ISO 23505:2025
(Main)Petroleum and liquid petroleum products — Calibration of spherical tanks — External electro-optical distance-ranging method
Petroleum and liquid petroleum products — Calibration of spherical tanks — External electro-optical distance-ranging method
This document specifies a method for the calibration of spherical tanks with a radius greater than 1 m by means of external measurements using an electro-optical distance-ranging instrument (EODR). It also specifies the subsequent calculation and the compilation of tank capacity tables. This document applies to spherical tanks built above ground, that are non-insulated, single-shell and with a radial variation up to 1 %. The method specified in this document can also apply to spherical tanks built above the deck when the carrying ship is in the dock. This document does not apply to the calibration of spheroidal tanks.
Pétrole et produits pétroliers liquides — Jaugeage des réservoirs sphériques — Méthode par mesurage électro-optique externe de la distance
General Information
Buy Standard
Standards Content (Sample)
International
Standard
ISO 23505
First edition
Petroleum and liquid petroleum
2025-08
products — Calibration of spherical
tanks — External electro-optical
distance-ranging method
Pétrole et produits pétroliers liquides — Jaugeage des réservoirs
sphériques — Méthode par mesurage électro-optique externe de
la distance
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Precautions . 2
6 Equipment . 2
7 General considerations . 3
8 Determination of the number and location of stations . 3
9 Determination of the number and position of tangential target points . 4
10 Calibration procedure . 5
10.1 Instrument set-up .5
10.2 Establishment of the reference target point .5
10.3 Measurement procedure .5
10.4 Measurement of the height of the spherical tank on the vertical centre line .8
11 Other measurements. 9
12 Calculation and development of capacity tables . 9
12.1 General requirements .9
12.2 Calculation of the inner radius of the spherical tank .10
12.2.1 Spherical radius at tangential target point .10
12.2.2 Spherical radius obtained at the station .10
12.2.3 Outer radius of spherical tank.10
12.2.4 Average wall thickness of spherical tank .10
12.2.5 Inner radius of spherical tank .11
12.2.6 Inner radius of spherical tank at reference temperature .11
12.3 Calculation of the total internal height of the spherical tank on the vertical centre line .11
12.4 Inspection of calibration data . 12
12.5 Calculation of the total volume of the spherical tank at reference temperature and
working pressure . 12
12.6 Calculation of partial volume of spherical tank at reference temperature and working
pressure . 13
Annex A (informative) Calibration uncertainties . 14
Annex B (informative) Effect of thermal changes on spherical tank shells .23
Annex C (normative) Certificate of calibration .24
Bibliography .25
iii
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of 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 www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 28 Petroleum and related products, fuels and
lubricants from natural or synthetic sources, Subcommittee SC 2, Measurement of petroleum and related
products.
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
International Standard ISO 23505:2025(en)
Petroleum and liquid petroleum products — Calibration
of spherical tanks — External electro-optical distance-
ranging method
1 Scope
This document specifies a method for the calibration of spherical tanks with a radius greater than 1 m by
means of external measurements using an electro-optical distance-ranging instrument (EODR). It also
specifies the subsequent calculation and the compilation of tank capacity tables.
This document applies to spherical tanks built above ground, that are non-insulated, single-shell and with
a radial variation up to 1 %. The method specified in this document can also apply to spherical tanks built
above the deck when the carrying ship is in the dock.
This document does not apply to the calibration of spheroidal tanks.
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 4512, Petroleum and liquid petroleum products — Equipment for measurement of liquid levels in storage
tanks — Manual methods
ISO 7507-1:2003, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks — Part 1:
Strapping method
ISO 7507-4:2010, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks — Part 4:
Internal electro-optical distance-ranging method
ISO 7507-5, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks — Part 5:
External electro-optical distance-ranging method
IEC 60825-1, Safety of laser products— Part 1: Equipment classification and requirements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7507-1, ISO 7507-5 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
station
position from which measurements of angles and slope distance are made
3.2
tangential target point
spherical tangential position of the electro-optical distance-ranging instrument aimed along the spherical
circumference
3.3
ranging target point
tank wall ranging point from the electro-optical distance-ranging instrument to the spherical tank centre
direction
3.4
reference target point
fixed point clearly marked on the pillar or wall of the spherical tank and visible to the electro-optical
distance-ranging instrument
4 Principle
A minimum of three stations, each with a sufficiently large viewing sphere, shall be equally spaced around
the spherical tank and superimposed to cover a circle of the spherical tank. The EODR instrument is operated
on the station to measure the spherical tank. The direction of the centre of the sphere is determined by the
intersection of the vertical bisectors of the horizontal and vertical strings, and ranging in this direction
provides the distance from the instrument to the tank wall. The horizontal and vertical angles of at least
eight evenly spaced tangent points on the sphere are then measured.
Given that the centre of the instrument, the centre of the sphere and the point of tangency form a right-
angled triangle, and assuming that the two radii making up the triangle are equal, the radius of the spherical
tank at the point of tangency can be calculated from:
— the horizontal angle, vertical angle and slope distance in the direction of the centre of the sphere; and
— the horizontal and vertical angles in the direction of the tangent.
The average of the radii of the tangent points obtained at all stations is calculated as the average radius of
the spherical tank, and the tank capacity table is then developed accordingly.
5 Precautions
The general and safety precautions contained in ISO 7507-1:2003, Clause 4, shall apply to this document. In
addition, the laser emitted by the distance ranging unit shall conform to IEC 60825-1 for a Class 1 or Class 2 laser.
The EODR instrument and other electrical equipment shall have a level of electrical protection appropriate
for the area classification of the
...
FINAL DRAFT
International
Standard
ISO/FDIS 23505
ISO/TC 28/SC 2
Petroleum and liquid petroleum
Secretariat: BSI
products — Calibration of spherical
Voting begins on:
tanks — External electro-optical
2025-05-16
distance-ranging method
Voting terminates on:
2025-07-11
Pétrole et produits pétroliers liquides — Jaugeage des réservoirs
sphériques — Méthode par mesurage électro-optique externe de
la distance
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 SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/FDIS 23505:2025(en) © ISO 2025
FINAL DRAFT
ISO/FDIS 23505:2025(en)
International
Standard
ISO/FDIS 23505
ISO/TC 28/SC 2
Petroleum and liquid petroleum
Secretariat: BSI
products — Calibration of spherical
Voting begins on:
tanks — External electro-optical
distance-ranging method
Voting terminates on:
Pétrole et produits pétroliers liquides — Jaugeage des réservoirs
sphériques — Méthode par mesurage électro-optique externe de
la distance
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 SUPPOR TING DOCUMENTATION.
© ISO 2025
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland Reference number
ISO/FDIS 23505:2025(en) © ISO 2025
ii
ISO/FDIS 23505:2025(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Precautions . 2
6 Equipment . 2
7 General considerations . 3
8 Determination of the number and location of stations . 3
9 Determination of the number and position of tangential target points . 4
10 Calibration procedure . 5
10.1 Instrument set-up .5
10.2 Establishment of the reference target point .5
10.3 Measurement procedure .6
10.4 Measurement of the height of the spherical tank on the vertical centre line .8
11 Other measurements. 9
12 Calculation and development of capacity tables . 9
12.1 General requirements .9
12.2 Calculation of the inner radius of the spherical tank .10
12.2.1 Spherical radius at tangential target point .10
12.2.2 Spherical radius obtained at the station .10
12.2.3 Outer radius of spherical tank.10
12.2.4 Average wall thickness of spherical tank .10
12.2.5 Inner radius of spherical tank .11
12.2.6 Inner radius of spherical tank at reference temperature .11
12.3 Calculation of the total internal height of the spherical tank on the vertical centre line .11
12.4 Inspection of calibration data . 12
12.5 Calculation of the total volume of the spherical tank at reference temperature and
working pressure . 12
12.6 Calculation of partial volume of spherical tank at reference temperature and working
pressure . 13
Annex A (informative) Calibration uncertainties . 14
Annex B (informative) Effect of thermal changes on spherical tank shells .23
Annex C (normative) Certificate of calibration .24
Bibliography .25
iii
ISO/FDIS 23505:2025(en)
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of 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 www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 28 Petroleum and related products, fuels and
lubricants from natural or synthetic sources, Subcommittee SC 2, Measurement of petroleum and related
products.
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
FINAL DRAFT International Standard ISO/FDIS 23505:2025(en)
Petroleum and liquid petroleum products — Calibration
of spherical tanks — External electro-optical distance-
ranging method
1 Scope
This document specifies a method for the calibration of spherical tanks with a radius greater than 1 m by
means of external measurements using an electro-optical distance-ranging instrument (EODR). It also
specifies the subsequent calculation and the compilation of tank capacity tables.
This document applies to spherical tanks built above ground, that are non-insulated, single-shell and with
a radial variation up to 1 %. The method specified in this document can also apply to spherical tanks built
above the deck when the carrying ship is in the dock.
This document does not apply to the calibration of spheroidal tanks.
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 4512, Petroleum and liquid petroleum products — Equipment for measurement of liquid levels in storage
tanks — Manual methods
ISO 7507-1:2003, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks — Part 1:
Strapping method
ISO 7507-4:2010, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks — Part 4:
Internal electro-optical distance-ranging method
ISO 7507-5, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks — Part 5:
External electro-optical distance-ranging method
IEC 60825-1, Safety of laser products— Part 1: Equipment classification and requirements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7507-1, ISO 7507-5 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
station
position from which measurements of angles and slope distance are made
ISO/FDIS 23505:2025(en)
3.2
tangential target point
spherical tangential position of the electro-optical distance-ranging instrument aimed along the spherical
circumference
3.3
ranging target point
tank wall ranging point from the electro-optical distance-ranging instrument to the spherical tank centre
direction
3.4
reference target point
fixed point clearly marked on the pillar or wall of the spherical tank and visible to the electro-optical
distance-ranging instrument
4 Principle
A minimum of three stations, each with a sufficiently large viewing sphere, shall be equally spaced
...
ISO/FDIS 23505:2025(en)
Style Definition: Heading 1
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ISO TC 28/SC2/WG9
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Secretariat: BSI
tab
Date: 2025-03-05-02
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Petroleum and liquid petroleum products — Calibration of spherical tanks — External electro-
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optical distance-ranging method
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Style Definition: ANNEX
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Kingdom)
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Pétrole et produits pétroliers liquides — Jaugeage des réservoirs sphériques — Méthode par mesurage
électro-optique externe de la distance
ISO/DISFDIS 23505:2025(en)
Formatted: Indent: Left: 0 cm, Right: 0 cm, Space
All rights reserved. Unless otherwise specified, or required in the context of its implementation,
Before: 0 pt, No page break before, Adjust space
no part of this publication may be reproduced or utilized otherwise in any form or by any means,
between Latin and Asian text, Adjust space between
electronic or mechanical, including photocopying, or posting on the internet or an intranet,
Asian text and numbers
without prior written permission. Permission can be requested from either ISO at the address
Formatted: Default Paragraph Font
below or ISO’sISO's member body in the country of the requester.
Formatted: Default Paragraph Font
ISO copyright officeCopyright Office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Formatted: Indent: Left: 0 cm, First line: 0 cm, Right: 0
cm, Adjust space between Latin and Asian text, Adjust
Phone: + 41 22 749 01 11 space between Asian text and numbers
Email: copyright@iso.org
Email: copyright@iso.org
Website: www.iso.orgwww.iso.org
Formatted: Indent: Left: 0 cm, First line: 0 cm, Right: 0
cm, Adjust space between Latin and Asian text, Adjust
Published in Switzerland.
space between Asian text and numbers
iv
ISO/DISFDIS 23505:2025(en)
Contents Page
Foreword . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Precautions . 2
6 Equipment . 2
7 General considerations . 3
8 Determination of the number and location of stations . 3
9 Determination of the number and position of tangential target points . 5
10 Calibration procedure. 6
10.1 Instrument set-up . 6
10.2 Establishment of the reference target point . 6
10.3 Measurement procedure . 7
10.4 Measurement of the height of the spherical tank on the vertical centre line . 11
11 Other measurements . 12
12 Calculation and development of capacity tables . 12
12.1 General requirements . 12
12.2 Calculation of the inner radius of the spherical tank . 13
12.2.1 Spherical radius at tangential target point . 13
12.2.2 Spherical radius obtained at the station . 13
12.2.3 Outer radius of spherical tank . 13
12.2.4 Average wall thickness of spherical tank. 14
12.2.5 Inner radius of spherical tank . 14
12.2.6 Inner radius of spherical tank at reference temperature . 14
12.3 Calculation of the total internal height of the spherical tank on the vertical centre
line . 15
12.4 Inspection of calibration data . 16
12.5 Calculation of the total volume of the spherical tank at reference temperature and
working pressure . 16
12.6 Calculation of partial volume of spherical tank at reference temperature and
working pressure . 16
Annex A (informative) Calibration uncertainties . 18
Annex B (informative) Effect of thermal changes on spherical tank shells . 27
Annex C (normative) Certificate of calibration . 29
Bibliography . 30
v
ISO/DISFDIS 23505:2025(en)
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 document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directiveswww.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of
(a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
Formatted: Font color: Auto
notice of (a) patent(s) which may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents.www.iso.org/patents. ISO shall not be held responsible for
identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of 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
www.iso.org/iso/foreword.htmlwww.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 28 Petroleum and related products, fuels
Formatted: Don't adjust space between Latin and Asian
and lubricants from natural or synthetic sources, Subcommittee SC 2, Measurement of petroleum and text, Don't adjust space between Asian text and
related products. numbers
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.htmlwww.iso.org/members.html.
vi
FINAL DRAFT International Standard ISO/FDIS 23505:2025(en)
Formatted: English (United Kingdom)
Petroleum and liquid petroleum products — Calibration of
spherical tanks — External electro-optical distance-ranging
method
1 Scope
This document specifies a method for the calibration of spherical tanks with a radius greater than 1 m
by means of external measurements using an electro-optical distance-ranging instrument (EODR). It
Formatted: English (United Kingdom)
also specifies the subsequent calculation and the compilation of tank capacity tables.
Formatted: English (United Kingdom)
This document applies to spherical tanks built above ground, that are non-insulated, single-shell and
Formatted: English (United Kingdom)
with a radial variation up to 1 %. The method specified in this document can also apply to spherical
tanks built above the deck when the carrying ship is in the dock.
This document does not apply to the calibration of spheroidal tanks.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
Formatted: English (United States)
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 4512, Petroleum and liquid petroleum products — Equipment for measurement of liquid levels in
storage tanks — Manual methods
ISO 7507--1:2003, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 1: Strapping method
ISO 7507--4:2010, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 4: Internal electro-optical distance-ranging method
ISO 7507--5:2000, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 5: External electro-optical distance-ranging method
IEC 60825--1, Safety of laser products— Part 1: Equipment classification and requirements
Formatted: English (United Kingdom)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7507-1 and, ISO 7507-5 and
Formatted: Default Paragraph Font, English (United
the following apply. Kingdom)
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/
3.1
station
position from which measurements of angles and slope distance are made.
Formatted: English (United Kingdom)
3.2
Formatted: TermNum
ISO/FDIS 23505:2025(en)
tangential target point
spherical tangential position of the electro-optical distance-ranging instrument aimed along the
spherical circumference.
3.3
ranging target point
tank wall ranging point from the electro-optical distance-ranging instrument to the spherical tank
centre direction.
3.4
reference target point
fixed point clearly marked on the pillar or wall of the spherical tank and visible to the electro-optical
distance-ranging instrument.
4 Principle
A minimum of three stations, each with a sufficiently large viewing sphere, shall be equally spaced
around the spherical tank and superimposed to cover a circle of the spherical tank. Operate the
...
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