ASTM E542-01(2021)

Standard Practice for Calibration of Laboratory Volumetric Apparatus

SIGNIFICANCE AND USE
4.1 The primary purpose of this practice is to provide uniform procedures that may be used to accurately calibrate a wide variety of volumetric ware. The techniques are simple in concept and can provide reliable results, provided the procedures are followed faithfully. Accordingly, the practice should provide a means for checking the original calibration of glassware and similar apparatus and for periodic rechecks as the need should arise.  
4.2 Borosilicate volumetric glassware will hold its calibration indefinitely provided that it is not exposed to hydrofluoric acid, hot phosphoric acid, or strong, hot alkalis, and that it is not heated above 150 °C when dry. A frosting of the glass surface (viewed when dry) indicates that chemical attack has occured, and recalibration may be in order. As a precaution, however, it is recommended that the glassware be recalibrated after ten years of service regardless of its appearance.  
4.3 Soda-lime volumetric glassware will become frosted with time because of attack from moisture in the atmosphere as well as from the chemicals mentioned above. In addition, it should not be heated above 90 °C when dry. It is recommended, therefore, that it be recalibrated after five years of service unless frosting (viewed when dry) is observed sooner.
SCOPE
1.1 This practice covers procedures for use in the calibration of volumetric ware, in accordance with Specification E694 such as is in common use in chemical and clinical laboratories. It is based on the gravimetric determination of the quantity of water either contained or delivered, and the conversion of this value to true volume at the standard temperature of 20 °C by means of suitable equations and standard tables. Calibration using mercury is excluded. Calibration may be performed using alternative gravimetric methodology, provided that it is demonstrated and documented that the results obtained are equivalent to those obtained using the methodology described herein.  
1.2 This practice is intended to encompass capacity ware between the limits of 0.1 cm3 and 2000 cm3. Typical products falling within the purview of this practice are burets graduated “to deliver”, graduated cylinders, volumetric flasks, specific gravity flasks, measuring and dilution pipets, and transfer and capacity pipets.  
1.3 The procedures are not recommended for calibration of apparatus with capacities below 0.1 cm3, such as microglassware.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Historical
• Publication Date: 31-Dec-2020
• ICS: 17.060 - Measurement of volume, mass, density, viscosity
• Technical Committee: E41 - Laboratory Apparatus
• Drafting Committee: E41.01 - Laboratory Ware and Supplies

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E542 − 01 (Reapproved 2021)
Standard Practice for
Calibration of Laboratory Volumetric Apparatus
This standard is issued under the fixed designation E542; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 Thispracticecoversproceduresforuseinthecalibration 2.1 ASTM Standards:
of volumetric ware, in accordance with Specification E694 E694Specification for Laboratory Glass Volumetric Appa-
suchasisincommonuseinchemicalandclinicallaboratories. ratus
It is based on the gravimetric determination of the quantity of
3. Summary of Practice
water either contained or delivered, and the conversion of this
3.1 This practice is based upon a determination of the
value to true volume at the standard temperature of 20°C by
volume of water either contained in or delivered by the vessel.
means of suitable equations and standard tables. Calibration
Procedures are given for cleaning, setting the meniscus,
using mercury is excluded. Calibration may be performed
manipulating the apparatus, weighing, and converting the
using alternative gravimetric methodology, provided that it is
weight to the appropriate standard volume.
demonstrated and documented that the results obtained are
equivalent to those obtained using the methodology described
4. Significance and Use
herein.
4.1 The primary purpose of this practice is to provide
1.2 This practice is intended to encompass capacity ware
uniform procedures that may be used to accurately calibrate a
3 3
between the limits of 0.1 cm and 2000 cm . Typical products
wide variety of volumetric ware. The techniques are simple in
falling within the purview of this practice are burets graduated
concept and can provide reliable results, provided the proce-
“to deliver”, graduated cylinders, volumetric flasks, specific
dures are followed faithfully.Accordingly, the practice should
gravity flasks, measuring and dilution pipets, and transfer and
provide a means for checking the original calibration of
capacity pipets.
glassware and similar apparatus and for periodic rechecks as
1.3 The procedures are not recommended for calibration of
the need should arise.
apparatus with capacities below 0.1 cm , such as microglass-
4.2 Borosilicate volumetric glassware will hold its calibra-
ware.
tion indefinitely provided that it is not exposed to hydrofluoric
1.4 This standard does not purport to address all of the
acid, hot phosphoric acid, or strong, hot alkalis, and that it is
safety concerns, if any, associated with its use. It is the
not heated above 150°C when dry. A frosting of the glass
responsibility of the user of this standard to establish appro-
surface (viewed when dry) indicates that chemical attack has
priate safety, health, and environmental practices and deter-
occured, and recalibration may be in order. As a precaution,
mine the applicability of regulatory limitations prior to use.
however, it is recommended that the glassware be recalibrated
1.5 This international standard was developed in accor-
after ten years of service regardless of its appearance.
dance with internationally recognized principles on standard-
4.3 Soda-lime volumetric glassware will become frosted
ization established in the Decision on Principles for the
withtimebecauseofattackfrommoistureintheatmosphereas
Development of International Standards, Guides and Recom-
well as from the chemicals mentioned above. In addition, it
mendations issued by the World Trade Organization Technical
should not be heated above 90 °C when dry. It is
Barriers to Trade (TBT) Committee.
recommended, therefore, that it be recalibrated after five years
of service unless frosting (viewed when dry) is observed
sooner.
This practice is under the jurisdiction ofASTM Committee E41 on Laboratory
Apparatus and is the direct responsibility of Subcommittee E41.01 on Laboratory
Ware and Supplies. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Jan. 1, 2021. Published February 2021. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approvedin1979.Lastpreviouseditionapprovedin2012asE542–01(2012).DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E0542-01R21. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E542 − 01 (2021)
5. Units of Measurement 7.2.2 After cleaning, the vessel should be rinsed with ethyl
alcohol and dried with clean air at room temperature. It is not
5.1 Capacity—The basic SI unit for volume is the cubic
3 necessary to dry any vessel marked “to deliver.” When
metre, m . Due to its large size, it is rarely used in volumetric
3 cleaning small articles such as pipets, it is usually easier to fill
calibration. Rather, the cubic centimetre, cm , is used and will
themwithcleaningsolutionbysuction,usingavacuumline,if
be employed in this practice. The unit, millilitre, mL, may be
available, or a small rubber bulb, but never by mouth. The
considered as equivalent to the cubic centimetre.
solution should be drawn through the pipet several times until
5.2 Standard Temperature—Volumetric ware is almost uni-
the entire inside surface is evenly coated. Rinse thoroughly
versally calibrated at 20°C. The procedures described provide
with tap water and then with distilled water. For cleaning
for such a calibration. When it is necessary to work at higher
flasks, pour in enough cleaning solution while rotating so that
ambient temperatures, such as is the case in tropical countries,
a film of solution will cover the entire interior surface.Abreak
calibration may be required at the International Standards
in the film indicates a contaminated area. For filling a buret
Organization(ISO)recommendedtemperatureof27°C.Equa-
with cleaning solution, it should be held in a vertical position
tions are given to correct the calibrated volume to other
and filled by pouring into the top. Open the stopcock to drain.
temperatures as this may be required or desired.
Regardless of the type of vessel, always rinse thoroughly, first
with tap water and then with distilled water. Plastic volumetric
6. Apparatus
ware should be cleaned in an appropriate manner before
6.1 Balance, having sufficient capacity to weigh the loaded
calibration.
vessel. The sensitivity of the balance will be a limiting factor
7.3 Reading and Setting a Liquid Meniscus:
in the accuracy of the measurements. Either a single-pan,
direct-reading balance or an equal-arm balance of adequate 7.3.1 Reading the Meniscus—Forallapparatuscalibratedby
sensitivityandcapacitymaybeused.Ineithercasetheweights this procedure, the reading is made on the lowest point of the
must be calibrated with adequate accuracy. Ordinarily, weights meniscus. In order that the lowest point may be observed, it is
with NBS Class S-1 tolerances are required. The balance must
necessary to place a shade of some dark material immediately
have physical dimensions to accept the size of the vessels below and behind the meniscus, which renders the profile of
which need to be weighed. the meniscus dark and clearly visible against a light back-
ground.Aconvenientdeviceforthispurposeisacollar-shaped
6.2 Thermometer, for measuring the temperature of the
section of thick black rubber tubing, cut open at one side and
water. The accuracy of this calibration will depend upon the
of such size as to clasp the tube firmly. Alternatively, black
accuracyrequirementofthevolumetriccalibration(seeSection
paper may be used. “Short line” graduated vessels where the
14 for tolerances).
lines are less than one half of the circumference may be read
6.3 Barometer, capable of providing atmospheric pressure
more accurately by placing a mirror against the rear of the
measurements, consistent with the tolerances given in Section
vessel to reflect the front line.
14. Alternatively, the existing barometric pressure may be
7.3.2 Setting the Meniscus—Settingofthemeniscusshallbe
obtained from the local weather service.
performed by one of the two methods detailed below. Wher-
6.4 Distilled or Deionized Water, suitable for general labo-
ever practical the meniscus should descend to the position of
ratory purposes.
setting.
7.3.2.1 The position of the lowest point of the meniscus
7. General Considerations
with reference to the graduation line is horizontally tangent to
7.1 This section describes manipulative techniques required
theplaneoftheupperedgeofthegraduationline.Theposition
to obtain accurate and reproducible volumetric measurements.
ofthemeniscusisobtainedbyhavingtheeyeinthesameplane
7.2 Cleaning Procedures: of the upper edge of the graduation line.
7.2.1 It is important that volumetric ware be thoroughly
7.3.2.2 The position of the lowest point of the meniscus
cleaned before being tested or used. Glass apparatus must be
with reference to the graduation line is such that it is in the
sufficiently clean to permit uniform wetting of the surface.
plane of the middle of the graduation line. This position of the
When clean, the walls will be uniformly wetted and the water
meniscus is obtained by making the setting in the center of the
will adhere to the glass surface in a continuous film.The clean
ellipse formed by the graduation line on the front and the back
walls of some plastic apparatus, however, will not be wetted.
of the tube as observed by having the eye slightly below the
(Follow the instructions of the manufacturer. Do not use
plane of the graduation line. The setting is accurate if, as the
materials which will attack, discolor, or swell the plasticware.)
eye is raised and the ellipse narrows, the lowest point of the
Lack of cleanliness causes irregularities in capacity by distort-
meniscus remains midway between the front and rear portions
ing the water surface. The liquids usually used for cleaning
of the graduation line. By this method it is possible to observe
glassware are sodium dichromatic-sulfuric acid cleaning solu-
the approach of the meniscus from either above or below the
tion (commercially available from laboratory supply houses),
line to its proper setting.
nitricacid,fumingsulfuricacid,alcohol,andwater.Thechoice
NOTE 1—The difference between meniscus positions resulting from the
of cleaning agent to be used depends on the nature of the
alternativemethodsofadjustmentisthevolumeequivalentofonehalfthe
contaminant. After cleaning with the cleaning solution and
thickness of the graduation line. In the case of articles where the capacity
thoroughly rinsing with tap water, the vessel should be rinsed
is read as the difference between two meniscus readings (for example on
with distilled water. a buret), then no error results if the article is manufactured using one
E542 − 01 (2021)
method of adjustment and is later used by the other method.
ceased to flow, wait 2s, then remove the pipet from contact
Eveninthemostunfavorablecasesofsingle-markarticles(forexample
withtheflask.Theflaskisnowstopperedandweighedwithits
large flasks), when working to the highest attainable accuracy, the
contained load.
difference between the two methods of adjustment is unlikely to exceed
30% of the Class A (precision apparatus) limit of error and a correction
10. Calibration of Flasks (to Contain)
can be calculated where necessary.
10.1 After cleaning and drying, weigh the empty flask
8. Calibration Procedure for Burets
including the stopper. Place an appropriate sized funnel in the
flasktodischargethewaterbelowthestopper.Fillfrombeaker
8.1 Clamp the buret vertically on a support stand; also
or supply line, maneuvering the funnel so as to wet the entire
clamp a plain glass test tube, large enough to hold a
neck below the stopper. Let stand for about 2 min to allow the
thermometer, near the buret if the buret is of such a size that it
walls to drain.
is not large enough to insert a thermometer in the top for
10.1.1 After cleaning and drying, weigh the empty flask
observing the temperature of the water. Fill the buret from a
including the stopper. Place an appropriate sized funnel or
reservoir or storage bottle, in which the water has reached
otherfillingdeviceintheflasktodischargethewaterbelowthe
equilibrium with room temperature, and check to verify that
capacity line. Fill from beaker or supply line taking care to
there is neither leakage from the tip nor from the stopcock
avoid wetting neck above capacity line.
plug. Drain and record the delivery time. Delivery time is
10.1.2 Placetheflaskunderaburetandcompletefillingand
determined by the unrestricted outflow of the water from the
setting the meniscus, taking care not to splash water on the
zero mark to the lowest graduation mark with the stopcock
walls, after which place stopper in neck to lessen evaporation
fully open. Refill the buret to approximately 10 mm above the
and weigh.Apipet or dropper with a finely drawn tip may be
zero mark and fill the test tube that holds the thermometer;
used to adjust the meniscus instead of the buret. Determine the
record the temperature. Set the meniscus on the zero mark
temperaturebyplacingathermometerinthefillingbeakerorin
usingtheburetstopcocktolowertheliquidlevelandtouchthe
one which has been filled from the water supply.The tempera-
tip with the wetted wall of a beaker to remove any excess
ture may be taken after final weighing by placing a thermom-
water. A weighing flask that has been tightly stoppered and
eter directly in the flask, provided the flask is of sufficient size
weighed empty is placed with the inside of the neck in contact
to accommodate it.
with the tip of the buret (the flask will be at a slight angle).
8.2 Fully open the stopcock until the water is only a few
11. Calibration of Flasks (to Deliver)
millimetres above the line being tested and then the stream is
11.1 Do not dry flasks that are calibrated to deliver prior to
slowed so as to make an accurate setting.When the setting has
the test. Fill the flask to approximately the index line and
been completed, move the flask horizontally, breaking the
empty rapidly by gradually inclining the flask so as to avoid
contact with the buret. Recheck the setting.
splashing on the walls as much as possible. When the main
8.3 Then stopper and weigh the flask a second time, after
drainage stream has ceased, the flask will be nearly vertical.
which refill the thermometer tube and test the next interval in
Hold in this position for 30 s and touch off the drop of water
the same manner as the first one—from the ze
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E542 − 01 (Reapproved 2012) E542 − 01 (Reapproved 2021)
Standard Practice for
Calibration of Laboratory Volumetric Apparatus
This standard is issued under the fixed designation E542; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice covers procedures for use in the calibration of volumetric ware, in accordance with Specification E694 such as
is in common use in chemical and clinical laboratories. It is based on the gravimetric determination of the quantity of water either
contained or delivered, and the conversion of this value to true volume at the standard temperature of 20°C20 °C by means of
suitable equations and standard tables. Calibration using mercury is excluded. Calibration may be performed using alternative
gravimetric methodology, provided that it is demonstrated and documented that the results obtained are equivalent to those
obtained using the methodology described herein.
3 3
1.2 This practice is intended to encompass capacity ware between the limits of 0.1 cm and 2000 cm . Typical products falling
within the purview of this practice are burets graduated“ tograduated “to deliver”, graduated cylinders, volumetric flasks, specific
gravity flasks, measuring and dilution pipets, and transfer and capacity pipets.
1.3 The procedures are not recommended for calibration of apparatus with capacities below 0.1 cm , such as microglassware.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E694 Specification for Laboratory Glass Volumetric Apparatus
3. Summary of Practice
3.1 This practice is based upon a determination of the volume of water either contained in or delivered by the vessel. Procedures
are given for cleaning, setting the meniscus, manipulating the apparatus, weighing, and converting the weight to the appropriate
standard volume.
This practice is under the jurisdiction of ASTM Committee E41 on Laboratory Apparatus and is the direct responsibility of Subcommittee E41.01 on ApparatusLaboratory
Ware and Supplies.
Current edition approved Nov. 1, 2012Jan. 1, 2021. Published November 2012 February 2021. Originally approved in 1979. Last previous edition approved in 20072012
as E542 – 01(2007).(2012). DOI: 10.1520/E0542-01R12.10.1520/E0542-01R21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E542 − 01 (2021)
4. Significance and Use
4.1 The primary purpose of this practice is to provide uniform procedures that may be used to accurately calibrate a wide variety
of volumetric ware. The techniques are simple in concept and can provide reliable results, provided the procedures are followed
faithfully. Accordingly, the practice should provide a means for checking the original calibration of glassware and similar apparatus
and for periodic rechecks as the need should arise.
4.2 Borosilicate volumetric glassware will hold its calibration indefinitely provided that it is not exposed to hydrofluoric acid, hot
phosphoric acid, or strong, hot alkalis, and that it is not heated above 150°C150 °C when dry. A frosting of the glass surface
(viewed when dry) indicates that chemical attack has occured, and recalibration may be in order. As a precaution, however, it is
recommended that the glassware be recalibrated after ten years of service regardless of its appearance.
4.3 Soda-lime volumetric glassware will become frosted with time because of attack from moisture in the atmosphere as well as
from the chemicals mentioned above. In addition, it should not be heated above 90°C90 °C when dry. It is recommended, therefore,
that it be recalibrated after five years of service unless frosting (viewed when dry) is observed sooner.
5. Units of Measurement
5.1 Capacity—The basic SI unit for volume is the cubic metre, m . Due to its large size, it is rarely used in volumetric calibration.
Rather, the cubic centimetre, cm , is used and will be employed in this practice. The unit, millilitre, mL, may be considered as
equivalent to the cubic centimetre.
5.2 Standard Temperature—Volumetric ware is almost universally calibrated at 20°C.20 °C. The procedures described provide for
such a calibration. When it is necessary to work at higher ambient temperatures, such as is the case in tropical countries, calibration
may be required at the International Standards Organization (ISO) recommended temperature of 27°C.27 °C. Equations are given
to correct the calibrated volume to other temperatures as this may be required or desired.
6. Apparatus
6.1 Balance, having sufficient capacity to weigh the loaded vessel. The sensitivity of the balance will be a limiting factor in the
accuracy of the measurements. Either a single-pan, direct-reading balance or an equal-arm balance of adequate sensitivity and
capacity may be used. In either case the weights must be calibrated with adequate accuracy. Ordinarily, weights with NBS Class
S-1 tolerances are required. The balance must have physical dimensions to accept the size of the vessels which need to be weighed.
6.2 Thermometer, for measuring the temperature of the water. The accuracy of this calibration will depend upon the accuracy
requirement of the volumetric calibration (see Section 14 for tolerances).
6.3 Barometer, capable of providing atmospheric pressure measurements, consistent with the tolerances given in Section 14.
Alternatively, the existing barometric pressure may be obtained from the local weather service.
6.4 Distilled or Deionized Water, suitable for general laboratory purposes.
7. General Considerations
7.1 This section describes manipulative techniques required to obtain accurate and reproducible volumetric measurements.
7.2 Cleaning Procedures:
7.2.1 It is important that volumetric ware be thoroughly cleaned before being tested or used. Glass apparatus must be sufficiently
clean to permit uniform wetting of the surface. When clean, the walls will be uniformly wetted and the water will adhere to the
glass surface in a continuous film. The clean walls of some plastic apparatus, however, will not be wetted. (Follow the instructions
of the manufacturer. Do not use materials which will attack, discolor, or swell the plasticware.) Lack of cleanliness causes
irregularities in capacity by distorting the water surface. The liquids usually used for cleaning glassware are sodium
dichromatic-sulfuric acid cleaning solution (commercially available from laboratory supply houses), nitric acid, fuming sulfuric
acid, alcohol, and water. The choice of cleaning agent to be used depends on the nature of the contaminant. After cleaning with
the cleaning solution and thoroughly rinsing with tap water, the vessel should be rinsed with distilled water.
E542 − 01 (2021)
7.2.2 After cleaning, the vessel should be rinsed with ethyl alcohol and dried with clean air at room temperature. It is not necessary
to dry any vessel marked “to deliver.” When cleaning small articles such as pipets, it is usually easier to fill them with cleaning
solution by suction, using a vacuum line, if available, or a small rubber bulb, but never by mouth. The solution should be drawn
through the pipet several times until the entire inside surface is evenly coated. Rinse thoroughly with tap water and then with
distilled water. For cleaning flasks, pour in enough cleaning solution while rotating so that a film of solution will cover the entire
interior surface. A break in the film indicates a contaminated area. For filling a buret with cleaning solution, it should be held in
a vertical position and filled by pouring into the top. Open the stopcock to drain. Regardless of the type of vessel, always rinse
thoroughly, first with tap water and then with distilled water. Plastic volumetric ware should be cleaned in an appropriate manner
before calibration.
7.3 Reading and Setting a Liquid Meniscus:
7.3.1 Reading the Meniscus—For all apparatus calibrated by this procedure, the reading is made on the lowest point of the
meniscus. In order that the lowest point may be observed, it is necessary to place a shade of some dark material immediately below
and behind the meniscus, which renders the profile of the meniscus dark and clearly visible against a light background. A
convenient device for this purpose is a collar-shaped section of thick black rubber tubing, cut open at one side and of such size
as to clasp the tube firmly. Alternatively, black paper may be used. “Short line” graduated vessels where the lines are less than one
half of the circumference may be read more accurately by placing a mirror against the rear of the vessel to reflect the front line.
7.3.2 Setting the Meniscus—Setting of the meniscus shall be performed by one of the two methods detailed below. Wherever
practical the meniscus should descend to the position of setting.
7.3.2.1 The position of the lowest point of the meniscus with reference to the graduation line is horizontally tangent to the plane
of the upper edge of the graduation line. The position of the meniscus is obtained by having the eye in the same plane of the upper
edge of the graduation line.
7.3.2.2 The position of the lowest point of the meniscus with reference to the graduation line is such that it is in the plane of the
middle of the graduation line. This position of the meniscus is obtained by making the setting in the center of the ellipse formed
by the graduation line on the front and the back of the tube as observed by having the eye slightly below the plane of the graduation
line. The setting is accurate if, as the eye is raised and the ellipse narrows, the lowest point of the meniscus remains midway
between the front and rear portions of the graduation line. By this method it is possible to observe the approach of the meniscus
from either above or below the line to its proper setting.
NOTE 1—The difference between meniscus positions resulting from the alternative methods of adjustment is the volume equivalent of one half the
thickness of the graduation line. In the case of articles where the capacity is read as the difference between two meniscus readings (for example on a buret),
then no error results if the article is manufactured using one method of adjustment and is later used by the other method.
Even in the most unfavorable cases of single-mark articles (for example large flasks), when working to the highest attainable accuracy, the difference
between the two methods of adjustment is unlikely to exceed 30 % of the Class A (precision apparatus) limit of error and a correction can be calculated
where necessary.
8. Calibration Procedure for Burets
8.1 Clamp the buret vertically on a support stand; also clamp a plain glass test tube, large enough to hold a thermometer, near the
buret if the buret is of such a size that it is not large enough to insert a thermometer in the top for observing the temperature of
the water. Fill the buret from a reservoir or storage bottle, in which the water has reached equilibrium with room temperature, and
check to verify that there is neither leakage from the tip nor from the stopcock plug. Drain and record the delivery time. Delivery
time is determined by the unrestricted outflow of the water from the zero mark to the lowest graduation mark with the stopcock
fully open. Refill the buret to approximately 10 mm above the zero mark and fill the test tube that holds the thermometer; record
the temperature. Set the meniscus on the zero mark using the buret stopcock to lower the liquid level and touch the tip with the
wetted wall of a beaker to remove any excess water. A weighing flask that has been tightly stoppered and weighed empty is placed
with the inside of the neck in contact with the tip of the buret (the flask will be at a slight angle).
8.2 Fully open the stopcock until the water is only a few millimetres above the line being tested and then the stream is slowed
so as to make an accurate setting. When the setting has been completed, move the flask horizontally, breaking the contact with the
buret. Recheck the setting.
E542 − 01 (2021)
8.3 Then stopper and weigh the flask a second time, after which refill the thermometer tube and test the next interval in the same
manner as the first one—from the zero mark to the next interval needed.
8.4 For burets with a specified waiting time, use the following procedure: after adjustment to the zero mark, fully open the
stopcock until the meniscus has reached a position a few millimetres above the graduation line for calibration. After the specified
waiting time (for example, 30 s), 30 s), adjust the meniscus to the graduation line, remove the flask, and weigh.
9. Calibration Procedure for Pipets (One Mark)
9.1 Fill the pipet with distilled water by suction to the index mark and measure the delivery time with the tip in contact with the
glass surface of the internal side of a beaker. Refill by suction slightly above the index line. Record the temperature of the distilled
water in the beaker from which the pipet is filled. Remove any water on the outside of the tip by a downward wipe with filter paper
after the filling is completed. Then slowly lower the meniscus to the index using either a stopcock or hose clamp for “fine control.”
The tip must be in contact with the wet wall of a beaker while the setting is made on the i
...