EN ISO 4787:2011

SLOVENSKI STANDARD
01-maj-2011
1DGRPHãþD
SIST EN ISO 4787:2010
/DERUDWRULMVNDVWHNORYLQD,QVWUXPHQWL]DYROXPHWULþQDPHUMHQMD0HWRGH]D
SUHVNXãDQMH]PRJOMLYRVWLLQXSRUDED,62SRSUDYOMHQDYHU]LMD

Laboratory glassware - Volumetric instruments - Methods for testing of capacity and for
use (ISO 4787:2010, Corrected version 2010-06-15)
Laborgeräte aus Glas - Volumenmessgeräte - Prüfverfahren und Anwendung (ISO
4787:2010, korrigierte Fassung 2010-06-15)
Verrerie de laboratoire - Instruments volumétriques - Méthodes de vérification de la
capacité et d'utilisation (ISO 4787:2010, Version corrigée 2010-06-15)
Ta slovenski standard je istoveten z: EN ISO 4787:2011
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
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 4787
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2011
ICS 17.060 Supersedes EN ISO 4787:2010
English Version
Laboratory glassware - Volumetric instruments - Methods for
testing of capacity and for use (ISO 4787:2010, Corrected
version 2010-06-15)
Verrerie de laboratoire - Instruments volumétriques - Laborgeräte aus Glas - Volumenmessgeräte -
Méthodes de vérification de la capacité et d'utilisation (ISO Prüfverfahren und Anwendung (ISO 4787:2010, korrigierte
4787:2010, Version corrigée 2010-06-15) Fassung 2010-06-15)
This European Standard was approved by CEN on 31 January 2011.

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 CEN-CENELEC 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 CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 4787:2011: E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
The text of ISO 4787:2010, Corrected version 2010-06-15 has been prepared by Technical Committee
ISO/TC 48 “Laboratory equipment” of the International Organization for Standardization (ISO) and has been
taken over as EN ISO 4787:2011 by 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 2011, and conflicting national standards shall be
withdrawn at the latest by September 2011.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 4787:2010.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 4787:2010, Corrected version 2010-06-15 has been approved by CEN as a EN ISO
4787:2011 without any modification.

INTERNATIONAL ISO
STANDARD 4787
Second edition
2010-04-15
Corrected version
2010-06-15
Laboratory glassware — Volumetric
instruments — Methods for testing of
capacity and for use
Verrerie de laboratoire — Instruments volumétriques — Méthodes de
vérification de la capacité et d'utilisation

Reference number
ISO 4787:2010(E)
©
ISO 2010
ISO 4787:2010(E)
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ii © ISO 2010 – All rights reserved

ISO 4787:2010(E)
Contents Page
Foreword .iv
1 Scope.1
2 Normative references.1
3 Terms and definitions .2
4 Summary of method.2
5 Volume and reference temperature .2
5.1 Unit of volume.2
5.2 Reference temperature .2
6 Apparatus and calibration liquid .2
7 Factors affecting the accuracy of volumetric instruments.3
7.1 General .3
7.2 Temperature.3
7.3 Cleanliness of glass surface .3
7.4 Quality of used volumetric instruments.4
7.5 Delivery time and waiting time.4
8 Setting the meniscus .4
8.1 General .4
8.2 Meniscus of transparent liquids .4
8.3 Meniscus of opaque liquids .5
9 Calibration procedure .5
9.1 General .5
9.2 Test room .5
9.3 Filling and delivery.6
9.4 Weighing.7
9.5 Evaluation.7
10 Use .7
10.1 General .7
10.2 Volumetric flasks (see ISO 1042) .8
10.3 Measuring cylinders (see ISO 4788) .8
10.4 Burettes (see ISO 385).8
10.5 Pipettes.9
Annex A (informative) Cleaning of volumetric glassware .10
Annex B (normative) Calculation of volume .11
Bibliography.21

ISO 4787:2010(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 2.
The main task of technical committees is to prepare International Standards. 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 document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 4787 was prepared by Technical Committee ISO/TC 48, Laboratory equipment, Subcommittee SC 6,
Laboratory and volumetric ware.
This second edition cancels and replaces the first edition (ISO 4787:1984), which has been technically revised
to incorporate the following changes:
a) the potassium dichromate cleaning method in Annex A has been deleted;
b) new tables for calculation of test results have been added to Annex B;
c) the description of the test (calibration) methods has been modified to be more precise;
d) test methods have been separated from recommendations for use.
This corrected version of ISO 4787:2010 incorporates the following corrections:
⎯ Figure 1 on page 5 has been corrected to show the correct setting of the meniscus as described in the
text;
⎯ Figure 2 on page 5 has been improved to better illustrate what the user of the instrument really sees
when setting the meniscus.
iv © ISO 2010 – All rights reserved

INTERNATIONAL STANDARD ISO 4787:2010(E)

Laboratory glassware — Volumetric instruments — Methods for
testing of capacity and for use
1 Scope
This International Standard provides methods for the testing, calibration and use of volumetric instruments
made from glass in order to obtain the best accuracy in use.
NOTE Testing is the process by which the conformity of the individual volumetric instrument with the appropriate
standard is determined, culminating in the determination of its error of measurement at one or more points.
The International Standards for the individual volumetric instruments include clauses on the definition of
capacity; these clauses describe the method of manipulation in sufficient detail to define the capacity without
ambiguity. This International Standard contains supplementary information.
The procedures are applicable to volumetric instruments with nominal capacities in the range of 0,1 ml to
10 000 ml. These include: single-volume pipettes (see ISO 648) without subdivisions; graduated measuring
pipettes and dilution pipettes, with partial or complete subdivisions (see ISO 835); burettes (see ISO 385);
volumetric flasks (see ISO 1042); and graduated measuring cylinders (see ISO 4788). The procedures are not
recommended for testing of volumetric instruments with capacities below 0,1 ml such as micro-glassware.
This International Standard does not deal specifically with pyknometers as specified in ISO 3507. However,
the procedures specified below for the determination of volume of glassware can, for the most part, also be
followed for the calibration of pyknometers.
2 Normative references
The following referenced documents are indispensable for the application 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 385, Laboratory glassware — Burettes
ISO 648, Laboratory glassware — Single-volume pipettes
ISO 835, Laboratory glassware — Graduated pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 4788, Laboratory glassware — Graduated measuring cylinders
ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated terms
(VIM)
ISO 4787:2010(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC Guide 99 apply.
4 Summary of method
The general procedure is based upon a determination of volume of water, either contained in or delivered by
the volumetric instrument. This volume of water is based upon knowledge of its mass under consideration of
buoyancy and its tabulated density (gravimetric method).
5 Volume and reference temperature
5.1 Unit of volume
The unit of volume shall be the millilitre (ml), which is equivalent to one cubic centimetre (cm ).
5.2 Reference temperature
The standard reference temperature, i.e. the temperature at which the volumetric instrument is intended to
contain or deliver its volume (capacity), shall be 20 °C.
When the volumetric instrument is required for use in a country which has adopted a standard reference
temperature of 27 °C (the alternative recommended in ISO 384 for tropical use), this figure shall be substituted
for 20 °C.
6 Apparatus and calibration liquid
6.1 Balance, with a resolution and standard deviation appropriate to the selected volume of the apparatus
under test (see Table 1).
The resolution of the display, the standard deviation and the linearity of the balance will be a limiting factor in
the accuracy of the measurements. The balance shall be calibrated with adequate accuracy (see 9.4).
Table 1 — Recommended balance
a
Selected volume under test Resolution Standard deviation Linearity
(repeatability)
V mg mg mg
100 µl < V u 10 ml 0,1 0,2 0,2
10 ml < V < 1 000 ml 1 1 2
1 000 ml u V u 2 000 ml 10 10 20
V > 2 000 ml 100 100 200
a
For practical purposes, the nominal volume may be used to choose the balance.
6.2 Thermometer, to measure the temperature of the calibration liquid (water) with a measurement error of
maximum 0,2 °C for liquid volumes < 1 000 ml and with a measurement error of maximum 0,1 °C for liquid
volumes W 1 000 ml.
6.3 Hygrometer, to measure the humidity in the test room with a measurement error of maximum 5 %
within the humidity range of 35 % to 85 %.
2 © ISO 2010 – All rights reserved

ISO 4787:2010(E)
6.4 Barometer, to measure the atmospheric pressure in the test room with a measurement error of
maximum 1 kPa.
6.5 Calibration liquid, distilled or deionized water complying with ISO 3696, Grade 3 should be used for
testing.
6.6 Receiving vessel, conical flask with ground joint, manufactured from glass, e.g. in accordance with
ISO 4797. The nominal volume of the conical flask shall correspond to the volume of liquid to be measured.
7 Factors affecting the accuracy of volumetric instruments
7.1 General
The same sources of error are, naturally, inherent both in calibration and use. In the former, every attempt is
made to reduce these errors to a minimum; in the latter, the care needed is dependent upon the degree of
accuracy required. When the greatest possible accuracy is desired, the volumetric instrument should be used
as closely as possible to the manner in which it has been calibrated.
7.2 Temperature
7.2.1 Temperature of the volumetric instrument
7.2.1.1 The capacity of the volumetric instruments varies with change of temperature. The particular
temperature at which a volumetric instrument is intended to contain or deliver its nominal capacity is the
“reference temperature” of the instrument (see 5.2).
7.2.1.2 A volumetric instrument which was adjusted at 20 °C, but used at 27 °C, would show an extra
error of only 0,007 % if it is made of borosilicate glass having a coefficient of cubical thermal expansion of
−6 −1
9,9 × 10 °C and of 0,02 % if it is made of soda-lime glass having a coefficient of cubical thermal expansion
−6 −1
of 27 × 10 °C . These errors are smaller than the limits of error for most volumetric instruments. It follows,
therefore, that the reference temperature is of minor importance in practical use. However, when performing
calibrations, it is important to refer to the reference temperature.
7.2.2 Temperature of calibration liquid
The temperature of the water used for the calibration shall be measured to ±0,1 °C. Corrections for differences
in temperature from the reference temperature shall be applied in accordance with Annex B.
7.3 Cleanliness of glass surface
The volume contained in, or delivered by, a volumetric instrument depends on the cleanliness of the internal
glass surface. Lack of cleanliness results in errors through a poorly shaped meniscus involving two defects:
⎯ incomplete wetting of the glass surface, i.e. the liquid surface meets the glass at an arbitrary angle
instead of forming a curve such that it meets the glass tangentially;
⎯ a generally increased radius of curvature, due to contamination of the liquid surface reducing the surface
tension.
The ascending or descending liquid meniscus shall not change shape (i.e. it shall not crinkle at its edges). To
ascertain whether a piece of glass apparatus is satisfactorily clean, it shall be observed during filling and
dispensing. Additionally, an experienced operator can recognize the shape of an uncontaminated meniscus, in
relation to its diameter.
ISO 4787:2010(E)
Lack of cleanliness causes additional errors with volumetric instruments used for delivery due to the film of
liquid on the walls being irregularly distributed or incomplete, e.g. forming drops on the glass surface.
Furthermore, chemical residues can introduce an error in the analytical result by contamination. Therefore,
where volumetric instruments are fitted with ground stoppers, special attention shall be paid to cleaning the
ground zone.
NOTE Small residues of acid, for example, could impair the concentration of the alkaline solution with which the
volumetric instrument is filled.
A satisfactory method of cleaning is described in Annex A.
7.4 Quality of used volumetric instruments
The glass surface shall be free from obvious damage, the graduations and inscriptions shall be clearly
readable and especially with instruments adjusted to deliver the jet shall be free from damage and allow an
unrestricted outflow of liquid.
7.5 Delivery time and waiting time
For volumetric instruments used for delivery of a liquid, the volume delivered is always less than the volume
contained, due to the film of liquid left on the inner walls of the volumetric instrument. The volume of this film
depends on the time taken to deliver the liquid, and the volume delivered decreases with decreasing delivery
time. For example, the delivered volume of a pipette or burette will decrease if the jet is broken (shorter
delivery time) or will increase if the jet is not clean and the outflow of liquid is restricted.
In view of the above, delivery times and waiting times have been specified in the International Standards on
volumetric instruments; these times shall be observed.
8 Setting the meniscus
8.1 General
Most volumetric instruments employ the principle of setting or reading a meniscus (the interface between air
and the liquid) against a graduation line or ring mark. Wherever practicable, the meniscus should descend to
the position of setting.
The tubing of the volumetric instrument shall be in a vertical position. The eye of the testing person shall be in
the same horizontal plane as the meniscus or the graduation line (ring mark).
8.2 Meniscus of transparent liquids
The meniscus shall be set so that the plane of the upper edge of the graduation line is horizontally tangential
to the lowest point of the meniscus, the line of sight being in the same plane (see Figure 1).
The lighting should be arranged so that the meniscus appears dark and distinct in outline. For this purpose, it
should be viewed against a white background and shaded from undesirable illumination. This can be achieved,
for example, by securing a strip of black or blue paper directly below the level of the graduation line or ring
mark or by using a short section of thick black rubber tubing cut open at one side and of such size as to clasp
the tube firmly. Parallax is avoided when the graduation lines are of sufficient length to be seen at the front
and back of the volumetric instrument simultaneously.
On volumetric instruments which have graduation lines on the front only, parallax can be made negligible
when making a setting on the top edge of the line by using the black shading strip, taking care that the top
edge of this is in a horizontal plane. In this case, the eye shall be placed so that the front and back portions of
the top edge appear to be coincident.
4 © ISO 2010 – All rights reserved

ISO 4787:2010(E)
On volumetric instruments fitted with a Schellbach ribbon, the meniscus shall be set using the constriction
produced by the interaction between the meniscus and the Schellbach ribbon. Setting is done when the tip of
the constriction points to the graduation line (see Figure 2).

Key Key
1 meniscus of liquid 1 meniscus
2 graduation line or ring mark 2 graduation line
3 blue or black (dark) paper or black rubber tubing 3 Schellbach ribbon
Figure 1 — Setting of the meniscus with Figure 2 — Meniscus with Schellbach ribbon
transparent liquids
8.3 Meniscus of opaque liquids
When the volumetric instrument is used with opaque wetting liquids, the horizontal line of sight shall be taken
through the upper edge of the meniscus, and, where necessary, an appropriate correction shall be applied.
In the case of a mercury meniscus, however, the highest point of the meniscus shall be set to the lower edge
of the graduation line.
9 Calibration procedure
9.1 General
Volumetric instruments other than disposable pipettes shall be thoroughly cleaned shortly before calibration
(see 7.3). Volumetric instruments adjusted to contain shall be dried after cleaning.
For volumetric instruments adjusted to deliver, it is important that receiving vessels manufactured from glass
are used. Capillary effects influencing the delivery time and the delivered volume depend considerably on the
material on which the liquid runs down. In addition, the electrostatic charges of glass are minimal; this is
important for the weighing procedure.
9.2 Test room
The test shall be carried out in a draught-free room with stable environment. The test room shall have a
relative humidity between 35 % and 85 % and shall provide a temperature locally constant to ±1 °C and
temporally constant to ±0,5 °C between 15 °C and 30 °C. Prior to the test, the volumetric instrument to be
tested and the test water shall have stood in the room for a sufficient time (1 h to 2 h) to reach equilibrium with
the room conditions. Test water should be covered to avoid evaporation cooling. Temperatures (room and
calibration liquid), atmospheric pressure and humidity should be recorded.
ISO 4787:2010(E)
9.3 Filling and delivery
9.3.1 Volumetric flasks and measuring cylinders
Volumetric flasks in accordance with ISO 1042 and measuring cylinders in accordance with ISO 4788 shall be
dried after cleaning. They shall be filled by means of a plastic tube with tip to a distance of a few millimetres
above the ring mark or the graduation line to be tested, so that the walls of the volumetric instrument
considerably above the ring mark are not wetted. The final setting of the meniscus to the ring mark or
graduation line shall be made by withdrawing the surplus water by means of a plastic tube drawn out to a jet.
The movement of the meniscus when setting shall be downwards. If a little refilling is necessary or if the
reading is delayed to the adjustment of the meniscus, careful swaying is necessary to refresh the meniscus
shape.
9.3.2 Pipettes adjusted to deliver
Pipettes adjusted to deliver according to the specifications in ISO 648 and ISO 835 shall be clamped in a
vertical position and filled through the jet to a few millimetres above the graduation line to be tested; any liquid
remaining on the outside of the jet shall be removed. The final setting of the meniscus shall then be made by
running out the surplus water through the jet. Any drop of liquid adhering to the jet shall be removed, for
example by bringing a ground glass surface into contact with the tip of the jet at an angle of about 30°. Draw
this ground glass surface downwards through a distance of about 10 mm to remove residual water. Delivery
into the tared receiving vessel shall then be made with the flow unrestricted while the tip of the jet is in contact
with the inner ground surface of the receiving vessel, finally drawing it over a distance of about 10 mm, with
the receiving vessel held inclined at an angle of about 30°.
Other precautions which are necessary to obtain the correct delivered volume vary with different types of
instruments and are described in the clause defining capacity in the appropriate International Standards.
Determine the delivery time while the tip of the jet is in contact with the inner surface of the receiving vessel,
above the level of any collected liquid, but without movement of one against the other throughout the delivery
period. The delivery time thus determined should be within the limits specified for the particular pipette. For
further details, see ISO 648 and ISO 835.
A waiting time, if specified, shall be observed before making the final setting of the meniscus for delivery of a
given volume. If the setting after delivery is done at a lower graduation line, the liquid flow shall be nearly
stopped a few millimetres above the graduation line. After observation of the waiting time, the final setting
shall be completed quickly.
9.3.3 Pipettes adjusted to contain
See 10.5.2.
9.3.4 Burettes adjusted to deliver
Burettes adjusted to deliver according to ISO 385 shall be clamped in a vertical position and filled through the
jet to a few millimetres above the graduation line to be tested. The stopcock and jet shall be freed from air
bubbles. Any liquid remaining on the outside of the jet shall be removed. The final setting of the meniscus
shall then be made by running out the surplus water through the jet. Any drop of liquid adhering to the jet shall
be removed by bringing a ground glass surface into contact with the tip of the jet at an angle of about 30°.
Draw this ground glass surface downwards through a distance of about 10 mm.
Delivery into the tared receiving vessel shall then be made with the flow unrestricted until the meniscus has
come to a few millimetres above the graduation line to be tested, while the stopcock is fully open and the jet is
not in contact with the receiving vessel. After the final setting of the meniscus, any drop of liquid adhering to
the jet is removed by bringing an inclined glass surface into contact with the tip of the jet at an angle of about
30°, finally drawing it over a distance of about 10 mm.
6 © ISO 2010 – All rights reserved

ISO 4787:2010(E)
Other precautions which are necessary to obtain the correct delivered volume vary with different types of
burettes and are described in the appropriate International Standards in the clause defining capacity.
Determine the delivery time by the unrestricted outflow of the liquid from the zero mark to the lowest
graduation mark with the stopcock fully open and the jet not being in contact with the surface of the receiving
vessel. The delivery time thus determined should be within the limits specified for the particular burette. For
further details, see ISO 385.
A waiting time, if specified, shall be observed before making the final setting of the meniscus for delivery of a
given volume. If the setting after delivery is done at a lower graduation line, the liquid flow shall be nearly
stopped a few millimetres above the graduation line. After observation of the waiting time, the final setting
shall be completed quickly.
9.4 Weighing
The volumetric instrument or the receiving vessel (see 6.6) shall be tared and weighed using a balance in
accordance with 6.1 and the temperature of the water shall be measured to ±0,1 °C.
Alternatively, two weighings can be performed, namely I , referring to the loaded vessel, and I , referring to
L E
the empty vessel. Usually, I and I are observed under the same conditions, hence a precise zero
E L
adjustment of the balance is not necessary. Both of the required weighings shall be carried out in as short a
time interval as convenient to ensure that they have been made at the same temperature. This temperature
and the barometric pressure shall be recorded for use in the subsequent calculations.
The manufacturer's instructions shall be followed in making the requisite measurements. Weighings shall be
made with care and made expeditiously to minimize evaporation losses which would constitute a source of
error.
9.5 Evaluation
The balance reading after tare or the difference of the results of the first and second weighing is the apparent
mass of the water contained in, or delivered by, the volumetric instrument tested.
NOTE The apparent mass, thus obtained, is the mass uncorrected for air buoyancy.
In order to obtain the volume contained in, or delivered by, the volumetric instrument under test at the
reference temperature from the apparent mass of water, the following factors shall be taken into account:
a) the density of water at the temperature of test;
b) the thermal expansion of the glass between the temperature of test and the reference temperature;
c) the effect of air buoyancy on the water and on the weights used.
Instructions for calculating the volume of the instrument and tables, in which these factors have been taken
into account for a reference temperature of 20 °C, are given in Annex B.
10 Use
10.1 General
Where the greatest attainable accuracy is required, volumetric instruments shall be manipulated in a manner
as similar as possible to that employed during calibration as described in Clause 9. For further details, see the
relevant clause “Definition of capacity” or “Basis of adjustment” in the appropriate International Standards.
Always clean volumetric instruments before use (see 7.3) and check the jet for possible damage and
unrestricted outflow of liquid with volumetric instruments adjusted to deliver.
ISO 4787:2010(E)
According to 7.5, the delivered volume of liquid with instruments adjusted to deliver depends on the delivery
time (specified in the appropriate standards) and physical properties of the liquid. Dilute aqueous solutions,
however, such as are ordinarily employed in volumetric analysis, can be used without significant error; for
example 1 mol/l solutions introduce errors smaller than Class A and Class AS tolerances and 0,1 mol/l
solutions introduce correspondingly smaller errors. The accuracy deteriorates when using liquids with a
viscosity and/or surface tension very different from water, e.g. non-aqueous liquids.
Liquids which are too opaque for the bottom of the meniscus to be visible may be read on the “upper edge” of
the meniscus, with rather less accuracy and precision than is possible when viewing the lowest point of the
meniscus.
The temperature of use is also important. Whereas the expansion of the volumetric instrument itself is
negligible (see 7.2.1.2), the expansion of liquid shall be considered. Ensure that all solutions used in
connection with each other are close to a common (everyday) temperature when their volumes are measured.
Especially when preparing standard solutions, pipetting of the sample, and for example titration, should be as
close as possible to the same temperature. Avoid large difference in temperatures between the instrument
and the liquid (see 7.2.2).
10.2 Volumetric flasks (see ISO 1042)
The procedure for setting of the meniscus on the ring mark shall reproduce the conditions of calibration and is
illustrated by the following example in the case of a dilute aqueous solution.
⎯ Introduce the solid material and add sufficient water to dissolve it by carefully swaying the flask without
contaminating the surface above the graduation line. (If necessary, this process can be assisted by no
more than moderate warming.)
⎯ Then, while still swaying the flask to mix its content, add more water to bring the liquid surface to within a
few centimetres below the graduation line.
⎯ Stopper and shake the flask upside down to mix the contents, then carefully remove and rinse the stopper,
gathering the water in the flask to bring the liquid surface to within 1 cm below the graduation line.
⎯ Leave the flask to stand without its stopper for 2 min to allow the liquid in the neck to drain. If necessary,
wait for the solution to regain room temperature. During the waiting time, the rinsed and dried stopper
may be replaced.
⎯ Then set the bottom of the meniscus on the graduation line by running the necessary water down the
neck from a point less than 1 cm above the graduation line.
⎯ Finally, stopper and shake the volumetric flask by multiple inversions for thorough mixing.
10.3 Measuring cylinders (see ISO 4788)
To set the meniscus precisely, fill the cylinder with the relevant liquid to a few millimetres above the nominal
capacity line or selected graduation line. Wait 2 min to allow liquid in the cylinder to drain. Then withdraw the
surplus of liquid by means of a tube drawn out to a jet.
10.4 Burettes (see ISO 385)
After rinsing with the liquid or reagent to be used, prime the stopcock and fill the burette, clamped in a vertical
position, a few millimetres above the zero graduation line. Wait 2 min for drainage before setting the meniscus
at the zero line. Now, titration can be performed until the endpoint is reached. The meniscus reading at the
relevant graduation line gives the amount of volume that has been delivered.
In practice, a burette is generally not employed in the same way as it is tested. Typically, in use, the approach
to the finally desired delivery point is made dropwise, to avoid overdelivery, and frequently takes a period of
time that is similar to, or even greater than, any specified waiting time observed during testing. Therefore, it
follows that in use, the waiting time, if specified, need generally not be observed.
8 © ISO 2010 – All rights reserved

ISO 4787:2010(E)
10.5 Pipettes
WARNING — Use an appropriate pipetting aid for filling to avoid any danger to the operator. Always
hold the pipette at the top while inserting in the aspiration adapter because pipettes in particular can
break and cause injury. It is recommended to use pipetting aids which allow the unrestricted outflow
of the liquid.
10.5.1 Pipettes adjusted to deliver (see ISO 648 and ISO 835)
After rinsing with the liquid or reagent to be used, fill the pipette by suction to a few millimetres above the
selected graduation line. Remove any liquid remaining on the outside of the jet.
The final setting of the meniscus shall then be made by dispensing the surplus liquid through the jet. Remove
any drops of liquid adhering to the jet by bringing an inclined ground glass vessel into contact with the tip of
the jet. Delivery shall then be made with the tip of the jet in contact with the inner surface of the inclined
receiving vessel.
If the setting after delivery is done at a lower graduation line, the liquid flow has to be nearly stopped a few
millimetres above the graduation line. After observing a waiting time, if specified, complete the final setting
quickly.
A waiting time, if specified, shall be observed before making the final setting for delivery of a given volume.
10.5.2 Pipettes adjusted to contain
Rinse the pipette with the reagent to be used to a few millimetres below the desired graduation line. Fill the
pipette by suction to as close as possible above the selected graduation line. Remove any liquid remaining on
the outside of the jet. Make the final setting of the meniscus to the line by withdrawing the surplus liquid by
means of filter paper. For the discharge, rinse the pipette several times with the diluting medium.
ISO 4787:2010(E)
Annex A
(informative)
Cleaning of volumetric glassware
A.1 The volume contained in or delivered from volumetric glassware depends on cleanliness of the entire
internal surface to ensure uniform wetting and performing a well shaped meniscus.
A.2 Glassware can be cleaned manually, in an immersion bath or in a laboratory washing machine. To
reduce volume changes through glass erosion and destruction of graduations, gentle cleaning with detergents
of low alkalinity at temperatures below 70 °C with short contact time and whenever possible immediately after
use is recommended. The cleanliness of the inner glass surface should be ascertained as specified in 7.3.
A.3 If the inner glass walls are not sufficiently clean after the above treatment, the volumetric instrument
should be filled with a mixture of equal parts of a 30 g/l solution of potassium permanganate (KMnO ) and
1 mol/l solution of sodium hydroxide (NaOH). After about 2 h, a residue of MnO may be removed by means
of dilute hydrochloric acid or oxalic acid.
The volumetric instrument should then be rinsed with distilled water and it should again be ascertained that
the walls are sufficiently clean. If they are not, the procedure should be repeated. If this treatment is not
successful, specific cleaning methods described in laboratory handbooks should be applied. The method shall
not change the volume of the instrument.
As a safeguard, it is recommended that volumetric instruments should not be heated to a temperature
considerably above 180 °C. Although the strain point of glasses used for volumetric purposes is in the range
of 500 °C, alterations of volume might occur at temperatures considerably below the strain point.
10 © ISO 2010 – All rights reserved

ISO 4787:2010(E)
Annex B
(normative)
Calculation of volume
B.1 General calculation
B.1.1 The general equation for calculation of the volume at the reference temperature of 20 °C, V (at a
reference temperature of 27 °C, V ), from the apparent mass of the water, contained or delivered, is as
follows:
⎛⎞
−1 ρ
A
VI=−I ×ρρ− ×11− ×⎡−γt−20⎤ (B.1)
()( ) ()
⎜⎟
20 L E W A
⎣ ⎦
ρ
⎝⎠B
where
I is the balance reading of vessel with water, in grams;
L
I is the balance reading of empty vessel, in grams (zero in case the balance was tared with the
E
volumetric instrument or receiving vessel);
ρ is the density of air, in grams per millilitre, obtained from Table B.3 at the temperature and
A
atmospheric pressure of the test;
ρ is either the actual density of the balance
...