerably longer.

When the POVA is required for use in a country which has adopted a standard reference temperature of

27 °C (the alternative temperature recommended in ISO 384 for such use), this figure shall replace the

reference to 20 °C.
7.3 Evaporation

Particularly for small volumes (< 50 µl) errors due to evaporation of the test liquid during weighing

shall be taken into consideration. Apart from the design of the weighing vessel, the test cycle time is

important.

NOTE Especially for testing apparatus of the lowest volume possible, evaporation loss is an issue. Ways to

handle evaporation loss are for example: Carefully select the geometry of the weighing vessel.

The geometry of the volume above the liquid surface shall always have a height-to-diameter ratio of at

least 3:1, or a weighing vessel with a lid shall be used.

In order to keep the error due to evaporation as small as possible, the use of an evaporation trap may be

considered.

The error due to evaporation for the measuring series shall be determined experimentally (see 8.3.2)

and compensated mathematically (see 9.1). The uncertainty of this compensation should be added to

the uncertainty of measurement.
7.4 Test cycle time

The test cycle time (time required to complete the weighing of one dispensed volume) shall be kept to a

minimum.

NOTE It is important that it is regular from cycle to cycle, so that a reliable mathematical compensation of

the error due to evaporation during the measuring series can be applied.
8 Procedure
8.1 General
8.1.1 Test volume

In the case of a fixed-volume apparatus, the test volume is the nominal volume. In the case of variable-

volume (user selectable volume) POVA, at least the following three volumes shall be tested:

— nominal volume;

— 50 % of the nominal volume or the closest possible (if equidistant, use the higher value);

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— the lower limit of the usable volume range or 10 % of the nominal volume (whichever is greater).

8.1.2 Number of measurements

To determine the measurement error of a POVA according to this part of ISO 8655, 10 measurements or

more for each volume to be tested shall be carried out. These measurements are used to calculate the

systematic and the random error of the POVA in accordance with Clause 9.
8.1.3 Weighing procedure

Weighing for apparatus designed to deliver (Ex) shall always involve delivering of the test liquid into

the weighing vessel. Weighing for apparatus designed to contain (In) shall always involve the removal

of test liquid from the weighing vessel.
NOTE An example of this is the sample uptake step in the use of a dilutor.

The weighing vessel shall be clean and have enough liquid inside to cover the bottom of the vessel when

the measurement procedure is started, to keep the relative humidity sufficiently high.

8.1.4 Test conditions during weighing procedure

At the start and at the end of the 10 measurements, the temperature of the test liquid in its container

shall be recorded. The air temperature, the barometric pressure and the relative humidity (RH) in the

test room shall be recorded (see 7.2).

NOTE Air temperature and barometric pressure are necessary for the calculation of the correction factor

Z (see 9.3 and Annex A); the relative humidity (RH) is necessary for the stability of the room conditions and is

necessary for documentation in the test report [see 10, item d)].
8.1.5 Dispensing of samples

The test liquid shall be delivered into the weighing vessel following the specific procedures described

in 8.2 to 8.9. Where manufacturer’s instructions specify a different volume delivery procedure than

described in 8.2 to 8.9, that delivery procedure shall be used. Such procedures shall be described in

sufficient detail to allow the test to be replicated and the deviation from this standard shall be noted in

the test report.

NOTE When testing variable volume apparatus at multiple volumes, it is good practice to start with the

largest volume followed by smaller partial volumes.
8.2 Preparation

Leave the POVA under test, test equipment, exchangeable parts, and test liquids to reach thermal

equilibrium.

If using a variable volume POVA, select the test volume; this setting shall not be altered during the test

cycle of all replicate measurements.

If testing a burette, dilutor, or dispenser, place the POVA under test, with its reservoir already filled

with test liquid, as close to the balance as possible. Prime the POVA under test in order to remove

any air bubbles inside the tubes and valves. Set the delivery velocity according to the manufacturer’s

instructions. The first drops of liquid might need to be discarded before starting the calibration, if

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